Photoprotective effect of coumarin and 3-hydroxycoumarin in sea urchin gametes and embryonic cells

Phenolics as Active Ingredients in Skincare Products: A Myth or Reality?

Phenolic compounds, with their diverse biological activities, are widely explored as cosmetic ingredients with photoprotective, antioxidant, anti-inflammatory, and anti-hyperpigmentation properties, offering a multitargeted approach to combat photo-induced skin aging. The study analyzed 1299 cosmetic products from 2021 to 2024 to understand the market impact of phenolic compounds and their mechanism of action against photo-induced skin damage. A total of 28 active phenolic compounds were identified and the prevalence of phenolics was 13.2% in anti-aging products, 5.2% in sunscreens and 4.8% in aftersun products. Bakuchiol and polyphenols, such as resveratrol, chrysin, and hesperidin methyl chalcone, were found in anti-aging products. Sunscreens and aftersun products were counted with ferulic and caffeic acids, and salicylic acid, respectively. Antioxidant activity was found to be the primary mechanism of action of phenolic compounds by scavenging reactive species, thus mitigating oxidative stress. Ferulic and caffeic acids, chrysin, and glucosylrutin can also absorb UV radiation, acting preventively against solar-induced skin damage. This study provides insights into the limited use of phenolic compounds in commercial cosmetics, despite their diverse biological activities, and suggests potential barriers to wider use in skin and sun care products.

Defense potential of secondary metabolites in medicinal plants under UV-B stress

Ultraviolet-B (UV-B) radiation has, for many decades now, been widely studied with respect to its consequences on plant and animal health. Though according to NASA, the ozone hole is on its way to recovery, it will still be a considerable time before UV-B levels reach pre-industrial limits. Thus, for the present, excessive UV-B reaching the Earth is a cause for concern, and UV-B related human ailments are on the rise. Plants produce various secondary metabolites as one of the defense strategies under UV-B. They provide photoprotection via their UV-B screening effects and by quenching the reactive oxygen- and nitrogen species produced under UV-B influence. These properties of plant secondary metabolites (PSMs) are being increasingly recognized and made use of in sunscreens and cosmetics, and pharma- and nutraceuticals are gradually becoming a part of the regular diet. Secondary metabolites derived from medicinal plants (alkaloids, terpenoids, and phenolics) are a source of pharmaceuticals, nutraceuticals, as well as more rigorously tested and regulated drugs. These metabolites have been implicated in providing protection not only to plants under the influence of UV-B, but also to animals/animal cell lines, when the innate defenses in the latter are not adequate under UV-B-induced damage. The present review focuses on the defense potential of secondary metabolites derived from medicinal plants in both plants and animals. In plants, the concentrations of the alkaloids, terpenes/terpenoids, and phenolics have been discussed under UV-B irradiation as well as the fate of the genes and enzymes involved in their biosynthetic pathways. Their role in providing protection to animal models subjected to UV-B has been subsequently elucidated. Finally, we discuss the possible futuristic scenarios and implications for plant, animal, and human health pertaining to the defense potential of these secondary metabolites under UV-B radiation-mediated damages.

Structure-Activity Relationship Study of Hydroxycoumarins and Mushroom Tyrosinase

The structure-activity relationships of four hydroxycoumarins, two with the hydroxyl group on the aromatic ring of the molecule and two with the hydroxyl group replacing hydrogen of the pyrone ring, and their interactions with mushroom tyrosinase were studied. These compounds displayed different behaviors upon action of the enzyme. The two compounds, ar-hydroxylated 6-hydroxycoumarin and 7-hydroxycoumarin, were both weak substrates of the enzyme. Interestingly, in both cases, the product of the catalysis was the 6,7-hydroxycoumarin, although 5,6- and 7,8-isomers could also theoretically be formed. Additionally, both were able to reduce the formation of dopachrome when tyrosinase acted on its typical substrate, L-tyrosine. Although none of the compounds that contained a hydroxyl group on the pyrone ring were substrates of tyrosinase, the 3-hydroxycoumarin was a potent inhibitor of the enzyme, and the 4-hydroxycoumarin was not an inhibitor. These results were compared with those obtained by in silico molecular docking predictions to obtain potentially useful information for the synthesis of new coumarin-based inhibitors that resemble the structure of the 3-hydroxycoumarin.