Noropacursane: A New Nortriterpenoid from the Methanolic Extract of Carissa opaca

Aerial parts of Carissa opaca have been investigated for the search of new bioactive secondary metabolites and a new nortriterpenoid: noropacursane (1) has been isolated together with three known compounds, namely, 6-methoxy-7-hydroxycoumarin (2), lupeol (3) and 4-ketopinoresinol (4). The structure of the new compound was established by 1D ( 1H-, 13C-NMR), 2D-NMR (HMBC, HSQC, COSY and NOESY) and high resolution mass spectrometry (HR-EI-MS), where as the structures of the known compounds were elucidated through 1D-NMR, mass spectrometric analysis and compared with the reported data in literature. All the isolates were evaluated for their biological potential against the enzymes acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and lipoxygenase (LOX) as well as for DPPH free radical scavenging assays. Compound 4 was found active against DPPH radical scavenging activity and BChE with IC 50 values of 83.41±0.17 and 101.81±0.24 µM, respectively, whereas compound 2 inhibited enzyme LOX with IC 50 value of 102.25±0.17 µM.