Antimicrobial Activity of Drimanic Sesquiterpene Compounds from Drimys winteri against Multiresistant Microorganisms.

In this work, a group of ten sesquiterpene drimanes, including polygodial ( 1 ), isopolygodial ( 2 ), and drimenol ( 3 ) obtained from the bark of Drimys winteri F. and seven synthetic derivatives, were tested in vitro against a unique panel of bacteria, fungi, and oomycetes with standardized procedures against bacterial strains K. pneumoniae , S. tiphy , E. avium , and E. coli. The minimum inhibitory concentrations and bactericidal activities were evaluated using standardized protocols. Polygodial ( 1 ) was the most active compound, with MBC 8 μg/mL and MIC 16 μg/mL in E. avium ; MBC 16 μg/mL and MIC 32 μg/mL in K. pneumoniae ; MBC 64 μg/mL and MIC 64 μg/mL in S. typhi ; and MBC 8 μg/mL and MIC 16 μg/mL and MBC 32 μg/mL and MIC 64 μg/mL in E. coli , respectively. The observed high potency could be attributed to the presence of an aldehyde group at the C8-C9 position. The antifungal activity of 1 from different microbial isolates has been evaluated. The results show that polygodial affects the growth of normal isolates and against filamentous fungi and oomycetes with MFC values ranging from 8 to 64 μg/mL. Sesquiterpene drimanes isolated from this plant have shown interesting antimicrobial properties.