Phytochemical constituents of Curcuma amada

Abstract

Dried ground rhizomes of C. amada (400 g) were subjected to repeated extraction using chloroform at room temperature (27 C) for 3 days. Removal of chloroform under reduced pressure gave 23 g of crude extract. This was subjected to column chromatography (CC) using gradient mixtures of petroleum ether and ethyl acetate of increasing polarity. Thus a total of 182 fractions of 100 ml each were collected and they were pooled together to get 19 fraction pools (FP 1–19) according to the similarities in TLC. FP-5 showing one major compound was subjected to Si gel CC and eluted with 2% EtOAc : petroleum ether to obtain (E)-labda-8(17),12-diene-15,16-dial (1) as the major constituent in 6.9 g, whose structure was confirmed based on spectral details reported in literature (Nakatani et al., 1994). FP-8 on purification using flash column chromatography using the solvents petroleum ether : ethyl acetate (95:5–90:10) yielded two compounds viz., b-sitosterol (7, 11 mg) and (E)-labda- 8(17)-13-diene-15,16-olide (2, 12 mg) identified based on spectral details and comparison with those reported in literature (Nakano et al., 1982; Zdero et al., 1991; Matsuda et al., 2002). FP-11 on further purification by preparative TLC using 20% ethyl acetate in petroleum ether afforded 59 mg of coronarin B (3), the structure of which was confirmed by comparison with the spectral values reported in the literature (Nakatani et al., 1994; Sy and Brown, 1997). FP-14 on purification using 25% EtOAc : petroleum ether afforded another UV active compound which was further purified by preparative thin layer chromatography using 30% EtOAc : petroleum ether to yield 135 mg of pure compound (4) thatwas confirmed as coronarin D based on spectroscopic data known in literature (Itokawa et al.,1988a). FP-17 was subjected to flash column chromatography using 30% EtOAc : petroleum ether to yield zerumin A (5, 13 mg) (Xu et al., 1996). Purification of FP-18 using 35% EtOAc : petroleum ether afforded curcumin (8, 6 mg) as yellow needles and zerumin B (6, 12 mg) as white needle like crystals (Xu et al., 1996).