Neogrisphenol A, a Potential Ovarian Cancer Inhibitor from a New Record Fungus Neohelicosporium griseum

From the rice fermentation product of a new record fungus, Neohelicosporium griseum, two new polyketides, neogrisphenol A (1) and neogrisphenol B (2), one new isochroman-1-one, (S)-6-hydroxy-7-methoxy-3,5-dimethylisochroman-1-one (3), and four known compounds (4-7) were isolated. Their structures were determined using 1D- and 2D-NMR, mass spectrometry, and chemical calculations. The C-3 similar to C-2 ' polymerization mode between the two alpha-naphthalenone derivative moieties is uncommon in compounds 1 and 2. Meanwhile, compounds 1-2 and 5 exhibited antibacterial activity against Bacillus subtilis, Clostridium perfringens, Staphylococcus aureus, and Staphylococcus aureus, with MIC values ranging between 16 and 31 mu g/mL. In addition, compound 5 showed antifungal activity against Sclerotinia sclerotiorum and Phytophthora nicotianae var. nicotianae, with respective IC50 values of 88.14 +/- 2.21 mu g/mL and 52.36 +/- 1.38 mu g/mL. Compound 1 showed significant cytotoxicity against A2780, PC-3, and MBA-MD-231 cell lines with respective IC50 values of 3.20, 10.68, and 16.30 mu M, and the cytotoxicity against A2780 cells was even higher than that of cisplatin (CDDP). With an IC50 value of 10.13 mu M, compound 2 also exhibited cytotoxicity against A2780. The in vitro results showed that compound 1 inhibited A2780 cell proliferation, induced apoptosis, and arrested the cell cycle at the S-phase in a concentration-dependent manner.

Automated summary

Two new polyketides, neogrisphenol A (1) and neogrisphenol B (2), one new isochroman-1-one (3), and four known compounds (4-7) were isolated from the rice fermentation product of Neohelicosporium griseum, a new record fungus. Their structures were determined using various analytical techniques. Compounds 1-2 and 5 showed antibacterial activity against multiple bacteria strains, while compound 5 exhibited antifungal activity against two different fungi strains. Compound 1 also demonstrated significant cytotoxicity against several cancer cell lines.