Diabetic nephropathy (DN), a microvascular complication of diabetes, has emerged as an important health problem worldwide. There is strong evidence to suggest that oxidative stress, inflammation, and fibrosis play a pivotal role in the progression of DN. Apigenin has been shown to possess antioxidant, anti-inflammatory, antiapoptotic, antifibrotic, as well as antidiabetic properties. Hence, we evaluated whether apigenin halts the development and progression of DN in streptozotocin (STZ)-induced diabetic rats. Male albino Wistar rats were divided into control, diabetic control, and apigenin treatment groups (5-20 mg/kg po, respectively), apigenin per se (20 mg/kg po), and ramipril treatment group (2 mg/kg po). A single injection of STZ (55 mg/kg ip) was administered to all of the groups except control and per se groups to induce type 1 diabetes mellitus. Rats with fasting blood glucose >250 mg/dl were included in the study and randomized to different groups. Thereafter, the protocol was continued for 8 mo in all of the groups. Apigenin (20 mg/kg) treatment attenuated renal dysfunction, oxidative stress, and fibrosis (decreased transforming growth factor-β1, fibronectin, and type IV collagen) in the diabetic rats. It also significantly prevented MAPK activation, which inhibited inflammation (reduced TNF-α, IL-6, and NF-κB expression) and apoptosis (increased expression of Bcl-2 and decreased Bax and caspase-3). Furthermore, histopathological examination demonstrated reduced inflammation, collagen deposition, and glomerulosclerosis in the renal tissue. In addition, all of these changes were comparable with those produced by ramipril. Hence, apigenin ameliorated renal damage due to DN by suppressing oxidative stress and fibrosis and by inhibiting MAPK pathway.

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Kaempferol (KMP), a dietary flavonoid, has antioxidant, anti-inflammatory, and antiapoptotic effects. Hence, we investigated the effect of KMP in ischemia-reperfusion (IR) model of myocardial injury in rats. We studied male albino Wistar rats that were divided into sham, IR-control, KMP-20 + IR, and KMP 20 per se groups. KMP (20 mg/kg; i.p.) was administered daily to rats for the period of 15 days, and, on the 15th day, ischemia was produced by one-stage ligation of left anterior descending coronary artery for 45 min followed by reperfusion for 60 min. After completion of surgery, rats were sacrificed; heart was removed and processed for biochemical, morphological, and molecular studies. KMP pretreatment significantly ameliorated IR injury by maintaining cardiac function, normalizing oxidative stress, and preserving morphological alterations. Furthermore, there was a decrease in the level of inflammatory markers (TNF-α, IL-6, and NFκB), inhibition of active JNK and p38 proteins, and activation of ERK1/ERK2, a prosurvival kinase. Additionally, it also attenuated apoptosis by reducing the expression of proapoptotic proteins (Bax and Caspase-3), TUNEL positive cells, and increased level of antiapoptotic proteins (Bcl-2). In conclusion, KMP protected against IR injury by attenuating inflammation and apoptosis through the modulation of MAPK pathway.

The effect of naringin, a bioflavanoid, with potent antioxidant activity was studied on kainic acid (KA)-induced seizures, cognitive deficit and oxidative stress. Rats were administered KA (10 mg/kg intraperitoneally (i.p.)) and observed for behavioral changes and incidence and latency of convulsions over 4 h. The rats were thereafter sacrificed and oxidative stress parameters like malondialdehyde (MDA) and glutathione (GSH) were estimated in the brain. The level of proinflammatory cytokine, tumor necrosis factor (TNF)-a a was also determined in the rat brain. It was observed that pretreatment with naringin (20, 40, 80 mg/kg, i.p.) significantly (pϽ Ͻ0.001) increased the latency of seizures as compared to the vehicle treated-KA group. Naringin (40, 80 mg/kg) also significantly prevented the increase in MDA and fall in GSH levels due to KA. In addition, naringin dose-dependently attenuated the KA-induced increase in the TNF-a a levels of brain. The pretreatment with naringin also significantly increased retention latency in the passive avoidance task. This shows that naringin reduced the cognitive deficit induced by KA. The results of our study suggest that naringin has therapeutic potential since it suppresses KA-induced seizures, cognitive impairment and oxidative stress in the brain. These neuroprotective effects are a result of its antioxidant and anti-inflammatory activity.

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