Phytochemical Profiles, in Vivo Antidiabetic, Immunomodulatory, and Toxicity Effects of Extracts of Pumpkin (Cucurbita maxima DUCHESNE)

Abstract

Diabetes is an increasing global public health concern. It is associated with microvascular and macrovascular complications and sometimes fatalities. There is a need for research on substitutes for antidiabetic drugs due to severe effects linked with synthetic drugs in use. Plant-derived phytochemicals are lead candidates in drug discovery. This study was designed to determine the phytochemical profiles and in vivo antidiabetic, immunomodulatory, and toxicity effects of seed and pulp of Cucurbita maxima (pumpkin) extracts. The shade-dried pulp and seeds of the pumpkin were ground and then extracted using ethanol and distilled water. The extracts' phytochemical profiles were examined using liquid chromatography-mass spectrometry analysis. In the antidiabetic assays, hyperglycemia was induced using alloxan monohydrate in male rats. The diabetic rats were then randomly categorized into ten groups: glibenclamide control, diabetic control, and extract-treated (Cucurbita maxima extracts at 200 and 400 mg/kg body weight (bw)) groups (n = 5). An additional group of non-diabetic control rats was also introduced. The experimental rats received treatments orally for 28 days. The experimental rats' fasting blood glucose (FBG) levels were monitored at weekly intervals. On the 29th day, the rats were euthanized, and the pancreas was obtained for histopathological analysis. In the immunomodulatory assays, the procedure similar to that of the antidiabetic assay was followed. On days 0, 7, 14, 21, and 28, the experimental rats were euthanized and blood was collected. The serum obtained was used to measure levels of interferon-gamma (INF-γ), tumor necrosis-alpha (TNF-α), interleukin-4 (IL-4), and interleukin-10 (IL-10) using enzyme-linked immunosorbent assay kits. Acute and sub-acute toxicity tests of the aqueous pulp and seed extracts were conducted following the Organization for Economic Co-operation and Development guidelines 423 and 405, respectively. One-factorial analysis of variance and Tukey’s multiple comparisons were utilized to analyze raw data. A p ≤ 0.05 was utilized as the significance level. The phytochemicals that were identified were fatty acids, phenolic acids, cucurbitacins, and flavonoids. Some of these phytocompounds are associated with antidiabetic and immunomodulatory effects. The studied extracts (200 and 400 mg/kg bw), as well as glibenclamide, significantly reduced the elevated (p < 0.05) levels of FBG in contrast to those in diabetic control rats, indicating an antidiabetic effect. The effect of the studied extracts, as well as glibenclamide also demonstrated regeneration of the islets of Langerhans in the pancreas tissue. The studied extracts (200 and 400 mg/kg bw) significantly downregulated TNF-α and INF-γ levels, as well as upregulated IL-4 and IL-10 levels (p < 0.05) in contrast to those in the diabetic control, indicating an immunomodulatory effect. The antidiabetic and immunomodulatory activities of the studied extracts were dose-dependent, and the ethanol seed extract had better effects than the other studied extracts. No fatalities or drug-related behavioral changes or toxicity signs were reported after single-dose exposure of the aqueous seed and pulp extracts at 1000 and 2000 mg/kg bw for 14 days. The LD50 of the two extracts exceeded 2000 mg/kg bw. The effects of ethanol seed and pulp extracts of Cucurbita maxima (200, 350, and 600 mg/kg bw) for 28 days did not cause any significant alterations in body weights, relative organ weights, haematological parameters, kidney function and liver function biomarkers, and lipid profiles, and these parameters statistically matched those in (p > 0.05) normal control rats, suggesting that the extracts were safe. In conclusion, the 4 studied extracts possess phytochemicals with antidiabetic and immunomodulatory effects. Additionally, the aqueous pulp and seed extracts were safe upon single dose exposure and repetitive dose exposure (28 days). This study validated the folkloric medicinal use of Cucurbita maxima by communities residing in Embu County, Kenya. The study recommends that the four studied extracts be harnessed in investigating and developing alternative antidiabetic and immunomodulatory agents.