Search Results (28)

Background: Olive pomace, a byproduct of olive oil production, represents approximately 85% of the processed material and poses environmental risks when improperly discarded. Its composition is rich in polyphenols with potential for cosmetic use, especially in skin barrier care. Objective: To develop a natural extract rich in antioxidants from olive pomace using sustainable solvents (water and 1,3-propanediol) for skin barrier support. Methods: The phenolic composition and in vitro biological activities of the extracts were analyzed. Results: The extracts demonstrated a reducing capacity (15 to 33 mg GAE/g) and flavonoid content (4 to 5 mg QE/g). In addition, their antioxidant capacity was proven through the inhibition of the DPPH radical (7% to 91%) and ABTS (7% to 95%) and the reduction in oxidation in the beta-carotene/linoleic acid system (6% to 35%), presenting results superior to those of tocopherol acetate. The hydroxytyrosol and oleuropein compounds, ranging from 28 to 54 and 51 to 85 µg/mL, respectively, were quantified via HPLC. The extract with the highest levels of hydroxytyrosol and oleuropein was analyzed via UHPLC-QqTOF-MS, and 33 compounds were identified. This extract showed antiglycation activity (24% to 40%). The incorporation of this extract into a cosmetic emulsion resulted in sufficient antioxidant capacity to replace tocopherol acetate. Conclusions: The use of effective extraction techniques and nontoxic solvents ensures the sustainability and safety of the extract for application as a natural cosmetic ingredient, aiming to promote the health and integrity of the skin barrier. Full article

Hydroxytyrosol (HT), the primary phenolic compound in virgin olive oil, has notable cardiovascular benefits, particularly in preventing low-density lipoprotein (LDL) oxidation. However, its hydrophilicity limits its solubility and integration into lipid-based formulations. This study aimed to enhance its lipophilicity by synthesizing hydroxytyrosyl eicosapentaenoate (HT-EPA), a derivative of HT and eicosapentaenoic acid (EPA), using a one-step enzymatic catalysis with lipase B from Candida antarctica (CALB). The reaction, performed as a suspension of HT in ethyl eicosapentaenoate (Et-EPA) (1:9 molar ratio) under vacuum, achieved higher yields and shorter reaction times than previously reported, with a purity exceeding 98%, confirmed by ¹H-NMR. For the first time, the antioxidant capacity of HT-EPA in comparison with other natural antioxidants was assessed using the FRAP assay, while its oxidative stability in an omega-3-rich oil matrix was evaluated via the Rancimat method. HT-EPA and hydroxytyrosyl acetate (HT-Ac) displayed antioxidant activity comparable to HT but significantly higher than α-tocopherol, a common food antioxidant. Given the scarcity of effective lipid-soluble antioxidants, HT-EPA represents a promising candidate for omega-3 nutraceuticals, offering enhanced stability and potential health benefits. This study provides a simple, efficient, and scalable strategy for developing functional lipid-based formulations with cardioprotective potential by improving HT solubility while preserving its antioxidant properties. Full article

Plant extracts, such as olive extract (OE), have been used in human and pet foods for their biological benefits; however, no available data have demonstrated OE’s effect on palatability in dogs. The current study aimed to evaluate acceptance of dry and canned dog foods with differing inclusions of OE as a flavor component. Flavor compounds in OE were analyzed by gas chromatography–mass spectrometry and high-pressure liquid chromatography, detecting 137 volatile compounds, including acetic acid and hydroxytyrosol. Dog kibbles were coated with liquid commercial palatants containing OE that resulted in application rates of 0 (control), 120, 200, and 500 ppm of OE in the diets. OE was also added at 0 (control), 120, 200, and 500 ppm into a wet food formulation with a commercial palatant before retort processing. Two separate panels of adult beagles were used for monadic testing to determine acceptance rates for kibble (5/treatment; 20 total) and canned foods (4/treatment; 16 total) in a 4 × 4 Latin square design. None of the tested inclusions impacted food acceptance in this preliminary study (p > 0.05). As a flavor ingredient, OE can be added into dry or wet dog food up to 500 ppm without deterring effects on palatability. Full article

