Abstract

This study aimed to assess the antioxidant activity of the pineapple crude juice extracted from the whole fruit, and its effect in stimulating thyroid hormones synthesis in hypothyroid rats, as well as anticipating the concomitant hyperlipidemia. Male Swiss albino rats were divided into: normal (euthyroid) controls; normal rats orally administrated with pineapple juice (0.75 ml/100g body weight) for 8 consecutive weeks; hypothyroid rats administrated methimazole (0.02% w/v) in drinking water for 15 days; and treated hypothyroid rats orally administrated with methimazole then pineapple juice for 8 weeks.

In vitro antioxidant studies demonstrated that pineapple juice has high scavenging activity for nitric oxide and α,α2-diphenyl-β-picrylhydrazyl radicals, a high ferric reducing antioxidant power and an inhibitory effect on lipid peroxidation. Supplementation of euthyroid rats with pineapple juice for 8 weeks reduced the body weight and elevated serum T3 and T4 levels, compared to normal controls. While, supplementing hypothyroid rats with the pineapple juice normalized serum levels of T3, free cholesterol and its percentage of esterification, LDL-C, HDL-C, atherogenic index and LCAT activity, as well as serum, heart and hepatic MDA concentration and GPX activity. The histological examination of thyroid tissue sections of hypothyroid supplemented rats revealed an improvement in the cellular architecture of the thyroid gland epithelium lining the follicles and partial filling of the follicular lumen with colloid. Pineapple juice attenuates the excessive methimazole induced oxidative stress and consequent hyperlipidemia, also, activates the thyroid gland functions, suggesting its benefit as therapeutic supplement or as an adjunct in hypothyroidism therapy.