Grape Cane Extracts as Multifunctional Rejuvenating Cosmetic Ingredient: Evaluation of Sirtuin Activity, Tyrosinase Inhibition and Bioavailability Potential

Grape canes are waste biomass of viticulture containing bioactive polyphenols valuable in cosmetics. Whereas several studies reported the cosmetic activities of E-resveratrol, only few described the potential of E-ε-viniferin, the second major constituent of grape cane extracts (GCE), and none of them investigated GCE as a natural blend of polyphenols for cosmetic applications. In this study, we considered the potential of GCE from polyphenol-rich grape varieties as multifunctional cosmetic ingredients. HPLC analysis was performed to quantify major polyphenols in GCE i.e., catechin, epicatechin, E-resveratrol, E-piceatannol, ampelopsin A, E-ε-viniferin, hopeaphenol, isohopeaphenol, E-miyabenol C and E-vitisin B from selected cultivars. Skin whitening potential through tyrosinase inhibition assay and the activation capacity of cell longevity protein (SIRT1) of GCE were compared to pure E-resveratrol and E-ε-viniferin. Drug-likeness of GCE polyphenols were calculated, allowing the prediction of skin permeability and bioavailability. Finally, the present data enabled the consideration of GCE from polyphenol-rich varieties as multifunctional cosmetic ingredients in accordance with green chemistry practices.

Mechanical stress rapidly induces E-resveratrol and E-piceatannol biosynthesis in grape canes stored as a freshly-pruned byproduct

Grape canes represent a promising source of bioactive phytochemicals. However the stabilization of the raw material after pruning remains challenging. We recently reported the induction of stilbenoid metabolism after winter pruning including a strong accumulation of E-resveratrol and E-piceatannol during the first six weeks of storage. In the present study, the effect of mechanical wounding on freshly-pruned canes was tested to increase the induction of stilbenoid metabolism. Cutting the grape canes in short segments immediately after pruning triggered a transient expression of phenylalanine ammonia-lyase (PAL) and stilbene synthase (STS) genes, followed by a rapid accumulation of E-resveratrol and E-piceatannol. The degree of stilbenoid induction was related to the intensity of mechanical wounding. Data suggest that a global defense response is triggered involving jasmonate signaling, PR proteins and stilbenoid metabolism. Mechanical wounding of freshly-pruned canes drastically shortens the time required to reach maximal stilbenoid accumulation from 6 to 2weeks.

Daily Preharvest UV-C Light Maintains the High Stilbenoid Concentration in Grapes

The fact that it is possible to induce stilbenoid synthesis in grapevine (Vitis vinifera) by UV-C light allows the possibility of stimulating grapevine phytoalexin production to increase disease resistance and immunity, and subsequently to limit the use of pesticides in vineyards. UV-C light was applied daily during three days before the harvesting of table grape variety Crimson seedless to study the accumulation of stilbenoid compounds during ripeness. The E-resveratrol concentration was monitored during daily preharvest UV-C light application and compared with that after a single application. Daily periodic preharvest UV-C light treatment showed a cumulative effect on grape stilbenoids. An 86-fold stilbenoid level increase (sum of E-resveratrol, E-piceatannol, ε-viniferin, E-piceid, isorhapontigenin, ω-viniferin, and Z-piceid) in grapes was achieved. The effects of UV-C light on stilbenoid in grape cane was also addressed for the first time. Stilbenoid oligomers such as hopeaphenol, ampelopsin A, and r-viniferin were quantified in cane samples. Quality grape parameters indicated an acceleration of ripening in UV-C samples.