ANTIDIABETIC EFFECT OF M. STENOPETALA: Evidences from Animal Experiments

Hailemesekl Mekonnen(PhD fellow, CDT-Africa/AAU), professor Eyasu Makonnen(PhD, AAU/CHS)

Moringa stenopetala belongs to family Moringaceae is commonly grown in Southern parts of Ethiopia. The leaves of Moringa stenopetala are cooked and row eaten as vegetables and the leaves and roots are used to treat different disease including diabetes.

This paper reviews several in-vitro studies are conducted on Moringa stenopetala in Ethiopia. To this effect different publications retrieved with the search term “Moringa and its organ effects`` from the MEDLINE, EMBASE, the Cochrane Controlled Trials Registry. Ghebreselassie et al. (2011) have studied the effect of the water extract of dried leaves of M. stenopetala on some blood parameters in mice. Six weeks daily treatment with the extract at a dose of 900 mg/kg via an oral route has shown a statistically significant decrease in serum glucose and cholesterol level. These results coupled with the observed body weight gain of the experimental animals were in line with the traditional uses of the plant as nutritionally valuable food source and antidiabetic agent. The crude ethanol extract and its polar fraction (e.g. n-butanol) have also shown to display antidiabetic activity in chronic and/or long-term treatment regime (Toma et al., 2012). The doses used in these studies appear to be somewhat high (300_900 mg/kg) but we should make a note of the lack of acute toxicity at high doses (Toma et al., 2012) and the plant already being used as food. Hence, the reported activity of the plant in vivo is a significant finding in establishing the antidiabetic potential of the leaves. In a subsequent study by the same authors (Toma et al., 2015), the antidiabetic activities of the aqueous ethanol and n-butanol fraction of M. stenopetala leaves were further validated through the streptozotocin-induced diabetic rat model.

The antihyperglycemic effects of M. stenopetala leaves have also been established by other authors. Administration of the aqueous and 70% ethanolic extract daily for 15 days in rats resulted in the reduction of the fructose (66%, w/v, ad libitum)-induced hyperglycemia (Geleta et al., 2016a). Similarly, Sileshi et al. (2014) have demonstrated the antihyperglycemic effect of the 70% ethanolic extract and its polar fraction (butanol) in alloxan-induced diabetes model in mice. The extracts administered at 500 mg/kg oral dosage appeared to reduce the glucose level in diabetic mice within 2 h. In another study employing the alloxan-induced diabetic mice model by Nardos et al. (2011), a single or repeated doses (300 mg/kg, i.p.) of the ethanol extract of the leaves as well as its fractions (chloroform, butanol, and aqueous residue) have been shown to display hypoglycemic (normal animals) and antihyperglycemic (diabetes mice) effects. These data were in agreement with a previous study by Makonnen et al. (1999) that demonstrated the glucose lowering effect of the leaves extract in nondiabetic rabbits.

The potential therapeutic value of M. stenopetala for diabetes was further substantiated by the finding of rutin and neochlorogenic acid as a major and minor component, respectively, of the leaves (Habtemariam, 2015; Habtemariam and Varghese, 2015). It is also worth noting that the level of rutin in M. stenopetala leaves was found to be comparable with commercial source plants that are utilized for large-scale extraction of this pharmacologically active natural product (Habtemariam and Varghese, 2015). The pharmacological properties of rutin are thus particularly important in explaining the antidiabetic potential of the leaves. A comprehensive review article by Habtemariam and Lentini (2015) has shown the various possible mode of action of rutin as an antidiabetic agent.