The Effects of the Ethanol Extract of Allium Ascalonicum L. in High-Fat-High-Fructose-Induced Insulin Resistance Swiss-Webster Male Mice

Abstract

Background: Insulin resistance (IR) is a condition where the body cannot respond properly to insulin, leading to elevated blood glucose and the development of type 2 diabetes mellitus (T2DM). The first-line anti-T2DM drug is metformin, however, it has shown adverse effects, challenging the search for alternative natural drugs. Plant flavonoids stimulate cellular glucose uptake, decrease hyperglycemia, and regulate key signaling pathways in glucose metabolism. Brebes shallots (Allium ascalonicum L.) are known to contain flavonoids and thus may have the potential to inhibit IR.

Purpose: To evaluate the effects of the ethanol extract of Brebes shallots in improving IR conditions.

Methods: Brebes shallots were collected from West Java, Indonesia. 500 g of the shallots were oven-dried and extracted using 70% ethanol for 3×24 h, the solvent was evaporated to a thick consistency, and the extract was abbreviated as EAA. The effects of EAA were studied in high-fat-high-fructose (HFHF)-induced Swiss-Webster male mice by performing the insulin tolerance test (ITT) and oral glucose tolerance test (OGTT), and the liver and pancreas index. The nutritional composition and quercetin levels in the extract were also determined.

Results: The extraction process yielded a 28.1% EAA. EAA reduces % weight gain, blood glucose levels in OGTT, and liver and pancreas index. EAA significantly improved insulin tolerance in the HFHF-induced mice (p < 0.05). Proximate analysis resulted in 3.92% ash, 0.12% fat, 13.45% protein, and 60.69% carbohydrate, while quercetin was at 0.0065%.

Conclusion: Allium ascalonicum L. extract may improve IR conditions as confirmed by its ability to increase the ITT value and reduce blood glucose levels. However, further studies are needed to confirm its role in alleviating metabolic disorders.

Keywords: Allium sp; diabetes mellitus; flavonoids; hypoglycemia; insulin resistance; quercetin.

Figure 1

Fresh Brebes shallot bulbs in their maturation stage, collected from Brebes, Central Java, Indonesia.

Figure 2

Thin-layer chromatography bands of EAA and quercetin were observed at 254 nm with band 1: EAA spiked with quercetin 250 µg/mL, band 2: EAA spiked with quercetin 500 µg/mL, band 3: EAA spiked with quercetin 750 µg/mL, band 4: EAA spiked with quercetin 1000 µg/mL, band 5: EAA spiked with quercetin 1250 µg/mL, band 6: EAA without quercetin spike, and band 7: standard quercetin.

Figure 3

Thin-layer chromatography-densitometry chromatograms of EAA and quercetin were measured at 320 nm. A mixture of toluene: ethyl acetate: and formic acid (5:4:0.5) was employed for the mobile phase. Chromatogram a: EAA spiked with quercetin 250 µg/mL, chromatogram b: EAA spiked with quercetin 500 µg/mL, chromatogram c: EAA spiked with quercetin 750 µg/mL, chromatogram d: EAA spiked with quercetin 1000 µg/mL, chromatogram e: EAA spiked with quercetin 1250 µg/mL, chromatogram f: EAA without quercetin spike, and chromatogram g: standard quercetin.

Figure 4

Quercetin standard addition curve of the thin-layer chromatography-densitometry of EAA. The linear regression equation of the standard addition curve is y = 93.12 x – 1196.4; R = 0.9715.

Figure 5

Effects of EAA on the % weight gain of the HFHF-induced mice. The asterisk (*) shows a significant difference compared to the negative control or untreated group, with p < 0.05.

Figure 6

Effects of EAA on insulin tolerance of the HFHF-induced mice. The asterisk (*) shows a significant difference compared to the negative control or untreated group, with p < 0.05.

Figure 7

Effects of EAA on the liver (a) and pancreas (b) indices of the HFHF-induced mice. The asterisk (*) shows a significant difference compared to the negative control or untreated group, with p < 0.05.