Tapinanthus dodoneifolius leaf inhibits the activity of carbohydrate digesting enzymes and improves the insulin resistance induced in rats by dexamethasone.

Background: Tapinanthus dodoneifolius is a plant used in traditional African medicine to treat diabetes mellitus. This study aimed to evaluate the preventive antidiabetic potential of the aqueous extract of T. dodoneifolius leaves (AETD) in insulin resistant rats. Methods: A quantitative phytochemical study of AETD was carried out to determine the contents of total phenols, tannins, flavonoids, and saponins. AETD was tested in vitro on the activity of α-amylase and α-glucosidase enzymes. Insulin resistance was induced for 10 days by daily subcutaneous injection of dexamethasone (1 mg/kg). One hour before, the rats were divided into 5 groups and treated as follows: group 1 received distilled water (10 mL/kg); group 2 received metformin (40 mg/kg), and groups 3, 4, and 5 were treated with AETD (125, 250, and 500 mg/kg). Body weight, blood sugar, food and water consumption, serum insulin level, lipid profile, and oxidative status were assessed. One-way analysis of variance followed by Turkey's post-test and two-way analysis followed by Bonferroni's post-test were used to analyze univariate and bivariate parameters, respectively. Results: Results showed that the phenol content of AETD (54.13 ± 0.14 mg GAE/g extract) was higher than that of flavonoids (16.73 ± 0.06 mg GAE/g extract), tannins (12.08 ± 0.07 mg GAE/g extract), and saponins (IC50 = 13.56 ± 0.03 mg DE/g extract). AETD showed a higher inhibitory potential on α-glucosidase activity (IC50 = 191.51 ± 5.63 µg/mL) than on α-amylase activity (IC50 = 1774.90 ± 10.32 µg/mL). AETD (250 and/or 500 mg/kg) prevented drastic loss of body weight and reduced food and water consumption in insulin resistant rats. The levels of blood glucose, total cholesterol, triglycerides, low-density lipoprotein cholesterol, and malondialdehyde were also reduced while high-density lipoprotein cholesterol level, reduced glutathion level, and catalase and superoxide dismutase activity increased after administration of AETD (250 and 500 mg/kg) in insulin resistant rats. Conclusion: AETD has significant antihyperglycemic, antidyslipidemic, and antioxidant potential, thus it can be used for the management of type 2 diabetes mellitus and its complications.

The Aqueous Extract of Dacryodes edulis (Burseraceae) Leaves Inhibits Cell Proliferation Induced by Estradiol on the Uterus and Vagina of Ovariectomized Female Wistar Rats.

Proliferation is a cellular process strongly linked to the genesis of cancer. Natural substances with antiproliferative activities are currently potential alternatives in the treatment of cancers. Dacryodes edulis, for instance, is a medicinal plant traditionally used in the treatment of cancer. Scientific studies have reported the antioxidant activity of this plant. In addition, the presence of prostate cancer chemopreventive polyphenols was reported in D. edulis extracts. Therefore, this study was aimed to evaluate the effects of the aqueous extract of D. edulis leaves on cell proliferation induced by estradiol in ovariectomized female Wistar rats. In this regard, ovariectomized (OVX) rats were cotreated with estradiol valerate (E2V) (0.75 mg/kg) and the aqueous extract of D. edulis leaves. Control groups received either the vehicle (sham-operated animals and the OVX control), E2V (0.75 mg/kg) only, or E2V (0.75 mg/kg) and tamoxifen (10 mg/kg). Treatments were administered orally for 3 consecutive days, and animals were sacrificed thereafter. Epithelial heights of the uterus and vagina were assessed. Uterine levels of total cholesterol and estradiol were determined as well. Results showed that the aqueous extract of D. edulis leaves reversed the effects of estradiol as it reduced uterine weight (p < 0.05), uterine (p < 0.05), and vaginal (p < 0.001) epithelium heights. This antiproliferative effect of D. edulis was associated with reduced tissue (uterine) levels of estradiol (p < 0.001). These results suggest that the aqueous extract of D. edulis leaves could be a potential alternative treatment for proliferation-related diseases.

Glucose, lipid and oxidative stress lowering activity of the aqueous extract from leafy stems of Cissus polyantha Gilg & Brandt in dexamethasone-induced hyperglycemia in rats.

