Modulatory Effect of Morinda lucida Aqueous Stem Bark Extract on Blood Glucose and Lipid Profile in Alloxan-Induced Diabetic Rats

Abstract

The present study evaluates the antidiabetic and antihyperlipidemic effects of 125 mg/kg, 250 mg/kg and 500 mg/kg of the 
Morinda lucida aqueous stem bark extract (MLASE) in alloxan-induced diabetic rats for 8 days based on the African traditional 
use of the water infusion of the stem bark of Morinda lucida (family: Rubiaceae) in the local management of diabetes mellitus 
and hyperlipidemia by the Yoruba herbal practitioners (Southwest Nigeria). In this study, experimental diabetes was induced in 
Wistar rats through intraperitoneal injection of 120 mg/kg of alloxan monohydrate dissolved in cold 0.9% normal saline and 
sustained hyperglycemia was monitored over the successive three days. Diabetic rats [with the fasting blood glucose (FBG) 
levels greater or equal to 200 mg/dl] randomly divided into Groups II-VI of six rats per group were daily and orally treated with 
10 m/kg of distilled water, 5 mg/kg of glibenclamide, 125 mg/kg, 250 mg/kg and 500 mg/kg of MLASE, respectiv ely, for 8 days 
after which the rats were sacrificed humanely under inhaled diethyl ether. FBG were determined in the treated diabetic rats on 
the 1st and 8th day of oral extract treatments while the blood samples for the lipid assays of were obtained dire ctly from heart 
chambers through cardiac puncture on the 8th day after an overnight fasting. In addition, preliminary qualitative and quantitative 
analyses of the aqueous stem bark of Morinda lucida were conducted using standard procedures. Results showed that the 
preliminary qualitative analysis of MLASE revealed the presence of presence of flavonoids, alkaloids, saponin, terpenoids, 
phenols, tannins and phlobatinnins while cardiac glycosides, steroid glycosides and anthraquinones were absent. Similarly, 
quantitative analysis of MLASE showed the presence of tannin, alkaloids, phenols, sugar and saponin at the concentrations of 
29.73 ± 0.38 mg/100 g, 25.69 ± 0.10 mg/100 g, 37.15 ± 0.10 mg/100 g, 37.38 ± 0.08 mg/100 g and 54.84 ± 0.21 mg/100 g of 
MLASE, respectively. Repeated daily oral treatments with 125-500 mg/kg of MLASE significantly (p<0.01 and p<0.001) 
lowered the FBG dose dependently with highest antidiabetic effect recorded for the highest dose . Similarly, 125-500 mg of 
MLASE significantly (p<0.05, p<0.01 and p<0.001) decreased serum TG, TC, LDL-c and VLDL-c levels while significantly 
increasing serum HDL-c levels. Overall, results of this study showed MLASE to possess antihyperglycemic and 
antihyperlipidemic effects in experimental diabetic rats which was probably mediated via enhanced peripheral glucose utilization 
and/or enhanced insulin secretion.