Anti-Inflammatory Benefits of Grape Pomace and Tomato Bioactives as Ingredients in Sun Oils against UV Radiation for Skin Protection

Featured Application

The valorization of grape- and tomato-derived extracts and/or bioactives, with anti-inflammatory and antioxidant properties, as bio-functional ingredients of anti-UV sun oils for skin protection.

Abstract

Daily exposure to solar light is not so harmless as previously thought, since UVA and UVB radiation has a significant effect on human health, by inducing skin-related inflammatory manifestations, such as hyperpigmentation, dermatitis, premature aging, erythema, and sunburn, among the most common skin conditions. At the same time, irreversible diseases such as various types of skin cancers, like basal cell carcinoma, melanoma, and squamous cell carcinoma, have begun to increase at dramatic rates, due to inflammatory and oxidative malignant effects of UV radiation exposure. Within this article, the health promoting effects of sunscreen for skin protection and especially of sunscreen enriched with natural antioxidant, anti-inflammatory, anti-allergic, and anti-cancer bio-functional ingredients are thoroughly reviewed. Emphasis is given to bioactives from grape by-products, such as bio-functional phytochemicals like flavonoids, stilbenes, and phenolic acids, as well as to tomato-derived bioactives like lycopene, which act either solely or synergistically and significantly enhance the antioxidant capacity of the composition product, as well as its photo-protection. The promising outcomes from in vitro studies and those reported from in vivo approaches, as well as the mechanisms of the obtained antioxidant, anti-inflammatory, anti-thrombotic, and antitumor action(s) of sunscreens infused with such natural bioactives, are also outlined. Limitations, such as the difficulties in incorporating lipophilic compounds like lycopene and/or amphiphilic phenolics into sunscreen cosmetic formulations, as well as future perspectives on the overall benefits that these compounds give to sunscreens, helping to improve properties such as smell, color, homogeneity, water resistance, and especially the Sun Protection Factor (SPF), are also discussed.

1. Introduction

In recent years, there has been an increasing number of incidents of serious skin problems caused by sunlight. Ultraviolet (UV) solar radiation is divided into three categories: UVA, UVB, and UVC. Of these, the latter is effectively filtered by the ozone layer in the atmosphere, while the other two pass through the ozone hole on earth and are capable of causing serious skin conditions, which can be quite painful. Of course, not all of these conditions are of the same severity. They are categorized according to the length of time that they can occur, into short-term ones, which cause skin problems such as erythema, sunburn, dermatitis, skin spots, and also additional damage to the human DNA. Some lesions can be visual, such as various types of benign nevi or the appearance of wrinkles, while others can develop into skin cancer. More specifically, there is a serious risk of developing various types of cancer, such as basal cell carcinoma, squamous cell carcinoma, and melanoma. Of course, a factor that is enhanced by UV radiation and is involved in these diseases is (chronic) oxidative stress, which is the result of the production of free radicals by solar radiation. Therefore, it is now imperative to use effective cosmetic products to prevent such problems [1,2,3,4,5].

Today, in the global industry, it is becoming increasingly common to formulate sunscreen products with integrated ingredients with antioxidant and anti-inflammatory activity, since consumers are now more demanding and informed about the ingredients they use on their skin and, by extension, on their bodies.

The skin is the largest organ of the human body and the one that is exposed daily to various exogenous factors. It is structured in three parts: the epidermis, dermis, and subcutaneous tissue. Its internal functions include dealing with external threats, regulating body temperature, and maintaining the moisture level. Over the years, the cell renewal cycle slows down and, as a result, collagen and elastin are produced in smaller and smaller quantities. It is therefore necessary to have sunscreens, which not only protect the skin from the sun, but also provide the majority of their composition with natural antioxidant ingredients.

With the use of synthetic chemicals (oxybenzone, nanoparticles, aminobenzoic acid, etc.) for radiation protection, there may be other toxic effects, such as contact allergies, endocrine disruption, photoallergies, reproductive toxicity, hormonal disruption, etc. An ideal sunscreen should contain a combination of natural and chemical filters. Some filters mainly used are titanium dioxide (TiO₂) and zinc oxide (ZnO), which are considered to be by far superior to organic sunscreens. Therefore, the use of plant-based sunscreen formulations tends to replace sunscreens with harmful effects. Plant metabolites have the ability to protect against UV rays, due to active pharmacophores such as antioxidants, lipids, terpenoids, flavonoids, vitamins, various enzymes, etc. [5,6,7,8].

In sunscreen, it is necessary to have agents that can counteract the adverse effects of free radicals, which cause oxidative stress. Such components are naturally present in several brightly colored fruits and vegetables, which are distinguished for their antioxidant, anti-cancer, and anti-inflammatory properties.

Grapes are an admirable source of such substances. They are divided into three main categories: flavonoids, phenolic acids, and stilbenes. But the compounds that deserve further attention, including their photoprotective capacity, are mainly various types of catechins, quercetin, gallic acid, and resveratrol. In addition, grapes are an ideal choice because these exact beneficial substances are present in large proportions in grape pomace, which makes it possible to exploit and reuse them in a circular economy. Consequently, the benefits of its use extend from the industry (production costs) to the consumer and, of course, the environment. The majority of grape bioactive molecules are of an amphiphilic nature, which suggests that when such bioactives are applied to the skin within ointments and/or sun oils, they can surpass the skin barriers and reach lower levels of skin cells where they can induce several anti-inflammatory and antioxidant protective effects against photo-oxidation and aging [1,4,5,9,10,11,12,13,14,15,16,17,18,19].

Therefore, the interactions of a more lipophilic molecule, such as the carotenoid lycopene, when it is also added to a sunscreen product, would be of interest. Lycopene is a component found in abundance in tomatoes and appears to have equally potent antioxidant and anti-inflammatory properties. In fact, research shows that it is superior to other carotenoids, such as beta-carotene and alpha-tocopherol [2,20,21,22,23,24,25,26,27].

2. Materials and Methods

We selected digital libraries for the automated search approach using well-known databases such as Scopus, PubMed, Scholar Google, and Science Direct for the following reasons: (i) the breadth of research it provides, in a variety of scientific domains, and (ii) the availability of powerful tools for conducting thorough searches. The keywords used were “grape” AND “grape pomace” AND “UV” AND “skin protection” AND “photoprotection” AND “cosmetics” AND “sunscreen” AND “sun oils” AND “applications” AND “effect” AND “bioactives” AND “antioxidant” AND “anti-inflammatory” AND “by-products” AND “sunburn” AND “erythema” AND “pigmentation” AND “skin cancer” AND “melanoma” AND “anti-wrinkle” AND anti-thrombotic AND “antitumor” AND “tomato” AND “lycopene” AND “a tocopherol” AND “L-ascorbic acid” AND “SPF” AND “carotenoids” AND “in vivo experiments” AND “in vitro experiments” AND “flavanols” AND “catechins” AND “epigallocatechin gallate” AND “quercetin” AND “rutin” AND “resveratrol”. The same terms were also used in several searches, in which instead of “AND” the term “OR” was used.

