Sesquiterpenoids from Curcuma phaeocaulis

Abstract

as by comparison of their data with the published values. Among them, compounds 1 and 2 were isolated as constituents of C. phaeocaulis for the first time. The dried rhizomes of C. phaeocaulis (6 kg) were extracted with 95% MeOH overnight at room temperature. The MeOH extract (294 g) was then suspended in water (2 L), and partitioned with hexane (2 L 3), EtOAc (2 L 3), and n-BuOH (2 L 3), sequentially. The hexane fraction (147 g) was subjected to silica gel column chromatography (CC) eluted with gradient mixtures of hexane–EtOAc (100:10:1) to afford 14 fractions (FI–FXIV). Fraction FIII (21 g) was subjected to silica gel CC eluted with hexanes–CH 2 Cl 2 (9:10:1), yielding germacrone (0.19 g) and 15 subfractions (FIII-1–FIII-15). Subfraction FIII-3 (2.4 g) was separated by silica gel CC eluted with gradient mixtures of MeOH in CH 2 Cl 2 (01%), affording 10 subfractions (FIII-3-1– FIII-3-10). Subfraction FIII-3-2 (320 mg) was subjected to reversed-phase CC eluted with an isocratic mixture of MeOH–H 2 O (1:1), yielding curdione (30 mg). Subfraction FIII-3-3 (140 mg) was purified by preparative HPLC using an isocratic mixture of MeOH–H 2 O (7:3, 3.5 mL/min) as a solvent system to afford 1 (t R 78.8 min, 49 mg). Subfraction FIII-5 (5 g) was subjected to reversed-phase CC eluted with an isocratic mixture of MeOH–H 2 O (4:1), furnishing (4S,5S)-(+)-germacrone-4,5-epoxide (50 mg), curzerenone (2.55 g), and (S)-(+)-ar-turmerone (120 mg). Subfraction FIII-7 (3 g) was subjected to reversed-phase CC eluted with gradient mixtures of MeOH–H 2 O (4:1) and then purified by preparative HPLC using an isocratic mixture of MeOH–H 2 O (7:3, 3.5 mL/min) as a solvent system to afford furanodienone (t R 52.0 min, 30 mg). Subfraction FIII-11 (200 mg) was subjected to preparative HPLC using an isocratic mixture of MeOH–H 2 O (75:35, 3 mL/min) as a solvent system, yielding isofuranodienone (t R 72.7 min, 10 mg) and 2 (t R 76.0 min, 1 mg).