In the present study, the influence of heating on the evolution of oxidative indices, antioxidant activity, phenolic and volatile compounds in monovarietal extra virgin olive oils (EVOOs) obtained from Leccino, Istarska bjelica, and Buža cultivars was investigated. The samples were submitted to heating in an air oven (180 °C and 220 °C), simulating usual roasting conditions typical for Mediterranean cuisine. The decreases in the oxidative indicators, phenolic and volatile compounds were more pronounced at higher heating temperatures, underlining the temperature dependency of the oxidative degradation during heating conditions. Despite this, it must be emphasized that a significant amount of phenolic compounds and antioxidative activity remained preserved after the heating treatment. Each oil cultivar showed some specificity during the course of the thermal degradation. Hydroxytyrosol acetate among phenolic compounds and octanal, (E)-2-octenal, hexanal, 3-pentanone, and 1-penten-3-one among the volatiles were underlined as possible markers of thermal oxidation. Principal component analysis revealed that the content of volatile compounds in monovarietal EVOO samples distinguished samples primarily by the heating temperature, while the changes in the phenolic compounds were cultivar-dependent aside from being influenced by the temperature of heating. Full article

Olive leaves are a rich source of polyphenols with healthful properties and represent one of the most abundant waste products of olive oil production. The aims of this study were to explore the phenolic composition of olive leaves from the three main Tuscan cultivars (Leccino, Moraiolo and Frantoio) collected in Siena and Grosseto provinces and to investigate the possible use of these compounds as varietal and geographic origin markers. Discriminant factorial analysis (DFA) was used for distinguishing between different cultivars and locations. Apigenin and caffeoyl-secologanoside showed significant differences between cultivars. DFA showed that ligstroside, apigenin and luteolin have the most influence in determining the differences between sites, whereas total polyphenols, olacein and hydroxytyrosol acetate allowed for separation between leaves from the same province. The results of the present study indicate that concentrations of phenolic compounds, measured through high-resolution mass spectrometry, can be used as a marker for both the cultivar and of geographical origin of olive leaves, and possibly of olive-related products, as well as across small geographic scales (less than 50 km distance between sites). Full article

Nuclear factor E2-related factor 2 (Nrf2) is fundamental to the maintenance of redox homeostasis within cells via the regulation of a series of phase II antioxidant enzymes. The unique olive-derived phenolic compound hydroxytyrosol (HT) is recognized as an Nrf2 activator, but knowledge of the HT derivative hydroxytyrosol acetate (HTac) on Nrf2 activation remains limited. In this study, we observed that an HT pretreatment could protect the cell viability, mitochondrial membrane potential, and redox homeostasis of ARPE-19 cells against a t-butyl hydroperoxide challenge at 50 μM. HTac exhibited similar benefits at 10 μM, indicating a more effective antioxidative capacity compared with HT. HTac consistently and more efficiently activated the expression of Nrf2-regulated phase II enzymes than HT. PI3K/Akt was the key pathway accounting for the beneficial effects of HTac in ARPE-19 cells. A further RNA-Seq analysis revealed that in addition to the consistent upregulation of phase II enzymes, the cells presented distinct expression profiles after HTac and HT treatments. This indicated that HTac could trigger a diverse cellular response despite its similar molecular structure to HT. The evidence in this study suggests that Nrf2 activation is the major cellular activity shared by HTac and HT, and HTac is more efficient at activating the Nrf2 system. This supports its potential future employment in various disease management strategies. Full article

