<i>In vitro</i> and <i>in vivo</i> antidiabetic potential of extracts and a furostanol saponin from <i>Balanites aegyptiaca</i>

<p><b>Context:</b><i>Balanites aegyptiaca</i> Del. (Zygophyllaceae) fruits are well-known antidiabetic drug in Egyptian folk medicine. Nevertheless, its mechanism of action is still unclear.</p> <p><b>Objectives:</b> Searching for the possible mechanisms of action of the plant and identification of its bioactive compounds.</p> <p><b>Materials and methods:</b> A bio-guided protocol based on the evaluation of α‐glucosidase (AG) and aldose reductase (AR) inhibitory activities was adopted to isolate the biologically active compounds from the methanol extract (MeEx). An <i>in vivo</i> antidiabetic study was conducted for the active extract, fraction and compound using streptozotocin-induced diabetic male albino Wistar rats at two dose levels (100 and 200 mg/kg.b/wt) for 2 weeks.</p> <p><b>Results:</b> Three compounds were isolated and identified: a sterol, (<b>1</b>) stigmasterol-3-<i>O</i>-β-d-glucopyranoside; a pregnane glucoside, (<b>2</b>) pregn-5-ene-3β,16β,20(R)-trio1-3-<i>O</i>-β-d-glucopyranoside; a furostanol saponin, (<b>3</b>) 26-(<i>O</i>-β-d-glucopyranosyl)-22-<i>O</i>-methylfurost-5-ene-3β,26-diol-3-<i>O</i>-β-d-glucopyranosyl-(1 → 4)-[α-l-rhamnopyranosyl-(1 → 2)]-β-d-glucopyranoside. Only compound <b>3</b> possessed significant AG and AR inhibitory activities (IC₅₀ = 3.12 ± 0.17 and 1.04 ± 0.02 μg/mL, respectively), while compounds <b>1</b> and <b>2</b> were inactive. The <i>in vivo</i> antidiabetic study revealed that MeEx and furostanol saponin <b>3</b> possessed significant activities at a dose of 200 mg/kg through reducing the fasting plasma glucose level by 46.14% and 51.39%, respectively, as well as reducing the total cholesterol by 24.44% and 31.90%, respectively. Compound <b>3</b> also caused increment in insulin and C-peptide levels by 63.56% and 65%, respectively.</p> <p><b>Discussion and conclusions:</b> We presented a scientific base for using <i>Balanites aegyptiaca</i>, and shed the light on one of its saponins, as an antidiabetic agent in fasting and postprandial hyperglycaemia along with the improvement of diabetic complications.