Ayman M. Mahmoud

Hesperidin and naringin attenuate hyperglycemia-mediated oxidative stress and proinflammatory cytokine production in high fat fed/streptozotocin-induced type 2 diabetic rats

Abnormal regulation of glucose and impaired carbohydrate utilization that result from a defective or deficient insulin are the key pathogenic events in type 2 diabetes mellitus (T2DM). The present study was hypothesized to investigate the beneficial effects of hesperidin and naringin on hyperglycemia-induced oxidative damage in HFD/STZ-induced diabetic rats. Diabetes was induced by feeding rats with an HFD for 2 weeks followed by an intraperitoneal injection of STZ (35 mg/kg body weight). An oral dose of 50mg/kg hesperidin or naringin was daily given for 4 weeks after diabetes induction. At the end of the experimental period, blood was obtained from jugular vein and livers were rapidly excised and homogenized for biochemical assays. In the diabetic control group, levels of glucose, glycosylated hemoglobin (HbA1c%), MDA, NO, TNF-α and IL-6 were significantly increased, while serum insulin, GSH, vitamin C, and vitamin E levels were decreased. Both hesperidin and naringin administration significantly reversed these alterations. Moreover, supplementation with either compound significantly ameliorated serum and liver MDA, NO and glutathione, and liver antioxidant enzymes. Although detailed studies are required for the evaluation of the exact mechanism of the ameliorative effects of hesperidin and naringin against diabetic complications, these preliminary experimental findings demonstrate that both hesperidin and naringin exhibit antidiabetic effects in a rat model of T2DM by potentiating the antioxidant defense system and suppressing proinflammatory cytokine production.

Limiting prolonged inflammation during proliferation and remodeling phases of wound healing in streptozotocin-induced diabetic rats supplemented with camel undenatured whey protein

BackgroundImpaired diabetic wound healing occurs as a consequence of excessive reactive oxygen species (ROS) and inflammatory cytokine production. We previously found that whey protein (WP) was able to normally regulate the ROS and inflammatory cytokines during the inflammatory phase (first day) in streptozotocin (STZ)-diabetic wound healing. This study was designed to assess the effect of WP on metabolic status, the inflammation and anti-inflammation response, oxidative stress and the antioxidant defense system during different phases of the wound healing process in diabetic rats. WP at a dosage of 100 mg/kg of body weight, dissolved in 1% CMC, was orally administered daily to wounded normal (non-diabetic) and STZ-induced diabetic rats for 8 days starting from the 1st day after wounding.ResultsThe data revealed that WP enhanced wound closure and was associated with an increase in serum insulin levels in diabetic rats and an alleviation of hyperglycemic and hyperlipidemic states in diabetic animals. The increase in insulin levels as a result of WP administration is associated with a marked multiplication of β-cells in the core of islets of Langerhans. WP induced a reduction in serum TNF-α, IL-1β and IL-6 levels and an increase in IL-10 levels, especially on the 4th day after wounding and treatment. WP also suppressed hepatic lipid peroxidation and stimulated the antioxidant defense system by increasing the level of glutathione and the activity of glutathione-S-transferase, glutathione peroxidase and superoxide dismutase (SOD) in wounded diabetic rats.ConclusionsWP was observed to enhance wound closure by improving the diabetic condition, limiting prolonged inflammation, suppressing oxidative stress and elevating the antioxidant defense system in diabetic rats.

Influence of rutin on biochemical alterations in hyperammonemia in rats

Flavonoids are non-nutritive dietary components that are widely distributed in plants. The present study was undertaken to examine the protective influence of rutin, a polyphenolic flavonoid, on oxidative stress during ammonium chloride (AC)-induced hyperammonemia by measuring the levels of oxidative damage as well as antioxidant status. The levels of tissue (liver, brain and kidney) lipid peroxides and the antioxidants (total thiols, catalase, reduced glutathione and glutathione peroxidase) were analyzed. Hyperammonemia was induced by daily intraperitoneal injections of AC at a dose of 100 mg/kg body weight for 8 weeks. Decreased levels of tissue lipid peroxidation accompanied with increased antioxidant levels in hyperammonemic rats were observed during oral administration of rutin (50 mg/kg body weight), which clearly shows the antioxidant property of rutin. The study of induction of the antioxidant status is considered to be a reliable marker for evaluating the antiperoxidative effect of the polyphenolic compound. Our present findings show the protective role of rutin against lipid peroxidation and suggest that rutin possesses antioxidant potential that may be used for therapeutic purposes.

