Abstract
Three new isopimarane diterpenes 7β-hydroxy-19α-methylmalonyloxy-isopimara-8(14),15-diene (1), 7β-hydroxy-14-oxo-isopimara-8(9),15-dien-19oic acid (2), and 7β-hydroxy-14-oxo-19α-methylmalonyloxy-isopimara-9(11),15-diene (3) in addition to the known compounds isopimaric acid (4), 7oxo-13-epi-pimara-14,15-dien-18oic acid (5), 7oxo-13-epi-pimara-8,15-dien-18oic acid (6), and 6β-hydroxyisopimaric acid (7) were isolated from the hexane extract of Rhizoclonium hieroglyphicum. The structures of compounds 1–7 were established by 1D and 2D NMR techniques. The isolated diterpenoids were screened for antimicrobial activity against gram-positive and gram-negative bacteria and yeast strains.