Synthesis and biological activity of α-methylene-γ-lactones as new aroma chemicals

Seven kinds of alpha -methylene-gamma -lactones with an alkyl group at the C-4 position were synthesized according to a previously described method, with yields of 28-34%. These alpha -methylene-gamma -lactones had characteristic and unique odors. All alpha -methylene-gamma -lactones added a roast-like odor to materials. The antimicrobial effects of alpha -methylene-gamma -lactones were investigated by using a paper disk diffusion method. The results showed the alpha -methylene-gamma -lactones inhibited the growth of three bacteria (Staphylococcus aureus, Escherichia coli, and Pseudomonas fluorescens) and two fungi (Saccharomyces cerevisiae and Aspergillus niger). In particular, alpha -methylene-gamma -undecalactone and alpha -methylene-gamma -dodecalactone exhibited potent inhibition of the growth of these microorganisms compared to butyl p-hydroxybenzoate as standard antibiotic. The umu test revealed that the alpha -methylene-gamma -lactones suppressed the SOS-inducing activity of three mutagens, furylfuramide, UV irradiation and Trp-P-1, respectively. The antimicrobial effects and the suppressive effects of SOS induction by alpha -methylene-gamma -lactones had a tendency to intensify as the number of carbons in the side chain increased.