Drugs that cure COVID-19 have been marketed; however, this disease continues to ravage the world without becoming extinct, and thus, drug discoveries are still relevant. Since M^pro has known advantages as a drug target, such as the conserved nature of the active site and the absence of homologous proteins in the body, it receives the attention of many researchers. Meanwhile, the role of traditional Chinese medicine (TCM) in the control of epidemics in China has also led to a focus on natural products, with the hope of finding some promising lead molecules through screening. In this study, we selected a commercial library of 2526 natural products from plants, animals and microorganisms with known biological activity for drug discovery, which had previously been reported for compound screening of the SARS CoV-2 S protein, but had not been tested on M^pro. This library contains compounds from a variety of Chinese herbs, including Lonicerae Japonicae Flos, Forsythiae Fructus and Scutellariae Radix, which are derived from traditional Chinese medicine prescriptions that have been shown to be effective against COVID-19. We used the conventional FRET method for the initial screening. After two rounds of selection, the remaining 86 compounds were divided into flavonoids, lipids, phenylpropanoids, phenols, quinones, alkaloids, terpenoids and steroids according to the skeleton structures, with inhibition rates greater than 70%. The top compounds in each group were selected to test the effective concentration ranges; the IC₅₀ values were as follows: (−)–gallocatechin gallate (1.522 ± 0.126 μM), ginkgolic acid C15:1 (9.352 ± 0.531 μM), hematoxylin (1.025 ± 0.042 μM), fraxetin (2.486 ± 0.178 μM), wedelolactone (1.003 ± 0.238 μM), hydroxytyrosol acetate (3.850 ± 0.576 μM), vanitiolide (2.837 ± 0.225 μM), β,β–dimethylacrylalkannin (2.731 ± 0.308 μM), melanin (7.373 ± 0.368 μM) and cholesteryl sodium sulfate (2.741 ± 0.234μM). In the next step, we employed two biophysical techniques, SPR and nanoDSF, to obtain K_D/K_obs values: hematoxylin (0.7 μM), (−)–gallocatechin gallate (126 μM), ginkgolic acid C15:1 (227 μM), wedelolactone (0.9770 μM), β,β–dimethylacrylalkannin (1.9004 μM,), cholesteryl sodium sulfate (7.5950 μM) and melanin (11.5667 μM), which allowed better assessments of the binding levels. Here, seven compounds were the winners. Then, molecular docking experiments were specially performed by AutoDock Vina to analyze the mode of interactions within M^pro and ligands. We finally formulated the present in silico study to predict pharmacokinetic parameters as well as drug-like properties, which is presumably the step that tells humans whether the compounds are drug-like or not. Moreover, hematoxylin, melanin, wedelolactone, β,β–dimethylacrylalkannin and cholesteryl sodium sulfate are in full compliance with the “Lipinski” principle and possess reasonable ADME/T properties, they have a greater potential of being lead compounds. The proposed five compounds are also the first to be found to have potential inhibitory effects on SARS CoV-2 M^pro. We hope that the results in this manuscript may serve as benchmarks for the above potentials. Full article

The aim of this study was to investigate the effects of two phenolic compounds found in extra virgin olive oil, hydroxytyrosol (HT) and luteolin (LUT), on the metabolism of breast cancer (BC) cells of different molecular subtypes. An untargeted metabolomics approach was used to characterize the metabolic responses of both triple-negative MDA-MB-231 cells and hormone-responsive MCF-7 cells to treatment with these phenols. Notably, while some effects were common across both cell types, others were dependent on the cell type, highlighting the importance of cellular metabolic phenotype. Common effects included stimulation of mitochondrial metabolism, acetate production, and formate overflow. On the other hand, glucose metabolism and lactate production were differentially modulated. HT and LUT appeared to inhibit glycolysis and promote the hexosamine biosynthetic pathway in MDA-MB-231 cells, while MCF-7 cells exhibited higher glycolytic flux when treated with phenolic compounds. Another significant difference was observed in lipid metabolism. Treated MDA-MB-231 cells displayed increased levels of neutral lipids (likely stored in cytosolic droplets), whereas treatment of MCF-7 cells with HT led to a decrease in triacylglycerols. Additionally, glutathione levels increased in MDA-MB-231 cells treated with HT or LUT, as well as in MCF-7 cells treated with LUT. In contrast, in HT-treated MCF-7 cells, glutathione levels decreased, indicating different modulation of cellular redox status. Overall, this work provides new insights into the metabolic impact of HT and LUT on different BC cell subtypes, paving the way for a better understanding of the nutritional relevance of these phenolic compounds in the context of BC prevention and management. Full article

