Guaianolides from two subspecies of Amphoricarpos neumayeri from Montenegro

Abstract

Quantitative 1H NMR measurements revealed Δ 11(13) sesquiterpene γ-lactones as the main constituents (≥ 1% per weight of dried plant material) in the crude extracts of the aerial parts of Amphoricarpos neumayeri ssp. neumayeri and ssp. murbeckii from mountains Orjen and Visitor (Montenegro), respectively. Preparative silica gel chromatography afforded thirteen guai-11(13)-en-12,6α-olides, named amphoricarpolides (1-13), with the same relative (1αH,4βH,5αH, 7βH) configuration of the basic skeleton. The common structural feature of lactones 2-13 was 3β,15-dioxygenation pattern. The only exception was 1 (3-deoxyamphoricarpolide), containing a single oxygen substituent (15-OH). Eight of them exhibited an additional oxygen substituent, 9β-OH (5 and 6), 2α-OH (8-12), or 2α-OAc (13). Compound 7 was epoxydated at 10α(14)-position, whereas the remaining lactones contained a 10(14) double bond. © 2004 Elsevier Ltd. All rights reserved.