Introduction:
Phenols are a large family of natural and synthetic compounds with known antioxidant activity. The aim of this study was to preform an in vitro screening of natural and natural-like phenol monomers and their C2-symetric dimers (hydroxylated biphenyls) in order to identify those representatives which 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 indicated significant antioxidant activity (compounds 6, 7, 12, 13, 26, and 27) whereas 4 indicated extremely weak antioxidant activity (compounds 2, 29, 30, and 31). Within the 36 compounds comprising of zingerone, dehydrozingerone, aurone, chalcone, 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 the synthesis of novel polyphenolic molecules with potential therapeutic applications.