The Effects of Citrus Leaf Extract on Renal Oxidative Stress, Renal Function and Histological Changes in Rats Fed With Heated Palm Oil

Prolonged consumption of heated palm oil causes detrimental effects on cardiovascular system, liver and kidneys. The detrimental effects of heated oils are associated with oxidative stress; hence the role of antioxidants in attenuating heated oil-induced effects has been widely studied. The aim of the present study was to determine the effects of polyphenol-rich Citrus leaf extract (CLE) on renal oxidative stress parameters, renal function and kidney histological changes in rats fed with heated palm oil. Fifty-six male Sprague-Dawley rats (n=56) were divided into seven groups. The control group was given normal rat chow, while other groups were fed with 15% weight/weight (w/w) palm oil-enriched diet of either fresh palm oil (FPO), five-time-heated palm oil (5HPO) or ten-time-heated palm oil (10HPO); with or without the addition of CLE (0.15%, w/w) supplementation. After 16 weeks, the rats were sacrificed and the kidneys were harvested for analysis. CLE supplementation improved heated palm oil-induced oxidative stress parameters in the kidneys, shown by reduced levels of renal thiobarbituric acid (TBARS) and renal nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in 5HPO and 10HPO groups. Renal haem oxygenase levels were restored with CLE supplementation in the heated oil groups. Decreased serum creatinine was observed in 5HPO group with CLE supplementation, but not in 10HPO group. Heated oil caused mild interstitial inflammation with vascular congestion in 5HPO and 5HPO+CLE groups, while 10HPO group had moderate inflammation and vascular congestion. CLE supplementation in 10HPO group was able to reduce these changes as only mild interstitial inflammation and congestion was observed. CLE has the potential to reduce renal oxidative stress parameters, improve renal function and reduce renal inflammation possibly mediated via its antioxidant properties.