Three new phenazine derivatives (1–3), along with known compounds (4–7) of saphenic acid derivatives, were isolated from a deep-sea sediment-derived yeast-like fungus Cystobasidium larynigs collected from the Indian Ocean. The structures of the new compounds (1–3) were determined by analysis of spectroscopic data, semi-synthesis and comparison of optical rotation values. All the isolated compounds (1–7), except for 2, showed nitric oxide (NO) production inhibitory effect against lipopolysaccharide (LPS)-induced murine macrophage RAW 264.7 cells without cytotoxicity at concentrations up to 30 μg/mL. This is the first report on the yeast-like fungus Cystobasidium laryngis producing phenazines and anti-inflammatory activity of 1–7 including saphenic acid (4).
A new compound containing a triene, a tetrahydropyran ring and glycine ester functionalities, restricticin B (1), together with four known compounds (2–5) were obtained from the EtOAc extract of the marine-derived fungus Penicillium janthinellum. The planar structure of 1 was determined by detailed analyses of MS, 1D and 2D NMR data. The relative and absolute configurations of 1 were established via the analyses of NOESY spectroscopy data, the comparison of optical rotation values with those of reported restricticin derivatives and electronic circular dichroism (ECD). All the compounds were screened for their anti-neuroinflammatory effects in lipopolysaccharide (LPS)-induced BV-2 microglia cells. Restricticin B (1) and N-acetyl restricticin (2) exhibited anti-neuroinflammatory effects by suppressing the production of pro-inflammatory mediators in activated microglial cells.
Aspergillus is well-known as the second-largest contributor of fungal natural products. Based on NMR guided isolation, three nitrogen-containing secondary metabolites, including two new compounds, variotin B (1) and coniosulfide E (2), together with a known compound, unguisin A (3), were isolated from the ethyl acetate (EtOAc) extract of the deep-sea fungus Aspergillus unguis IV17-109. The planar structures of 1 and 2 were elucidated by an extensive analysis of their spectroscopic data (HRESIMS, 1D and 2D NMR). The absolute configuration of 2 was determined by comparison of its optical rotation value with those of the synthesized analogs. Compound 2 is a rare, naturally occurring substance with an unusual cysteinol moiety. Furthermore, 1 showed moderate anti-inflammatory activity with an IC50 value of 20.0 µM. These results revealed that Aspergillus unguis could produce structurally diverse nitrogenous secondary metabolites, which can be used for further studies to find anti-inflammatory leads.
Chemical investigation of the ethyl acetate extract from the culture broth of the marine-derived actinobacterium Streptomyces ardesiacus 156VN-095 led to the isolation of three hitherto undescribed angucycline glycosides, including urdamycins W and X (1 and 2) and grincamycin U (9), as well as their seven known congeners. The structures of the new compounds were elucidated by means of spectroscopic methods (HRESIMS, 1D and 2 D NMR) and comparison of their experimental data with literature values. Compounds 1–3 and 9 were evaluated for their anti-Gram-positive bacterial effect and cytotoxicity against six cancer cell lines. Compound 1 displayed significant cytotoxicity against all the tested cell lines with GI50 values of 0.019–0.104 µM. Collectively, these findings highlight the potential of angucycline glycosides as leading structures for the development of new anti-cancer drugs.
Ten secondary metabolites, including a new grifolin analog, grifolin B (1); a new homovalencic acid derivative, 12-hydroxyhomovalencic acid (7); and a compound isolated from a natural source for the first time (9), along with seven known compounds, grifolin (2), averantin (3), 7-chloroaverantin (4), 1′-O-methylaverantin (5), 7-hydroxy-2-(2-hydroxypropyl)-5-pentylchromone (6), homovalencic acid (8), and bekeleylactone E (10), were isolated from two fungal strains. The structures of 1–10 were identified by detailed analysis and comparison of their spectroscopic data with literature values. Compounds 9 and 10 showed moderate cytotoxic activity against a panel of cancer cell lines (PC-3, HCT-15, MDA-MB-231, ACHN, NCI-H23, NUGC-3), with the GI50 values ranging from 1.1 µM to 3.6 µM, whereas 1 displayed a weak 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity without cytotoxicity against all tested cell lines.