Capacidade antigenotóxica e antimutagênica dos extratos hidroetanólicos da amêndoa de baru (Dipteryx alata) e da castanha-do-brasil (Bertholletia excelsa) in vitro

Abstract

Nuts and seeds intake is associated with a protective effect on several diseases, mainly those related to DNA lesions, which can be lowered by various natural compounds. Brazil nuts and baru almonds are rich in minerals, lipids and phenolic compounds that play an important role in cellular antioxidant capacity. This study evaluated the concentration of phenolic compounds and antioxidant activity of hydroethanolic extracts of Brazil nut and baru almonds, and the antigenotoxic and antimutagenic capacity of these extracts in potassium bromate (KBrO3)-induced cell damage in vitro. Phenolic compounds were measured by the Folin-Ciocalteau method and antioxidant capacity was evaluated by DPPH, FRAP and ABTS assays. The Brazil nuts and baru almonds extract antimutagenic and antigenotoxic ability was assessed in pre-incubation, in which cells were treated with extracts prior to the KBrO3-induced damage, and in post-incubation, in which cells had a previously induced damage and then were treated with the extracts. The extracts’ antigenotoxic ability was evaluated by modified comet assay with formamidopyrimidine DNA glycosylase, which allowed assessing oxidative DNA damage. The extracts’ antimutagenic potential was evaluated by cytokinesis-blocked micronucleus assay. The baru almond extract (70:30, ethanol: water) showed higher values of phenolic compounds (636 mg EAG/100G) when compared with Brazil nut extract (428 mg EAG/100g), likewise, the baru antioxidant capacity was greater (DPPH= 38.69 mM Trolox/g, FRAP= 138.38 mM ferrous sulphate /g, ABTS = 4.9 mM Trolox/g) than Brazil nut (DPPH= 1.8 mM Trolox/g, FRAP= 9.97 mM ferrous sulphate /g, ABTS = 10.92 mM Trolox/g). None of the extracts alone showed a genotoxic or mutagenic effect. The cell treatment with baru almond and Brazil nut extracts was not able to reduce the KBrO3 genotoxicity. However, the pre-treatment with Brazil nut extract result in a significant decrease (p=0.0209) in KBrO3-induced micronuclei, showing a reduction of 50% with the higher concentration tested (0.010µg/mL). Also in pre-treatment, baru almond extract showed antimutagenic effect (p=0.0304), with a decrease of 44.4% in micronuclei frequency. Post-treatment showed no antimutagenic effect. Our results showed that Brazil nut extracts, and especially baru almond extracts, are rich in phenolic compounds and have increased antioxidant capacity. In addition, the two extracts showed antimutagenic activity, probably due to the modulation of DNA damage repair mechanisms, since they did not show a genotoxic effect. Thus, our study suggests that dietary consumption of these seeds may have a protective effect against oxidative damage and DNA damage.