The anti-inflammatory potential of oleacein, the main polyphenolic compound found in olive oil, and its main metabolites were characterized by their effects on RAW 264.7 macrophages challenged with lipopolysaccharide (LPS), and by their ability to inhibit enzymes of the arachidonic acid metabolism with a key role in the synthesis of pro-inflammatory lipid mediators. Oleacein at 12.5 µM significantly decreased the amount of L-citrulline and ^●NO generated by LPS-stimulated macrophages. Hydroxytyrosol, hydroxytyrosol acetate and hydroxytyrosol acetate sulfate were also able to reduce the cellular amount of ^●NO, although to a lesser extent. In contrast, hydroxytyrosol glucuronide and sulfate did not show detectable effects. Oleacein was also able to inhibit the coupled PLA₂ + 5-LOX enzyme system (IC₅₀ = 16.11 µM), as well as the 5-LOX enzyme (IC₅₀ = 45.02 µM). Although with lower activity, both hydroxytyrosol and hydroxytyrosol acetate were also capable of inhibiting these enzymes at a concentration of 100 µM. None of the other tested metabolites showed a capacity to inhibit these enzymes. In contrast, all compounds, including glucuronides and sulfate metabolites, showed a remarkable capacity to inhibit both cyclooxygenase isoforms, COX-1 and COX-2, with IC₅₀ values lower than 3 µM. Therefore, oleacein and its metabolites have the ability to modulate ^●NO- and arachidonic acid-dependent inflammatory cascades, contributing to the anti-inflammatory activity associated with olive oil polyphenols. Full article

Cardamine violifolia, a species belonging to the Brassicaceae family, is a selenium hyperaccumulator and a nutritious leafy vegetable. Our previous study showed that C. violifolia leaves are rich in total phenolic acids, but the composition and corresponding genes remain unknown. In this study, we investigated the phenolic acid compounds and potential gene regulation network in the outer leaves (OL) and central leaves (CL) of C. violifolia using transcriptome and metabolome analyses. Results showed that the OL contained a higher total phenolic acid content than the CL. Metabolome analysis revealed a total of 115 phenolic acids, 62 of which (e.g., arbutin, rosmarinic acid, hydroxytyrosol acetate, and sinapic acid) were differentially accumulated between the CL and OL of C. violifolia. Transcriptome analysis showed that the differentially expressed genes were significantly enriched in the pathways of secondary metabolite biosynthesis and phenylpropanoid biosynthesis. Conjoint analysis of the transcriptome and metabolome indicated that seven genes (CYP84A1, CYP84A4, CADH9, SGT1, UGT72E1, OMT1, and CCR2) and eight phenolic acids (sinapic acid, sinapyl alcohol, 5-O-caffeoylshikimic acid, sinapoyl malate, coniferin, coniferyl alcohol, L-phenylalanine, and ferulic acid) constituted a possible regulatory network. This study revealed the phenolic acid compounds and possible regulatory network of C. violifolia leaves and deepened our understanding of its nutrient value. Full article

The recovery of phenolic compounds from olive leaves (Olea europaea L.) has received special attention due to their significant potential for applications in food, nutraceuticals, cosmetics, and pharmaceuticals. In this work, the extraction of the phenolic compounds from olive leaves was examined by means of conventional extraction and microwave-assisted extraction (MAE) using nontoxic common solvents such as ethanol and water as well as using promising environmentally friendly, Deep Eutectic Solvents (DESs) and their mixtures with ethanol or water. The effects of the various parameters that likely govern the extractability of the bioactive compounds of olive leaves (OL), such as the solvent type, temperature, and biomass to solvent mass ratio, were studied and evaluated with regard to the oleuropein and hydroxytyrosol content, antioxidant activity, and total phenolic content of the extracts. The study also explores the effects of the microwave-assisted extraction parameters, namely irradiation power and time, on the total phenolic content and antioxidant activity of the extracts. The findings of this work suggest that among the solvents studied, the solvent mixture consisting of the DES choline chloride:acetic acid with a molar ratio of 1:2 and ethanol (80:20 w/w) is highly effective in recovering extracts rich in phenolic compounds and with significant antioxidant activity. Moreover, it is demonstrated that the MAE method allows for the recovery of bioactive compounds in a very short processing time. Full article

