Estudos dos componentes bioativos de extratos polares da polpa de Attalea phalerata Mart. ex Spreng e os seus efeitos na citotoxicidade, na atividade antioxidante e no metabolismo animal

Abstract

The fruit of Attalea phalerata Mart. Ex Spreng (Arecaceae) is considered one of the most important parts of the palm tree, when ripe it has fleshy pulp with a sweet flavor and characteristic aroma, rich in minerals, vitamin C, pro vitamin A, carotenoids and phenolic compounds. Consequently, the pulp of the fruit is widely used due to its composition with bioactive properties. In this perspective, this work aims to obtain polar extracts from the pulp of A. phalerata, identify the bioactive components and evaluate their effects on cytotoxicity, in vitro antioxidant activity and biochemical processes related to ex vivo metabolism. Data were presented as mean ± mean standard error (ANOVA-1 and 2 or Student's t-test; p<0.05). The contents of total reducing sugars in the extracts did not show significant difference. Regarding protein content, the dichloromethane fraction (FDCM) is 1.5 times more concentrated than the hydroethanolic extract (EEtOH). The polar extracts showed low cytotoxicity. In addition, they induced the formation of lipids in V79 cells, without altering cell viability, at the highest dose tested (1280 μg/mL), being more evident in FDCM. The analysis of transcription factors related to the regulation of fatty acid synthesis showed that the relative expression of the PPAR-γ gene mRNA was reduced in V79 cells treated with EEtOH (31%) and FDCM (40%) at 1280 μg/mL when compared to controls. At the same concentration, the expression of the PPAR-α gene was reduced by 52% in cells treated with EEtOH compared to the control without treatment, on the other hand, PPAR-α was 72% more expressed in FDCM when compared to EEtOH. The PPARα/PPARγ ratio was higher in FDCM both when compared to controls and EEtOH. In the study of enzymes related to fatty acid synthesis, the activity of glucose 6-phosphate dehydrogenase was 80% lower in both EEtOH and FDCM in adipose tissue incubated with EEtOH and FDCM at 500 μg/mL. In inguinal adipose tissue, the activity of this enzyme was 200% higher in FDCM. ATP-citrate lyase activity showed no changes in epididymal and inguinal tissues. The content of phenolic compounds and total flavonoids found in FDCM are higher than that determined in EEtOH. These results were reflected in the free radical scavenging DPPH, highlighted at the dose of 500 μg/mL at which FDCM can reduce by 78%, while EEtOH inhibits about 45% of the radical. The same behavior is evaluated in the face of intracellular induction mediated by reactive oxygen species, at a concentration of 500 μg/mL, FDCM had a higher inhibitory character (76%) than EEtOH (49%). Finally, EEtOH reduced intestinal glucose absorption at the evaluated dose (500 μg/mL). The intestinal glucose absorption in FDCM in the presence of glucose showed a difference only with the control without glucose, which demonstrates that FDCM has no effect on uptake at the intestinal level, while EEtOH presented a possible hypoglycemic effect. These findings open the way for future investigations into the use of these extracts in health contexts, such as in the prevention of metabolic diseases such as obesity and diabetes.