Antioxidant and pro-oxidant effects of oil palm (Elaeis guineensis) leaves extract in experimental diabetic nephropathy: a duration-dependent outcome

Abstract

BackgroundCatechins-rich oil palm (Elaeis guineensis) leaves extract (OPLE) is known to have antioxidant activity. Several polyphenolic compounds reported as antioxidants such as quercetin, catechins and gallic acid have been highlighted to have pro-oxidant activity at high doses. Therefore, the present study was conducted to investigate the antioxidant and pro-oxidant effects of chronically administering high dose of OPLE (1000 mg kg-1) in an animal model of diabetic nephropathy (DN).MethodsAnimal body weight, indexes of glycaemia, renal function and morphology were assessed in diabetic animals with and without OPLE (1000 mg kg-1) for 4 and 12 weeks respectively. Oxidative stress was quantified by measuring levels of 8-hydroxy-2’-deoxyguanosine (8-OHdG), lipid peroxides (LPO) and reduced glutathione (GSH). Transforming growth factor-beta1 (TGF-β1), a key mediator of extracellular matrix accumulation, was analysed in plasma. The mechanisms of OPLE action were evaluated by assessing nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits (p22phox and p67phox) expression.ResultsOral administration with high dose of catechins-rich OPLE (1000 mg kg-1) to STZ-induced diabetic rats for 4 weeks attenuated renal dysfunction (hyperfiltration, proteinuria) and development of glomerulosclerosis and tubulointerstitial fibrosis, features that are associated with DN. Suppression of increases in oxidative stress markers (8-OHdG, LPO) and the fibrotic cytokine, TGF-β1 was observed. OPLE also reduced renal expression of NADPH oxidase subunits p22phox and p67phox. In contrast and surprisingly, identical dose of OPLE when administered to diabetic animals for 12 weeks caused worsening of renal dysfunction, histopathology in addition to further elevation of oxidative stress marker (LPO) and TGF-β1. These unfavourable effects of prolonged treatment with 1000 mg kg-1 OPLE were accompanied by increase expression of one of the NADPH oxidase subunits, p22phox.ConclusionOur study indicates that chronic administration of 1000 mg kg-1 OPLE exerts both antioxidant and pro-oxidant effects in DN depending on the duration of treatment. The present study also reveals that the antioxidant/pro-oxidant effects of OPLE are in part, due to modulation of NADPH activity.

Effects of infliximab against carbon tetrachloride-induced intestinal injury via lipid peroxidation and apoptosis

“…Previous studies have reported that 8-OHdG expression increases in oxidative stress DNA damage caused by ROS. 24,25,32,36,37 Deniz and coworkers reported that CCL 4 increased 8-OHdG expression in their studies. 18 Similarly, in our study, we observed that CCL 4 causes an increase in 8-OHdG positivity in enterocytes.…”

Effects of fermented red bean extract on nephropathy in streptozocin-induced diabetic rats

“…Our results revealed that oral administration of NRBE decreased AGE and ROS production and, on the other side, increased GSH concentration and SOD activity in streptozocin-induced diabetic kidneys. However, a high dose of NRBE did not increase SOD activity compared with those of the DC group, which could imply that an overdose of NRBE might play two roles, as an antioxidant and oxidant agent, in animal tissues simultaneously (33). NRBE contained 6.30 mg gallic acid equivalent/g of total phenols and 12.03 mg rutin equivalent/g of total anthocyanin (data not shown), and therefore, it can provide powerful antioxidant protection.…”

Role of Dietary Antioxidant Agents in Chronic Kidney Disease

“…Varatharajan et al [65] evaluated the antioxidant and pro-oxidant effects of catechins-rich oil palm leaves extract (OPLE) on DN. Rats were divided into control, diabetes, and diabetes + OPLE groups.…”

“…These unfavorable effects were accompanied by increased expression of p22 phox . Therefore, OPLE exerts both antioxidant and pro-oxidant effects in DN depending on the duration of the treatment [65].…”