In vitro and in vivo evaluation of the anti-diabetic, anti-hyperlipidemic and antioxidant properties of aqueous extract of Millettia laurentii bark (Fabaceae)

Hyperglycemia, oxidative stress and dyslipidemia play a major role in the pathophysiology of diabetes and its macro and microvascular complications. Therefore, managing hyperglycemia, oxidative stress and dyslipidemia is an effective way to control diabetes. The present study aimed to evaluate in vitro and in vivo the anti-diabetic, anti-hyperlipidemic and antioxidant potential of the aqueous extract of M. laurentii barks.

The M. laurentii barks were harvested, treated, dried, ground and an aqueous extraction was carried out (1:10 weight/volume). Subsequently, the anti-hyperglycemic (inhibition of α-amylase and invertase activity) and antioxidant (DPPH radical scavenging, iron III reduction and metal chelating) properties of the aqueous extract was evaluated in vitro. In the in vivo study, 20 male Wistar strain rats with an average weight of 230 to 250 gramme divided into two groups; a negative control group (NC) and a batch of 15 rats. This last batch received an intraperitoneal injection of 45mg/kg BW of streptozotocin then subdivided into 3 groups of 5 rats: positive control group (PC) receiving distilled water, a test group receiving aqueous extract of M. laurentii barks (AEML) at the dose of 300 mg/kg BW and a reference group receiving metformin at 20 mg/kg BW. After 21 days of experimentation, the animals were sacrificed, the plasma, serum, hemolysate and liver homogenate were used to evaluate the biomarkers of oxidative stress (catalase, MDA), lipid profile (triglyceride, total cholesterol and HDL-cholesterol) and immunological biomarkers (CRP and NFS).

It emerged that the aqueous extract presented in vitro an anti-hyperglycemic activity (inhibition of invertase and alpha amylase with IC50 values 0.015 and 0.38 mg/mL, respectively) and antioxidant activity (DPPH radicals scavenging, reduction of iron III and inhibition of haemolysis). The extract also reduced in vivo, chronic hyperglycemia by -28.44% after 21 days of treatment, improved endogenous antioxidant status, inflammation and lipid profile.

The findings show that AEML has an anti-diabetic, anti-hyperlipidemic and antioxidant properties. Therefore, could be used traditionally in the management of diabetes and its complications in Cameroon. Extending the current control of chronic hyperglycemia is urgently needed in Cameroon to protect human lives.