Narinder K. Kapoor

Picroliv, picroside-I and kutkoside from Picrorhiza kurrooa are scavengers of superoxide anions

Picroliv, the active principle of Picrorhiza kurrooa, and its main components which are a mixture of the iridoid glycosides, picroside-I and kutkoside, were studied in vitro as potential scavengers of oxygen free radicals. The superoxide (O2-) anions generated in a xanthine-xanthine oxidase system, as measured in terms of uric acid formed and the reduction of nitroblue tetrazolium were shown to be suppressed by picroliv, picroside-I and kutkoside. Picroliv as well as both glycosides inhibited the non-enzymic generation of O2- anions in a phenazine methosulphate NADH system. Malonaldehyde (MDA) generation in rat liver microsomes as stimulated by both the ascorbate-Fe2+ and NADPH-ADP-Fe2+ systems was shown to be inhibited by the Picroliv glycosides. Known antioxidants tocopherol (vitamin E) and butylated hydroxyanisole (BHA) were also compared with regard to their antioxidant actions in the above system. It was found that BHA afforded protection against ascorbate-Fe(2+)-induced MDA formation in microsomes but did not interfere with enzymic or non-enzymic O2- anion generation; and tocopherol inhibited lipid peroxidation in microsomes by both prooxidant systems and the generation of O2- anions in the non-enzymic system but did not interfere with xanthine oxidase activity. The present study shows that picroliv, picroside-I and kutkoside possess the properties of antioxidants which appear to be mediated through activity like that of superoxide dismutase, metal ion chelators and xanthine oxidase inhibitors.

Age-Related Elevation of Lipid Peroxidation Products: Diminution of Superoxide Dismutase Activity in the Central Nervous System of Rats

Alteration in lipid peroxidation products such as lipid peroxides, lipid hydroperoxides were studied in different regions of CNS of ageing rats (13, 26, 52, 78 and 104 weeks). The levels of lipid peroxide and lipid hydroperoxide were increased in various regions of brain and spinal cord. However, the activity of superoxide dismutase was decreased in cerebrum, hypothalamus, hippocampus, cerebellum, brain stem and spinal cord. The present communication demonstrates that the different parts of CNS at 13 and 26 weeks of age have lipid peroxidation products different from that of 104-week-old rats.

Stimulation of low density lipoprotein receptor activity in liver membrane of guggulsterone treated rats

Chronic feeding of guggulsterone to rats showed hypolipidaemic activity in blood serum and liver membrane lipids. The decrease in serum cholesterol is associated with enhanced uptake of LDL by the liver through receptor mediated endocytosis, located on the surface of the cell membrane. In the present communication it has been shown that membranes prepared from liver of guggulsterone treated rats exhibit up to 87% increase in binding sites for human 125I-LDL. Significant decrease in lipid levels of serum as well as of membrane were observed. Lipid lowering activity of the drug in relation to LDL catabolism and other possible mechanisms have been explained.

High density lipoprotein is a scavenger of superoxide anions

Present work describes a new property of HDL to act as a scavenger of O2- free radicals in vitro. This lipoprotein prevents both enzymic and non-enzymic generation of O2- anions as evidenced by inhibition of xanthine oxidase, peroxidase, peroxidation of pyrogallol and phenazine methosulphate-NADH reaction. Ascorbate stimulated MDA formation in microsomes has been shown to be suppressed by HDL and these effects are comparable with that of BHA.

Lipid Lowering Activity of Guggulsterone from Commiphora mukul in Hyperlipaemic Rats

The lipid lowering action of guggulsterone, the active constituent of guggulipid, has been studied in triton and cholesterol fed hyperlipaemic rats. Serum lipids were found to be lowered by guggulsterone (50 mg/kg, b.w.) in triton WR‐1339 induced hyperlipaemia. Chronic feeding of this drug (5 mg/kg, b.w.) in animals simultaneously fed with cholesterol (25 mg/kg, b.w.) for 30 days, caused lowering in the lipid and apoprotein levels of very low density and low density lipoproteins in experimental animals. Guggulsterone activates lipolytic enzymes in plasma and liver as well as stimulated receptor mediated catabolism of low density lipoprotein. The hypolipidaemic activity of this drug is mediated through inhibition of hepatic cholesterol biosynthesis, increased faecal bile acid excretion and enhanced plasma lecithin:cholesterol acyltransferase activity.

