Helvolic acid, an antibacterial nortriterpenoid from a fungal endophyte, sp. of orchid endemic to Sri Lanka.

An endophytic fungus was isolated from surface sterilized leaf segments of an orchid endemic to Sri Lanka, and was identified as sp. by morphological characters and DNA sequencing. Bioassay-guided chromatographic fractionation of the organic extract of a laboratory culture of this fungus led to the isolation of the known antibacterial helvolic acid. Helvolic acid was active against the Gram-positive bacteria, [minimal inhibitory concentrations (MIC), 2 μg mL] and methicillin-resistant (MIC, 4 μg mL).