Chemical studies on the root of Heracleum candicans Wall.

Two new alkyl coumarins, isophellodenol C (1) and candinol A (2); four new spirobifuranocoumarins, candibirins B-E (3-6); and two trifuranocoumarins, canditririns A and B (7 and 8), were isolated from the roots of Heracleum candicans Wall. Their structures were established using chemical and spectral means.

Candibirin A, a furanocoumarin dimer isolated from Heracleum candicans WALL.

Candibirin A [systematic name: 9,9'-(1,4-dioxane-2,5-diyldimethylenedioxy)di(7H-furo[3,2-g]chromen-7-one)], a new furanocoumarin dimer, was isolated from Heracleum candicans WALL. (1)H NMR and MS spectra had indicated that the title compound was a dimer of heraclenin or heraclenol, but the linkage structure and its chirality were undetermined. The dioxane linkage, having the R,R configuration, has now been elucidated from dimethyl sulfoxide-solvated crystals, C(32)H(28)O(10).