Antioxidant Status of Rats Fed with Products Derived from Fruits of Different Varieties of Oil Palm (Elaeis guineensis)
Anunike Uchenna Chukwueloka *
Department of Applied Biochemistry, Faculty of Biosciences, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria.
Eneh Frank Uchenna
Department of Applied Biochemistry, Faculty of Biosciences, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background and Aims: Palm oil products are staples of the Nigerian diet, and both palm kernel oil and the aqueous palm-fruit extract used to prepare Ofe-akwu or Banga are eaten in large quantities. Their effect on the body's antioxidant defences, however, has received little attention. This study compared antioxidant enzyme activities and lipid peroxidation in rats fed palm products prepared from three palm fruit varieties, with soybean oil as the reference.
Study Design: Randomised, controlled animal experiment.
Place and Duration of Study: Department of Applied Biochemistry, Faculty of Biosciences, Nnamdi Azikiwe University, Awka, Nigeria, over an eight-week feeding period (following a three-day acclimatisation).
Methodology: Sixty male Wistar rats (40–50 g) were divided into ten groups of six. A baseline group was sampled at the start; the remaining groups were fed diets fortified with 9% refined soybean oil (control), crude soybean oil, refined palm kernel oil, or the palm-fruit water extract (PFWE) and crude palm kernel oil (CPKO) of the Nigrescens, Virescens, and Albo-nigrescens varieties, for eight weeks. Serum superoxide dismutase (SOD) and catalase activities and malondialdehyde (MDA) concentration were determined spectrophotometrically. Data were analysed by one-way ANOVA with Tukey's HSD.
Results: SOD activity was highest in the CPKO Nigrescens group (2.395×10⁻⁵ U/mL) and soybean oil groups and lowest in the PFWE Virescens group (0.789×10⁻⁵ U/mL). Catalase showed a similar pattern, with activity highest at baseline (11.226×10⁻² U/mL) and lowest in the Virescens groups. MDA was highest at baseline (2.533×10⁻⁶ µmol/mL) and lowest in PFWE Virescens (1.509×10⁻⁶ µmol/mL) and the two soybean oils. None of the differences were statistically significant (SOD P > .05; catalase P = .08; MDA P = .15).
Conclusion: At normal dietary proportions, neither the palm kernel oils nor the Ofe-akwu water extracts disturbed antioxidant status or raised lipid peroxidation relative to soybean oil. The soybean oil and the Virescens water extract were associated with the least lipid peroxidation, and the Virescens variety deserves closer study.
Keywords: Palm kernel oil, superoxide dismutase, catalase, malondialdehyde, lipid peroxidation, Elaeis guineensis