Seaweed-Based Molecules and Their Potential Biological Activities: An Eco-Sustainable Cosmetics

Amongst the countless marine organisms, seaweeds are considered as one of the richest sources of biologically active ingredients having powerful biological activities. Seaweeds or marine macroalgae are macroscopic multicellular eukaryotic photosynthetic organisms and have the potential to produce a large number of valuable compounds, such as proteins, carbohydrates, fatty acids, amino acids, phenolic compounds, pigments, etc. Since it is a prominent source of bioactive constituents, it finds diversified industrial applications viz food and dairy, pharmaceuticals, medicinal, cosmeceutical, nutraceutical, etc. Moreover, seaweed-based cosmetic products are risen up in their demands by the consumers, as they see them as a promising alternative to synthetic cosmetics. Normally it contains purified biologically active compounds or extracts with several compounds. Several seaweed ingredients that are useful in cosmeceuticals are known to be effective alternatives with significant benefits. Many seaweeds’ species demonstrated skin beneficial activities, such as antioxidant, anti-melanogenesis, antiaging, photoprotection, anti-wrinkle, moisturizer, antioxidant, anti-inflammatory, anticancer and antioxidant properties, as well as certain antimicrobial activities, such as antibacterial, antifungal and antiviral activities. This review presents applications of bioactive molecules derived from marine algae as a potential substitute for its current applications in the cosmetic industry. The biological activities of carbohydrates, proteins, phenolic compounds and pigments are discussed as safe sources of ingredients for the consumer and cosmetic industry.


Introduction
Cosmeceuticals are defined by cosmetic producers as products to improve or alter the skin functions and appearance, causing skin benefits [1]. The term "cosmeceutical" refers to products that can combine both cosmetic and pharmaceutical uses to improve skin characteristics, such as the appearance, structure, and functions of the skin [2,3]. This cosmeceutical sector is highly innovative and always looking for principally active molecules that serve better characteristics to open up many possibilities [4]. The cosmetic sector continues to develop in many developing countries that started by the global beauty market [5]. Skinceuticals Daily Moisture, Mario Badescu Seaweed Night Cream, and Dr. Dennis Gross Skincare Hyaluronic Marine Oil-Free Moisture Cushion, etc., also occupy the cosmetic market. In addition, Heo et al. [26] reported that seaweed is a promising and focused group of novel biochemically active principal molecules and nowadays appreciated in the developments of new biotechnological or cosmeceutical purposes.
The chemically diversified nature and unique potential of seaweeds are the reason why they have been the focus of interest for the past few years in various cosmetic applications. Seaweed-based protein, polysaccharides, phenolic compounds, and pigment profiles present cosmetic and cosmeceutical potential. This review study gives an overall view of an exploitation of seaweed for cosmetic beneficial activities. Mainly, the role of polysaccharide, protein, phenolic compounds, and pigments in different skin cosmetic beneficial activities are discussed.
Additionally, Yu and Gu [67] reported the role of algae-derived polysaccharides in the formation of protective membrane to prevent water evaporation in skin. Likewise, Sulfated polysaccharide from the red algae appear to be an excellent candidate to substitute hyaluronic acid as a bio lubricant and antioxidant [68]. Low-molecular-weight polysaccharides derived from red algae Pyropia yezoensis had skin beneficial functions, such as antioxidant, anti-inflammation, photoaging protection, etc. [69]. In the case of pigment, red carotenoid pigment, astaxanthin, scavenges free radicals and blocks proinflammatory cytokine production [70]. Moreover, Thomas and Kim [71] isolated fucoxanthin from Laminaria japonica; it is reported to inhibit tyrosinase activity and melanogenesis in UVB-irradiated mice.

