Isolation and identification of a new tetrahydro-β-carboline diketopiperazine from a predominant endophytic fungus in ancient Camellia taliensis

To investigate the chemical constituents of Diaporthe tectonigena, a predominant endophytic fungus in the ancient tea tree of Camellia taliensis, the rice solid-state fermentation extract was isolated and purified by silica gel, Diaion HP20 and Sephadex LH-20 column chromatographies, and the chemical structures were elucidated by extensive HRMS, 1H-NMR, 13C-NMR, HSQC, HMBC and COSY spectroscopic analyses. The results were as follows: (1) Four compounds were isolated from the rice solid-state fermentation extract of Diaporthe tectonigena, including a new tetrahydro-β-carboline diketopiperazine alkaloid named tectonicgenazine A (1). (2) Three known compounds, trans-cyclo-(D-tryptophanyl-L-tyrosyl) (2), 1H-indole-3-carboxylic acid-2,3-dihydroxypropyl ester (3) and N-hydroxyethyl-2-acetylpyrrole (4) were obtained and identified, and Compound 3 was isolated from nature for the first time.