Determination of the Antidiabetic Effectiveness of Green Round Eggplant (Solanum xanthocarpum) Compounds in a Nanoliposome Preparation on Insulin Levels of Alloxan-Induced Diabetic Rats

The low oral bioavailability of plant secondary metabolites remains a major obstacle in developing antidiabetic phytopharmaceuticals. This study aimed to determine the antidiabetic effectiveness of green round eggplant (Solanum xanthocarpum Schrad. & Wendl.) fruit compounds, formulated as an ethyl acetate extract (EEATBH) and as nanoliposomes of the ethyl acetate extract (NEEATBH), based on serum insulin levels in alloxan-induced diabetic rats. The dried crude drug was characterised according to the Indonesian Materia Medica, macerated with ethyl acetate, and formulated into three nanoliposomes (F1–F3) with varying Span 60 content (70, 80, and 90 mg) using thin-film hydration followed by 30-minute sonication. Thirty male Wistar rats were divided into six groups (n = 5) and rendered diabetic with alloxan 150 mg/kg BW intraperitoneally, then treated orally with 1% Na-CMC (negative control), glibenclamide 0.09 mg/kg BW (positive control), NEEATBH at 25, 50, and 100 mg/kg BW, and EEATBH at 100 mg/kg BW. Serum insulin was quantified by ELISA at 450 nm and analysed by one-way ANOVA followed by Tukey’s test (α = 0.05). The extract contained saponins, tannins, flavonoids, glycosides, and steroids/triterpenoids, with a yield of 1.71%. Formula F3 produced the smallest particle size (44.93 nm) at pH 6.0 ± 0.12 and was selected for the in vivo assay. All treatment groups significantly raised insulin levels relative to the negative control (107.443 ± 0.836 pg/mL; p < 0.001). The highest insulin level was achieved by NEEATBH 100 mg/kg BW (615.223 ± 4.599 pg/mL), exceeding both glibenclamide (507.000 ± 1.000 pg/mL) and the equivalent dose of EEATBH (485.000 ± 1.837 pg/mL), corresponding to a relative effectiveness of 127.09% against glibenclamide. The insulin response was dose-dependent (r2 = 0.970). Liposomal nanoencapsulation increased the net insulinotropic effect of the extract by 34.5% at an identical dose. Nanoliposomes of the S. xanthocarpum ethyl acetate extract are therefore more effective than the conventional extract in elevating insulin levels in diabetic rats.