Novel A-seco-rearranged lanostane triterpenoids from Abies sachalinensis

Abstract

From the needles of Abies sachalinensis, novel rearranged lanostane type triterpenes, 1-4, were isolated along with a known triterpene (5). The structures of the new compounds, 1-4, were elucidated to be 3,4-seco-8-(14→13R)abeo-17,13-friedo-9β-lanosta-4(28),7,14(30),22Z, 24-pentaen-26,23-olide-3-oic acid, methyl 3,4-seco-8-(14→13R)abeo-17,13-friedo-9β-lanosta-4(28),7,14(30),22Z, 24-penten-26,23-olide-3-oate, 3,4-seco-8(14→13R)abeo-17,13-friedo-9β-lanosta-4(28),7,14,22Z,24-pe ntaene-26,23-olide-3-oic acid and methyl 3,4-seco-8(14→13R)abeo-17,13-friedo-9β-lanosta-4(28),7,14,22Z,24-pe ntaene-26,23-olide-3-oate, respectively, by means of spectral experiments, especially two dimensional NMR spectroscopy, such as 1H-detected multiple quantum coherence (HMQC), 1H-detected heteronuclear multiple bond connectivity (HMBC) and 1H-1H-correlation spectroscopy (COSY) experiments. These new compounds have novel structures containing A-seco, rearranged spiro structure and a γ-lactone conjugated with a diene. Some of these compounds showed potent antibacterial activity against gram positive bacteria.