Saikat Dewanjee

Antidiabetic activity of Diospyros peregrina fruit: Effect on hyperglycemia, hyperlipidemia and augmented oxidative stress in experimental type 2 diabetes

Diospyros peregrina is an edible fruit of costal West-Bengal. The present investigation was undertaken to evaluate the role of aqueous extract of D. peregrina fruit in streptozotocin-nicotinamide induced type 2 diabetic rats. Oral administration of extract at the doses of 50 and 100mg/kg body weight per day for 28 days to diabetic rats was found to possess significant dose dependant hypoglycemic and hypolipidemic activity. An increased reactive oxygen species and insufficient antioxidant activity is associated with diabetes mellitus, which is mainly responsible for diabetic pathogenesis. The role of extract on antioxidant markers of liver and kidney were estimated. The diabetic rats exhibited lower activities of superoxide dismutase (SOD), catalase (CAT), and reduced glutathione (GSH) content in hepatic and renal tissues as compared with normal rats. The activities of SOD, CAT, and GSH were found to be increased in extract treated diabetic rats in selected tissues. The increased level of lipid peroxidation (thiobarbituric acid reactive substances and hydroperoxide) in diabetic rats was also found to be reverted back to near normal status in extract treated groups.

Protective effect of Corchorus olitorius leaves on sodium arsenite-induced toxicity in experimental rats.

The present study was undertaken to evaluate the protective effect of aqueous extract of Corchorus olitorius leaves (AECO) against sodium arsenite-induced toxicity in experimental rats. The animals exposed to sodium arsenite at a dose of 10mg/kg body weight p.o. for 10days exhibited a significant inhibition (p<0.01) of hepatic and renal antioxidant enzymes namely superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase and glutathione reductase. In addition, arsenic intoxication significantly decreased (p<0.01) the level of reduced glutathione and increased (p<0.01) the levels of oxidized glutathione and thiobarbituric acid reactive substances in selected tissues. Treatment with AECO at doses of 50 and 100mg/kg body weight p.o. for 15days prior to arsenic intoxication significantly improved hepatic and renal antioxidant markers in a dose dependant manner. AECO treatment also significantly reduced the arsenic-induced DNA fragmentation of hepatic and renal tissues. Histological studies on the ultrastructural changes of liver and kidney supported the protective activity of the AECO. The results concluded that the treatment with AECO prior to arsenic intoxication has significant role in protecting animals from arsenic-induced hepatic and renal toxicity.

Mechanistic insight of diabetic nephropathy and its pharmacotherapeutic targets: An update.

Diabetic nephropathy (DN), a chronic complication of diabetes, is charecterized by glomerular hypertrophy, proteinuria, decreased glomerular filtration, and renal fibrosis resulting in the loss of renal function. Although the exact cause of DN remains unclear, several mechanisms have been postulated, such as hyperglycemia-induced renal hyper filtration and renal injury, AGEs-induced increased oxidative stress, activated PKC-induced increased production of cytokines, chemokines, and different inflammatory and apoptotic signals. Among various factors, oxidative stress has been suggested to play a major role underlying the onset and propagation of DN. It triggers several signaling pathways involved in DN, like AGEs, PKC cascade, JAK/STAT signaling, MAPK, mTOR, and SMAD. Oxidative stress-induced activation of both inflammatory and apoptotic signals are two major problems in the pathogenesis of DN. The FDA approved pharmacotherapeutic agents affecting against polyol pathway principally include anti-oxidants, like α-lipoic acid, vitamin E, and vitamin C. Kremezin and benfotiamine are the FDA approved AGEs inhibitors, another therapeutic target against DN. Ruboxistaurin, telmizartan, rapamycin, fenofibrate, aliskiren, and manidipine are some FDA approved pharmacotherapeutics effective against DN via diverse mechanisms. Beside this, some therapeutic agents are still waiting for FDA approval and few drugs without FDA approval are also prescribed in some countries for the management of DN. Despite the medications available in the market to treat DN, the involvement of multiple mechanisms makes it difficult to choose an optimum therapeutic agent. Therefore, much research is required to find out new therapeutic agent/strategies for an adequate pharmacotherapy of DN.

Toxic effects of lead exposure in Wistar rats: Involvement of oxidative stress and the beneficial role of edible jute (Corchorus olitorius) leaves

Lead (Pb) is considered to be a multi-target toxicant. The present study was undertaken to evaluate the protective effect of aqueous extract of Corchorus olitorius leaves against Pb-acetate induced toxic manifestation in blood, liver, kidney, brain and heart of Wistar rats. The Pb-acetate (5mg/kg body weight) treated rats exhibited a significant inhibition of co-enzymes Q, antioxidant enzymes and reduced glutathione levels in the tissues. In addition, the extent of lipid peroxidation, DNA fragmentation and haematological parameters were significantly altered in the Pb-acetate treated rats as compared to control. Simultaneous administration of test extract (25, 50 and 100mg/kg body weight), could significantly restore the biochemical and haematological parameters near to the normal status through antioxidant activity and/or by preventing bioaccumulation of Pb within the tissues of experimental rats. Presence of substantial quantity of phenolics and flavonoids in the extract may be responsible for the observed protective role against Pb-intoxication.

Arsenic-induced myocardial injury: protective role of Corchorus olitorius leaves.