Initially, the search was focused on the dates 2020–2024; however, the results were not sufficient, and thus the search time frame was expanded to 2014–2024. In some cases, some important studies published earlier than 2014 were also included, which were not previously thoroughly reviewed. Articles in other languages than English, duplicates, and the majority of review articles were excluded, apart from some important review articles on general information about these bioactives, photoprotection, and sun oils.

3. Sunscreens and Filters against UV Radiation and Its Detrimental Effects on the Skin

In recent years, the incidence of skin damage due to solar radiation has increased. Exposure to UV radiation plays a major role in acute and chronic skin damage, as well as in many skin conditions, such as sunburn, pigmentation, wrinkles, dermatitis, urticaria, aging, immune system suppression, and skin cancers (Figure 1). Covering the skin with the use of sunglasses, a hat, or other external clothing are no longer sufficient solutions for sun protection. Therefore, the use of sunscreen is essential. Sunscreen agents protect against the sun, by absorbing ultraviolet and visible sun rays. Solar Ultraviolet Radiation (UVR) is divided into three categories: UVA (320–400 nm), UVB (380–320 nm), and UVC (200–280 nm) [27,28,29].

Of the three forms of UVR, UVC is the form with the highest energy. It would therefore be evident that it is the one that causes the most biological damage. However, this is not the case, since it is effectively filtered by the ozone layer [1]. The amount of UVB and UVA radiation reaching the earth is affected by latitude, altitude, season, time of day (10 am–4 pm is strongest), cloud cover, and the ozone layer. UVB is mainly associated with erythema and sunburn, and it cannot be excluded from being able to cause immunosuppression and photocarcinogenesis. During a summer day, the spectrum of UV radiation reaching the earth’s surface consists of 3.5% UVB and 96.5% UVA (ratio: 1:20) [1]. UVA radiation is less affected by the conditions mentioned above (latitude, altitude, etc.) because of its longer wavelength, compared to UVB. UVA has been shown to penetrate deeper into the skin, passing through glass and 50% of its exposure is from shaded areas. It is also known to have multiple adverse effects on the skin including immunosuppression, photoaging, eye damage, and skin cancer. But in addition to the damage it causes, it stimulates the production of vitamin D3 through the irradiation of 7-dihydrocholesterol and enhances the dark color of preformed melanin that promotes tanning.

UVR can cause several disorders (

Table 1. The table below classifies the acute diseases caused by UVR into molecular/cellular, clinical, and chronic [4].

Molecular/Cellular	Clinics	Chronic
DNA photo-destruction (and repair)/mutation (C */T *, CC/TT) Reactive oxygen species Expression of genes and proteins Melanogenesis Apoptosis Langerhans cell exhaustion Vitamin D photosynthesis Nitric oxide (UVA *) release	Erythema Tan Suppressing acquired immunity Enhancing innate immunity Reduction in blood pressure through nitric oxide	Photoaging Skin cancer

* C: Cytosine, T: Thymine, UVA: Ultraviolet-A Radiation.

), by inducing a plethora of molecular and cellular manifestations, including the increase in reactive oxygen species (ROS), expression of genes, and production of proteins that induce aging, inflammation, and oxidative stress and associated manifestations, DNA photo-destruction, melanogenesis, and several other pathological manifestations. Thus, erythema, tanning, modulation of immunity, and reduction in blood pressure are some of the observed clinical manifestations, as well as some more severe ones, including photoaging and several types of skin cancer.

On the other hand, UVR induces the production of beneficial molecules like vitamin D, and thus insufficient exposure to UVR may cause vitamin D deficiencies, as observed in several places all over the world during winter time. In these cases, and since vitamin D can be obtained by ingestion, the dietary supplementation of vitamin D is suggested, either through incorporating diet foods with a rich content in vitamin D, or through the supplementation of vitamin D with food supplements, nutraceuticals, and nutricosmetics, or even cosmeceuticals and cosmetics that can increase the levels of vitamin D in the body and especially in the skin.

In all these cases, exposure to UV radiation without proper protection is the main factor leading to damage to both cellular components, such as proteins, and human DNA. This damage can occur through two mechanisms: either by the direct absorption of UV light by cellular components, leading to damaging chemical reactions, or by photosensitization. In one mode of photosensitization (type 1), light activates eutrophic factors that affect cells through electron transfer and hydrogen removal, whereas in the second mode (type 2), cells are affected through oxygen energy transfer, generating a reactive oxygen singlet. In particular, the direct absorption of UV radiation by DNA stimulates the formation of DNA base dimers and related molecular species. Therefore, there is an urgent need to develop innovative and environmentally sustainable strategies to mitigate the damage caused by UV radiation. In the context of this concept, the present research aims at using natural ingredients and discarded biomass in a circular bioeconomy framework.

There are many types of sunscreens on the market in various forms (gels, creams, lotions, sticks) and they are divided into two main types: chemical or organic and mineral-based or inorganic sunscreens. Chemical sunscreens absorb UV light and convert it into heat energy that is then released from the skin. The other ones are considered sunblocks, acting by reflecting and scattering the UV light [30].

Most substances block a small part of the UV spectrum. For this reason, chemical sunscreens contain a majority of compounds, each of which blocks a separate wavelength of UV radiation. UVA radiation is blocked by very few substances. Most substances target UVB radiation. A sunscreen that combines natural and chemical characteristics is considered ideal in this case [4]. Sunscreens should be formulated to prevent the adverse effects of radiation, rather than promote it. By using filters such as TiO₂ or ZnO, it is possible to prevent the aggregation of nanoparticles (NPs), enhance the photostability of the sunscreen, increase efficacy, and reduce skin permeability. Skin barrier function may change as a result of surfactant characteristics in NP formulations. The fact that sunscreen is typically applied to huge portions of the skin makes this topic important. High systemic NP concentrations could arise from a tiny proportion of NPs passing through the epidermal barrier. Additionally, formulations have the ability to improve NP aggregation throughout time or even in the production process. This may have a detrimental effect on the particle’s capacity to penetrate skin [31].

Nevertheless, although sunscreens containing these substances as filters are considered less harmful than organic absorbent sunscreens, there are no long-term safety data. Recent research has focused on natural sunscreens, which appear to be of particular interest, as they can provide protection without compromising the health of the consumer. The main agents of skin damage are oxygenated molecules, called free radicals. Their action gives rise to many degenerative disorders resulting from persistent oxidative stress. Therefore, our body needs substances that will naturally and effectively protect it from oxidative damage and act as built-in cellular protectors. Τhese substances are called antioxidants.

4. Grape Pomace Extracts and Their Bioactives as Ingredients in Sun Oils for Skin Care

Vitis vinifera L. is one of the most commonly cultivated grape species and is economically important for the production of food, wine, and other beverages. In fact, it has recently gained the attention of cosmetic companies, due to its numerous natural and antioxidant ingredients and combined with its high biocompatibility, has penetrated many cosmetic products such as creams, serums, and natural sunscreens.

