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The grass root endophytic fungus Flavomyces fulophazii: An abundant source of tetramic acid and chlorinated azaphilone derivatives

Berek-Nagy, Péter János and Tóth, Gergő and Bősze, Szilvia and Horváth, Lilla Borbála and Darcsi, András and Csíkos, Sándor and Knapp, Dániel G. and Kovács, Gábor M. and Boldizsár, Imre (2021) The grass root endophytic fungus Flavomyces fulophazii: An abundant source of tetramic acid and chlorinated azaphilone derivatives. PHYTOCHEMISTRY, 190. p. 112851. ISSN 0031-9422

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Abstract

Fungal endophytes are remarkable sources of biologically active metabolites of ecological and pharmacological significance. In this study, fungal isolates producing yellow pigments and originating from grass roots, were identified as the recently described grass root colonizing dark septate endophyte (DSE), Flavomyces fulophazii (Periconiaceae, Pleosporales). While analyzing the metabolite composition of 17 isolates of this fungus, 11 previously undescribed compounds, including four tetramic acids (dihydroxyvermelhotin, hydroxyvermelhotin, methoxyvermelhotin, oxovermelhotin), and seven chlorinated azaphilones (flavochlorines A–G), together with the known tetramic acid vermelhotin, were tentatively identified by high performance liquid chromatography (HPLC)-tandem mass spectrometry (MS/MS). Among them, flavochlorine A, flavochlorine G, hydroxyvermelhotin and vermelhotin could be isolated by preparative HPLC, thus their structures were also confirmed by nuclear magnetic resonance (NMR) spectroscopy. Vermelhotin was found to be the main compound, reaching its maximum level of 5.5 mg/g in the in vitro cultures of a selected F. fulophazii isolate. A significant amount of vermelhotin was isolated by preparative HPLC from these cultures (4.8 mg from 1.0 g lyophilized culture), confirming the practical utility of F. fulophazii in high-yield vermelhotin production. The main compounds of this endophyte expressed no activity in standardized plant bioassays (i.e., in the Lactuca sativa seed germination and Lemna minor growth tests). An antiproliferative study of the isolated compounds confirmed moderate activity of vermelhotin against a panel of twelve cancer cell lines, with IC50 ranges of 10.1–37.0 μM, without inhibiting the non-cancer Vero cells, suggesting its selectivity towards cancers.

Item Type: Article
Subjects: Q Science / természettudomány > QD Chemistry / kémia > QD01 Analytical chemistry / analitikai kémia
Q Science / természettudomány > QK Botany / növénytan
Q Science / természettudomány > QR Microbiology / mikrobiológia
Depositing User: Dr. Gergő Tóth
Date Deposited: 22 Sep 2022 13:16
Last Modified: 03 Apr 2023 08:01
URI: http://real.mtak.hu/id/eprint/149288

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