The influence of bilateral superior cervical ganglionectomy, continuous light and continuous darkness on the diurnal rhythm of hydroxymethylglutaryl-coenzyme a reductase in rat liver

Consortia of bioactives in supercritical carbon dioxide extracts of mustard and small cardamom seeds lower serum cholesterol levels in rats: new leads for hypocholesterolaemic supplements from spices

Melatonin-rich and 1,8-cineole-rich extracts have been successfully obtained from yellow mustard (YM) and small cardamom (SC) seeds, respectively, employing green technology of supercritical CO₂ (SC-CO₂) extraction. Chemical profiling confirmed the presence of melatonin and 1,8-cineole and co-extractants in the respective extracts. Electron paramagnetic resonance spectroscopy attested strong antioxidant activities of the extracts foregoing pan-assay interference compounds involved in spectroscopic analysis. These extracts also exhibited synergistic efficacies greater than unity confirming antioxidant synergy among the co-extracted bioactives therein. To ascertain hypocholesterolaemic efficacies, these extracts were co-administered orally with Triton X (at the pre-optimised dose of 175 mg/kg body weight (BW)) to Wistar albino rats at doses of 550, 175 and 55 mg/kg BW. Serum total cholesterol levels in the rats were monitored on days 3, 7, 15 and 21. On day 21, total cholesterol level reduced appreciably by 49·44 % in rats treated with YM seed extract and by 48·95 % in rats treated with SC seed extract, comparable with atorvastatin-administered rats (51·09 %). Either extract demonstrated inhibitory effects on hepatic 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase activity. A molecular docking exercise identified specific compounds in the extracts which possessed binding affinities comparable with therapeutically used HMG-CoA reductase inhibitors. In silico and in vivo studies concertedly concluded that the consortium of bioactive components in the extracts cannot be considered as invalid metabolic panaceas and therefore these 'green' extracts could be safely subjected to clinical studies as preventive biotherapeutics for hypercholesterolaemia. These extracts could be consumed per se as hypocholesterolaemic supplements or could be ingredients of new spice-based therapeutic foods.

Effect of melatonin on the maintenance of cholesterol homeostasis in the rat

The effect of melatonin on cholesterol metabolism in the rat was investigated in the dietary and hypothyroid models of hypercholesterolemia. In normal and dietary hypercholesterolemia (induced by 1% cholesterol, 0.5% bile acid), melatonin treatment (12.5mg/kg i.p.) reduced total serum cholesterol concentration and total low density lipoprotein (VLDL+LDL) cholesterol. The protective action of melatonin was manifested only following the induction of cholesterolemia in such animals. Enhanced catabolism of cholesterol to bile acids is likely involved as shown by an increase in fecal bile acid excretion following melatonin treatment. Incorporation of 1-14C acetate into sterols was unaffected by melatonin treatment which suggests its lack of influence on sterol biosynthesis. In secondary hypercholesterolemia (hypothyroidism induced by 2-thiouracil), melatonin exerted a beneficial effect by increasing the HDL/total LDL cholesterol ratio. These findings suggest that the hypocholesterolemic effect of melatonin may work through the augmentation of endogenous cholesterol clearance mechanisms. This is accompanied by the lowering of the cholesterol fraction associated with low density lipoproteins.