BACKGROUND: Diabetes mellitus is a metabolic disorder characterised by chronic hyperglycemia. The present research work aimed to evaluate the hypoglycaemic, hypolipidemic and antioxidant effects of leafy stems of Cissus polyantha Gilg & Brandt in insulin resistant rats. METHODS: The oral glucose tolerance test (OGTT) was performed in normal rats. Hyperglycemia was induced for 8 days by a daily subcutaneous injection of dexamethasone (1 mg/kg) one hour after pretreatment of animals with metformin (40 mg/kg) and C. polyantha extract (111, 222 and 444 mg/kg). Body weight, blood glucose, insulin level, lipid profile, insulin biomarkers, cardiovascular indices and oxidative stress biomarkers were evaluated. RESULTS: For OGTT, the extract (444 mg/kg) produced a significant drop in blood sugar at the 60th (p < 0.01), 90th (p < 0.01) and 120th min (p < 0.05). Morever, the extract at doses of 222 and 111 mg/kg significantly reduced blood sugar at the 60th (p < 0.01) and 90th min (p < 0.05) respectively. Otherwise, C. polyantha (444 and 222 mg/kg) significantly (p < 0.001) increased body weight and decreased blood sugar on the 4th and 8th days of treatment in insulin resistant rats. The extract also significantly decreased (p < 0.001) serum insulin level, hyperlipidemia, insulin resistance index and cardiovascular indices, and increased gluthathione level, and superoxide dismutase and catalase activity. CONCLUSION: The aqueous extract of Cissus polyantha leafy stems (AECPLS) possess hypoglycemic, hypolipidemic and antioxidant activities that could justify its use in traditional medicine for the prevention and treatment of diabetes mellitus and its complications.

Antioxidant Properties and Digestive Enzyme Inhibitory Activity of the Aqueous Extract from Leafy Stems of Cissus polyantha.

Cissus polyantha (Vitaceae) is a plant used in Cameroonian traditional medicine for the treatment of diabetes. The aims of this study were to evaluate the in vitro antioxidant and antidiabetic activities of the aqueous extract of Cissus polyantha leafy stems. The enzyme inhibitory activity was determined in vitro on α-amylase and α-glucosidase enzymes, followed by confirmative study in vivo on normal rats (oral starch and sucrose tolerance tests at doses of 111, 222, and 444 mg/kg). The ferric reducing antioxidant power and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) antiradical activity of the extract were examined to evaluate the antioxidant potential of the extract. The total content of phenols, flavonoids, and tannins of the extract were also determined. The results showed an inhibitory effect of the extract on the α-amylase and α-glucosidase activities with IC50 values of 216.14 and 182.40 µg/mL, respectively. The extract at doses of 222 and 444 mg/kg induced a significant decrease in postprandial glycaemia during the starch and sucrose tolerance tests. A remarkable antiradical activity of the extract was obtained although lower than that of the standard product. The aqueous extract of leafy stems of Cissus polyantha has an interesting inhibitory activity on the α-amylase and α-glucosidase enzymes, as well as an antioxidant potential, thus validating its use in traditional medicine for the treatment of diabetes mellitus and its complications.

Protective Effects of Aqueous Extract of Baillonella toxisperma Stem Bark on Dexamethasone-Induced Insulin Resistance in Rats.

The aim of this study was to evaluate the effects of the aqueous extract of Baillonella toxisperma stem bark on dexamethasone-induced insulin resistance in rats. A quantitative phytochemical study was done on the aqueous extract of Baillonella toxisperma for the total phenol, flavonoid, and flavonol determination. Insulin resistance was induced by intraperitoneal injection of dexamethasone (1 mg/kg) for 8 days, one hour before oral administration of different treatments (extract at doses of 60, 120, and 240 mg/kg and metformin at 40 mg/kg). During the test, body weight and blood glucose level were evaluated on days 1 and 8. At the last day of treatment, the glucose tolerance test was performed in rats; after that, blood samples were collected for triglycerides, total cholesterol, LDL and HDL cholesterols, transaminases (ALT and AST), and total protein level determination. Organs (heart, liver, pancreas, and kidneys) were also collected for the relative organ weight determination. The results showed that the aqueous extract of B. toxisperma is rich in total phenols, flavonoids, and flavonols. This extract significantly reversed the metabolic alterations (lipid profile, protein level, and transaminase activity) induced by dexamethasone in rats. At doses of 120 and 60 mg/kg, Baillonella toxisperma also significantly decreases (p < 0.05; p < 0.01) postprandial hyperglycemia in insulin resistance rats. The results suggest that Baillonella toxisperma can manage insulin resistance and may be useful for the treatment of type 2 diabetes mellitus.