Cajanuslactone, a new coumarin with anti-bacterial activity from pigeon pea [Cajanus cajan (L.) Millsp.] leaves

The bioassay-guided fractionation of the CHCl3 extract from pigeon pea leaves led to the isolation of a new natural coumarin, named as cajanuslactone (1), together with two known phytoalexins, pinostrobin (2) and cajaninstilbene acid (3). The structure of 1 was elucidated by interpreting spectroscopic data of UV, IR, MS, 1D and 2D NMR. It was determined as 7-hydroxy-5-O-methyl-8-(3-methyl-2-butylene)-4-phenyl-9,10-dihydro-benzopyran-2-one. The...