An acylated phloroglucinol with antimicrobial properties from Helichrysum caespititium

A new acylated form of a phloroglucinol with significant antimicrobial prop erties was isolated by bioactivity guided fractionation from Helichrysum ca espititium (Asteraceae). The structure elucidation, and conformation of the new phloroglucinol, 2-methyl-4-[2',4',6'-trihydroxy-3'-(2-methylpropanoyl) phenyl]but-2-enyl acetate, was established by high field NMR spectroscopic and MS data. The compound inhibited growth of Bacillus cereus, B. pumilus, B. subtilis and Micrococcus kristinae at the very low concentration of 0.5 mu g/ml and Staphylococcus aureus at 5.0 mu g/ml. Six fungi tested were si milarly inhibited at low MICs, Aspergillus flavus and A. niger (1.0 mu g/ml ), Cladosporium cladosporioides (5 mu g/ml), C. cucumerinum and C. sphaeros permum (0.5 mu g/ml) and Phytophthora capsici at 1.0 mu g/ml. (C) 2000 Else vier Science Ltd. All rights reserved.