Hypolipidaemic Activity of Abana in Rats

Chronic administration of Abana, an Indian herbomineral preparation, showed a significant hypolipidaemic activity in rats. Serum β lipoprotein lipid components and apoprotein levels were significantly lowered, low-density lipoprotein being more affected than very low-density lipoprotein. However, serum high-density lipoprotein lipids and apoproteins were slightly increased. The reduction in the lipid components of serum and liver were accompanied with decreased level of serum free fatty acids and hepatic lipolytic enzyme activities. Abana caused marked inhibition in hepatic biosynthesis of cholesterol and enhanced the excretion of faecal bile acids. The mode of action of Abana as a cardioprotective and hypolidaemic agent is explained. Several herbs have been reported to possess potent cardioprotective activity. Abana is a cardiotonic formulation of selected ingredients which provide significant protection against hypertension and ischemia. Abnormalities with lipid and lipoprotein metabolism are mainly responsible for cardiac diseases. Therefore the aim of this study is to investigate the action of Abana on the lipid and lipoprotein metabolism in albino rats. Experimental Materials – Heparin, dextrin sulfate M.W. 5x10, protamine sulfate, cholic acid, deoxycholic acid were purchased from Sigma chemicals, U.S.A. (I-C). Sodium acetate was purchased from Bhabha Atomic Centre, Trombay, India and the other chemicals used were of analytical grade. Abana tablets were gifted by The Himalaya Drug Co., Bangalore. Each tablet consists of Terminalia arjuna 30 mg, Withania somnifera (Ashwagandha) 20 mg, Tinospora cordifolia (Giloe) 10 mg, Nepeta hindostana (Billilotan) 20 mg, Phyllanthus emblica (Amla) 10 mg, Terminalia chebula (Hirda) 10 mg, Dashamoola 20 mg (a mixture of ten herbs containing equal proportions of Aegle marmelos, Premna integrifolia, Oroxylum indicum, Stereospermum suaveolens, Gmelina arborea, Desmodium gangeticum, Uraria picta, Solanum indicum, Solanum xanthocarpum and Tribulus terrestris), Eclipta alba (Bhrangraj) 10 mg, Glycyrrhiza glabra (Yashtimadhu) 10 mg, Asparagus racemosus (Shankhapushpi) 10 mg, Ocimum sanctum (Tulsi) 10 mg, Nardostachys jatamansi (Jatamansi) 10 mg, Cyperus rotundus (Motha) 5 mg, Acorus calamus (Vach) 5 mg, Embelia ribes (Vidang) 5 mg, Piper longum (Pipali) 10 mg, Carum copticum (Ajwain) 10 mg, Zingiber officinale (Sonth) 10 mg, Syzygium aromaticum (Lavang) 5 mg, Celastrus paniculatus (Malkangni) 5 mg, Santalum album (Chandan) 5 mg, Elettaria cardamomum (Choti elaichi) 5 mg, Foeniculum vulgare (Sonf) 5 mg, Rosa damascena (Gulab ka phool) 5 mg, Cinnamomum cassia (Taja) 5 mg, Crocus sativus (Keshar) 2 mg, Asphaltum (Shilajeet) 20 mg, Serpent stone, the silicate of magnesium and iron (Jaharmohra) 10 mg, Conch (Shankh bhasma) 10 mg, Sulphide of mercury (Makardhwaj) 10 mg, Mica (Abrak bhasma) 5 mg, Mytilus magaritiferus (Pearl pishti) 5 mg, Agate (Akik pishti) 5 mg, Jade (Yeshab pishti) 5 mg, Ruby (Yakut pishti) 5 mg and Corallium rubrum (Coral pishti). Bhasma and Pishti are the typical Ayurvedic preparations from the said raw materials. Before feeding, Abana tablets were macerated with gum acacia and suspended in water. Male adult rats of Charles Foster strain (150-200 g) inbred in the C.D.R.I. Animal House were divided into control and Abana-fed groups of six rats each. The suspension of Abana was administered (50 mg/kg b.wt.) by gastric tubing once a day for 30 days. The control group received the equivalent amount of gum acacia solution. At the end of the experiment, animals were fasted overnight, blood was withdrawn by retro-orbital plexus and the liver was promptly excised. The serum was fractionated into very low-density lipoprotein (VLDL), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) by the polyanionic precipitation method using heparin, dextran sulfate and MnCl2 as reactants. The lipoproteins were dialysed with 0.15 M NaCl containing 0.2% EDTA and delipidated with ethanol-ether (3:1, v/v). However, liver homogenate was delipidated with chloroform-methanol (2:1 v/v). These lipid extracts were used for the estimation of total lipid (TL), total cholesterol (TC), phospholipid (PL) and triglyceride (TG), phospholipid (PL) and triglyceride (TG) according to the method of Zollner, Zlatkis et al., Wagner et al., and Van Handel et al.. The apoprotein and protein contents were estimated by the method of Radding et al. and Lowry et al. The liver was homogenized (10%, w/v) in 0.2 M phosphate