Chemical Constituents Of The Indian Mangrove Xylocarpus Moluccensis

Mangrove plants are a kind of woody plants growing in intertidal zones of tropical,subtropical coastlines,which can be divided into two categories,true mangrove plants and semi mangrove plants.Plants of the genus Xylocarpus belong to the family Meliaceae.Limonoid is chemically distinctive natural product of the Xylocarpus,Due to complex cage structures and a series of biological activities such as antifungal,antitumor,antimalarial,anti-feeding insecticidal,limonoids have attracted considerable attention in this century.In this paper,26 compounds,which were isolated from the seeds of Xylocarpus moluccensis,collected in the mangrove swamp of Krishna estuary,Andhra Pradesh in India,were obtained by extraction with 95%ethanol,ethyl acetate extraction,silica gel column chromatography,C18 revised-phase column chromatography,and high performance liquid chromatography(HPLC).There were eight new compounds and eighteen known compounds.The structures of these compounds were determined by extensive NMR investigations,MS,UV,optical rotation spectrum,ECD spectrum,and single-crystal X-ray diffraction analyses(Cu Ka).Eight new compounds consist of three khayanolides,krishnolides E-G(6,10-11),three mexicanolides,krishnolides H-I(17,23)and compound 26,a derivative of trangmolin A,krishnolide J(24),and an andirobin,krishnolide K(25).Eighteen known compounds include xylomolin A1(1),2-hydroxy-3-Oisobutyrylproceranolide(2),methyl angolensate(3),2-hydroxy-6-deoxyswietenolide tiglate(4),hainanxylogranin S(5),moluccensin H(7),andirolide U(8),6-O-acetyl-6dehydroxymoluccensin T(9),krishnolide C(12),6-hydroxymexicanolide(13),moluccensin T(14),moluccensin R(15),angustinolide Ⅱb(16),proceranolide(18),utilin C(19),7-deacetoxy-7α-hydroxygedunin(20),krishnolide D(21),cipadesin N(22).Compounds 6,10-11,17,23-26 are new compounds.The absolute configurations of compounds 6,23-25 were unambiguously determined by single-crystal X-ray diffraction,whereas compounds 10-11 were assigned based on the comparison of their experimental ECD spectra with the known compound of krishnolide B.The results of activity screening showed that krishnolide F(10)had a significant agonistic effect on hPXR(human pregnane X receptor)in the concentration range of 1.0-10.0μM.Molecular docking revealed that krishnolide F could bind a helix near the region of the Helix 12 of hPXR.This is the first report of agonistic effects on hPXR of khayanolide.