Study On The Secondary Metabolites From Two Endophytic Fungal Strains HNWSW-1 And HNWSW-2 Of Mangrove Plants

Mangroves, with the name of "sea forest",are the trees and shrubs which growed in saline coastal habitats in thetropics and subtropics. It is a special marine ecosystem and contains a wealth of microbial resources. In order to adapt the special environment with subjecting to seawater flooding periodically, mangrove plants and its associated microbes may have their unique metabolic mechanism. Thus, they could produce secondary metabolites with novel structures and diverse biological activities. Mangrove endophytic fungus are the main components of mangrove microorganisms and the second largest groups of marine fungi. In recent years, a series of monomeric compounds with novel structures and biological activities have been found from the secondary metabolites of mangrove endophytic fungus, so it has become one of the research focus.Ceriops tagal is a plant of Rhizophoraceae of Ceriops, and Xylocarpus granatumis a plant of Maliaceae of Xylocarpus. In the early stage of the research, hundreds of endophytic fungus strains were isolated from the roots, stems and leaves of Ceriops tagal and Xylocarpus granatum, and a number of monomeric compounds were isolated from their secondary metabolites which have new structures and a variety of bioactivitise. On this basis, fermention optimization was carried out by cultivated the aim fungal strains HNWSW-1 and HNWSW-2 of mangrove plants in different media combining with methods of chemistry (TLC and HPLC-UV analysis) and biology, and the media which produce the secondary metabolites most intereting was choosed for large scale cultivation.Two endophytic fungus were identified by molecular biological methods. The secondary metabolites from the endophytic fungus were isolated and purified by various column chromatographic techniques and the structures of the compounds were identified through a combined analysis of physicochemical properties and spectroscopic evidence. The anti-bacterial, anti-acetylcholinesterase activities, anti-?-glucosidase activities, cytotoxic activities and the inhibitory activity of the Panagrellus redivivusin vitro of the compounds were tested.Thirteen compounds were isolated from the secondary metabolites of marine fungi HNWSW-1. Their structures were determined as: cladoconvolutin A (1), cladoconvolutin B (2), cladoconvolutin C (3), (10S)-3-(3, 3-dichloro-2-hydroxy-propyl)-8-hydroxy-6-methoxy-isochromen-1-one (4), (E)-7-hydroxy-5-methyl-2-(prop-1'-en-1'-yl)-4H-chromen-4-one (5), (11R)-2,4,7-trihydroxy-6-(1-hydroxyethyl)anthracene-9,10-dione (6),(5S)- 5-hydroxy-7-(4"-hydroxy-3"-methoxy-phenyl)-1 -phenyl-3-heptan-one (7), (7R)-methoxypurpuride (8), (5aS,9S,9aS)-1,3,4,5,5a,6,7,8,9,9a-decahydro-6,6,9a-tri- methyl-3-oxonaphtho[ 1,2-c]furan-9-yl N-acetyl-L-valinate (9), 2-chloro-3, 5-dimethoxybenzyl alcohol (10), 2-chloro-5-methoxy-3-methylphenol (11), ergosterolperoxide(3?- hydroxy-5,8-epidioxyergosta-6, 22-diene) (12), ilicicolin H (13), compounds 1-6 were new compounds. Compounds 7-13 were known structure of compounds, and 1HNMR and 13CNMR data of compound 11 was reported for the first time.Seven compounds were isolated from the secondary metabolites of marine fungi HNWSW-2. Their structures were determined as: xylquinone (14), xylalkaloid (15),5-(1'-hydroxy-3' -methylpentyl)-2-(hydroxymethyl)-4H-pyran-4-one (16 and 17),astropyrone (18), guaidiol (19), indazole (20), compounds 14-17 were new compounds.Compound 20 was isolated from the secondary metabolites of the microorganism for the first time.Bioassay results showed that compounds 7 and 10 exhibited anti-bacterial activities;Compounds 7-10 displayed the inhibitory activities against the Panagrellus redivivus;Compounds 6-10, 13 and 18-19 revealed the inhibitory activities against acetylcholinesterase. Compounds 1,6 and 18 showed anti-?-glucosidase activities;Furthermore, compounds 1 and 13 displayed cytotoxic activity against BEL-7402 and HeLa.In this study, two endophytic fungus from mangrove were studied, and we found that parts of monomeric compounds from the secondary metabolites had the anti-nematode activities,which provided research basis for the study of agricultural nematode inhibitors.