Antihyperglycemic Activity of TLC Isolates from the Leaves of Aloe megalacantha Baker in Streptozotocin-Induced Diabetic Mice

Abstract

Background: Diabetes mellitus (DM) is a group of metabolic disorders that are characterized by hyperglycemia which results from defects in insulin release or its efficient use by the human body. Although significant progress has been made to manage DM and related complications, it remains a major global health problem. To this end, the search for new antidiabetic drugs from traditionally claimed medicinal plants is important. Aloe megalacantha Baker is an endemic plant used traditionally to treat diabetes in Ethiopia. This study aimed to investigate antidiabetic activity of isolates from the leaf of A. megalacantha Baker in streptozotocin-induced diabetic mice.

Methods: The exudate of A. megalacantha was collected by cutting the leaves and scraping the yellow sap and then dried at room temperature. The dried exudate was subjected to repeated thin layer chromatographic (TLC) separations using a mixture of solvent system to isolate the major compounds identified on the TLC plate. A single dose of streptozotocin (50 mg/kg) was injected intraperitoneally to overnight fasted mice to induce diabetes. Antidiabetic activity of TLC isolates was assessed by in vivo methods including oral glucose tolerance test, antihyperglycemic and hypoglycemic activity tests.

Results: Three major isolates were obtained from the TLC analysis of the exudate of A. megalacantha. Exudate and TLC isolates were found to be non-toxic up to a dose of 2000 mg/kg. The TLC isolates (Ia and Ib) significantly (p<0.05) reduced blood glucose levels and also increased body weight change of the diabetic mice compared with control groups.

Conclusion: The present study demonstrated the ability of the exudate of A. megalacantha and its TLC isolates to significantly decrease blood glucose levels and increase body weights in mice, thus strengthening the claim of its traditional use in DM-related disorders.

Keywords: Aloe megalacantha Baker; antidiabetic; diabetes; streptozotocin; thin layer chromatography.

Figure 1

TLC isolates of the leaf exudate of A. megalacantha using ethyl acetate, methanol and water in the ratio of 77:13:10, v/v/v. (A) under UV 365 nm, (B) under UV 254 nm.

Figure 2

Time dependent decrease in glucose levels of the OGTT test of exudate of A. megalacantha in normal mice. Group I: 2% DMSO; Group II: 2% DMSO + 2 g/kg glucose; Group III: 100 mg/kg exudate +2 g/kg glucose; Group IV: 200 mg/kg exudate +2 g/kg glucose; Group V: 400 mg/kg exudate +2 g/kg glucose; Group VI: 2 mg/kg GA + 2 g/kg glucose.

Figure 3

Time dependent decrease in glucose levels of the OGTT test of A. megalacantha isolates in normal mice. Group I: 2% DMSO; Group II: 2% DMSO + 2 g/kg glucose; Group III: 200 mg/kg Ia +2 g/kg glucose; Group IV: 400 mg/kg Ia +2 g/kg glucose; Group V: 200 mg/kg Ib +2 g/kg glucose; Group VI: 400 mg/kg Ib +2 g/kg glucose; Group VII: 200 mg/kg Ic +2 g/kg glucose; Group VIII: 400 mg/kg Ic +2 g/kg glucose; Group IX: 2 mg/kg GA + 2 g/kg glucose.