Natural and natural-like polyphenol compounds: in vitro antioxidant activity and potential for therapeutic application

Introduction: Phenols are a large family of natural and synthetic compounds with known antioxidant activity. The aim of this study was to perform in vitro screening of natural and natural-like phenol monomers and their C2-symmetric dimers (hydroxylated biphenyls) in order to identify those representatives whose pharmacophores have the strongest antioxidant and the lowest prooxidant activity.

Material and methods: Antioxidative properties of 36 compounds (monomers and their C2-symmetric dimers) were evaluated in vitro. Different (red/ox) assays were used to measure their total oxidative potential (TOP), their total antioxidative capacity (TAC), the pro-oxidative-antioxidant balance (PAB) and total SH-group content (SHG) in a biologically relevant environment. The Pro-oxidative Score, Antioxidative Score and the Oxy Score were also calculated. Trolox, a water soluble analogue of α-tocopherol, was used as a positive control.

Results: In an assay consisting of pooled human serum, 6 of the 36 compounds showed significant antioxidant activity (compounds 6, 7, 12, 13, 26, and 27), whereas 4 showed extremely weak antioxidant activity (compounds 2, 29, 30, and 31). Within the 36 compounds comprising zingerone, dehydrozingerone, aurone, chalcone, and magnolol derivatives, in both monomeric and dimeric forms, the 2 compounds that indicated the highest antioxidant activity were dehydrozingerone derivatives (compounds 6 and 12). Trolox's activity was found between the strong and weak antioxidant compounds analysed in our study.

Conclusions: In this study selected dehydrozingerones were identified as good candidates for in-depth testing of their biological behaviour and for possible precursors for synthesis of novel polyphenolic molecules with potential therapeutic applications.