Anti-staphylococcal and cytotoxic compounds from Hyptis pectinata

Bioassay-guided fractionation of a CHCl3 extract prepared from the Mexican medicinal plant Hyptis pectinata led to the isolation of four pyrones, pectinolides A-C (1-3) and H (4). Activity was tracked using cultured KB cells. Multidrug-resistant strains of Staphylococcus aureus were sensitive to pectinolide H (4; KB > 20 mu g/mL) in the concentration range of 32-64 mu g/mL. The absolute stereochemistry of this new compound was established as 5S-[(4S-acetyloxy)-(1S-hydroxy)-2Z-octenyl]-2(5H)-furanone on the basis of spectral, chiroptical data and chemical correlation with pectinolide A (1). Mosher ester derivatives were used with pectinolide B (2) for confirmation of the 3 '-(S) absolute stereochemistry on the side chain chiral center of pectinolides A-C.