Effect of an aqueous extract of Cucurbita ficifolia Bouché on the glutathione redox cycle in mice with STZ-induced diabetes

ETHNOPHARMACOLOGICAL IMPORTANCE

Cucurbita ficifolia is used in Mexican traditional medicine as an anti-diabetic and anti-inflammatory agent and its actions can be mediated by antioxidant mechanisms. Disturbance in the homeostasis of glutathione has been implicated in the etiology and progression of diabetes mellitus and its complications.

MATERIAL AND METHODS

It was evaluated, the effect of an aqueous extract of Cucurbita ficifolia on glycemia, plasma lipid peroxidation; as well as levels of reduced (GSH) and oxidized (GSSG) glutathione and activities of enzymes involved in glutathione redox cycle: glutathione peroxidase (GPx) and glutathione reductase (GR) in liver, pancreas, kidney and heart homogenates of streptozotocin-induced diabetic mice.

RESULTS

Increased blood glucose and lipid peroxidation, together with decreased of GSH concentration, GSH/GSSG ratio and its redox potential (E(h)), and enhanced activity of GPx and GR in liver, pancreas and kidney were the salient features observed in diabetic mice. Administration of the aqueous extract of Cucurbita ficifolia to diabetic mice for 30 days, used at a dose of 200 mg/kg, resulted in a significant reduction in glycemia, polydipsia, hyperphagia and plasma lipid peroxidation. Moreover, GSH was increased in liver, pancreas and kidney, and GSSG was reduced in liver, pancreas and heart, therefore GSH/GSSG ratio and its E(h) were restored. Also, the activities involved in the glutathione cycle were decreased, reaching similar values to controls.

CONCLUSIONS

An aqueous extract of Cucurbita ficifolia with hypoglycemic action, improve GSH redox state, increasing glutathione pool, GSH, GSH/GSSG ratio and its E(h), mechanism that can explain, at least in part, its antioxidant properties, supporting its use as an alternative treatment for the control of diabetes mellitus, and prevent the induction of complications by oxidative stress.

Antioxidant and anti-inflammatory effects of a hypoglycemic fraction from Cucurbita ficifolia Bouché in streptozotocin-induced diabetes mice

Type 2 diabetes is characterized by oxidative stress and a chronic low-grade inflammatory state, which also play roles in the pathogenesis of this disease and the accompanying vascular complications by increasing the production of free radicals and pro-inflammatory cytokines. Cucurbita ficifolia Bouché (C. ficifolia) is an edible Mexican plant whose hypoglycemic activity has been demonstrated in several experimental and clinical conditions. Recently, D-chiro-inositol has been proposed as the compound responsible for the hypoglycemic effects; however, the antioxidant and anti-inflammatory potential of this plant has not yet been explored. The aim of this research is to study the influence of a hypoglycemic, D-chiro-inositol-containing fraction from the C. ficifolia fruit (AP-Fraction) on biomarkers of oxidative stress, as well as on the inflammatory cytokines in streptozotocin-induced diabetes. The AP-Fraction obtained from the mature fruit of C. ficifolia contained 3.31 mg of D-chiro-inositol/g of AP-Fraction. The AP-Fraction was administrated daily by gavage to normal mice for 15 days as a preventive treatment. Then these animals were given streptozotocin, and the treatments were continued for an additional 33 days. Pioglitazone was used as a hypoglycemic drug for comparison. Administration of the AP-Fraction significantly increased glutathione (GSH) and decreased malondialdehyde (MDA) in the liver without significantly affecting the levels in other tissues. The AP-Fraction reduced TNF-α and increased IL-6 and IFN-γ in serum. Interestingly, the AP-Fraction also increased IL-10, an anti-inflammatory cytokine. These results suggest that C. ficifolia might be used as an alternative medication for the control of diabetes mellitus and that it has antioxidant and anti-inflammatory properties in addition to its hypoglycemic activity.

Anti-inflammatory and antioxidant effects of a hypoglycemic fructan fraction from Psacalium peltatum (H.B.K.) Cass. in streptozotocin-induced diabetes mice

ETHNOPHARMACOLOGICAL IMPORTANCE

Psacalium peltatum (H.B.K.) Cass. (Asteraceae) is used medicinally to treat diabetes, rheumatic pains, as well as gastrointestinal and kidney ailments. Previous pharmacological and chemical assays have demonstrated that an aqueous fraction from Psacalium peltatum (AP-fraction) contains a carbohydrate-type compound with hypoglycemic activity. Nevertheless, studies have not yet considered the hypoglycemic action of the AP-faction by sub-chronic administration nor on other healing properties, some of which might be associated with DM2 and other inflammatory processes.

AIM OF STUDY

To determine whether a hypoglycemic carbohydrate fraction (AP-fraction) from Psacalium peltatum roots has antioxidant and anti-inflammatory effects in streptozotocin-induced diabetes mice.

MATERIAL AND METHODS

Healthy mice received either saline, the AP-fraction with a high content of fructans, or pioglitazone (a positive control) daily by gavage. After 15 days of treatment, these animals received a single intraperitoneal administration of streptozotocin and all treatments were continued for additional 33 days. The antioxidant and anti-inflammatory properties of the AP-fraction were evaluated through the quantification of biomarkers of oxidative stress (glutathione (GSH) and malondialdehyde (MDA)) and inflammation (interleukin (IL)-6, tumor necrosis factor alpha (TNF-α), interferon-gamma (IFN-γ), and IL-10).

RESULTS

The AP-fraction reduced glycemia and the glycated hemoglobin. Furthermore, animals treated with the AP-fraction had increased GSH, while MDA was decreased in the liver and the heart, without changes in the kidneys and the pancreas. The AP-fraction significantly reduced TNF-α serum levels but did not modify IL-6; in addition, this fraction increased IFN-γ and IL-10 levels. The increase in IL-10 levels may indicate an inhibition of the production of pro-inflammatory cytokines such as TNF-α, whereas the increase in IFN-γ might be indicative of a beneficial effect on the immune system.

CONCLUSIONS

The AP-fraction hypoglycemic fructans from Psacalium peltatum roots showed antioxidant and anti-inflammatory properties in mice with streptozotocin-induced diabetes. The Psacalium peltatum hypoglycemic fructans may be valuable in preventing insulin resistance, as well as the development and progression of diabetic complications caused by chronic inflammation.