Avaliação de atividade antioxidante e antineuroinflamatória de flavonoides e derivados de síntese em células gliais

Abstract

Astrocytes actively participate in redox regulation in the brain. The imbalance between overproduction of reactive species and antioxidant mechanisms can result in reactive astrogliosis. Astrogliosis associated with oxidative stress can promote changes in cell morphology and function, reduced enzymatic activity and increased cytokines and inflammatory mediators. In this context, flavonoids, which have antioxidant and anti-inflammatory properties, are promising candidates for the study of adjuvant therapies in diseases whose pathophysiology is oxidative stress. This work evaluated, in vitro, the cytotoxicity and antioxidant activity of flavonoids and synthetic derivatives (naringenin, (S) – naringenin, 7,4'- O-diprenylnaringenin, (S)-7,4'-O-diprenylnaringenin, 7 -O-prenylnaringenin, naringin, hesperidin, chrysin, apigenin and rhoifolin), associated with the control of the glial inflammatory response. The cellular antioxidant activity of flavonoids and synthesis derivatives (1, 10 and 50μM) was determined by the free radical scavenging reaction 2,2-diphenyl-1-picryl-hydrazyl (DPPH). Hesperidin and the diprenylated derivative (S)-7,4'-O-diprenylnaringenin showed higher potential antioxidants and naringenin and its other prenylated derivatives showed moderate antioxidant activity after this cell-free test in a 15min reaction. Primary cultures of astrocyte-enriched glia derived from neonatal Wistar rats (P0-P2) exposed to lipopolysaccharide (LPS, 1 µg/mL for 24 h) and treated with the molecules (5 or 10 µM for 24 h) were used. An antioxidant effect was observed through the increase in GSH levels, promoted by naringenin and its derivatives, through the glutathione depletion test with monochlorobimane after treatments (5 µM for 24 h). The enzymatic levels of SOD, LPS and chrysin increased SOD and other molecules did not interfere with enzymatic levels. Through the cytotoxicity test (MTT) it was demonstrated that the prenylated derivative 7-O-prenylnaringenin (1, 10 and 50 and 100μM for 24 h) was the most cytotoxic for the proliferative cells of GL15 (human) and C6 (murine), however, without presenting toxicity and morphological changes for primary culture cells of astrocyte-enriched glia. In Rosenfeld staining, apigenin and chrysin (10 µM for 24 h) induced morphological changes such as retraction of the cytoplasm and nucleus of cells from primary culture of astrocyte-enriched glia and other molecules attenuated morphological changes promoted by LPS (1 µg/mL) when on concomitant treatment. In addition, flavonoids and synthetic derivatives (10 µM, 24 h) promoted a reduction in nitric oxide (NO) levels and did not induce NO production in isolated treatment. Together, these findings indicate that flavonoids and synthesis derivatives have significant antioxidant and antineuroinflammatory capacity, in vitro, and may be allied as candidates for adjuvant treatments in neurodegenerative diseases.