Catunaregin and Epicatunaregin, Two Norneolignans Possessing an Unprecedented Skeleton from Catunaregam spinosa

Catunaregin (1) and epicatunaregin (2), two novel norneolignans with a unique O-bridged furopyran ring, together with three known neolignans, ficusal, balanophonin, and 5 ''-methoxy-4 ''-O-(8-guaiacylglycerol)buddlenol A, were isolated from the stem bark of Catunaregam spinosa. a Chinese mangrove associate. Their structures were elucidated by spectroscopic means, including two-dimensional NMR techniques. Compounds 1 and 2 exhibited moderate inhibition against the mammary cancer F10 cell line.