Natural Compounds 2021

Biography:

Abstract:

Background: Abrus precatorius is used in folklore medicine in Ghana to treat diabetes mellitus and asthma.

Objective: The study investigated hypoglycaemic effect of Abrus precatorius leaf extract (APLE) and its possible mechanisms of action by using in vivo and in vitro models.

Method: Diabetes mellitus (DM) was experimentally established in normoglycaemic Wistar rats (16 weeks) by sequential injection of Streptozotocin (STZ)-citrate buffer (60 mg/kg ip) and nicotinamide (NIC)-saline solution (110 mg/kg ip).  With the exception of the sham group (No STZ/NIC injection; normal saline, 5 ml/kg ip; baseline FBG = 6.48 mmol/L), rats with fasting blood glucose (FBG) stable between 28 – 32.5 mmol/L seven days post STZ/NIC injection were randomly re-assigned to the following groups: model (STZ/NIC-induced hyperglycemia in rats; no treatment), APLE (100, 200 and 400 mg/kg respectively po) and  metformin (300 mg/kg po) and treated for 28 days. Bodyweight and FBG were measured on weekly basis. FBG was determined by using standard glucose test strips on blood obtained from tail-puncture. At the end of treatment rats were sacrificed under chloroform anesthesia, blood collected via cardiac puncture and brain, kidney, liver and pancreas harvested. While the pancreas was processed, sectioned and H&E-stained for histological examination, the kidney and liver were homogenized for assessment of total anti-oxidant capacity. Median cross-sectional area of the pancreatic islets of Langerhans was determined for each group. Total antioxidant capacity of plasma and DPPH scavenging ability were determined by using ascorbic acid as standard. Also, α-glucosidase inhibitory effect of APLE was assessed relative to acarbose standard.

Results: At the end of 28 days post STZ/NIC treatment, cumulatively APLE (100, 200 and 400 mg/kg respectively) significantly (P < 0.05) decreased the initial FBG by 55.22, 76.15 and 77.77 % respectively) compared to model (-1.04 %) and metformin (72.29 %) groups. APLE increased median cross-sectional area (x10⁶ μm²) of pancreatic islets compared to that of model group. APLE produced dose-dependent decrease in immune cell infiltration relative to model group.  Generally APLE (400 mg/kg; 5.21 ± 0.02 AscAE μg/mL) produced significant (P < 0.05) plasma ascorbic acid equivalent (AscAE μg/mL) TAC compared to model (4.06 ± 0.04 AscAE μg/mL) and metformin (4.87 ± 0.03 AscAE μg/mL) groups. APLE produced concentration-dependent inhibitory activity against α-glucosidase activity at an IC₅₀ of 33.89 ± 0.06 μg/mL comparable to that of acarbose standard at an IC₅₀ 37.10 ± 0.45 μg/mL. APLE produced concentration-dependent DPPH scavenging activity though lower in potency compared to ascorbic acid.

Conclusion: APLE produced hypoglycemic effect in STZ/NIC-induced hyperglycemic rats possibly mediated through inhibition of α-glucosidase activity; increased free radical scavenging and antioxidant activities as well as amelioration of pancreatic islet atrophy.