Synthesis and antimicrobial and antifungal activities of cyclopentene Delta b, Delta b'-triketones and their methyl enol ethers

The natural cyclopentene Delta *b, Delta *b'-triketone coruscanone B and its methyl enol ether coruscanone A, metabolites of the higher plant Piper coruscans, in addition to 19 of their simple analogs have been synthesized. The antimicrobial activity of the synthesized compounds against Gram-positive (Staphylococcus aureus ATCC 21027) and Gram-negative (Escherichia coli ATCC 15034) bacteria, yeast (Sofale S-04 and Candida albicans KMM455), and fungi (Aspergillus niger KMM4634 and Fusarium oxysporum KMM4639) was studied. The nature and number of substituents at the 4- and 5-positions of the five-membered ring and also the nature of the substituent in the 2-position were found to have a profound effect on the level of activity and the spectrum of antimicrobial action of the tested compounds. Free Delta *b, Delta *b'ect. It is established that the level of activity and the spectrum of the antimicrobial action of coruscanone A and 2-(1-methoxyethylidene)-4,5-dichlorocyclopent-4-ene-1,3-dione are almost identical to those of the reference drug nitrofungin.