Atividades biológicas do suco e do óleo essencial da laranja sanguínea moro (Citrus sinensis (L.) Osbeck)

Abstract

The blood orange of the Moro variety (Citrus sinensis (L.) Osbeck) is characterized by an intense red coloration of the pulp and differs from the other blood oranges because of the high levels of anthocyanins that it possesses, this being an important form of enrichment of the fruit. In this study, the objective was to evaluate the activation of anthocyanins present in Moro oranges by means of refrigeration, to verify metabolic alterations of obese and diabetic rats treated with the juice from refrigerated Moro oranges and to evaluate the antioxidant, antifungal, antitumor, cytotoxic and genotoxic properties of the essential oil extracted from the peels of the refrigerated Moro oranges. The oranges were stored for 60 days at 4 and 8 ºC, and analyzed periodically for the content of bioactive compounds and antioxidants and in relation to quality parameters. Initially, obesity was induced over 42 days and, later, Diabetes Mellitus. After this period, the animals were treated with Moro orange juice for 28 days. Throughout the experiment, body mass, water, feed and juice consumption, Lee's index and glycemia were monitored. After euthanasia, histopathological, histological, biochemical and enzymatic analyses were performed. The essential oil from the Moro orange peel was obtained by hydrodistillation during 2 hours, and it was characterized by gas chromatography coupled to mass spectrometry (GC/MS) and gas chromatography with a flame ionization detector (GC/FID). The antioxidant activity was evaluated by the DPPH, ABTS and β-carotene methods. The antifungal potential against Aspergillus carbonarius and Aspergillus flavuswas evaluated by the disc diffusion test. The cytotoxic and antitumoral evaluation was performed by the determination of cell viability on the fibroblast-derived lineages and neoplastic lines of lung, breast and melanoma adenocarcinomas, respectively. Genotoxicity was assessed by the Comet assay on fibroblast-derived lines. After 40 days of storage, an higher anthocyanin content was observed until the end of the period at a temperature of 8 °C. The storage had a positive influence on the levels of phenolic compounds and antioxidants, except for vitamin C, but it altered the color, acidity and pH of the fruits. However, it did not make commercial use impossible. Juice intake reversed most of the metabolic abnormalities exhibited by obese rats, such as biochemical profile and body mass. However, no improvement was observed in diabetic and obese diabetic animals, making this model of treatment inviable in these categories of rats. A high extraction yield of the essential oil from the oranges was obtained, and it was composed mainly of monoterpene limonene. No antioxidant activity was observed using the evaluated methods, but antifungal effect with a minimum inhibitory concentration of 125 μL mL -1 for both fungi was found. The essential oil had no antitumor activity on the melanoma lines and an absence of cytotoxic and genotoxic effect in the evaluated concentrations. Presented positive results related to the biological activities of juice and essential oil were obtained with the use of Moro oranges, making possible the cultivation and commercialization in Brazil. New human studies are being performed involving the testing of the therapeutic efficacy of the juice in combating obesity, and new studies in food matrices and drugs to test the effects of the essential oil as a natural preservative and for the treatment of cancer are being planned.