Syntheses and antibacterial activities of 4 linear nonphenolic diarylheptanoids

Four linear nonphenolic diarylheptanoids were synthesized and their antibacterial activities were studied. (S)-2-Me-CBS-catalysed reduction of alnustone with BH3.SMe2 gave (R) (-)(4E,6E)-1,7-diphenylhepta-4,6-dien-3-ol, a natural product. Reduction of alnustone with Na in t-BuOH at -15 degrees C under NH3 atm gave ( E)-1,7-diphenylhept-5-en-3-one as a Birch-type reduction product. t-BuOK catalysed condensation of benzalacetone with propionyl chloride gave (4Z,6E)-5-hydroxy-1,7-diphenylhepta-4,6-dien-3-one, a natural product. (1E,4Z,6E)-5-Hydroxy-4-phenethyl-1,7-diphenylhepta-1,4,6-trien-3-one, a curcuminoid, was synthesized starting from pentan-2,4-dione in 3 steps. The synthesized chemical compounds were applied against 2 gram-positive bacteria (Bacillus cereus and Arthrobacter agilis), 4 gram-negative bacteria (Pseudomonas aeruginosa, Xanthomonas campestris, Klebsiella oxytoca, and Helicobacter pylori), and 1 yeast (Candida albicans) by the disc diffusion method. All of the synthesized compound exhibited different degrees of antimicrobial activity at concentrations between 20-100 mu g/disc against the test organisms.