Abstract:
The preliminary biological activity screening from seventeen Thai plants revealed that the dichloromethane extract from the heartwood of Xylia xylocarpa exhibited high antifeedant activity against the common cutworm, Spodoptera litura and low phytotoxicity against lettuce seedlings. The chemical constituents investigation disclosed eight pure compounds and two mixtures. By means of physical properties, chemical reactions and spectroscopic evidences, the structures of isolated compounds could be deduced as 8(14),15-isopimaradiene, 8(14),15-isopimaradiene-3-one, 3-oxomanoyl oxide, 8(14),15-isopimaradiene-3α-ol, 8(14),15-isopimaradiene-3β-ol, 8(14),15-isopimaradiene-18-oic acid, β-sitosterol and 8(14),15-isopimaradiene-3,18-diol, including two mixtures: a mixture containing 8(14),15-isopimaradiene-3-one and 7,15-isopimaradiene-3-one and a mixture of 8(14),15-isopimaradiene-3β-ol, 7,15-isopimaradiene-3β-ol and 8(14),15-isopimaradiene-18-ol. Among isolated substances, 8(14), 15-isopimaradiene-18-oic acid exhibited the highest antifeedant activity against S. litura at ED₅₀ = 2.75x10⁻⁷ mol/cm². In addition, all of the isolated compounds showed strongly feeding inhibitory against termites and gave negative tests for phytotoxicity against lettuce seedlings.
