Studies on the glycemic and lipidemic effect of Murraya koenigii in experimental animals

Abstract

Diabetes is often accompanied by lipid abnormalities, which contribute significantly to cardiovascular morbidity and mortality in diabetic patients. Previously, we have demonstrated potent hypoglycemic activity of lyophilized aqueous extract of Murraya koenigii leaves in normal and alloxan induced diabetic rabbits for short duration of 6 h. In this study, we examined the effect of 1 month oral administration of Murraya koenigii aqueous leaves extract in normal and STZ induced severe diabetic rats, at the dose of 300 mg/kg bw, on various biochemical parameters, viz., fasting blood glucose (FBG), total cholesterol (TC), HDL-cholesterol (HDL), triglyceride (TG), alkaline phosphatase (ALKP), serum glutamate oxaloacetate and pyruvate transaminases (SGOT and SGPT) and serum creatinine. In case of diabetic animals fasting blood glucose (FBG) levels of treated animals reduced by 48.2% after 30 days treatment with the aqueous leaves extract. A fall of 19.2 and 30.8% in TC and 22.97 and 37.1% in TG levels were also observed in the case of treated normal as well as diabetic rats, respectively. Feeding the extract increased the HDL-cholesterol level by 16 and 29.4% in normal and diabetic rats, respectively, as compared with their initial values.

In the normal rats after 1 month of oral administration of the extract SGOT and SGPT levels were decreased by 21.7 and 25.0%. Serum alkaline phosphatase values of the treated normal animals were also reduced by 33% while negligible change was observed in the normal control animals. In the case of diabetic rats, SGOT and SGPT levels were reduced by 36.7 and 32.2%, respectively, whereas ALKP levels decreased by 39.7% after 1 month oral administration of the extract.

The serum creatinine levels decrease in normal as well as in the diabetic animals by 17.75 and 18.2%, respectively, as compared to initial values. In the diabetic control animals the urinary sugar remains at +4 level but there was a decrease of 75% in urine sugar in the case of treated diabetic rats. This indicates that the aqueous extract of Murraya koenigii has favorable effect in bringing down the severity of diabetes.

Introduction

Type II diabetes is the commonest form of diabetes constituting 90% of the diabetic population (King et al., 1998). The countries with the largest number of diabetic patients in the year 2025 will be India, China and United States (Ramchandran et al., 2002). Therefore, it has become necessary to look for novel oral therapeutically effective treatment especially for usage in the developing as well as under-developed countries.

India is a country with a vast reserve of natural resources and a rich history of traditional medicine (Grover and Vats, 2001). Ethnopharmacological surveys indicate that more than 1200 plants are used in traditional medicine for their alleged hypoglycemic activity (Marles and Farnsworth, 1995, Jouad et al., 2001, Grover et al., 2002). The hypoglycemic activity of a large number of these plants/plant products has been evaluated and confirmed in animal models (Gupta et al., 2005a, Gupta et al., 2005b, Kesari et al., 2005, Kesari et al., 2006, Ruzaidi et al., 2005) as well as in human beings (Jaouhari et al., 1999, Herrera-Arellano et al., 2004, Jayawardena et al., 2005).

Murraya koenigii (L.) Spreng (family: Rutaceae) is an aromatic pubescent shrub or small tree commonly known as ‘Curry patta’ in India. The plants originated in Tarai regions of Uttar Pradesh, India and now widely found in all parts of India. It adorns every house yard of Southern India and is also cultivated in Sri Lanka, China, Australia and the Pacific islands (Anon., 1962, Joseph and Peter, 1985). The plant is used in Indian system of medicine to treat various ailments (Chopra et al., 1996, Warmann, 1999, Kesari et al., 2005). The aromatic leaves, which retains their flavour and other qualities even after drying, are slightly bitter, acrid, cooling, weakly acidic in tastes and are considered as tonic, anthelminthic, analgesic, digestive, appetizing and are widely used in Indian cookery for flavouring food stuffs. The green leaves are used to treat piles, inflammation, itching, fresh cuts, dysentery, vomiting, burses and dropsy. The roots are slightly purgative, stimulant and used for general body aches, whilst the bark is used to treat snakebite (Kong et al., 1986). The essential oil of the leaves is reported to possess antimicrobial (Goutam and Purohit, 1974), antifungal (Deshmukh et al., 1986) and pesticidal (Pathak et al., 1997) activities.

Murraya koenigii (MK) leaves mixed with fat separated butter fat are used for the treatment of amoebiasis, diabetes and hepatitis in Ayurveda (Pillai, 1958, Bose, 1985, Satyavati et al., 1987). The aqueous extract of the leaves of Murraya koenigii produced hypoglycemia in normal and alloxan diabetic dogs (Narayan and Sastry, 1975). Oral feeding of Murraya koenigii leaves diet for 60 days to normal rats showed hypoglycemic effect associated with increase in the concentration of hepatic glycogen (Khan et al., 1995). Dietary supplement with curry leaves has been shown to increase lecithin cholesterol acyl transferase activity (Khan et al., 1996). Curry leaves powder supplementation (12 g providing 2.5 g fibre) for a period of 1 month in 30 type II diabetes patients showed reduction in fasting and post-prandial blood sugar levels at 15-day period with no significant changes in serum glycosylated protein levels, glycosylated low density lipoprotein cholesterol fraction, serum lipids, lipoprotein cholesterol levels, uronic acid and total amino acids (Iyer and Mani, 1990). Daily intraperitoneal injection of 80 mg/kg of curry leaf extract to diabetic ob/ob mice for 10 days showed decrease of blood cholesterol and blood glucose levels in them (Xie et al., 2006). Yadav et al. (2002) has reported that feeding different doses of Murraya koenigii leaves to diabetic rats play role in control of mild diabetes but in case of moderate, severe and type I diabetes this agent alone is not likely to be useful.

In continuation of our research work with Murraya koenigii leaves (Kesari et al., 2005) we have further extended our study for severe diabetic models. The present work deals with the antidiabetic and hypolipidemic action of aqueous extract of Murraya koenigii leaves in case of severe diabetic rats.