A chemical investigation of the endophyte Penicillium sp. (strain ZO-R1-1), isolated from roots of the medicinal plant Zingiber officinale, yielded nine new indole diterpenoids (1–9), together with 13 known congeners (10–22). The structures of the new compounds were elucidated by 1D and 2D NMR analysis in combination with HRESIMS data. The absolute configuration of the new natural products 1, 3, and 7 was determined using the TDDFT-ECD approach and confirmed for 1 by single-crystal X-ray determination through anomalous dispersion. The isolated compounds were tested for cytotoxicity against L5178Y, A2780, J82, and HEK-293 cell lines. Compound 1 was the most active metabolite toward L5178Y cells, with an IC50 value of 3.6 μM, and an IC50 against A2780 cells of 8.7 μM. Interestingly, 1 features a new type of indole diterpenoid scaffold with a rare 6/5/6/6/6/6/5 heterocyclic system bearing an aromatic ring C, which is suggested to be important for the cytotoxic activity of this natural product against L5278Y and A2780 cells.

OSMAC approach on endophytic Bulgaria inquinans by addition of a mixture of salts (MgSO4, NaNO3 and NaCl) to solid Czapek medium induced the accumulation of new secondary metabolites.

Sponge-derived fungi have recently attracted attention as an important source of interesting bioactive compounds. Aspergillus nomius NC06 was isolated from the marine sponge Neopetrosia chaliniformis. This fungus was cultured on rice medium and yielded four compounds including three new oxisterigmatocystins, namely, J, K, and L (1, 2, and 3), and one known compound, aspergillicin A (4). Structures of the compounds were elucidated by 1D and 2D NMR spectroscopy and by high-resolution mass spectrometry. The isolated compounds were tested for cytotoxic activity against HT 29 colon cancer cells, where compounds 1, 2, and 4 exhibited IC50 values of 6.28, 15.14, and 1.63 µM, respectively. Under the fluorescence microscope by using a double staining method, HT 29 cells were observed to be viable, apoptotic, and necrotic after treatment with the cytotoxic compounds 1, 2, and 4. The result shows that compounds 1 and 2 were able to induce apoptosis and cell death in HT 29 cells.