The incomplete extraction of compounds, such as polyphenols, results in 70% of the original active substances remaining in the waste from grape stems, 20–30% in the skins and 60–70% in the seeds. Grapes are a source of a variety of antioxidants, anti-inflammatory, anti-cancer, and anti-allergic compounds. Their antioxidant activity, which is found in the extracts, has been attributed to the presence of phenolic compounds, particularly flavonoids, which have a low molecular weight and shield the plant from photodamage. The bioactive potential of polyphenols, especially flavonoids, makes them ideal for their utilization as a relatively low-cost and widely available natural raw material [32].

4.1. Composition

Grapes are a major source of bioactive phenolic compounds. Phenolic compounds are secondary metabolites of plants and have a beneficial effect on human health. They are produced in the plant in response to different stresses, such as infections, injuries, ozone, pollutants, and UV radiation. The phenolic compounds present in wastewater and by-products of winemaking belong to several categories, of which the main ones are

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Phenolic acids (hydroxybenzoic acids and hydroxyquinamic acids);

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Simple flavonoids (flavanols or flavan-3-ols, proanthocyanidins, flavones, and flavonols);

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Stilbenes;

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Tannins and proanthocyanidins [5,32,33].

4.2. Grape Pomace—Circular Economy

Grape Pomace (GP) is a by-product of winemaking and it is divided into two categories, the seedless pomace (pulp, skin, and stem) and the grapeseed (GS). GP is rich in bioactive compounds (BACs), such as unsaturated fatty acids, vitamins, and natural antioxidants, primarily in the form of PC (phenolic acids, flavonoids, tannins, carotenoids, etc.). GS contains the majority of the overall extractable PC, with the norm being phenolic acids, flavonoids, and procyanidins. In fact, studies have shown that these compounds have anti-aging, anti-cancer, antimicrobial, etc., properties, but their antioxidant capacity, which can be contributed to the PC’s ability to neutralize cellular oxidative stress, deserves to be highlighted [34,35]. Also, these antioxidants reinforce the photoprotection and as a result, play an important role in photoaging and the prevention of UV-induced erythema [34].

Furthermore, GP and GS obtain oils that mostly consist of unsaturated fatty acids (linoleic acid, oleic and palmitic acid, etc.), with their emollient properties being the reason why they are so broadly used in the cosmetic industry. GS oil is being used in the cosmetic industry and more specifically in skin hydration products, moisturizing cremes, sunscreens, etc., because of its soothing and moisturizing effects [34]. It is also important to note that the vitamin E contained in GS and GP oils contributes to the high concentrations of tocopherols and tocotrienols, which are effective in anti-aging [34,35,36].

Grape stems are products produced by the viticulture industry and if treated as waste, there is a risk of pollution, contamination, costly disposal issues, and economic losses. Their reuse is mainly for animal feed and fertilizers. However, grape stems are distinguished from other food by-products because of their high content of high-value compounds, such as bioactive lipids, phenolics, and other natural antioxidants. The bioactive compounds contained in the by-products are available in large quantities, at a fairly low cost, making their utilization economically viable and at the same time environmentally friendly. Recent studies focus mainly on their antioxidant activity, due to their rich content in several phenolic bioactives with free radical-scavenging antioxidant capacity and potent anti-inflammatory benefits (Figure 2) [10]. Consequently, the recycling of bioactive compounds that are beneficial to human health has started to attract interest over synthetics in dietary supplements and medicines and is increasingly active in cosmetics [9,10,11,37].

4.3. Grape Pomace—Phenolic Bioactive Ingredients

Most studies focus on the concentrations of individual phenolics found in grapes, such as resveratrol, quercetin, and gallic acid, in terms of their activity against oxidative and inflammatory damage. However, it is worth mentioning that more and more new experimental data show that grapes, along with grape pomace extracts, are more effective than a single bioactive ingredient, as they interfere with more than one pathophysiological mechanism. Therefore, the different individual bioactive compounds contained in grape pomace are an excellent natural and effective solution for reducing chronic inflammation and oxidative stress.

The use of grape stem extracts in cosmetics and more specifically in sunscreens is a promising venture. Based on recent research, these extracts have shown that they can combat skin aging, by reducing the appearance of wrinkles, fine lines, and age spots. Its action is mainly focused on neutralizing free radicals, which contribute to premature aging and skin deterioration, while improving skin elasticity and firmness. In addition, the phenolic compounds contained in grape pomace have significant anti-inflammatory action and are ideal for reactive, sensitive skin, as they help soothe the skin.

Overall, grape pomace bioactives help achieve an even skin tone and protect against hyperpigmentation. Research based on the composition of grape pomace has shown that catechin, trans-resveratrol, quercetin, and viniferin are the phenolic compounds in the highest proportion in the extract [9].

Interestingly, most grape pomace bioactives are of an amphiphilic nature, according to the physicochemical properties of these molecules, as predicted by their structures and molecular weight using the quantitative structure–activity relationship (QSAR) in silico modeling approach (Figure 3). It should also be stressed that according to the Directive of the European Parliament and of the Council concerning the protection of animals used for scientific purposes, the number of experiments involving the use of animals needs to be reduced. The methods that can replace animal testing include computational prediction methods, including QSAR. These methods are designed to find a cohesive relationship between differences in the values of the properties of molecules and the biological activity of a series of test compounds. More specifically, QSAR models are used to predict biological activities and undesired effects of untested or novel compounds and to provide insight into relevant and consistent chemical properties or structural features that define biological activity.

One of the chemical properties of bioactives that can be predicted by QSAR is the determination of n-octanol/water partition coefficient (log Kow value), which is an index of their polarity and can be estimated based on the chemical structure of the target compounds. Thus, an insight of the behavior of the bioactives is given and the outcome can enhance further the research in the grape pomace bioactives and their functionality. As demonstrated in Figure 3, the majority of the bioactives found in grape pomace are semi-polar amphiphilic ones (log Kow values between 1 and 4). Only gallic acid and protocatechuic acid have polar behavior (log Kow < 1). This amphiphilic nature for these molecules is important, as it suggests that these molecules can surpass the external skin barrier of keratinocytes, as well as be diffused in the inner levels of the skin, including fibroblasts, where they can translocate from cell membranes to intracellular sites that facilitate their proposed skin protective properties, by being able to affect specific intracellular signaling pathways and gene expressions against oxidative stress, photoaging, and inflammation.

