Prenyl-butyrylphloroglucinol and kaurenoic acid: Two antibacterial compounds from Helichrysum kraussii

An ethnobotanical lead has resulted in the identification of prenyl-butyryl phloroglucinol (1) from the aerial parts of Helichrysum kraussii Schultz Bi p. (Asteraceae). Characterisation was achieved by H-1- and C-13-NMR spectro scopy and EI-MS. Kaurenoic acid (2) was also isolated and identified by CC- MS. Both 1 and 2 were shown to have antibacterial activity against five Gra m + and two Gram - bacteria. The minimum inhibitory concentration (MIC) of 2 was particularly potent against E. coli at 1 mu g/ml.