Proteins
Biological macromolecule protein is a polymer of amino acids that is present in all living organisms. It is a basic building block of almost all cellular processes. It may present itself in the form of enzymes, hormones, vitamins, and pigments [164,165]. Moreover, macroalgae contain different types of aliphatic amino acids, hydroxyl-group-containing amino acid, aromatic amino acid, mycosporine amino acids, etc., which are summarized in Table 2. In addition, different species of Palmaria palmata, Chondrus crispus, Porphyra sp. (Rhodophyta), Undaria pinnatifida (Phaeophyceae), Ulva sp. (Chlorophyta), and Euchema sp. (Rhodophyta) are reported for the quantity of amino acids they contain [166][167][168]. It is widely applicable in cosmeceutical preparation as a functional part. It exhibits many cosmeceutical activities, such as anti-inflammatory, antiaging, antioxidant, and photoprotection activities [169,170]. According to Fabrowska et al. [171], protein showed a moisturizing effect on human skin. MAAs (mycosporine-like amino acids) play their role in the absorption of solar energy that beneficiary in photoaging, as well as photo-damaging protection. There are different roles of MAAs, such as in UV protection, anti-photoaging, antioxidant, and anti-hypertensive activities, reported by researchers [172][173][174][175]. Moreover, Dunalp and Yamamoto [176] reported the importance of mycosporine amino acids (MAAs) as sunscreens to reduce UV-induced damage. MAAs play a major role in protection against damage caused by sunlight. They acting as antioxidant molecules which scavenge toxic oxygen radicals and protect skin against UV-induced damage [177]. Furthermore, MAAs act as protective solutes of cells against salt stress, desiccation, and thermal stress [178]. Scytosiphon lomentaria Antioxidant [188] 10.
The red alga Porphyra rosengurtii-derived mycosporine-like amino acids Porphyra-334 and Shinorine are isolated and found to be very photostable and photoprotective when exposed to radiation [204]. These MAAs both played a role in sunburn cell formation and to be protective after UV radiation and eliminate damaged cells [205]. This combination also used in treatment of prevention towards skinfold thickening in the epidermis/dermis of hypodermic of mice.
Carotenoids are widely applicable as natural dyes and antioxidants with antitumor, anti-inflammatory, and radical sequestering benefits [285][286][287]. They modulate UVA-induced gene expression and protect the skin against UV light [288]. Moreover, astaxanthin has a variety of roles in the prevention of UV-mediated photo-oxidation, tumors, and inflammation [289]. Additionally, fucoxanthin has protective effects on skin, making it consequently beneficial in cosmetics [290,291] Likewise, Kushwaha et al. [292] and Morabito et al. [282] reported carotenoids having antioxidant and anti-inflammatory properties that help for photoprotection and against UVA-damaging effects.

Discussion
Cosmetic researchers have focused their attention on marine organisms as an additional source of novel and useful natural ingredients. Diversified marine-algae-derived secondary metabolites are structurally more complex, with unique functionalities and properties. This review surveyed the potential applications of marine-algae-derived compounds for various skin benefits in the cosmetic industry. Though many seaweeds are exploited for their cosmetic properties, the research work on them is still incomplete, and so many species, either in full or in part, have not been explored. Hence, the cost-effective and efficient alternative standardized method to extract the bioactive phyco-constituents with significant productivity and activity is in growing demand. In future perspectives, the responsible molecular mechanism and safety concerns of these compounds are very important for future challenges in cosmeceuticals. Therefore, further investigations to study the precise molecular basis for the beneficial activity of marine algal components should be undertaken. Recently, in silico tools and techniques have been used to select functional materials derived from natural resources quickly and to predict the mechanisms of actions. Thus, this approach will be a helpful strategy for finding and understanding more effective compounds with the novel property.

Conclusions
The overexposure of human skin to different environmental stresses, such as pollutants and sun radiation, as well as chemical cosmeceutical ingredients-it increases the production of reactive oxygen species (ROS)-leads to many skin-damaging problems, such as aging, dullness, carcinogenesis, wrinkles, age spots, dark circles, etc. Marine-algae-based bioactive purified compounds demonstrated highly significant beneficiary applications in cosmetic formulas, as multiple functions, where they can be natural active constituents to the synthetic ingredients. Under different environmental factors, marine algae have the biosynthesis of primary and secondary metabolites for their survival. These biologically active constituents can be used as an active ingredient in the cosmetic industries due to their various skin benefits. It could be used as an antioxidant, antimicrobials, antibacterial, whitening agent, antiaging, anti-wrinkle, anti-acne, moisturizing, UV protection, deodorizing, anti-allergic, anti-inflammatory, sensory enhancer, viscosifying, stabilizer, and also for thickening in cosmetic industries. Sustainable use of marine algae and marinealgae-based molecules is crucial for humankind. Moreover, there are many cosmeceutical industries that already use extracts of marine algae and compounds in the formulation of many products. However, the monitoring of its biochemical profile presents a problem that needs to overcome. This can be solved by the development of seaweed cultivation and green extraction methods that are being analyzed with promising research results. However, many cosmetic companies' collaboration at the national and international level can improve the analytical methods of its screening for safety, thus enhancing consumer's safety towards marine-algae-based bioactive compounds in the cosmetic products. All mentioned marine algae in this review, possessing various bioactivities, are considered and utilized as a natural inexhaustible source for different cosmeceutical benefits.   [CrossRef] [PubMed]