Phytopharmacological Evaluation of Gmelina Arborea Roxb. with Special reference to Antidiabetic and Anticonvulsant Activity

Abstract

Herbal medicines remain the major source of health care for the world’s population. The world health organization (WHO) has recognized herbal medicine as an essential building block of primary health care of vast countries like India and China. We have yet to explore fully the vast storehouse of indigenous, tribal or folklore and traditional system of medicine of our country. Gmelina arborea (Verbenaceae), is commonly known as Gambhari, a fast growing tree throughout India and is widely distributed in West Africa, from Senegal to Cameroon. In Ayurveda it has been observed that root bark and fruits are useful in treatment of leprosy, vaginal discharge and also anthelmintic. The root decoction is used in folk remedies for abdominal tumors in India. It is also a folk remedy for anasarca, anthrax, bilious disorder, bites, blood disorder, cholera, convulsions, delirium, diarrhea, dropsy, dyspepsia, epilepsy, fever, gout, headache, hemorrhage, intoxication, madness, rat bite, rheumatism, rinderpest, septicemia, small pox, snake bite, sores, sore throat, stomachic, swelling and urticaria. Bioactive compounds such as Alkaloids, Saponins, Steroids,lignans, Flavonoids, phenolics, Terpenoids and Glycosides were investigated in Methanol extracts of Gmelina arborea. In present study detailed morphological and microscopical studies of Root, stem bark and whole stem was carried out. Powder microscopy and florescence analysis of roots and stems were also performed. The physicochemical parameters of both roots and stems of G. arborea were carried out. Methanolic extract of powdered roots and stems of G. arborea were studied for preliminary phytochemical Screening. Methanolic extract of powdered root revealed presence of flavonoids, phenolics, lignanas and fixed oil and fats and methanolic extract of powdered stems revealed presence of flavonoids and phenolics. Alkaloids, flavonoids, phenolic, lignans, terpenoids, and phenylpropenes were also confirmed by thin layer chromatography. The estimation of the total phenolics and flavonoids content of the different extracts of of G. arborea was also done. The methanolic extract of root contained highest amount of phenolic substance (0.925 %) and aqueous extract of root contained highest amount of flavonoid content (0.8%). In case of stems, methanolic extract contained highest amount of flavonoid content (0.634%) and phenolic content (0.9%). In present study the methanolic extract of roots and stems of G. arborea were investigated for its antidiabetic and anticonvulsant activity. The antidiabetic activity was investigated on streptozotocin induced diabetic for 21 days treatment period. Glibenclamide used as a standard drug at dose of 0.25 mg/kg. Two doses of methanolic extract of roots and stems of G. arborea, 250 and 500 mg/kg, were administered in normal and experimental diabetic rats. Significant (p<0.001) reduction in fasting blood glucose level were observed in both normal and diabetic rats. Methanolic extract of stem in dose of 500 mg/kg showed significant (74.41% ) change in blood glucose level and methanolic extract of root in dose of 500 mg/kg showed remarkable decrease (68.89%) in blood glucose level. In addition, change in body weight, serum lipid profile and GHb (whole blood) level were compared with normal control, induced control and standard (glibenclamide) group. Significant results were observed in estimated parameters, thereby justifying the use of plant in the indigenous system of medicine. Methanolic extract of both roots and stems of G. arborea were also investigated on two different animal model including pentylenetetrazole and strychnine induced seizure in mice. Both methanolic extract showed significant (P<0.001) delay onset of convulsion. In pentylenetetrazole induced convulsion model, methanolic extract of stem in dose of 500 mg/kg showed maximum delay in onset of convulsion (8.188 min) and methanolic extract of root in dose of 500 mg/kg also showed remarkable increase in onset of convulsion (5.51 min). in case of strychnine induced convulsion model, methanolic extract of stem and methanolic extract of root at dose of 500 mg/kg found significant (P<0.001) as they delay onset of convulsion, 11.81 and 10.3 min respectively. The methanolic extract also subjected to screening for their possible antioxidative activities by using different method like 2, 2 diphenyl picryl - 1- hydrazyl (DPPH), hydrogen peroxide and reducing power assay. Methanolic extract of powdered stem of G. arborea was able to reduce free DPPH with IC50 values 44.84 μg/ml. The IC50 value for scavenging of H2O2 for methanolic extract of powdered stem of G. arborea was found to be 181.46 μg/ml and extract also showed the reductive capabilities in a concentration-dependent manner as results showed reduction in absorbance.