Antihepatotoxic Activity of Diterpenes of Andrographis Paniculata (Kal-Megh) Against Plasmodium Berghei-Induced Hepatic Damage in Mastomys Natalensis

AbstractAdministration of an alcohol extract of Andrographis paniculata (25 mg/kg) and two of its constituent diterpenes, andrographolide and neoandrographolide (6 mg/kg/day for two weeks) showed significant antihepatotoxic action in P. berghei K173- induced hepatic damage in M. natalensis. The increased levels of serum lipoprotein-X, alkaline phosphatase, GOT, GPT and bilirubin were markedly reduced by A. paniculata and its diterpenes. In the liver, these preparations decreased the levels of lipid peroxidation products and facilitated the recovery of superoxide dismutase and glycogen. The protective effects of andrographolide were comparable to those of neoandrographolide.

Terminalia arjuna: an Ayurvedic cardiotonic, regulates lipid metabolism in hyperlipaemic rats

The lipid lowering action of the bark powder of Terminalia arjuna (T. arjuna) has been studied in triton and cholesterol fed rats. Serum lipids were found to be lowered by T. arjuna (100 mg/kg, b.w.) in triton induced hyperlipaemia. Chronic feeding of this powder (100 mg/kg, b.w., p.o.) in animals simultaneously fed with cholesterol (25 mg/kg, b.w.) for 30 days, caused lowering in lipids and protein levels of β‐lipoproteins followed by an increase in high density lipoprotein‐cholesterol compared with the cholesterol fed groups. T. arjuna alters lipolytic activities in plasma, liver, heart and adipose tissues of hyperlipaemic rats. The lipid lowering action of this natural product is mediated through inhibition of hepatic cholesterol biosynthesis, increased faecal bile acid excretion and enhanced plasma lecithin:cholesterol acyltransferase activity and stimulation of receptor mediated catabolism of low density lipoprotein.

Guggulsterone, a potent hypolipidaemic, prevents oxidation of low density lipoprotein

The oxidation of low density lipoprotein (LDL) induced by Cu+2 caused marked oxidative changes in the lipid and protein constituents of this lipoprotein in vitro. Guggulsterone prevented the generation of lipid peroxides measured as thiobarbituric acid reactive substances, lipid hydroperoxides and conjugated dienes. This compound protected LDL against depletion of lipid constituents such as cholesterol, cholesterol esters, triglyceride and phospholipids as well as inhibiting the conversion of cholesterol into oxygenated cholesterols. Oxidized LDL containing less apoprotein B with a high protein carbonyl value, was more electronegative, as evidenced by the increase in relative electrophoretic mobility (REM) on agarose gel. Guggulsterone significantly protected LDL apoprotein as measured by reversal of REM after oxidation. The protective action of guggulsterone may be due to its free radical scavenging property as this compound significantly inhibited the generation of hydroxyl radicals in a nonenzymic system.

The effect of propranolol on rat brain catecholamine biosynthesis

The effect of propranolol on the levels of catecholamine in different parts of rat brain has been studied. The catecholamine contents of different regions were lowered by the drug. Dopamine Β-hydroxylase activity was also reduced, bothin vivo andin vitro. Propranolol is taken up by the brain tissue and the uptake is time-dependent. These results suggests that reduction in brain catecholamine levels and dopamine Β-hydroxylase activity may be one of the possible ways through which the drug manifests its clinical effects.

Effect of hypocholesterolemic agents of plant origin on catecholamine biosynthesis in normal and cholesterol fed rabbits

The effect of lipid lowering agents of plant origin garlic oil and guggulipid on the levels of catecholamine and dopamine Β-hydroxylase activity of normal and cholesterol fed rabbit tissues has been studied. The catecholamine levels and enzyme activity were found to be decreased in cholesterol (500 mg/kg body wt) fed animals. The feeding of garlic oil (5 mg/kg body wt) and guggulipid (100 mg/kg body wt) an exudate ofCommiphora mukul, to normal rabbits caused significant increase in the dopamine-Β-hydroxylase activity and catecholamine levels, while the feed helped the hypercholesterolemic rabbits to recover the decrease in catecholamine biosynthesis