Possible involvement of Nrf2 and PPARγ up-regulation in the protective effect of umbelliferone against cyclophosphamide-induced hepatotoxicity

Umbelliferone (UMB) is a coumarin derivative with promising hepatoprotective effects. In this study, we examined the possible protective effects of UMB against cyclophosphamide (CP)-induced hepatotoxicity, addressing the question of the possible role of nuclear factor erythroid 2-related factor 2 (Nrf2) and peroxisome proliferator activated receptor gamma (PPARγ). Wistar rats were orally administered UMB at doses 50 and 100mg/kg two weeks prior to CP injection. Five days after CP administration, the rats were sacrificed and samples were collected for analyses. CP induced a significant increase in circulating liver marker enzymes and pro-inflammatory cytokines. Hepatic lipid peroxidation and nitric oxide levels, and nuclear factor-kappaB (NF-κB) and inducible nitric oxide synthase (iNOS) expression were significantly increased following CP administration. UMB supplementation attenuated CP-induced inflammation and oxidative stress as assessed by restoration of the activity and expression of the antioxidant defenses, and suppression of pro-inflammatory cytokines. Histological examination also showed that UMB could significantly reduce CP-induced alterations. CP-induced rats showed significant down-regulation of Nrf2, HO-1 and PPARγ, an effect that was markedly reversed by UMB. In conclusion, the hepatoprotective effects of UMB appear to depend on co-activation of PPARγ and Nrf2, and subsequent suppression of oxidative stress and inflammation.

A novel role for small molecule glycomimetics in the protection against lipid-induced endothelial dysfunction: Involvement of Akt/eNOS and Nrf2/ARE signaling

BACKGROUND Glycomimetics are a diverse array of saccharide-inspired compounds, designed to mimic the bioactive functions of glycosaminoglycans. Therefore, glycomimetics represent a unique source of novel therapies to target aberrant signaling and protein interactions in a wide range of diseases. We investigated the protective effects of four newly synthesized small molecule glycomimetics against lipid-induced endothelial dysfunction, with an emphasis on nitric oxide (NO) and oxidative stress. METHODS Four aromatic sugar mimetics were synthesized by the stepwise transformation of 2,5-dihydroxybenzoic acid to derivatives (C1-C4) incorporating sulfate groups to mimic the structure of heparan sulfate. RESULTS Glycomimetic-treated human umbilical vein endothelial cells (HUVECs) were exposed to palmitic acid to model lipid-induced oxidative stress. Palmitate-induced impairment of NO production was restored by the glycomimetics, through activation of Akt/eNOS signaling. Furthermore, C1-C4 significantly inhibited palmitate-induced reactive oxygen species (ROS) production, lipid peroxidation, and activity and expression of NADPH oxidase. These effects were attributed to activation of the Nrf2/ARE pathway and downstream activation of cellular antioxidant and cytoprotective proteins. In ex vivo vascular reactivity studies, the glycomimetics (C1-C4) also demonstrated a significant improvement in endothelium-dependent relaxation and decreased ROS production and NADPH oxidase activity in isolated mouse thoracic aortic rings exposed to palmitate. CONCLUSIONS The small molecule glycomimetics, C1-C4, protect against lipid-induced endothelial dysfunction through up-regulation of Akt/eNOS and Nrf2/ARE signaling pathways. Thus, carbohydrate-derived therapeutics are a new class of glycomimetic drugs targeting endothelial dysfunction, regarded as the first line of defense against vascular complications in cardiovascular disease.

