Syntheses and antibacterial activities of 4 linear nonphenolic diarylheptanoids

Four linear nonphenolic diarylheptanoids were synthesized and their antibacterial activities were studied. $S $-2-Me-CBS-catalysed reduction of alnustone with BH$_{3}$.SMe$_{2}$ gave $R $ - 4$E$,6$E $-1,7-diphenylhepta-4,6-dien-3-ol, a natural product. Reduction of alnustone with Na in t-BuOH at -15 $^{\circ}$C under NH$_{3}$ 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 4$Z$,6$E $-5-hydroxy-1,7-diphenylhepta-4,6-dien-3-one, a natural product. 1$E$,4$Z$,6$E $-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 μg/disc against the test organisms.