Chemical Constituents from Rhizomes of Curculigo capitulata

Figure 1. Structures of compounds 1-9. The herb Curculigo capitulata (Lour.) Ktze is widely distributed in Southern and Southwestern China. It has been used as a tonic and a medicine for the treatment of dysmenorrhea and rheumatism. This species has been reported to be rich in phenolic compounds and norlignan compounds with skeletons Ph-C5-Ph, which have been found to possess some beneficial pharmacological effects, including anti-arrhythmic properties, antioxidant activity, and vasoconstrictor activity. Previously, we reported the chemical constituents from the rhizomes of C. capitulata collected in xishuangbanna region of Yunnan Province, China. To compare the chemical constituents' differences of the same Curculigo species belonging to different geographical distribution and climatic conditions, we investigated the rhizomes of C. capitulata collected in Napo region of Guangxi Province, China. Recently, we reported two novel norlignan derivatives with the rearranged skeletons, named as crassifoside I and sinensigenin C, from this species collected in Napo region of Guangxi Province, China. To further search more novel compounds, the minor constituents of this plant were investigated. This paper deals with the isolation and structure elucidation of one novel norlignan derivative, named as capituloside B (1), together with eight known compounds, curcapicycloside (2), capituloside (3), breviscaside B (4), crassifogenin C (5), breviscapin A (6), methyl-4-O-coumaroylquinate (7), orcinol glucoside (8) and 2,6-dimethoxy-benzioc acid (9), from its rhizomes as shown in Figure 1. Their structures were established by spectroscopic analysis, especially using 2DNMR techniques (H-H COSY, HMQC, HMBC, and NOESY) and comparisons of their data with literature values. Compounds 4-7 were isolated for the first time from this plant, and compound 7 was the first example isolated from the family.