Secondary Metabolites of the Endophytic Fungi Talaromyces wortmannii Cultivated in Maize Medium and their Bioactivity
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SECONDARY METABOLITES OF THE ENDOPHYTIC FUNGI Talaromyces wortmannii CULTIVATED IN MAIZE MEDIUM AND THEIR BIOACTIVITY
Bo Yang,1 Zhong-Duo Yang,1* Xiao-Fei Li,1 and Zong-Mei Shu1,2
Endophytic fungi, which have co-evolved for millions of years with their eukaryotic hosts, are relatively unstudied and potential sources of novel natural products for exploitation in medicine, agriculture, and industry [1, 2]. Recently, many bioactive compounds with antitumor, antimicrobial, and antituberculosis properties were isolated from fungal endophytes [3]. Talaromyces is a subgenus of Penicillium, which produces many novel bioactive secondary metabolites, including alkaloids, peptides, lactones, and miscellaneous structure type compounds [4]. In this paper, we described the isolation and identification of eight compounds (1–8) from an endophytic fungus LGT-4 (identified as Talaromyces wortmannii) of Tripterygium wilfordii. The fungal strain (LGT-4) was isolated from the roots of Tripterygium wilfordii and identified as Talaromyces wortmannii based on both morphology on PDA and analysis of the DNA sequences of the ITS1-5.8S-ITS2 ribosomal RNA gene region. A GenBank search for DNA sequence (GenBank Accession No. KF850714) similarity revealed that ITS1-5.8S-ITS2 of LGT-4 was 99% homologous to that of Talaromyces wortmannii reference strains (GenBank Accession Nos. FR667650.1 and JN807336.1). The strain Lgt-4 was cultivated in maize medium (100 mL × 80 Erlenmeyer flask) for 40 days at 28°C in a constant temperature oscillation incubator. The culture was extracted with EtOAc (8 L) to afford the crude extract (26 g), which was subjected to column chromatography using silica gel, Sephadex LH-20, MCI-CHP20P gel, and HPLC, etc. A total of eight compounds was isolated and identified based on NMR spectra. To the best of our knowledge, this is the first report on the isolation of the 4, 5, and 7 from Talaromyces wortmannii. 5-(Acetyloxy)-1-(aminomethylene)-4,4a,5,6,6a,8,9,9a-octahydro-11-hydroxy-4-(methoxymethyl)-4a,6adimethylcyclopenta[5,6]naphtho[1,2-c]pyran-2,7,10(1H)-trione (1), white powder. 1H NMR (600 MHz, CDCl3, δ, ppm, J/Hz): 9.37 (1H, d, J = 15.1, NH2), 8.62 (1H, dd, J = 15.1, 8.3, H-20), 7.15 (1H, br.s, NH2), 5.99 (1H, dd, J = 7.8, 3.1, H-11), 4.34 (1H, dd, J = 7.0, 1.2, H-1), 3.26 (3H, s, OMe), 3.18 (2H, m, H-2), 2.96–2.83 (2H, m, H-16a, H-14), 2.57 (1H, m, H-12a), 2.36–2.25 (3H, m, H-15a, 16b, 12b), 2.04 (3H, s, COCH3), 1.87 (1H, dd, J = 15.0, 3.2, H-15b), 1.55 (3H, s, H-19), 0.82 (3H, s, H-18). 13C NMR (150 MHz, CDCl3 + CD3OD, δ, ppm): 82.4 (C-1), 74.4 (C-2), 167.7 (C-3), 129.2 (C-4), 139.6 (C-5), 138.9 (C-6), 180.2 (C-7), 150.4 (C-8), 159.9 (C-9), 43.3 (C-10), 68.7 (C-11), 39.3 (C-12), 49.3 (C-13), 43.2 (C-14), 23.4 (C-15), 37.3 (C-16), 216.8 (C-17), 17.1 (C-18), 26.0 (C-19), 160.0 (C-20), 59.6 (OMe), 21.1 (COCH3), 171.8 (COCH3) [5]. Monomethylsulochrin [5-hydroxy-2-(2-hydroxy-6-methoxy-4-methylbenzoyl)-3-methoxybenzoic acid methyl ester] (2), white needles. 1H NMR (600 MHz, CD3OD, δ, ppm, J/Hz): 6.96 (1H, d, J = 2.0, H-6),
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