Thus, phenolic compounds are a broad group of bioactive substances in grape stems that perform numerous tasks. Their main characteristic is that they protect plant tissues from UV radiation, oxidative stress, and pests and are responsible for the color of plants. Therefore, having such decisive effects on plant organisms, their influence on the human body is inevitable. As part of the diet, they act as powerful antioxidants and help protect human cells from oxidative stress, premature tissue aging, and a range of diseases such as inflammation, cancer, and cardiovascular disease. Furthermore, polyphenols have antifungal, antimicrobial, and antiviral properties (quercetin, resveratrol). Polymeric tannins have astringent and antidiarrheal effects, and the ability to bind metal ions and coagulate proteins, while some polyphenols may affect the contractility of smooth muscle cells and the anticoagulant activity of platelets. All these substances have in common a strong antioxidant activity and the ability to eliminate oxygen radicals both internally (in the form of food) and externally (in contact with the skin and mucous membranes). The in vitro and in vivo beneficial effects of the main phenolic bioactives on the skin are shown in Table 2. The combination of all the above properties makes phenolic bioactives potential candidate ingredients that can help in wound healing, while at the same time they have shown promising outcomes in sunscreens too, due to the free radicals produced by UV radiation [4,9].

4.3.1. Anthocyanins

Anthocyanins are plant pigments that give color to plant flowers, leaves, and sometimes the underground parts of the plant. These colors are usually shades of orange, pink, red, purple, and blue. They are usually associated with a simple type of sugar (glucose) and are most often found in the form of glycosides, which are aglycones (anthocyanidins) sensitive to high temperature, pH, and radiation. In plants, they absorb ultraviolet radiation and thus they act as a protective filter for plant cells against the harmful effects of UVR. However, their resistance to light is low, while their color varies according to changes in pH. In alkaline conditions, anthocyanins gradually change to the familiar form of the colorless carbinol base, then become blue and violet-blue, while in strongly alkaline conditions, they become colorless. The latter can be explained, since the phenyl aromatic group opens in order to form yellow chalcones and their irreversible degradation [4,12]. Anthocyanins protect cell membrane lipids from oxidation by a variety of harmful substances, and the most recent research shows that they are four times more powerful antioxidant-wise than vitamin E. Their antioxidant capacity focuses on neutralizing enzymes that destroy connective tissue, as well as repairing damaged proteins in blood vessel walls [12]. Of these, quercetin is distinguished by protecting human keratinocytes from UVA damage, primarily by increasing intracellular antioxidant potential (Table 2) [13].

4.3.2. Quercetin

Quercetin is known to have several interesting physiological actions on the skin. It has strong antioxidant activity, since it protects keratinocytes from exogenous oxidants and removes free radicals. At the same time, it prevents the depletion of endogenous antioxidants and inhibits lipid peroxidation during exposure to UV radiation. However, it is worth noting the anti-inflammatory action of quercetin, which appears to be stronger than other flavonoids (apigenin, (-)-epicatechin, biochanin A), particularly in terms of the inhibition of swelling after contact with inflammatory agents. However, its anti-inflammatory action is not limited there, and quercetin may also contribute to the fight against skin aging. Skin elasticity is related to the skin’s hydration status, which is related to the proper biosynthesis and modulation of lipids. Thus, quercetin can protect the skin from dehydration by acting as an inhibitor of lipid peroxidation. The inhibition of matrix metalloproteinase activity may have an impact on protecting skin collagen from destruction during inflammatory responses to exogenous aging factors, such as UVR (Table 2) [13,14].

4.3.3. Resveratrol

Resveratrol is a natural polyphenolic phytoalexin. It belongs to a class of polyphenolic compounds called stilbenes. It is a fat-soluble compound and exhibits both cis and trans conformation. It has been shown to act as both an antioxidant and an antimutagenic. In particular, studies have shown that it can reduce oxidative stress caused by UV radiation in human keratinocytes (HaCaT) [24]. The second action of this component is that it induces the differentiation of human promyelocytic leukemia cells. Also important is its action as a topical application (both before and after treatment), in inhibiting the appearance of tumors caused by UVB radiation and delaying the onset of cutaneous carcinogenesis (Table 2) [1,16].

4.3.4. Catechins

Catechins are a general class of polyphenols present in grapes in large quantities. In particular, gallic catechin and Epigallocatechin Galate (EGCG) are the ones that show protective ability against UV radiation and overall benefits to the skin by having anti-aging effects. Research has shown that epigallocatechin in particular inhibits UVB-induced hydrogen peroxide release in human HaCaT keratinocytes, where it suppresses MAPK kinase phosphorylation (Table 2) [17,18,19].

4.4. Impact of Phenolics on the Skin

Phenolic compounds have demonstrated a wide range of effects on the skin, targeting, depending on which compound is active, various structures within the skin, such as fibroblasts, keratinocytes, and the extracellular matrix. In particular, certain polyphenols have been found to inhibit melanin production in the epidermis, contributing to the reduced occurrence of conditions such as hyperpigmentation and also improving skin tone. One of the most important mechanisms of action of phenolic compounds is their ability to neutralize free radicals and reduce oxidative stress, which contributes to skin aging. Finally, phenolic compounds help protect the skin from damage caused by ROS, specifically by suppressing the formation of ROS and Reactive Nitrogen Species (RNS), by downregulating and inhibiting enzymes or trace chelators that take part in free radical production, and thus by up-regulating incremental or prophylactic antioxidant defenses (Table 2) [9,28].

4.4.1. Rutin and Quercetin

A phytocosmetic emulsion enriched with the flavonoids rutin and quercetin demonstrated stability when kept in storage at low temperatures. Qualities that were appropriate for topical application were high spreadability, low rupture strength, and adhesiveness, as well as greater brittleness, shear shining, and viscoelastic behaviors. In in vitro tests, it demonstrated photostability, antioxidant activity, and UVA protection. Skin irritation was avoided by the phytocosmetic emulsion, and rutin was present in both the stratum corneum and the deeper epidermis, augmenting antioxidant activity and providing sun protection—two properties that are beneficial for anti-aging and sunscreen properties. Such a phytocosmetic emulsion appears to be a promising product for sunscreens, despite having a low SPF rating, particularly when combined with physical sunscreens to boost UV protection (Table 2) [33,38].

4.4.2. Epigallocatechin-3-gallate

There have been rumors that cell aging can be assessed by measuring an increase in senescence-related β-galactosidase (SA-β-gal) as cell age increases. According to the research, UVA did cause the cells to reach the photoaging stage. In the meantime, the percentage of aging cells in fibroblasts pre-treated with EGCG significantly decreased, suggesting that EGCG could reduce fibroblast photoaging (Table 2) [39].

4.4.3. Caffeic and Chlorogenic Acid

Active ingredients must pass through several phases in a complicated process to penetrate the skin. The first phase is the active component’s diffusion inside the topical formulation, which is impacted by both the formulation and the physicochemical characteristics of the material. The second phase involves the active ingredient being released from the formulation; this process is influenced by temperature, pH, and viscosity. Considering how uneven the skin is, the most difficult part is really getting the active ingredient through it. All of the skin’s layers may be accessible to chlorogenic and caffeic acids. The outcomes showed that GSE-based formulations successfully reduced roughness, scaliness, and wrinkles while increasing skin elasticity and moisture (Table 2) [9,40].

