A Study on Synthesis and Antioxidant Activity Comparison of Novel Stilbenebenzamide Compounds

Stilbene phytalexis (1,2-diphenyloethylen) and benzamide are beneficial for human health. To increase the stilbene ring activity, a new series of its derivatives containing benzamide structure was synthesized and evaluated for their in vitro antioxidant power.

1H nuclear magnetic resonance, mass spectroscopy, and chromatographic analyses were used to confirm the successful synthesis. The antioxidant properties were determined by the elimination of O₂˙-, HO˙ , DPPH˙ , ABTS+˙ radicals, total antioxidant status (TAS) and the ferric reducing antioxidant activities (TAC) measurements.

Stilbenebenzamide compounds showed a wide spectrum of antioxidant ability; however, their total antioxidant power was weaker than those of butylated hydroxytoluene (BHT), ascorbic acid, and resveratrol. The highest antiradical activity towards O₂˙ and HO˙ was shown by the compounds with structures containing amine group (SBEBA, SBA) (O₂˙: 37.7 - 38.0% and 40.8 - 43.5%, HO˙ : 29.8%, 28.7% inhibition, respectively) at1.25 mM concentration. The antiradical power of SBEBA (0.29) in DPPH˙ assay was lower than those of resveratrol (1.83), ascorbic acid (3.63) and BHT (4.09). The TAS values of the synthesized compounds ranged from 152.9±5.3 to 240.2±6.7μM trolox equivalent/gram (TE/g) and were much lower than those of BHT (1304±43.0), reservatrol (1360±29.0) and ascorbic acid (2782±39.7) μM TE/g. Similarly, the TAC values ranging from 29.7±0.9 to 41.5±1.6 μM TE were weaker than that of resveratrol (239.2 ±6.7 μM TE/g).

The results suggest that the presence of the hydroxyl group in the stilbene ring should be considered in the further design of stilbenebenzamide compounds to enhance their antioxidant activity.