Three novel terpenoids from the rhizomes of Curcuma longa

Investigation of the EtOH extract of the rhizomes of Curcuma longa led to the isolation of two new sesquiterpenes, 2-methoxy-5-hydroxybisabola-3,10-diene-9-one (1) and 2,8-epoxy-5-hydroxybisabola-3,10-diene-9-one (2), one new monoterpene, 2-(2,5-dihydroxy-4-methylcyclohex-3-enyl)propanoic acid (3), together with five known sesquiterpenes (4-8). Among the known compounds, bisacurone A (5) and 4-methylene-5-hydroxybisabola-2,10-diene-9-one (6) were isolated from C. longa and genus Curcuma for the first time, respectively. Their structures were established on the basis of various spectroscopic analyses including HR-ESI-MS, 1D and 2D NMR, IR spectra, and by comparison of their spectral data with those of related compounds.