This study tackles the individual and joint effect of alpha-tocopherol and hydroxytyrosol acetate on the oxidation of sunflower oil submitted to accelerated storage conditions at intermediate temperature, in order to deepen the understanding of antioxidant–prooxidant behaviour. This was accomplished by ¹H Nuclear Magnetic Resonance. For this purpose, the evolution of the degradation of both the main components of the oil and the aforementioned added compounds was monitored by this technique throughout the storage time. Furthermore, the formation of a very large number of oxylipins and the evolution of their concentration up to a very advanced stage of oil oxidation, as well as the occurrence of lipolysis, were also simultaneously studied. The results obtained show very clearly and thoroughly that in the oxidation process of the oil enriched in binary mixtures, interactions occur between alpha-tocopherol and hydroxytyrosol acetate that notably reduce the antioxidant effect of the latter compound with the corresponding negative consequences that this entails. The methodology used here has proved to be very efficient to evaluate the antioxidant power of mixtures of compounds. Full article

The aim of the present study was to explore the high-yield production of hydroxytyrosol, a phenolic compound with very high antioxidant capacity. Olea europaea leaves were chosen as feedstock as they contain significant amounts of oleuropein, which can be hydrolyzed to hydroxytyrosol. The chosen techniques are widely used in the industry and can be easily scaled up. Olive leaves underwent drying and mechanical pretreatment and extractives were transported to a solvent by solid–liquid extraction using water–ethanol mixtures. The use of approximately 60–80% ethanol showed an almost 2-fold increase in extracted phenolics compared to pure water, to approximately 45 g/kg of dry leaves. Extracted oleuropein was hydrolyzed with hydrochloric acid and the hydrolysate was extracted with ethyl acetate after pH adjustment. This step led to a hydroxytorosol content increase from less than 4% to approximately 60% w/w of dry extract, or 10–15 g of hydroxytyrosol recovery per kg of dry leaves. Full article

Sunflower oil samples, both unenriched and enriched with four different concentrations of hydroxytyrosol acetate, were subjected to accelerated storage at 70 °C until a very advanced oxidation stage and the process was monitored by ¹H NMR spectroscopy. The aim of the study is to know the effect that the presence of this antioxidant has on the oxidation process of sunflower oil under the aforementioned conditions, as well as on the formation and evolution of the concentration of a significant number of oxylipins. The oxidation process was studied globally by monitoring, during storage time, the degradation of both the linoleic acyl group of sunflower oil, which is the main component of sunflower oil, and the added hydroxytyrosol acetate. Simultaneously, the identification of up to twenty-six different types of oxylipins formed in the oxidation process and the monitoring of the evolution of their concentration over the storage time were carried out. In this way, essential information about the effect that hydroxytyrosol acetate provokes on the oxidation of this oil rich in omega-6 polyunsaturated acyl groups, has been obtained. It has also been shown that the enrichment of sunflower oil with this antioxidant under the conditions tested does not prevent the oxidation process but slows it down, affecting the entire oxidation process. Full article

Olive pomace (OP) is a valuable food byproduct that contains natural phenolic compounds with health benefits related to their antioxidant activities. Few investigations have been conducted on OP from the United States while many studies on European OP have been reported. OP of Arbequina, the most common cultivar from California, was collected and extracted by water, 70% methanol and 70% ethanol, followed by purification using macroporous absorbing resin. Results showed that the extractable total phenolic content (TPC) was 36–43 mg gallic acid equivalents (GAE)/g in pitted, drum-dried defatted olive pomace (DOP), with major contributions from hydroxytyrosol, oleuropein, rutin, verbascoside, 4-hydroxyphenyl acetic acid, hydroxytyrosol-glucoside and tyrosol-glucoside. Macroporous resin purification increased TPC by 4.6 times the ethanol crude extracts of DOP, while removing 37.33% total sugar. The antioxidant activities increased 3.7 times Trolox equivalents (TrE) by DPPH and 4.7 times TrE by ferric reducing antioxidant power (FRAP) in the resin purified extracts compared to the ethanol crude extracts. This study provided a new understanding of the extraction of the bioactive compounds from OP which could lead to practical applications as natural antioxidants, preservatives and antimicrobials in clean-label foods in the US. Full article