Avaliação da atividade antioxidante, mutagênica e antimutagênica de polpas de frutas

Abstract

Several studies have pointed out that consumption of fruits is related to the reduced risk of diseases, such as coronary heart and neurodegenerative diseases, as well as certain types of cancer. Although several fruits in natura and compounds isolated from them have been already studied, there exist little data on frozen fruits composition and their biological activity. Frozen fruits are widely employed to prepare juices, and also as a raw material for the food industry. Therefore, this study aims to evaluate the composition and the antioxidant, mutagenic and antimutagenic activities of 23 frozen fruit pulps. Carbohydrates, lipids, proteins, vitamin C, total polyphenols, carotenoids and mineral contents were assessed in all fruits. Antioxidant activity was determined by the chemical measurement of 1-diphenyl-2-picrylhydrazyl (DPPH*) radical scavenging activity and superoxide dismutase and catalase-like activities. Tissue homogenates from Wistar rats´ brain only assayed in açai pulp. Mutagenic and antimutagenic activities, strain XV185-14C of S. cerevisiae, that allows the detection of specific locus and frameshift mutations. As expected, all pulps showed low lipids and proteins contents (absence or lower than 1 mg%). Coconut was the only fruit which presented insignificant carbohydrate values in its composition. Even frozen, the fruits contained significant polyphenols, carotenoids, vitamin C, macro and micro minerals and trace elements. Most of the assayed pulps (74%) showed in vitro antioxidant capacity equal or superior to vitamin C. This effect was positively correlated with carotenoid content (r = 0.366; p minor or equal 0.01). All samples showed catalase-like activity and 56% of the fruits showed superoxide dismutase activity. Acai fruit was able to revert hydrogen peroxide induced oxidative damages in Wistar rats´ cortex, cerebellum and hippocampus. When tested in high concentrations (5, 10, 15 %w/v), acaí, cashew apple, kiwi and strawberry pulps showed mutagenic activity, which was positively correlated with carotenoids (r = 0.793, p minor or equal 0.05), polyphenols (r = 0.793, p minor or equal 0.05) and vitamin C (r = 0.793, p minor or equal 0.05). Twelve fruits demonstrated important antimutagenic activity, which was positively correlated with catalase-like activity (r = 0.400, p minor or equal 0.01). Our findings show that frozen fruits have important roles in antioxidant and antimutagenic activities, reducing oxidative damages associated to several diseases.