Synthesis and antioxidant properties of diphenylmethane derivative bromophenols including a natural product

摘要

Bromination of bis(3,4-dimethoxyphenyl)methanone ( 5 ) gave four products ( 6–9 ) with mono, di, tri, and tetra Br under different conditions. Reduction and demethylation reactions of product 9 with tetra Br were performed, consecutively and a natural product, 5,5′-methylene bis(3,4-dibrombenzene-1,2-diol) (1) , was obtained with a 53% yield. Five derivatives, ( 13–17) (bromophenols), of 1 were also synthesised. The antioxidant and radical scavenging activities of bromophenols 1 and 13–17 were determined by employing various in vitro assays such as 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH•), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS•+), N,N-dimethyl-p-phenylenediamine dihydrochloride radical cation (DMPD•+), and superoxide anion radical (O₂•-) scavenging, reducing ability determination by the Fe3+-Fe2+ and Cu2+-Cu+ cupric reducing antioxidant capacity (CUPRAC) transformation methods, hydrogen peroxide scavenging, and ferrous ion (Fe2+) chelating activities. Moreover, these activities were compared to those of synthetic standard antioxidant compounds such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), α-tocopherol, and trolox. The results showed that the synthesised bromophenols had effective antioxidant power.