4.4.4. Cyanidin-3-glucoside

The most prevalent anthocyanin in nature, cyanidin-3-glucoside, provides photoprotection against UVA and UVB radiation for human keratinocytes; pre-treating the cells with cyanidin-3-glucoside reduces some of the negative effects of UVB exposure [41]. For example, cyanidin-3-glucoside exhibited protective effects in human keratinocytes against UVB-induced oxidative stress and apoptosis [42]. More specifically, in a non-tumorigenic human immortalized keratinocyte cell line (HaCaT), cyanidin-3-glucoside decreased the levels of intracellular ROS generated by UVB treatment, as well as the UVB-augmented levels of DNA damage indicators, while cyanidin-3-glucoside protected keratinocytes from UVB-induced injury by overturning the disruption of mitochondrial membrane potential and reversing apoptosis. Moreover, in such UVB-exposed cells, the attenuated expression of antiapoptotic protein B-cell lymphoma 2 (Bcl-2) was restored after treatment with cyanidin-3-glucoside, while the expressions of the proapoptotic proteins Bcl-2-associated X (Bax) and the key apoptosis executer cleaved caspase-3 were increased in UVB-irradiated cells and decreased in UVB/cyanidin-3-glucoside-treated cells (Table 2).

Table 2. The main findings of some in vitro studies of the impact of phenolics on the skin.

Component Structure	Main Findings/Type of Study	Year of Study	References
Rutin Quercetin	• Sun Protection      • Photostability      • Antioxidant Activity	2019, 2020	[33,38]
	In vitro
	▪ Reconstructed Human Epidermis (RHE) was used to perform in vitro skin irritation, in accordance with Test Guideline number 439 by Organization for Economic Co-operation and Development (OECD) Guidelines for the Testing of Chemicals ▪ In a 3D Reconstructed Human Tissue model, extract-containing formulations were topically dosed for 42 minutes ▪ Following a 42-hour incubation period, the tissue sample was subjected to a 3-hour MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Thiazolyl blue tetrazolium bromide] solution, at a concentration of 1 mg/mL ▪ Using a spectrophotometer, the amount of blue formazan that developed in live cells was quantified at 570 nm ▪ The assay's reliability was assessed using SkinEthicTM RHE (1% Triton X-100).
Epigallocatechin-3-gallate	• Photoaging Prevention	2023	[39]
	In vitro
	▪ Investigating the function and processes of EGCG in delaying skin photoaging ▪ Treatment of Human Skin Fibroblasts (HSFs) with UVA and EGCG ▪ Following treatment, alterations in cell shape, telomeres, antioxidant capacity, cell cycle, and associated genes were assessed ▪ EGCG regulates TGF β-1, P66Shc, the cell redox system, MMPs, and TIMP-1 and delays telomere shortening and UVA-induced photoaging of dermal fibroblasts → the latter makes it a more appealing target for photoaging prevention and treatment
Caffeic Acid/Chlorogenic Acid	• Anti-Wrinkle      • Skin Elasticity      • Moisture	2023, 2007	[9,39]
	In vitro
	▪ An in vitro assessment was conducted on the penetration of caffeic acid, chlorogenic acid, and oraposide through the skin of pigs ▪ All of the skin's layers had traces of chlorogenic and caffeic acids ▪ GSE-based formulations successfully reduced roughness, scaliness, and wrinkles, while increasing skin elasticity and moisture
Cyanidin-3-glucoside	• Antioxidant      • Photoprotection from UVA and UVB      • Anti-aging	2018	[41]
	In vitro
	▪ Cyanidin-3-glucoside: The most prevalent anthocyanin in nature ▪ It provides photoprotection against UVA and UVB radiation for human keratinocytes ▪ Pre-treating the cells with cyanidin-3-glucoside reduces some of the negative effects of UVB exposure
p-Coumaric Acid/Trans-Resveratrol	• Photoprotection from UVB	2023	[43]
	In vitro
	▪ GPE-CHF and GPE-EAF: Fractions recovered from the V. vinifera waste of the winemaking process, with the highest concentration of quercetin, trans-resveratrol, and syringic and p-coumaric acids ▪ In normal conditions, both fractions were cytobiocompatible with fibroblasts ▪ When the cells were exposed to H2O2 (stressed environment), GPE-CHF acquired cytotoxicity ▪ GPE-EAF: Had a higher content of the assessed phytocompounds and established a protective profile in the fibroblast culture in the presence of H2O2 Increased the in vitro SPF and its photostability for a minimum of one hour, suggesting that winery waste may be a viable source of active compounds and/or dermocosmetic adjuvant

Table 2. The main findings of some in vitro studies of the impact of phenolics on the skin.

Component Structure	Main Findings/Type of Study	Year of Study	References
Rutin Quercetin	• Sun Protection      • Photostability      • Antioxidant Activity	2019, 2020	[33,38]
	In vitro
	▪ Reconstructed Human Epidermis (RHE) was used to perform in vitro skin irritation, in accordance with Test Guideline number 439 by Organization for Economic Co-operation and Development (OECD) Guidelines for the Testing of Chemicals ▪ In a 3D Reconstructed Human Tissue model, extract-containing formulations were topically dosed for 42 minutes ▪ Following a 42-hour incubation period, the tissue sample was subjected to a 3-hour MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Thiazolyl blue tetrazolium bromide] solution, at a concentration of 1 mg/mL ▪ Using a spectrophotometer, the amount of blue formazan that developed in live cells was quantified at 570 nm ▪ The assay's reliability was assessed using SkinEthicTM RHE (1% Triton X-100).
Epigallocatechin-3-gallate	• Photoaging Prevention	2023	[39]
	In vitro
	▪ Investigating the function and processes of EGCG in delaying skin photoaging ▪ Treatment of Human Skin Fibroblasts (HSFs) with UVA and EGCG ▪ Following treatment, alterations in cell shape, telomeres, antioxidant capacity, cell cycle, and associated genes were assessed ▪ EGCG regulates TGF β-1, P66Shc, the cell redox system, MMPs, and TIMP-1 and delays telomere shortening and UVA-induced photoaging of dermal fibroblasts → the latter makes it a more appealing target for photoaging prevention and treatment
Caffeic Acid/Chlorogenic Acid	• Anti-Wrinkle      • Skin Elasticity      • Moisture	2023, 2007	[9,39]
	In vitro
	▪ An in vitro assessment was conducted on the penetration of caffeic acid, chlorogenic acid, and oraposide through the skin of pigs ▪ All of the skin's layers had traces of chlorogenic and caffeic acids ▪ GSE-based formulations successfully reduced roughness, scaliness, and wrinkles, while increasing skin elasticity and moisture
Cyanidin-3-glucoside	• Antioxidant      • Photoprotection from UVA and UVB      • Anti-aging	2018	[41]
	In vitro
	▪ Cyanidin-3-glucoside: The most prevalent anthocyanin in nature ▪ It provides photoprotection against UVA and UVB radiation for human keratinocytes ▪ Pre-treating the cells with cyanidin-3-glucoside reduces some of the negative effects of UVB exposure
p-Coumaric Acid/Trans-Resveratrol	• Photoprotection from UVB	2023	[43]
	In vitro
	▪ GPE-CHF and GPE-EAF: Fractions recovered from the V. vinifera waste of the winemaking process, with the highest concentration of quercetin, trans-resveratrol, and syringic and p-coumaric acids ▪ In normal conditions, both fractions were cytobiocompatible with fibroblasts ▪ When the cells were exposed to H2O2 (stressed environment), GPE-CHF acquired cytotoxicity ▪ GPE-EAF: Had a higher content of the assessed phytocompounds and established a protective profile in the fibroblast culture in the presence of H2O2 Increased the in vitro SPF and its photostability for a minimum of one hour, suggesting that winery waste may be a viable source of active compounds and/or dermocosmetic adjuvant