18β-Glycyrrhetinic acid protects against methotrexate-induced kidney injury by up-regulating the Nrf2/ARE/HO-1 pathway and endogenous antioxidants

Abstract Objectives: 18β-glycyrrhetinic acid (18β-GA) has multiple beneficial and therapeutic effects. However, its protective roles on methotrexate (MTX)-induced renal injury are not well defined. In the present study, we investigated the possible protective effects of 18β-GA against MTX-induced nephrotoxicity in rats. Materials: 18β-GA (50 and 100 mg/kg) was administered for 7 days either before or after MTX. The rats were decapitated and kidney and serum samples were collected. Results: MTX-induced renal injury in rats was evidenced by the significant (p < 0.001) increase in circulating kidney function markers and tumor necrosis factor alpha (TNF-α), as well as the histopathological alterations. MTX-induced rats exhibited significantly increased lipid peroxidation (p < 0.05) and nitric oxide (p < 0.001) levels, with concomitant marked (p < 0.001) decline in the antioxidant defenses. 18β-GA, administered either before or after MTX, produced a significant amelioration of circulating kidney function markers, TNF-α, kidney lipid peroxidation, nitric oxide, and antioxidant defenses. In addition, 18β-GA supplementation significantly up-regulated the mRNA abundance of both nuclear factor-erythroid 2-related factor 2 (Nrf2) and hemoxygenase 1 (HO-1) in the kidney of MTX-induced rats. Conclusions: These results indicate that 18β-GA has a protective effect on MTX-induced nephrotoxicity with possible mechanisms of attenuating oxidative stress and inflammation through up-regulating the Nrf2/ARE signaling. These findings make 18β-GA candidate as a potent agent in preventing MTX-induced kidney injury.

Sitagliptin attenuates cardiomyopathy by modulating the JAK/STAT signaling pathway in experimental diabetic rats

Sitagliptin, a dipeptidyl peptidase-4 inhibitor, has been reported to promote cardioprotection in diabetic hearts by limiting hyperglycemia and hyperlipidemia. However, little is known about the involvement of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway modulation in the cardioprotective effects of sitagliptin. The current study aimed to investigate the protective effects of sitagliptin against diabetic cardiomyopathy (DCM), focusing on the modulation of the JAK/STAT pathway. Diabetes was induced by streptozotocin injection, and rats received sitagliptin orally and daily for 90 days. Diabetic rats exhibited hyperglycemia, hyperlipidemia, and a significant increase in heart-to-body weight (HW/BW) ratio. Serum troponin I and creatine kinase MB, cardiac interleukin-6 (IL-6), lipid peroxidation, and nitric oxide levels showed significant increase in diabetic rats. In contrast, both enzymatic and nonenzymatic antioxidant defenses were significantly declined in the heart of diabetic rats. Histopathological study revealed degenerations, increased collagen deposition in the heart of diabetic rats. Sitagliptin alleviated hyperglycemia, hyperlipidemia, HW/BW ratio, histological architecture, oxidative stress, and inflammation, and rejuvenated the antioxidant defenses. In addition, cardiac levels of pJAK2 and pSTAT3 were increased in diabetic rats, an effect which was remarkably decreased after sitagliptin treatment. In conclusion, these results confer an evidence that sitagliptin has great therapeutic potential on DCM through down-regulation of the JAK/STAT signaling pathway.

Thymoquinone and curcumin attenuate gentamicin-induced renal oxidative stress, inflammation and apoptosis in rats