buffer pH 7.4 and assay for lipolytic and triglyceride lipase (TGL) activities. Lipoprotein lipase (LPL) activity was deduced by subtracting the TGL activity from total lipolytic activity and expressed as nmol free fatty acid released/h/mg protein. Hepatic cholesterol biosynthesis was estimated by the method of Nityanand et al. The faecal excretion of bile acids was quantitated as described by Mosbach. The percentage alteration of biochemical parameters by the test drug was calculated by comparison with control. Student’s ‘t’ test was used for statistical evaluation of the results. RESULTS AND DISCUSSION The effect of chronic administration of Abana on serum lipid and protein components in rats is shown in Table 1. It may be seen that the levels of TC, PL and TG in serum were significantly decreased by 37 to 45% as compared to control. The hypolipidaemic effect was more pronounced in case of serum TG (45%). The levels of TC, PL, TG and apoprotein in VLDL and LDL fractions in the treated group were shown to be decreased by 20 to 28%. However, administration of Abana produced a slight increase in the level of the lipid and protein components of HDL. The abnormalities of lipid and lipoprotein metabolism possess a positive correlation with heart diseases. The increase in LDL cholesterol and lipid peroxidation significantly suppresses the catabolism of the lipoprotein through hepatic receptors. Other plants have demonstrated hypolipidaemic activity by enhancement of LDL receptor activity and faecal bile acid excretion. Table 1: Effect of Abana on serum lipid and protein composition in rats Serum/serum fractions Experimental schedule Total cholesterol mg/dl Phospholipids mg/dl Triglycerides mg/dl Apoprotein mg/dl Control 85.73 ± 5.37 69.22 ±5.23 74.12 ± 3.23 54.35 ± 0.99 Serum Abana 50.96 ± 3.16** 43.37 ± 2.21** 40.41 ± 4.72** 53.80 ± 1.14** Control 5.30 ± 0.18 9.07 ± 0.15 35.60 ± 0.46 4.35 ± 0.10 VLDL Abana 4.20 ± 0.79** 7.21 ± 0.23** 26.32 ± 0.49** 3.40 ± 0.14** Control 7.23 ± 0.60 8.14 ± 0.47 17.47 ± 1.56 18.48± 1.30 LDL Abana 5.50 ± 0.35* 6.67 ±0.40* 14.00 ± 1.40** 13.27 ± 1.00** Control 51.39 ± 1.58 38.14 ± 1.39 14.30 ± 0.32 150.35 ± 7.80 HDL Abana 54.59 ± 1.90* 41.52 ± 1.47** 14.99 ± 0.53* 141.39 ± 3.73* Each value is the mean of 6 rats ± SD. *p<0.05, **p<0.01 as compared to control Data in Table 2 show that hepatic LPL, TGL and total lipolytic activities were decreased by 33, 19 and 23% respectively, under the action of this drug. Table 3 shows that administration of Abana in rats caused a marked inhibition (58%) in the hepatic cholesterol biosynthesis followed by a significant decrease in the incorporation of labeled (I-C) sodium acetate into fatty acids. These modifications produced by Abana caused hypolipidaemia by affecting both the anabolism and catabolism of liver lipids. Besides this the faecal excretion of cholic acid and deoxycholic acid was also enhanced by 26 and 45% respectively in the treated groups. Table 2: Effect of Abana on hepatic lipolytic activity, liver lipids and protein composition in rats Lipolytic enzymes (Unit/mg protein) Lipid and protein contents (mg/dl) Experimental schedule Total lipolytic activity LPL activity TGL activity Total cholesterol Phospholipids Triglycerides Proteins Control 88.88 ± 4.97 15.25 ± 1.24 73.63 ± 2.73 8.44 ± 0.90 19.90 ± 1.50 7.29 ± 0.24 145.17 ±8.11 Abana 68.69* ± 5.80 10.29* ± 0.80 58.50* ± 3.40 6.93* ± 0.53 11.09* ± 0.54 5.67* ± 0.35 114.77* ± 9.50 Each value is the mean of 6 rats ± SD. *p<0.001 as compared to control. Table 3: Effect of Abana on hepatic cholesterol biosynthesis and faecal excretion of bile acids in rats Biochemical parameters Control Abana Non-saponified (counts/min/mg protein) 1533.00 ± 45.35 953.00* ± 3.50 Cholesterol digitonoid (Counts/min/mg protein) 1162.41 ± 50.62 485.42* ± 28.57 Hepatic lipid biosynthesis Saponified (Counts/min/mg protein) 1128.96 ± 23.68 835.00* ± 28.53 Cholic acid (μg/g faeces) 76.47 ± 3.10 103.58* ± 5.56 Faecal excretion of bile acids Deoxycholic acid (μg/g faeces) 35.97 ± 2.51 64.99* ± 2.90 Each value is the mean of 6 rats ± SD. *p<0.001 as compared to control. The hypocholesterolesterolaemic effect of Abana may be due in part to stimulation of the faecal excretion of bile acids which in turn are responsible for cholesterol homeostasis. Recently we have found that Picroliv from Picrorrhiza kurroa significantly maintained the secretion of biliary cholesterol in thioacetamide-induced hepatic damage in rats. 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