Studies On The Secondary Metabolites Of Endophytic Fungi Phomopsis Sp.

Previous investigations on fungi concerning the genus Phomopsis shown that these fungi could produce various structurally interesting and biologically active secondary metabolites, such as terpenoids, cytochalasins, steroids, and naphthoquinones. Aimed to discover more structurally unique and bioactive compounds, the secondary metablites of Phomopsis sp. were systematically studied.Phomopsis sp. was isolated from the medicinal plant Phyllanthus glaucus,which was chemically investigated by means of repeated gel chromatographies,including silica gel, ODS column, and Sephadex LH-20 chromatographies, as well as semi-preparative HPLC. This work led to the isolation and identification of 26 compounds, including 10 novel ones. Compounds 1 and 2 were novel steroid of13(14?8)abeo-8-methylergostane and sesquiterpenoid of 2,3-seco-protoilludanes,respectively. Compounds 3-10 were new sesquiterpenes and theirs derivatives. The structures of all known compounds were determined by comparing their NMR data and physicochemical parameters with those reported in the literatures, including:granulone B(11), radulone B(12), onitin(13), pterosin Z(14),2-(2,2,4,6-tetramethylindan-5-yl)ethanol(15), dehydrobotrydienol(16),7-hydroxy-10-oxodehydrodihydrobotrydial(17), dankasterones A(18),(14?,22E)-14-hydroxyergosta-4,7,22-triene-3,6-dione(19),(14?,22E)-14-hydroxy-ergosta-7,22-diene-3,6-dione(20),ergosta-4,7,22-diene-3,6-dione(21),(14?,22E)-9,14-dihydroxyergosta-4,7,22-triene-3,6-dione(22), calvasterol B(23),isocyathisterol(24), ergosta-4,6,8(14),22-tetraen-3-one(25), and ganodermasides D(26). The compounds 11-21, 24, 25 were isolated from Phomopsis sp. for the first time.The planar and relative structures of these new compounds were determined by analyzing their HRESIMS, IR, UV, as well as 1D and 2D-NMR spectroscopic data.The absolute configuration of compound 18 has been previously confirmed by X-raycrystallography in the literature, in this case, the absolute configuration of compound1 has been established by comparison of their electronic circular dichroic(ECD)spectra due to their structural similarities. Additionally, the absolute configuration of compound 3 and 4 have been established by a modified Mosher's method. In this study, the cytotoxic activities of 1 and 18-26 against a panel of human tumor cell lines were also evaluated in vitro, some of which exhibited moderate cytotoxic activities.