Moreover, cyanidin-3-glucoside has also been found to reduce UVB-induced chronic photodamage by inhibiting oxidative stress and inflammation in mice [44]. More specifically, the dorsal of Kunming mice was treated with moisturizing gel containing cyanidin-3-glucoside (100, 200, 300 μmol/L) after UVB exposure, where it was shown that chronic photodamage caused by UVB was reduced by such a treatment, while the UVB-induced epidermal barrier dysfunction was ameliorated, including an increase in the skin hydration and decrease in the transepidermal water loss. This cyanidin-3-glucoside-containing cosmetic product inhibited UVB-induced epidermal hyperplasia, the destruction of collagen fibers, ROS levels, and the expression of the inflammatory enzyme COX-2 and the inflammatory cytokine IL-6.

4.4.5. Trans-Resveratrol and p-Coumaric Acid

Three naturally occurring derivatives (one extract and two fractions) were recovered from the V. vinifera waste of the winemaking process. The fractions with the highest concentration of quercetin, trans-resveratrol, and syringic and p-coumaric acids were the chloroform-based one (GPE-CHF) and the ethyl acetate-based one (GPE-EAF). In normal condition culture, both fractions were cytobiocompatible with fibroblasts; however, when the cells were exposed to H₂O₂ (a stressed environment), GPE-CHF acquired cytotoxicity. Its potential as an adjuvant for sunscreens was studied, since GPE-EAF had a higher content of the assessed phytocompounds and established a protective profile in the fibroblast culture in the presence of H₂O₂. GPE-EAF increased the in vitro SPF and its photostability for a minimum of one hour, suggesting that winery waste may be a viable source of active compounds and/or a dermocosmetic adjuvant. P-coumarinic acid and trans-resveratrol, at low concentrations, were able to increase the sample’s protection against UVB radiation, by raising the SPF in vitro [43].

5. Tomato Bioactives as Ingredients in Sun Oils for Skin Care

5.1. Tomato Bioactive Compounds

There are different varieties of tomatoes, round, oval, and “cherry”, with all of them having the same nutritional characteristics as they are an important source of potassium, phosphorus, magnesium, and iron, necessary for the normal activity of nerves and muscles; and vitamins such as A, B, and C (tomatoes are the third source of vitamin C in our diet and the fourth source of vitamin A, thanks to their beta-carotene content). In addition, they contain phytosterols that help maintain cholesterol and folic acid, which helps eliminate homocysteine (an amino acid, whose metabolism depends on the metabolism of B vitamins, especially folic acid). In addition to the carotenoids, with the most predominant being lycopene, they also contain ascorbic acid, as well as important polyphenols (such as flavones and anthocyanidins), components with strong anti-cancer properties.

The combination of different carotenoids or the association of carotenoids with tocopherol (vitamin E) or phenolic acid has simultaneous effects in inhibiting pathological effects of free radicals, which are capable of affecting DNA. It has been evident that lycopene may act as a natural sunscreen, protecting the skin from UV rays [20,21,22].

Tomatoes contain considerable amounts of polyphenols, flavonoids, monoterpenoids, sesquiterpenes, and saponins. They contain lycopene as a derivative of a terpenoid compound. Lycopene is a vital antioxidant, which is not naturally produced within the body and the human body requires sources of lycopene in order to fight free radicals. Furthermore, carotenoids like lycopene absorb wavelengths ranging from 400 to 550 nanometers (violet to green light) and thus these compounds are usually deeply colored as yellow, orange, or red, while due to this capacity, lycopene seems to have twice the antioxidant power of other carotenoid antioxidants, such as the beta-carotene. Tomatoes are one of the richest sources of lycopene (compared to other fruits and vegetables) that is the cause of their intense color [21,23,24].

The in vitro and in vivo health benefits of the main tomato-derived bioactives used for photoprotection and skin care are shown in Table 3.

5.2. Lycopene as a Bioactive Agent with Beneficial Effects in the Skin

Lycopene is the main carotenoid found in tomatoes (Solanum lycopersicum; SL). As an antioxidant agent, it can prevent oxidative damage to DNA and the possible conversion of normal cells to cancer cells through the quenching of simple oxygen and absorption of free radicals. Indeed, in a recent study (2023) on the incorporation of a lycopene extract in an attempt to synthesize a sunscreen with zinc oxide (ZnO) nanoparticles, it was found that lycopene is an excellent non-toxic antioxidant and can play multiple roles. In particular, lycopene could act as a solvent, but also as a reducing agent and a stabilizer, which facilitated the synthesis of ZnO nanoparticles (NPs) [22]. Furthermore, in an attempt to synthesize sunscreen lotion with a tomato extract in a concentration of 1.5% (2017), it was demonstrated that at the end of 28 days, the sunscreen lotion had retained its physical characteristics (unchanged), as observed by organoleptic observation, measurement of viscosity, pH, centrifugation, and freezing of the fluidization, while the SPF index of this lotion had a value of 22.24 [23].

Lycopene is, as mentioned above, the main antioxidant in tomatoes. It is an anti-carcinogenic carotenoid, which neutralizes free radicals, especially those from oxygen, present under the lipid membrane and skin covering. In particular, it removes lipid radicals, reduces lipid peroxidation, and prevents erythema caused by UV radiation on the skin. It has the ability to remove ROS twice as good as beta-carotene and ten times better than alpha-tocopherol [20,24]. In topical application, lycopene provides protection against acute damage caused by UVB radiation by inhibiting epidermal ornithine decarboxylase. Thus, it reduces inflammatory reactions and prevents further damage to DNA. Of particular interest is a study performed in human keratinocytes (HaCaT cell line), arguing that depending on the level of photodamage, lycopene may have a corrective function in irradiated cells [23,25]. However, surprisingly, it enhances skin protection from both short-term effects (e.g., sunburn) and additive effects of sun exposure (e.g., skin cancer) [2,20,26,27]. More specifically, skin protection mechanisms are enhanced in the presence of lycopene, since prostaglandins and phospholipids (which are components of the cell membrane) are synthesized. Therefore, the topical application of lycopene appears to be effective in reducing inflammatory infiltration. Studies conducted in mouse ears demonstrated that anthralin-induced swelling and erythema were significantly attenuated by the epidermal application of 0.05% lycopene, compared to a 1mg/g betamethasone solution [25]. In addition to its moisturizing properties, lycopene antioxidants as nanoemulsion components promote skin suppleness and its ability to protect against UV rays [27].

