Extracts of Different Organs of Macadamia Nut Tree (Macadamia Integrifolia) Ameliorate Oxidative Damage in D-Galactose Accelerated Aging Model in Rats

Macadamia nut tree, Macadamia integrifolia (Maiden & Betche), is cultivated for the production of the edible macadamia nuts, which are a good source of monounsaturated fatty acids. We investigated the effect of ethanolic extracts of leaves, nuts, and nutshells of macadamia in D-galactose accelerated aging model in rats. Administration of D-galactose (150 mg/kg) in rats for 60 days resulted in impairment of cognitive function and motor coordination and caused an increase in oxidative stress and deterioration of liver and kidney functions. Macadamia nut extract ameliorated cognitive impairment induced by D-galactose as inferred from Morris water maze test and balance test using rotarod. Also, nut extract was superior to leaves and shell extract in reducing serum levels of malondialdehyde (50%), alanine transaminase (63%), aspartate transaminase (63%), total bilirubin(24%), creatinine (38%), and urea (16%) compared to animals that received no treatment. Chemical analysis showed that macadamia nut extract has a high percentage of oleic acid (81%) followed by palmitoleic acid (6.9%). This study encourages further investigation of the health benefits of macadamia nuts and the underlying mechanism of these effects.