Phytopharmacological Evaluation of the Bark of Ailanthus Excelsa Roxb. with Special reference to its Anti-Hyperlipidemic Activity.

Abstract

The importance of serum lipoprotein disturbances and abnormal lipid metabolism characterized by hyperlipidemia or hyperlipoproteinemia as etiological factors in the development of coronary heart diseases and potentiating of arteriosclerosis is now supported by a considerable body of evidence amassed from epidemiological and population studies (Anonymous, 1971 and 1984; Turpanen, 1979). Infect, it is almost accepted that arteriosclerosis is a disorder of lipid transport and metabolism. Cholesterol by-product would form thick, tough deposit called plague on the inner wall of the arteries, stiffening them and then starving the heart of blood, creating choke point where a clot could stop the flow entirely (Duff and Macmillian, 1951; Goldstein et al., 1979). Ailanthus is a deciduous tree belonging to the family Simaroubaceae and is widely distributed in Asia and north Australia. Its native origin is China and it is known as ‘tree of heaven’, ‘tree of sun’ or ‘Persian sumach’ (Adamik and Brauns, 1957). In traditional medicine A. excelsa is used to cure wounds and skin eruptions and is used in the indigenous system of medicine as a antipyretic, and for bronchitis, asthma and in conditions of diarrhoea and dysentery (British Pharmacopoeia, 1988). Macroscopical and microscopical characters were studied first for authentication of the bark of A.excelsa. Various physicochemical parameters like ash values, extractive values, moisture content and swelling index were also evaluated for the bark powder. Preliminary phytochemical screening showed the presence of phytoconstituents like flavonoids, triterpenoids, phenolics, tannins, carbohydrates etc. Estimations of flavonoids, triterpenoids and phenolics showed higher amount of presence of all above three classes of constituents in aqueous extracts as compared to methanolic extracts. High fat diet (containing 20% ground nut oil, 1% cholesterol, and 0.5 % cholic acid) model was used for in-vivo evaluation of anti hyperlipidemic activity. Both aqueous and methanolic extracts showed significant reduction in total cholesterol, triglyceride and LDL levels and increase in HDL and total protein levels in serum when compared to HFD group. Both the extracts showed anti hyperlipidemic activity comparable with standard drug atorvastatin. Antioxidant parameters for liver were also measured at the end of the study. Significant lower levels of MDA and Glutathion were found in all treated groups when compared to disease induced group. Histopathology studies also showed the less amounts of fatty infiltration in treated groups when compared to disease induced group. Both aqueous (200mg and 400mg) and methanolic (200mg and 400mg) extracts produced no significant effects in all lipid parameters. Significant reduction in body weight and food intake was also observed in all treated groups as compared to high fat diet groups. In intravenous lipid tolerance test in rats, all the treated and control group animals showed rise in the triglyceride levels at 20 minute interval, and then in all the groups significant reduction in triglyceride levels in next 40 and 60 minute time intervals. Methanolic extracts (200 mg/kg) and quassinoid rich fraction (200 mg/kg) showed significant reduction in triglyceride levels at 60 minutes when compared to 20 min time interval. The aqueous extracts also produced decrease in triglyceride levels at 60 min when compared to 20 min triglyceride levels. In-vitro lipase assay was also performed and IC 50 value of the aqueous extracts was found to be 400 μg/ml. DPPH free radical scavenging activity was also carried out for anti oxidant activity. Quassinoid rich fraction showed highest anti oxidant activity (with IC 50 value of 85.77± 0.13 μg/ml) as compared to aqueous and methanolic extracts. All three above observed effects may be due to presence of the predominant phytoconstituents like triteprenoids and flavonoids. In conclusion, aqueous and methanolic extracts of A.excelsa possesses anti hyperlipidemic and anti obesity potentials. Hence, it can be suggested that the bark of A. excelsa could be useful for the treatment of lipid disorders.