Bioactive polyphenols from muscadine grape and blackcurrant stably concentrated onto protein-rich matrices for topical applications

Synopsis Objectives Natural botanical agents that are antimicrobial, or that modulate skin hyperpigmentation via tyrosinase inhibition, are increasingly sought in the cosmetic industry. Methods In this study, an efficient tactic is demonstrated for concentrating and stabilizing skin-beneficial bioactive compounds from muscadine grape and blackcurrant juice or muscadine pomace, into hemp flour (HF), hemp protein isolate (HPI) and soy protein isolate (SPI) matrices suitable for cosmetic applications. Results Anthocyanins were most efficiently captured from blackcurrant juice into HF (8.39 mg g^-1). HPI most effectively captured total phenolics from muscadine pomace (72.32 and 77.32 mg g^-1 from Noble and Carlos, respectively), while the three matrices incorporated highest levels of ellagic acid, gallic acid, and PAC B1 from Noble muscadine grape juice. The enriched matrices demonstrated effective in vitro inhibition of tyrosinase (up to 57.29% for blackcurrant juice-HPI matrix), and in general, juice sources provided greater inhibition on L-dopamine oxidation by tyrosinase than pomace sources. The polyphenol-enriched matrices effectively inhibited microbial proliferation in a screening assay against Staphylococcus aureus bacteria, whereas untreated HF, HPI or SPI did not inhibit bacterial growth. Conclusion The technology of combining and stably concentrating phytoactive polyphenols with proteins has potential use for cosmetic topical applications.