Allelopathic Activity of a Novel Compound and Two Known Sesquiterpene from Croton oblongifolius Roxb.

Abstract

Plant extracts with allelopathic activity and their related compounds have been investigated for a long time as an eco-friendly approach to sustainable weed management. Croton oblongifolius (Roxb.) is a traditional medicinal plant valued for its diverse source of bioactive compounds that have been used to treat various diseases. C. oblongifolius leaf extract was previously described to involve a number of allelochemicals. Therefore, we conducted this research to explore more of the allelochemicals in the leaves of C. oblongifolius. The leaf extracts showed significant inhibitory activity against two test plants, Lolium multiflorum (monocot) and Medicago sativa (dicot). The bioassay-directed chromatographic purification of the leaf extracts yielded three compounds, including one novel compound, identified using spectral data, as follows: (1) alpinolide peroxide, (2) 6-hydroxy alpinolide, and (3) 3-hydroxy-5-isopropyl-3-methyl-2,3-dihydro-1H-inden-1-one (a novel sesquiterpene). These compounds considerably limited the growth of L. sativum. The compound concentrations affecting a 50% growth limitation (IC50) of L. sativum varied from 0.16 to 0.34 mM. Therefore, these characterized compounds may be allelopathic agents that cause the allelopathy of C. oblongifolius.