Antibacterial and antimutagenic activities of novel zerumbone analogues

•Two new compounds viz. azazerumbone 1 and azazerumbone 2 were synthesized.•Azazerumbone 2 showed better antibacterial and antimutagenic activity than azazerumbone 1.•Important structure–activity relationship has been delineated for these compounds.•Zerumbone and its analogues possess potential for use as nutraceuticals and in food preservation. Zerumbone, the key constituent of Zingiber zerumbet Smith, is a very important bioactive phytochemical. Two new compounds viz. azazerumbone 1 and azazerumbone 2 were synthesised by ZnCl2-catalysed Beckmann rearrangement of the zerumbone oxime. The structure elucidation of these analogues of zerumbone was carried out by 1D (1H NMR and 13C NMR) and 2D-NMR (COSY, HSQC and NOESY) spectral analysis. Studies on the antibacterial activity established that azazerumbone 2 had better activity than zerumbone. Among the tested bacteria, Bacillus cereus was the most sensitive and Yersinia enterocolitica was found to be the most resistant. These compounds exhibited strong protection against sodium azide induced mutagenicity of Salmonella typhimurium strains TA 98 and TA 1531. Azazerumbone 2 showed better antibacterial and antimutagenic activity than azazerumbone 1. The antibacterial and antimutagenic activities exhibited by zerumbone and its analogues demonstrate their potential for use as nutraceuticals and in food preservation.