Browsing by Author "Maneemegalai, S."

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Antidiabetic effect of Coccinia grandis Linn. on streptozotocin induced diabetic rats and its role in regulating hepatic key enzymes
(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Meenatchi, P.; Maneemegalai, S.
Coccinia grandis (L.) Voigt is an herb, growing throughout India widely used in traditional treatment of diabetes. The aim of present study was to evaluate the antidiabetic potential of ethanol extract of mature unripe fruits of Coccinia grandis (CGE) in streptozotocin (STZ)induced diabetic rats with reference to carbohydrate metabolizing hepatic enzymes. Male albino rats of Wistar strain with body weight, 180 ± 20 g were divided into 5 groups of 6 rats in each (normal control, normal + 250 mg CGE, diabetic control, diabetic + 250 mg CGE and Diabetic + 5 mg glibenclamide (GBE)). Diabetes was induced in overnight fasted experimental rats by a single intraperitoneal injection of STZ (40 mg/kg body weight) dissolved in freshly prepared citrate buffer (0.1 M, pH 4.5). The animals were considered as diabetic, if their blood glucose values were above 250 mg/dl on the third day after STZ injection. The treatment was started on the third day after STZ injection and continued for 30 days at 24 h intervals during the entire period of the experiment. After the experimental period, the plasma glucose was estimated by the method of Trinder using a reagent kit (1969) and the glycated hemoglobin (HbA1c) was estimated by the method of Drabkin and Austin (1932) and Sudhakar and Pattabiraman (1981). Administration of CGE at 250 mg/kg body weight showed a significant (p<0.05) reduction in the levels of plasma glucose, from 289.65 ± 22.63 to 154.36 ± 4.64 mg/dL and HbA1c from 1.26 ± 0.027 to 0.62 ± 0.039 mg/g of Hb when compared to diabetic control group. The levels of hepatic key enzymes viz. hexokinase, glucose-6-phosphate dehydrogenase, glucose 6-phosphatase, fructose 1,6bisphosphatase were assayed using methods of Brandstrup et al. (1957), Koide and Oda (1956), Gancedo and Gancedo (1971) and Bergmeyer (1984) respectively. Oral administration of CGE to diabetic group significantly (p<0.05) increased the activity of hexokinase from 87.53 ± 3.57 to 98.64 ± 4.63 nmoles of glucose-6-phosphate liberated/min/mg protein and glucose-6-phosphate dehydrogenase from 1.38 ± 0.14 to 1.72 ± 0.13 IU/L. In contrast, oral administration of CGE to diabetic group of animals significantly (p<0.05) decreased the gluconeogenic enzymes glucose 6-phosphatase from 0.31 ± 0.03 to 0.08 ± 0.04 IU/L and fructose 1,6-bisphosphatase from 8.26 ± 0.41 to 3.72 ± 0.36 IU/L. The results of this study demonstrated unequivocally the antidiabetic effect of C. grandis by modulating hepatic key enzymes and a good candidate for complementary and alternative medicine in the management of diabetes mellitus.
Antidiabetic efficacy of two major compounds isolated from Coccinia grandis (L.) Voigt and their effect on insulin-producing cell line RINm5F in vitro
(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Meenatch, P.; Purushothaman, A.; Maneemegalai, S.
Coccinia grandis (L.) Voigt (Cucurbitaceae family) is widely used in traditional treatment of diabetes. The present study aimed to isolate and characterize major bioactive compounds from mature unripe fruits of Coccinia grandis (L.) Voigt and evaluate their insulinotropic properties in insulin producing rat RINm5F cells in vitro. The n-butanolic concentrate of the fruit extract was subjected to thin layer chromatography (TLC) and repeated silica gel column chromatography followed by elution with various solvents. The compounds were identified based on observed spectral (IR, 1H NMR, 13C NMR and mass spectrometry) data. The structure of two major compounds isolated from Coccinia grandis was elucidated as β-sitosterol (C29H50O) and lupeol (C30H50O) by extensive spectroscopic studies. Furthermore, the isolated compounds viz. β-sitosterol and lupeol were assessed for insulinotropic properties using RINm5F cells in vitro. Insulin secretion activity of βsitosterol/lupeol was determined after 60 min incubation with RINm5F cells. Glucose-free Krebs-Ringer bicarbonate (KRB) buffer was used as Vehicle and Glibenclamide (10 µM) dissolved in DMSO, further diluted with Kreb’s Ringer buffer was used as positive control. Aliquots (10 μL) were removed from each well, centrifuged (2000 rpm for 5 min, at 4 °C), and assayed for insulin with Mercodia Rat Insulin ELISA kit as per Manufacturer's protocol. A concentration dependent increase in insulin secretion was observed for both the compounds. The isolated compound β-sitosterol significantly (p < 0.05) increased the insulin secretion from 0.0198 ± 0.0065 (vehicle control) to 0.098 ± 0.0058 μg/105 cells at the concentration of 15 μg/mL. Likewise, lupeol increased the insulin secretion from 0.0187 ± 0.0054 (vehicle control) to 0.065 2 ± 0.0043 μg/105 cells at the same concentration. The anti-diabetic compounds isolated from mature unripe fruits of Coccinia grandis (L.) Voigt validates the use of this plant in traditional medicine for diabetes. However, as this is only a preliminary study, further studies are in progress to evaluate the possible molecular mechanisms underlying the insulin-producing action of β-sitosterol and lupeol and in vivo oral rodent efficacy studies in a disease model.