Antidiabetic effects of Aloe ferox and Aloe greatheadii var. davyana leaf gel extracts in a low-dose streptozotocin diabetes rat model

The medicinal use and commercialisation of the plants Aloe ferox and Aloe greatheadii are primarily based on research done on Aloe vera and Aloe arborescens. Consequently, in this study we investigated the possible antidiabetic effects of ethanol extracts of A. ferox and A. greatheadii var. davyana leaf gel in a streptozotocin (STZ)-induced type 2 diabetes rat model. Fifty male Wistar rats, weighing 200 g - 250 g, were randomly divided into five groups of n = 10: normal control rats, diabetic control rats, diabetic rats receiving A. ferox leaf gel extract (300 mg/kg), diabetic rats receiving A. greatheadii leaf gel extract (300 mg/kg), and diabetic rats receiving glibenclamide (600 μg/kg). Diabetes was induced by a single intraperitoneal injection of STZ (40 mg/kg). Rats were sacrificed 5 weeks after injection, following a 12-hour fast, and blood and tissue samples were collected. Compared to the normal control group, STZ significantly increased relative liver and kidney weights, end-point plasma glucose, fructosamine, oxidative stress, liver enzymes, total cholesterol (TC), triglycerides, very low density lipoprotein-cholesterol and TC: high density lipoprotein-cholesterol (HDL-C) values and reduced serum insulin levels. Treatment with A. greatheadii moderately increased serum insulin and HDL-C levels and moderately reduced end-point plasma glucose and liver alkaline phosphatase (ALP) and significantly decreased TC:HDL-C ratios. A. ferox supplementation similarly resulted in moderately increased serum insulin, accompanied by slight corrections in ALP and HDL-C, without any change to end-point plasma glucose values. A. greatheadii and, to a lesser extent, A. ferox, resulted in a clinically relevant improved diabetic state (indicated by moderate to high effect sizes), suggesting that these Aloe species may show promise for treating diabetes.