5.3. In Vivo Studies—Main Findings

5.3.1. Vitamin C and E-Synergistic Behavior

Studies on humans and animals have demonstrated that topically administered vitamin E and, to a lesser extent, vitamin C offer UV protection. It is possible to modify a number of endpoints that show phototoxic damage, including DNA damage, lipid peroxidation, UV-dependent erythema, sunburn cell development, and wrinkles in the skin. In comparison to sunscreen alone, adding botanical antioxidants and vitamins C and E to a broad-spectrum sunscreen may significantly reduce UV-induced damage. It has been demonstrated that these medicines improve defense against UV-induced epidermal thickening, MMP-1 and MMP-9 overexpression, and CD1aξ Langerhans cell reduction. When applied topically to human skin in vivo, non-sunscreen substances like antioxidants, DNA repair enzymes, and plant extracts can be beneficial [45,46].

5.3.2. Tocopherol

Tocopherol is a naturally occurring lipophilic vitamin with strong antioxidant properties. It has also been shown to have cytoprotective properties and to be a scavenger of ROS, specifically peroxyl radicals, which prevents the oxidation of biomolecules like proteins and lipids. It helps prevent oxidative stress on the cell membrane and resists UV-induced cellular deterioration, including photoaging, lipid peroxidation, immunosuppression, and photocarcinogenesis [47,48]. Pre-treatment with formulations containing vitamin E offers strong protection against photosensitivity, while areas treated with topical vitamin E formulation showed better results in comparison to areas treated with the simple vehicle or with vitamin A.

Nevertheless, tocopherol has low photo- and chemical stability as well as a unique vulnerability to alkoxyl radical oxidation, which leads to the production of chromanoxyl radicals. Tocopheryl acetate and tocopheryl glucoside are two novel derivatives that have been developed as a result of molecular alterations to the original molecule [47]. While tocopherol acetate results from the acetylation of the free aromatic hydroxyl group of α-tocopherol, tocopheryl glucoside results from the addition of a glucose sugar unit. Furthermore, tocopherol has poor water solubility and topical formulation due to its high hydrophobicity; however, these issues may be resolved with the use of both these forms of vitamin E. These forms of vitamin E have no action on their own, and thus cutaneous phosphatases or esterases activate them in order to release the active vitamin E at the desired location.

More specifically, even though tocopheryl acetate presents a more lipophilic character than its parent compound, the higher stabilization, and less probability of being oxidized, along with its insertion in the skin phospholipid bilayer, potentiates the neutralization of free radicals. Thus, α-tocopheryl acetate is often used in dermatological products such as skin creams, as it is not easily oxidized and can penetrate through the skin to the living cells, where about 5% is converted to free tocopherol, with claims for beneficial antioxidant effects. α-Tocopheryl acetate is used as an alternative to tocopherol itself because the phenolic hydroxyl group is blocked, providing a less acidic product with a longer shelf life. It is believed that the acetate is slowly hydrolyzed after it is absorbed into the skin, regenerating tocopherol and providing protection against the sun’s ultraviolet rays. Subsequently, vitamin E and its derivative tocopheryl acetate are placed in the first and second positions, respectively, among the top six most commonly used antioxidants in sunscreens [47].

The opposite was seen with the glycosylated tocopheryl derivative (tocopheryl glucoside), which was found to be used in a much lower number of sunscreen formulations, among all the formulations analyzed. Tocopheryl glucoside turns into a more lipophilic and active molecule from which free tocopherol is released after cleavage of the glycosidic bond, catalyzed by β-glucocerebrosidase in the stratum corneum. Although tocopheryl glucoside is the vitamin E derivative less used in sunscreen formulations, some studies were performed to confirm its multifunctional antioxidant and photoprotective effectiveness, in both reconstituted human epidermis and viable human skin, where it was shown that tocopheryl glucoside reveals a higher percentage of metabolization to the active form (α-tocopherol) than tocopheryl acetate, even though skin diffusion was slower, by producing a significant reservoir effect, associated with a progressive supply of free tocopherol, first in the stratum corneum and then in the other skin compartments, conferring protection.

Nevertheless, further studies are required to clarify the photoprotective effectiveness of both these tocopheryl derivatives, as well as to improve their delivery and bioactivation and vitamin E release in human skin.

Table 3. The main findings of some in vitro and in vivo studies of lycopene and vitamin C and E.

Component Structure	Main Findings/Type of Study	Year of Study	References
Lycopene	• Antioxidant      • Moisture      • Skin suppleness      • Photoprotection	2011	[27]
	In vitro
	▪ The medication was provided with an 8-h target sustained release in vitro ▪ The developed formulations' intended outcome did not show any tissue degradation, and they demonstrated increased therapeutic efficacy and offered greater therapeutic efficacy in addition to a longer testing period (24 hours), as compared to normal suspension ▪ Tissues examined in preliminary fashion revealed that the experimental formulations did not cause irritation ▪ The analgesic impact of propolis and lycopene aqueous extract nanoemulsion applied locally showed great potential in therapeutic safety, as well as efficacy
Vitamin C Vitamin E	• Minor UV protection      • Anti-wrinkle      • Phototoxic damage - Erythema - Sunburn cell development	2004, 2009	[43,45]
	In vivo
	▪ Four treatment groups were examined on the cooperative activity of vitamins C and E against UV-induced erythema over a 50-day period: RRRα-tocopherol (2 g/d) and ascorbate (3 g/d) as single components, a combination of α-tocopherol and ascorbate (2 and 3 g/d, respectively), and controls receiving no treatment. The sunburn threshold dramatically increased with combined treatment; MED was approximately 100 mJ/cm2 prior to supplementation while approximately 180 mJ/m2 afterwards ▪ L-Ascorbic Acid: Increased amounts obtained through topical application protect the skin from UV light → through the neutralization of reactive oxygen species produced by UV light Can reduce photodamage, which is quantified histologically as sunburn cells Protection against UVA damage appears to be particularly good Sunburn can be treated with topical ascorbic acid, probably via reducing inflammation ▪ Tocopherol: Prevents oxidative stress on the cell membrane and resists UV-induced cellular deterioration (including photoaging, lipid peroxidation, immunosuppression, and photocarcinogenesis)

Table 3. The main findings of some in vitro and in vivo studies of lycopene and vitamin C and E.

