One pair of new cyclopentaisochromenone enantiomer from Alternaria sp. TNXY-P-1 and their cytotoxic activity.

One pair of new cyclopentaisochromenone derivatives, (+)-(S)-6-hydroxy-1,8-dimethoxy-3a-methyl-3,3a-dihydrocyclopenta[c]isochromene-2,5-dione (1a) and (-)-(R)-6-hydroxy-1,8-dimethoxy-3a-methyl-3,3a-dihydrocyclopenta[c]isochromene-2,5-dione (1b), together with seven known analog 2‒8, were isolated from a rice solid culture of the endophytic fungus Alternaria sp. TNXY-P-1, obtained from fresh leaf of Arisaema heterophyllum. Their structures were elucidated on the basis of detailed 1D, 2D NMR, and HRESIMS analysis. Among them, compounds 1a and 1b were enantiomers separated from 1 by chiral HPLC. The absolute configurations of 1a and 1b were assigned by quantum chemical calculations of the electronic circular dichroic spectra. All isolated compounds were evaluated for cytotoxic activities. Interestingly, enantiomers (+)-1a and (-)-1b showed distinct selective antitumor activities against HL-60 cell lines with IC50 values of >200, 75.3 µM, respectively.

Bioactive metabolites from Phoma species, an endophytic fungus from the Chinese medicinal plant Arisaema erubescens.

Through bioassay-guided fractionation, the EtOAc extract of a culture broth of the endophytic fungus Phoma species ZJWCF006 in Arisaema erubescens afforded a new α-tetralone derivative, (3S)-3,6,7-trihydroxy-α-tetralone (1), together with cercosporamide (2), ß-sitosterol (3), and trichodermin (4). The structures of compounds were established on the basis of spectroscopic analyses. Compounds 1, 2, and 3 were obtained from Phoma species for the first time. Additionally, the compounds were subjected to bioactivity assays, including antimicrobial activity, against four plant pathogenic fungi (Fusarium oxysporium, Rhizoctonia solani, Colletotrichum gloeosporioides, and Magnaporthe oryzae) and two plant pathogenic bacteria (Xanthomonas campestris and Xanthomonas oryzae), as well as in vitro antitumor activities against HT-29, SMMC-772, MCF-7, HL-60, MGC80-3, and P388 cell lines. Compound 1 showed growth inhibition against F. oxysporium and R. solani with EC50 values of 413.22 and 48.5 µg/mL, respectively. Additionally, compound 1 showed no cytotoxicity, whereas compound 2 exhibited cytotoxic activity against the six tumor cell lines tested, with IC50 values of 9.3 ± 2.8, 27.87 ± 1.78, 48.79 ± 2.56, 37.57 ± 1.65, 27.83 ± 0.48, and 30.37 ± 0.28 µM, respectively. We conclude that endophytic Phoma are promising sources of natural bioactive and novel metabolites.