Sinuhirtins A and B, two uncommon norhumulene-type terpenoids from the South China Sea soft coral Sinularia hirta

Two new uncommon norhumulene-type norsesquiterpenoids, namely sinuhirtins A (1) and B (2), along with two known norcaryophyllene-type norsesquiterpenoids (3 and 4), were isolated from the South China Sea soft coral Sinularia hirta. The structures and absolute configurations of the new compounds were determined by extensive spectroscopic data analyses, and computer-assisted methods including GIAO C-13 NMR and TDDFT-ECD calculations. A plausible biogenetic relationship of 1-4 was proposed. (C) 2019 Elsevier Ltd. All rights reserved.