Antioxidant Capacity, in Silico Study and Histological Effects of Orange Peel on Obese Wistar Rats

Abstract

Abstract Citrus peel is an industrial by-product, and it is far from being considered as waste. It is an inexhaustible source of bioactive substances, including phenolic acids, flavonoids, catechins, and tannins. For this purpose, we evaluated the biological activities of Citrus sinensis peel based on four parameters: HPLC phytochemical analysis, antioxidant properties (DPPH, FRAP), in vivo histology, and in silico modelling. In fact, in vivo study was designed as follows: adult male Albino Wistar rats were randomly divided into 5 groups. Group I: served as a control, group II: received 10% of orange peel, group III: received an obesogene diet (20% corn oil), group IV: received (20% corn oil, eight weeks + 10% of orange peel as corrective diet, four weeks), and group V: received (20% corn oil + 10% of orange peel protective diet). After 12 weeks, the liver, kidney, pancreas, and thyroid were removed for histology examination. Additionally, docking modelling was performed using Molecular Operating Environment software (MOE) to predict the interactions of thyroid hormone receptor with agonist ligands. Results revealed that methanolic and ethyl acetate extracts presented a high level of significant activity, respectively, in the DPPH and FRAP tests. Histology demonstrated that 10% of Citrus sinensis peel had a protective effect on the liver and possessed a hypothyroid effect on obese rats. In-silico data, illustrated that the complex of quercetin, (-)-epicatechin, and (+)-epicatechin with the target protein did not match with control at the binding site, suggesting that these docked ligands may play an antagonist action mode against thyroid hormone. To sum up, orange peels could be beneficial or harmful, depending on the drive and methods used.