Identification of a new C-23 metabolite in sterol degradation of Mycobacterium neoaurum HGMS2 and analysis of its metabolic pathways / 生物工程学报

Mycobacterium neoaurum has the ability to produce steroidal intermediates known as 22-hydroxy-23, 24-bisnorchol-4-en-3-one (BA) upon the knockout of the genes for either the hydroxyacyl-CoA dehydrogenase (Hsd4A) or acyl-CoA thiolase (FadA5). In a previous study, we discovered a novel metabolite in the fermentation products when the fadA5 gene was deleted. This research aims to elucidate the metabolic pathway of this metabolite through structural identification, homologous sequence analysis of the fadA5 gene, phylogenetic tree analysis of M. neoaurum HGMS2, and gene knockout. Our findings revealed that the metabolite is a C23 metabolic intermediate, named 24-norchol-4-ene-3, 22-dione (designated as 3-OPD). It is formed when a thioesterase (TE) catalyzes the formation of a β-ketonic acid by removing CoA from the side chain of 3, 22-dioxo-25, 26-bisnorchol-4-ene-24-oyl CoA (22-O-BNC-CoA), followed by spontaneously undergoing decarboxylation. These results have the potential to contribute to the development of novel steroid intermediates.

Relación entre acumulación de rodamina 6G y resistencia a fluconazol en Saccharomyces cerevisiae S288c / Relationship between rhodamine 6G accumulation and fluconazole resistance in Saccharomyces cerevisiae S288c

Severe mycotic infections are a source of concern in immunocompromised patients or in those who receive chemotherapy for hematological malignant diseases. One of the causes is referred to the appearance of antimycotic resistant microorganisms. Fluconazole is one of the antimycotic used for invasive mycoses treatment. Therefore it is necessary to evaluate the factors that originate this resistance. In the present report the yeast Saccharomyces cerevisiae S288c was used as a model system. In resistant strains the accumulation of the lipophilic cation Rhodamine 6G, L-leucine uptake and growth inhibition by crystal violet dye were determined. The results presented herein demonstrate the correlation between the membrane potential and the resistance to fluconazole presented by S. cerevisiae strain S288c.

Effects of S-allyl cysteine sulfoxide isolated from Allium sativum Linn and gugulipid on some enzymes and fecal excretions of bile acids and sterols in cholesterol fed rats.

S-allyl cysteine sulfoxide, isolated from garlic, A. sativum, is more or less as active as gugulipid in controlling hypercholestermia, obesity and derangement of enzyme activities in cholesterol diet fed rats. The beneficial effects of the drugs are partly due to their inhibitory effects on transaminases, alkaline phosphatase, lipogenic enzymes and HMG CoA reductase and partly due to their stimulatory effects on plasma lecithin-cholesterol acyl transferase lipolytic enzymes and fecal excretion of sterols and bile acids.

Changes in the blood lipid profile after administration of Ocimum sanctum (Tulsi) leaves in the normal albino rabbits.

Administration of fresh leaves of Ocimum sanctum (Tulsi) mixed as 1 g and 2 g in 100 gms of diet given for four weeks, brought about significant changes in the lipid profile of normal albino rabbits. This resulted in significant lowering in serum total cholesterol, triglyceride, phospholipid and LDL-cholesterol levels and significant increase in the HDL-cholesterol and total faecal sterol contents.

Neutral sterol excretions in rats fed skim milk and skim milk yogurt diets.

Acceleration of cholesterol catabolism (through feces) has been proposed as one of the mechanisms for the hypocholesterolemic effect of dairy products. This study examined the effects of feeding two milk products (skim milk and skim milk yogurt) on fecal neutral sterol excretions in rats. Six groups of nine rats each were fed iso-caloric Chow-based diets containing water, 45% skim milk (SM), or 45% skim milk yogurt (SMY), without or with cholesterol. The results indicate that both SM and SMY increased the excretion of total neutral sterols under hyperlipemic conditions. The SMY diet (with cholesterol) also increased the excretion of coprostanol, a bacterial metabolite.

Effect of pH stress on lipid composition of Saccharomyces cerevisiae.

Total lipids (% dry weight basis) of S. cerevisiae increased when pH of the growth medium was altered. Phospholipid content increased when the yeast was grown at a pH higher than its optimal (pH 6). Sterol content was not affected much. Sterol:phospholipid ratio was not affected by pH of the medium. Phosphatidylcholine content of S. cerevisiae was inversely related to pH of its growth medium. Glycolipids were more when the yeast was grown at pH 9. Fatty acids of S. cerevisiae grown at pH 3 were more saturated which makes the membranes less fluid.