Cochlioquinone A

A novel acyl-CoA : cholesterol acyltransferase (ACAT) inhibitor, designated epi-cochlioquinone A has been isolated from the fermentation broth of Stachybotrys bisbyi SANK 17777. The molecular formula, physicochemical properties, NMR spectroscopic analysis and X-ray crystallographic analysis revealed that this compound was a stereoisomer of cochlioquinone A, which has been previously reported as a nematocidal agent. It inhibited ACAT activity in an enzyme assay using rat liver microsomes with an IC50 value of 1.7 microM. However, it showed about 10-fold less potent inhibitory effect on plasma lecithin cholesterol acyltransferase (LCAT) than on ACAT. In addition, it inhibited in vivo cholesterol absorption in rats by 50% at 75 mg/kg.

1) Repeated administration of pravastatin significantly increased serum and liver cholesterol in rats. Hepatic LDL receptor activity was not changed and VLDL cholesterol secretion from the liver was increased. Net cholesterol synthesis in rat liver was increased after 7 days of repeated pravastatin administration. These results suggest that for rats, unlike other animals for which serum cholesterol is decreased, induced HMG-CoA reductase activity due to pravastatin treatment might overcome the inhibitory capability of pravastatin. 2) In the course of screening for squalene synthase inhibitors, novel zaragozic acids-F10863A, B, C and D-containing zaragozic acid D3 were isolated. F10863A was most potent and selectively inhibited cholesterol synthesis in freshly isolated rat hepatocytes among several cultured and isolated cells. It also showed in vivo serum cholesterol-lowering effects in hamsters and marmosets. However, the inhibition for squalene synthase proved to cause acidosis due to the accumulation of farnesol-derived dicarboxylic acids in urines. 3) A novel acyl-CoA: cholesterol acyltransferase (ACAT) inhibitor, designated epi-cochlioquinone A, a stereoisomer of cochlioquinone A, which has been previously reported as a nematocidal agent, was isolated from the fermentation broth of Stachybotrys bisbyi. It inhibited in vivo cholesterol absorption in rats by 50% at 75 mg/kg.

A new cochlioquinone derivative, cochlioquinone F (1), as well as three known compounds, anhydrocochlioquinone A (2), isocochlioquinone A (3), and isocochlioquinone C (4), were isolated from the PDB (potato dextrose broth) culture of the phytopathogenic fungus Bipolaris luttrellii. The structure of 1 was elucidated on the basis of NMR techniques. The apoptosis-inducing effects of compounds 1-4 were evaluated against HCT116 cancer cells. Compound 2 exhibited the strongest activity in inducing apoptosis on HCT116 cells within the range of 10-30 μM. In addition, the caspase activation, the release of cytochrome c from mitochondria, and the downregulation of Bcl-2 protein in HCT116 cells treated with compound 2 were detected.