UNUSUAL ANTIMICROBIAL COMPOUNDS FROM AEOLLANTHUS-BUCHNERIANUS

Using bioassay guided isolation, three novel 12 carbon polyoxygenated fatty acids and a novel abietane diterpene have been isolated from the the chloroform extract of aerial parts of Aeollanthus buchnerianus (L amiaceae). Rigorous spectroscopic methods were used for compound ident ification. (Z,Z)-8 zeta-acetoxy-5 zeta-hydroxydodeca-2,6-dienoic acid and (Z,Z)-5 zeta,8 zeta-dihydroxydodeca-2,6-dienoic acid inhibited the spore germination of Cladosporium cucumerinum (both with Minimum Inhi bitory Dose (MID) values of 1 mu g) and Aspergillus niger (MID 5 and 2 5 mu g respectively). Further, they also reduced the hyphal growth of Pythium ultimum. (Z)-5 zeta-hydroxy-6 zeta,7 zeta,8 zeta-triacetoxydod eca-2- dienoic acid exhibited short term inhibition of the growth of C ladosporium cucumerinum. The novel abietane diterpenoid, (rel)-14 alph a-acetoxyabiet-7-en-18-oic acid inhibited the growth of the gram posit ive bacteria Bacillus subtilis, Staphylococcus aureus and Streptomyces scabies (MIC values 80, 20 and 20 mu g ml(-1) respectively).