Component Structure	Main Findings/Type of Study	Year of Study	References
Lycopene	• Antioxidant      • Moisture      • Skin suppleness      • Photoprotection	2011	[27]
	In vitro
	▪ The medication was provided with an 8-h target sustained release in vitro ▪ The developed formulations' intended outcome did not show any tissue degradation, and they demonstrated increased therapeutic efficacy and offered greater therapeutic efficacy in addition to a longer testing period (24 hours), as compared to normal suspension ▪ Tissues examined in preliminary fashion revealed that the experimental formulations did not cause irritation ▪ The analgesic impact of propolis and lycopene aqueous extract nanoemulsion applied locally showed great potential in therapeutic safety, as well as efficacy
Vitamin C Vitamin E	• Minor UV protection      • Anti-wrinkle      • Phototoxic damage - Erythema - Sunburn cell development	2004, 2009	[43,45]
	In vivo
	▪ Four treatment groups were examined on the cooperative activity of vitamins C and E against UV-induced erythema over a 50-day period: RRRα-tocopherol (2 g/d) and ascorbate (3 g/d) as single components, a combination of α-tocopherol and ascorbate (2 and 3 g/d, respectively), and controls receiving no treatment. The sunburn threshold dramatically increased with combined treatment; MED was approximately 100 mJ/cm2 prior to supplementation while approximately 180 mJ/m2 afterwards ▪ L-Ascorbic Acid: Increased amounts obtained through topical application protect the skin from UV light → through the neutralization of reactive oxygen species produced by UV light Can reduce photodamage, which is quantified histologically as sunburn cells Protection against UVA damage appears to be particularly good Sunburn can be treated with topical ascorbic acid, probably via reducing inflammation ▪ Tocopherol: Prevents oxidative stress on the cell membrane and resists UV-induced cellular deterioration (including photoaging, lipid peroxidation, immunosuppression, and photocarcinogenesis)

5.3.3. L-Ascorbic Acid

The skin is protected from UV light by the increased amounts of L-ascorbic acid obtained through topical application. L-ascorbic acid can reduce UVB- or UVA-induced photodamage, which is quantified histologically as sunburn cells; protection against UVA damage appears to be particularly satisfactory. L-ascorbic acid functions differently from sunscreens since it does not absorb UVB or UVA rays. Through the neutralization of reactive oxygen species produced by UV light, L-ascorbic acid appears to offer protection. Even sunburns can be treated with topical ascorbic acid, probably via reducing inflammation. According to the results thus far, topical vitamin C is a helpful addition to sunscreens. Because of its anti-inflammatory and photoprotective properties, topical vitamin C is employed. L-ascorbic acid is used for its ability to heal wounds since it is necessary for the creation of collagen [49,50,51,52]. Patients having CO₂ laser resurfacing have also employed topical vitamin C. In half-face research that was published, the side that had topical l-ascorbic acid showed reduced erythema.

In contrast to most sunscreens, vitamin C cannot be removed from the skin by rubbing, washing, or sweating. The protection offered by this vitamin remains unchanged, in the span of a couple of days. In addition, topical vitamin C inhibits UV immunosuppression, which has been linked to skin malignancies other than melanoma. It involves the following: using ascorbate’s oxidation capacity to neutralize ROS radicals in the skin’s aqueous compartments; minimizing the development of sunburn cells, erythema, and immunosuppression; preventing tyrosinase synthesis; and preserving hydration to safeguard the skin’s epidermal barrier. Despite its positive effects, L-ascorbic acid shows insufficient skin penetration and instability [53,54].

6. Conclusions

In conclusion, it seems that the inclusion of natural extracts either as active ingredients or as supporting ingredients is a promising project, laying the foundation for more and more natural and sustainable solutions in the field of cosmetic chemistry.

Grape stems contain a variety of antioxidants, with flavonoids playing a dominant role. The main bioactive compounds are gallic acid, catechin, epicatechin, epigallocatechin, and quercetin. However, flavonoids alone do not sufficiently attenuate or suppress photochemical reactions catalyzed by UV radiation, but synergism between flavonoids and UV filters can reduce the formation of harmful photodegradation products, enhancing the photoprotection provided. Various studies correlate the Total Polyphenol Content (TPC) of extracts with their photoprotective effect. The incorporation of such substances in sunscreen products may therefore be particularly beneficial.

However, in research (2015) on changes likely to occur in the bioactive components of grapes after exposure to UV radiation in a day, it was found that in components such as polyphenols, anthocyanins were significantly reduced in amounts (in aqueous solutions), but retained their ability to bind free radicals even after 24 h. Moreover, tannins, due to the stability of their properties, are evaluated as candidate compounds not only for sunscreen products, but also many more. In addition, in subsequent research (2021) on the utilization of grape by-products in cosmetic chemistry, it was found that more extensive investigation is needed in terms of extraction techniques, which allow for the recovery of certain classes of polyphenols, as special attention is needed to establish the correct link between the extraction parameters, the recovered components, and their effect on the stability of cosmetic formulations.

Sunscreens with the majority of their composition consisting of natural ingredients, in addition to preventing serious diseases such as basal cell carcinoma, melanoma, sunburn, premature aging, and many others, also act against inflammation. In other words, they are anti-irritant and often healing (especially due to the moisturizing agents they contain) and have a hypoallergenic composition, making them ideal for the most sensitive skins. But the main advantage of the action of these molecules is their ability to bind ROS; i.e., they bind free radicals, which cause serious problems in human health such as oxidative stress.

Both the bioactive compounds in grape stems and lycopene in tomatoes are antioxidants that fight free radicals and provide a degree of photoprotection, especially in combination with sunscreen filters.

In fact, it is worth pointing out that lycopene, while reducing the damaging effects of UV radiation, also enhances skin protection against both short-term UV effects (sunburn) and cumulative effects (cancer).

However, even though lycopene has a variety of biological properties, it presents some difficulties due to characteristics like high lipophilicity and insolubility in aqueous solvents, as well as it exhibiting stability and degradation problems. For this reason, solutions are being sought for its proper utilization, such as its association with nanotechnology, in order to circumvent these difficulties.

Moreover, it is worth highlighting the importance of grape stems and tomato extracts for their use in sunscreen products and in cosmetic chemistry products in general, as an alternative solution that represents a step towards a circular economy. The circular economy contributes to the mitigation of major environmental, economic, and social problems related to the ever-increasing increase in food waste due to the continuous growth of the population, while simultaneously allowing the obtaining of compounds of a plant origin with high added value. This reduces the amount of waste, while, at the same time, benefits human beings, since these by-products are not in any way inferior in terms of the antioxidant benefits they offer, in comparison to the original fruit. Therefore, there are good indications so far for the incorporation of more and more natural ingredients, but there is still a lot of research to be done to overcome any problems in the experimental process and for these products to achieve the optimal result. Unfortunately, it is difficult to apply natural extracts as sunscreen filters without their co-existence with conventional UV filters (TiO₂ or ZnO), because natural ingredients alone cannot provide such high levels of protection. However, they do provide impressive results by enhancing existing UV filters, protecting against further skin damage, boosting the skin’s antioxidant defenses, and often helping smooth the existing damage.