Identification of polyphenols using UPLC-QTOF MS/MS, in-vitro photoprotective and antiaging activities of brown macroalga Padina tetrastromatica

Abstract

Brown algae produce several bioactive compounds including unique secondary metabolites like polyphenols, which are known for various pharmacological activities. The present study focused on the cosmeceutical properties of polyphenol-rich fraction from brown macroalga (Padina tetrastromatica). Two fractions (ethyl acetate and aqueous) were obtained by liquid-liquid purification. Total phenolic and phlorotannin contents were assessed by in-vitro methods (Folin-Ciocalteu test and 2,4-dimethoxybenzaldehyde assay). Antioxidant properties were assessed through 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, nitric oxide radical scavenging activity, and ferric-reducing antioxidant power assay. Ethyl acetate fraction showed high radical scavenging activity and was used for in-vitro photoprotective assays, cell viability tests, and anti-aging related enzyme inhibition tests (anti-tyrosinase, anti-elastase, anti-collagenase). Ethyl acetate fraction showed potential ultraviolet A absorption and a strong sun protection factor (SPF) value and was not toxic to the human skin cell line up to a concentration of 100 μg mL−1. Interestingly, this fraction also showed a strong tyrosinase inhibition and a significant inhibition of elastase and collagenase enzymes. Major polyphenols including phlorotannins present in the fraction were identified using Fourier transform infrared (FTIR) spectroscopy, Ultra pressure liquid chromatography (UPLC)-quadrupole-time of flight (QTOF) mass spectrometry (MS) and NMR spectroscopy. The findings suggest the ethyl acetate fraction of P. tetrastromatica as a promising source for cosmetic use with photoprotection and anti-aging properties.