ANTIMICROBIAL PHENOLIC-COMPOUNDS FROM 3 SPANISH HELICHRYSUM SPECIES

From the aerial parts of Helichrysum decumbens, H. stoechas and H. italicum, antibacterial (anti-gram positive) phloroglucinol and acetophenone derivatives have been identified. Phloroglucinol derivatives showed eight times more antibacterial activity (MIC 12.5 μg/ml) than the acetophenone derivative, but the latter was also active against gram negative bacteria (Escherichia coli). Both types of compounds showed antifungal activity against different fungi (Penicillium sp., Cladosporium herbarum and Phythophtora capsicii) but proved to be inactive against Aspergillus species at MIC of 100 μg/ml. These results confirm that the co-occurrence of acidic phenolic hydroxyls and lipophilic residues is an important chemical feature for the expression of antifungal activity. © 1990.