New prenylated indole diketopiperazine alkaloids and polyketides from the mangrove-derived fungus Penicillium sp

Two new prenylated indole diketopiperazine alkaloids (PIDAs) penicamides A and B (1 and 2) and three new polyketides penicinones A−C (6−8), along with four known compounds deoxybrevianamide E (3), brevianamide V (4), 12,13-dehydroprolyl-2-(1,1-dimethylallyltryptophyl)diketopiperazine (5), and 4-hydroxyphenethyl 2-(4-hydroxyphenyl)acetate (9), were isolated and identified from the culture extract of the mangrove-derived fungus Penicillium sp. Their structures were fully elucidated by analyzing spectroscopic data. The absolute configurations of these compounds were determined by the comparison of experimental and calculated electronic circular dichroism (ECD) data and Mo2(OAc)4-induced and Rh2(OCOCF3)4-induced ECD experiments. Structurally, compound 1 is the first example of PIDAs featuring a 6/5/8/6/5 pentacyclic ring system with an α-hydroxy group at C-11, while compound 2 is a new analogue of PIDAs possessing the unique 3-methyleneindolin-2-ol moiety. In addition, compound 6 is a new lactone with the furo[3,4-b]pyran-5-one moiety. Compound 6 displayed potent cytotoxicity against murine melanoma (B16) cells, human breast adenocarcinoma (MCF-7) cells, and human hepatocellular carcinoma (HepG2) cells at 50.0 µM with inhibitory ratios of 82.7%, 75.1% and 95.9%, respectively. In addition, compound 6 exhibited significantly cytotoxic activity against the HepG2 cells, with an IC50 value of 3.87 ± 0.74 µM.</jats:p

Two New Pyrone Derivatives from the Plant Endophytic Fungus <i>Exserohilum</i> sp

Two new α-pyrones, Exserolide G–H (1–2), together with one known metabolite, stemphypyrone (3), were isolated from the solid-substrate fermentation cultures of the plant endophytic fungus Exserohilum sp. The structures of the new compounds were elucidated primarily by analysis of NMR data. Compounds 1–3 were tested for cytotoxicity against a small panel of human carcinoma cell lines. Compound 1 showed cytotoxicity against HeLa, A549 and HCT116 cells. </jats:p

Pestalotiones A–D: Four New Secondary Metabolites from the Plant Endophytic Fungus Pestalotiopsis Theae

Two new xanthone derivatives, pestalotiones A (1) and B (2), one new diphenyl ketone riboside, pestalotione C (7), and one new diphenyl ether, pestalotione D (8), along with five known compounds isosulochrin dehydrate (3), 3,8-dihydroxy-6-methyl-9-oxo-9H-xanthene-1-carboxylate (4), isosulochrin (5), chloroisosulochrin (6), and pestalotether D (9), were isolated from the crude extract of the plant endophytic fungus Pestalotiopsis theae (N635). The structures of the new compounds were unambiguously deduced by HRESIMS and 1D/2D-NMR spectroscopic data. Compound 6 showed modest cytotoxicity against the HeLa cell line with an IC50 value of 35.2 μM. Compound 9 also showed cytotoxic to the HeLa and MCF-7 cell lines, with IC50 values of 60.8 and 22.6 μM, respectively. Additionally, compounds 1 and 2 exhibited antioxidant activity in scavenging DPPH radical with IC50 values of 54.2 and 59.2 μg/mL, respectively.</jats:p