The present study was aimed to investigate the possible protective effects of thymoquinone (TQ) and curcumin (Cur) on gentamicin (GM)-induced nephrotoxicity in rats. Rats were divided into four groups as follows: group 1 received normal saline and served as normal controls, group 2 received GM only, group 3 concurrently received GM and TQ and group 4 concurrently received GM and Cur. At day 21, rats were sacrificed and samples were collected for assaying serum tumor necrosis factor alpha (TNF-α), urea and creatinine levels, and renal lipid peroxidaion, glutathione (GSH) content as well as glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities. In addition, kidneys were collected for histopathological examination and immunohistochemical determination of the antiapoptotic protein, B-cell lymphoma 2 (Bcl-2). The biochemical results showed that GM-induced nephrotoxicity was associated with a significant increase in serum TNF-α, urea and creatinine as well as renal lipid peroxidation. On the other hand, renal GSH content and GPx and SOD activities were significantly declined. Concomitant administration of either TQ or Cur efficiently alleviated the altered biochemical and histopathological features. In conclusion, both TQ and Cur showed more or less similar marked renoprotective effect against GM-induced nephrotoxicity through their antioxidant, anti-inflammatory and anti-apoptotic efficacies.

Berberine ameliorates methotrexate-induced liver injury by activating Nrf2/HO-1 pathway and PPARγ, and suppressing oxidative stress and apoptosis in rats

Berberine (BBR) is a natural isoquinoline alkaloid with very impressive health benefits. It is one of the most effective natural supplements available; however, its ameliorative mechanism against methotrexate (MTX)-induced liver injury is not well defined. This study investigated the protective effect of BBR against MTX hepatotoxicity, focusing on its ability to attenuate oxidative stress and apoptosis and to activate nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling and peroxisome proliferator activated receptor gamma (PPARγ). Rats received BBR (25 and 50mg/kg) orally for 7days before MTX injection. Other groups received MTX followed by BBR (25 and 50mg/kg) orally for 7 days. MTX-induced rats showed significant body weight loss, increased serum liver function marker enzymes, bilirubin and tumor necrosis factor alpha (TNF-α). Liver lipid peroxidation, nitric oxide (NO) and caspase-3 were significantly increased following MTX administration. BBR supplemented either before or after MTX significantly ameliorated body weight, liver function markers, TNF-α, lipid peroxidation, NO and caspase-3. BBR increased serum albumin and liver antioxidant defenses in MTX-induced rats. Histological and immunohistochemical examination showed improved histological structure and decreased expression of Bax in liver of MTX-induced rats treated with BBR. In addition, BBR up-regulated Nrf2, HO-1 and PPARγ expression in the liver of MTX-induced rats. In conclusion, BBR attenuated MTX-induced oxidative stress and apoptosis, possibly through up-regulating Nrf2/HO-1 pathway and PPARγ. Therefore, BBR can protect against MTX-induced liver injury.

Gamma-Glutamylcysteine Ethyl Ester Protects against Cyclophosphamide-Induced Liver Injury and Hematologic Alterations via Upregulation of PPARγ and Attenuation of Oxidative Stress, Inflammation, and Apoptosis

Gamma-glutamylcysteine ethyl ester (GCEE) is a precursor of glutathione (GSH) with promising hepatoprotective effects. This investigation aimed to evaluate the hepatoprotective effects of GCEE against cyclophosphamide- (CP-) induced toxicity, pointing to the possible role of peroxisome proliferator activated receptor gamma (PPARγ). Wistar rats were given GCEE two weeks prior to CP. Five days after CP administration, animals were sacrificed and samples were collected. Pretreatment with GCEE significantly alleviated CP-induced liver injury by reducing serum aminotransferases, increasing albumin, and preventing histopathological and hematological alterations. GCEE suppressed lipid peroxidation and nitric oxide production and restored GSH and enzymatic antioxidants in the liver, which were associated with downregulation of COX-2, iNOS, and NF-κB. In addition, CP administration significantly increased serum proinflammatory cytokines and the expression of liver caspase-3 and BAX, an effect that was reversed by GCEE. CP-induced rats showed significant downregulation of PPARγ which was markedly upregulated by GCEE treatment. These data demonstrated that pretreatment with GCEE protected against CP-induced hepatotoxicity, possibly by activating PPARγ, preventing GSH depletion, and attenuating oxidative stress, inflammation, and apoptosis. Our findings point to the role of PPARγ and suggest that GCEE might be a promising agent for the prevention of CP-induced liver injury.