Secondary Metabolites And Bioactivities From Two Deep-Sea-Derived Fungi

Deep-Sea extraordinarily harsh conditions necessitate fungi regulating biosynthetic gene which may lead to express unique secondary metabolites to adapt to their habitat environments. So, deep-sea fungi are expected to have a higher probability of containing structurally novel metabolites. These new bioactive metabolites are important in drug discovery and development. In order to search for new novel compounds with potent bioactivities, a study on two deep-sea-derived fungi was carried out. Studies include isolation and screen fungal strains, purification and identification metabolites, bioactivities evaluation, discussion the biogenetical relationships and the mechanism of compound 23 to influenza viruses.43 fungi were isolated from 16 sediments collected from deep sea. Using antibacterial bioactive screen and 1H NMR, HPLC, TLC chemical screen, two deep-sea fungi, Spiromastix sp.F19 and Eutypella sp. F1, were selected as aimed strains for further sturdy.Chemical constituents and bioactivities of Spiromastix sp.F19 were studied. From the ethyl acetate extracts,61 compounds, involving 57 new compounds, were isolated. Based on X-ray, NMR, HRESIMS and chemical conversion, structures of all isolated compounds were identified. The structural patterns are classified into 19 depsidones (1-19); 13 benzofuranones (20-32); 11 polyphenols (35-45); 4 guaiane-type sesquiterpenoids (46-49); 2 isocoumarins (50,51); 2 isobenzothiazoles (52,53); 6 chain ployketides (54-59); 4 benzol derivatives (33,34,60,61). Except for four benzol derivatives, other 57compounds are new. Bioactivities evaluation:1) Depsidones exhibited significant inhibition against G+bacteria. Subsquently, depsidones were tested against multidrug-resistant bacteria. Compound 14 displayed potent inhibition MRSA, MRSE and VRE better than clinical medicine levofloxacin. 2) Seven benzofuranones strongly inhibited influenza viral activities with IC50 ranging from 6-40 μM, positive control oseltamivir was 10.0μM. Compound 23, the most potent benzofuranone, inhibited H1N1 with IC506 uM. Mechanistic studies suggested 23 targets virus entry and replicaton with HA and replicase simultaneously as the potential targets.3) Polyphenols 35-37 showed potent inhibitory effects against seven indicator strains with MIC values ranging from 0.25-4 μg/mL. Especial compounds 35 and 37showed strong inhibition activities with MIC ranging from 0.25-0.5μg/mLStudy on secondary metabolites and bioactivities of another deep-sea-fungus Eutypella sp. F1. Using repeatedly chromatography over silica gel, Sephadex LH20, ODS, and semi-preparative HPLC,93 compounds (62-154) were isolated from the ethyl acetate extracts, of which 67 are new compounds. These metabolites are including 29 eremophilane-type sesquiterpenoids (62-90); 2 eudesmane-type sesquiterpenoids (91,92); 8 new bergarnotane-type sesquiterpenoids (93-100); 3 unprecedented skeleton sesquiterpenoids (101-103); 6 new bisabolane-type sesquiterpenoids (104-109); 38 thiodiketopiperazines (113-150,20 compounds are new). Anti-HIV bioactivities screen:EtOAc extracts and 10 fractions (10 μg/mL) which divided from extracts were evaluated their anti-HIV activities. EtOAc extracts and fr7 showed inhibition rate 46.26% and 99.61% respectively. In fr7, thiodiketopiperazines were main products. So, we deduce that thiodiketopiperazines excert potent anti-HIV activity. Pure thiodiketopiperazines against HIV assay are underway.In this study,154 compounds were isolated and identified from the two deep-sea-derived fungi, of which 124 compounds are new. We first report secondary metabolites from the fungal genus Spiromastix sp.; Thiodiketopiperazines were first isolated from Eutypella sp.; We firstly use methanolysis depsidones under alkaline conditions to identify their structures. In anti-multidrug-resistant bacterial assay, we found compound 14 selective potent inhibit MRSA, MRSE and VRE. So,14 may become promising lead compounds for treatment of Gram-positive related diseases. Compounds 35,37 exhibiting potent broad-spectrum antibacterial activities suggest that they have great potential to be development as a new drug for treating bacterial infection diseases. In anti-virus assay, Compound 23 showed strongly inhibited influenza viral activities. Mechanistic studies suggested 23 targets virus entry and replicaton. So, it may a new lead compound for development of potential inhibitors of influenza viruses with dual targets. Three unprecedented skeleton sesquiterpenoids (101-103) were isolated from Eutypella sp. F1. Our research prove that deep-sea fungi have potent capability to produce novel bioactivity secondary metabolites. This study provided some marine-derived novel compounds for discovering new antibacterial and antiviral drugs.