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Vestnik FEB RAS. 2018. № 6 Supplement
UDC 547.94+547.99 DOI: 10.25808/08697698.2018.202.6S.038
E.V. IVANETS, A.N. YURCHENKO, P.T.H. TRINH, SH.SH. AFIYATULLOV
Polyketides and echinulin-derivatives
from Vietnamese strain
of marine fungus Eurotium niveoglaucum
Key words: marine-derived fungi, secondary metabolites, polyketides, echinulin
The marine fungi are perspective sources of bioactive compounds, which are usually have a cytotoxic, antibiotic and anti-inflammatory activities [1]. Since marine environment possesses complicated conditions for living, marine fungi can produce compounds with unique structure. Recently cephalosporin C was the only marine fungal compound that used as a medical drug, but today fingolimod developed from myriocin is approved by FDA and EMA, and plinabulin, the synthetic derivative of diketopiperizine phenylahistin, is under phase III of clinical trials (according to clinicaltrials.gov) [3, 4].
The coast of Vietnam is an insufficiently studied area of South China Sea, because most researches are focus on the coast of China and Taiwan Strait. Besides the high level of bacterial colonization in tropical seas is a stimulating factor for marine fungi. Therefore, exploration of fungi of Vietnamese coast is topical.
In this research work the metabolite composition of marine-derived fungus Eurotium niveoglaucum (sediments, Nha Trang Bay, South China See) was investigated. The fungus was cultured on a rice medium in Erlenmeyer cobles at 25°C during 21 days. The fungal mycelium
* IVANETS Elena Vladimirovna -Graduate Student, YURCHENKO Anton Nikolaevitch - PhD, Researcher, AFIYATULLOV Shamil Sheribzyanovich - PhD, The Head of The Laboratory (G.B. Elyakov Pacific Institute of Bioorganic Chemistry, FEB RAS, Vladivostok, Russia); TRINH Phan Thi Hoai - Researcher (Nhatrang Institute of Technology Research and Application, Vietnam Academy of Science and Technology, Nha Trang, Vietnam, Graduate University of Science and Technology, Vietnam Academy of Science and Technology, Ha Noi, Vietnam). *E-mail: ev.ivanets@yandex.ru
The work was supported by RFBR grant № 18-34-00621 mol_a.
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dissolved in EtOH-H2O system (1:4), and sequentially extracted by hexane, EtOAc and BuOH. The EtOAc fraction was purified by column chromatography on SiO2, LH-20 and normal- and reversed-phase HPLC. As a result, two new polyketides niveoglaucines A-B (1-2) together with number of known metabolites such as (+)-cryptoechinulin B (3) and (-)-cryptoechinulin B (4), flavoglaucin (5), tetrahydoauroglaucin (6), isodihydroauroglaucin (7), 5-hydroxy-6-(3-metylbut-2-enyl)-2-(pent-1-enyl)benzofuran-4-carbaldehyde (8), echinulin (9) and neoechinulin (10) were isolated. Structures of isolated compounds were established by combination of 1D and 2D 'H and 13C NMR and HR ESIMS data, as well as ECD spectra (for compounds 3 and 4).
It should be noted, it is a first case of isolation of (+)-cryptoechinulin B (3) and (-)-cryptoechinulin B (4) as the individual compounds [2]. Besides niveoglaucine B (2) have a unique fragment of 3-hydroxyisobutiric acid (3-HIBA). To the best of our knowledge there are no cases of isolation of natural compounds with this moiety.
The supposed biosynthesis scheme of niveoglaucines A-B (1-2) was proposed.
REFERENCES:
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