Groundwater arsenic contamination in Bangladesh and its adjoining part of West Bengal (India) is reported to be the biggest arsenic calamity in the world in terms of the affected population. Tossa jute, Corchorus olitorius is a popular crop of this arsenic prone population. The present study was undertaken to evaluate the protective effect of aqueous extract of C. olitorius leaves (AECO) against sodium arsenite (NaAsO(2)) induced cardiotoxicity in experimental rats. The animals exposed to NaAsO(2) (10mg/kg, p.o.) for 10days exhibited a significant inhibition (p<0.01) of superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase, glutathione reductase and reduced glutathione level in myocardial tissues of rats. In addition, it significantly increased (p<0.01) oxidized glutathione, malondialdehyde and protein carbonyl content in myocardial tissue. Treatment with AECO (50 and 100mg/kg, p.o.) for 15days prior to NaAsO(2)-intoxication significantly protected cardiac tissue against arsenic-induced oxidative impairment. In addition, AECO pretreatment significantly prevented NaAsO(2) induced hyperlipidemia, cardiac arsenic content and DNA fragmentation in experimental rats. Histological studies of myocardial tissue supported the protective activity of the AECO. The results concluded that the treatment with AECO prior to arsenic intoxication has significant protecting effect against arsenic-induced myocardial injury.

Protective effect of Corchorus olitorius leaves against arsenic-induced oxidative stress in rat brain

The present study was undertaken to evaluate the protective effect of an aqueous extract of Corchorus olitorius leaves (AECO) against NaAsO(2) induced brain toxicity in experimental rats. The animals exposed to NaAsO(2) (10mg/kg, p.o.) for 10 days exhibited a significant inhibition (p<0.01) of superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase, glutathione reductase and reduced glutathione levels in rat brain. In addition, the toxin increased (p<0.01) the levels of oxidized glutathione and thiobarbituric acid reactive substances in the brain tissue of experimental rats. Treatment with AECO (50 and 100mg/kg, p.o.) for 15 days prior to arsenic intoxication significantly improved antioxidant markers in a dose dependant manner. Histological studies on the ultrastructural changes of brain tissue supported the protective activity of the AECO. The results suggest that treatment with AECO prior to arsenic intoxication has a significant role in protecting animals from arsenic-induced toxicity.

Effective Control of Type 2 Diabetes through Antioxidant Defense by Edible Fruits of Diospyros peregrina

The matured fruits of Diospyros peregrina are successfully employed by the traditional healers and local people of costal West Bengal, India for the treatment of diabetes. Present investigation was undertaken to evaluate the role of hydroalcoholic extract of D. peregrina (HDP) on type 2 diabetes as well as the augmented oxidative stresses associated with it. Oral administration of HDP at 25, 50 and 100 mg kg−1 body weight per day to diabetic rats was found to possess significant dose-dependent hypoglycemic and hypolipidemic activity. The diabetic rats showed lower activities of superoxide dismutase (SOD), catalase (CAT) and reduced glutathione (GSH) content in hepatic and renal tissues as compared to normal rats. The activities of SOD, CAT and GSH were found to be increased in extract-treated diabetic rats in selected tissues. The increased level of lipid peroxidation (thiobarbituric acid reactive substances) in diabetic rats was also found to be reverted back to near normal status in extract-treated groups. Thus it may be concluded that the HDP may produce its hypoglycemic effect through antioxidant defense mechanism.

Bioautography and its scope in the field of natural product chemistry

Medicinal plants, vegetables and fruits are the sources of huge number of bioactive lead/scaffolds with therapeutic and nutraceutical importance. Bioautography is a means of target-directed isolation of active molecules on chromatogram. Organic solvents employed in chromatographic separation process can be completely removed before biological detection because these solvents cause inactivation of enzymes and/or death of living organisms. They offer a rapid and easy identification of bioactive lead/scaffolds in complex matrices of plant extracts. Bioautography is a technique to isolate hit(s)/lead(s) by employing a suitable chromatographic process followed by a biological detection system. This review critically describes the methodologies to identify antimicrobial, antioxidant, enzyme inhibitor lead/scaffolds by employing bioautography. A significant number of examples have been incorporated to authenticate the methodologies.

Swietenine: A potential oral hypoglycemic from Swietenia macrophylla seed

Swietenine, a tetranortriterpenoid, was isolated from the Swietenia macrophylla seeds. The in vivo hypoglycemic activity was evaluated against neonatal-streptozotocin induced type 2 diabetic rats. Oral administration of swietenine at 25 and 50 mg/kg body weight per day to diabetic rats was found to possess significant dose dependant hypoglycemic and hypolipidemic activity in type 2 diabetic rats.

Microwave-assisted extraction of total bioactive saponin fraction from Gymnema sylvestre with reference to gymnemagenin: a potential biomarker

OBJECTIVE To develop a fast and ecofriendly microwave assisted extraction (MAE) technique for the effective and exhaustive extraction of gymnemagenin as an indicative biomarker for the quality control of Gymnema sylvestre. METHODOLOGY Several extraction parameters such as microwave power, extraction time, solvent composition, pre-leaching time, loading ratio and extraction cycle were studied for the determination of the optimum extraction condition. Scanning electron micrographs were obtained to elucidate the mechanism of extraction. RESULTS The final optimum extraction conditions as obtained from the study were: 40% microwave power, 6 min irradiation time, 85% v/v methanol as the extraction solvent, 15 min pre-leaching time and 25 : 1 (mL/g) as the solvent-to-material loading ratio. The proposed extraction technique produced a maximum yield of 4.3% w/w gymnemagenin in 6 min which was 1.3, 2.5 and 1.95 times more efficient than 6 h of heat reflux, 24 h of maceration and stirring extraction, respectively. A synergistic heat and mass transfer theory was also proposed to support the extraction mechanism. CONCLUSION Comparison with conventional extraction methods revealed that MAE could save considerable amounts of time and energy, whilst the reduction of volume of organic solvent consumed provides an ecofriendly feature.