EFFECT OF RED PITANGA EXTRACT AND ITS BIOACCESSIBLE FRACTION ON THE VIABILITY OF C6 GLIOMA CELLS

Glioma is the most common primary tumor of the central nervous system (CNS) and the most lethal. Currently, few chemotherapeutic agents are available for treatment, making further research necessary to identify and develop new therapeutic agents. In this regard, the red pitanga is a Brazilian fruit rich in phenolic compounds, with recognized antioxidant activity and in vitro anticancer potential. The objective of this study was to evaluate the effect of red pitanga extract and its bioaccessible fraction on the viability of glioma cells. Ripe fruits obtained from Embrapa Clima Temperado in Pelotas, Rio Grande do Sul, were used. The extract was prepared from pulp samples, homogenized for 35 min in 95% ethanol (1:3 w/v), and centrifuged at 3000 rpm for 5 min. The supernatant was collected, and the procedure was repeated. The final volume was concentrated in a rotary evaporator at 40°C. The bioaccessible fraction of the extract was obtained after in vitro digestion, according to the INFOGEST 2.0 protocol. The total phenolic compound content was determined using the Folin method; the crude extract contained 2035.29 μg of gallic acid equivalents/mL, and its bioaccessible fraction contained 147.30 μg GAE/mL. A glioma cell line (C6), obtained from the Rio de Janeiro Cell Bank, was used. The cells were cultured in low-glucose medium supplemented with 10% fetal bovine serum and antibiotics at 1% of the total volume, in an incubator at 37°C, under a humidified atmosphere with 5% CO₂. The cells were seeded in 24-well plates and, after reaching confluence, treated with the crude extract at concentrations of 1, 5, 10, 25, 50, and 100 μg/mL of GAE/mL and, for the bioaccessible fraction, at concentrations of 1, 5, and 10 μg/mL of GAE/mL. The plates were incubated for 24 hours for subsequent analysis of cell viability using the MTT assay. The data were analyzed using one-way ANOVA and Dunnet’s post hoc test, with a significance level of p < 0,05. Treatment with the extract resulted in a significant (p < 0,0001) concentration-dependent reduction in cell viability starting at a concentration of 25 μg/mL. In contrast, for the bioaccessible fraction, at the lowest concentration (1 μg GAE/mL), there was a significant increase (p < 0,01) in viability, indicating a possible proliferative effect via metabolic stimulation. However, at the highest concentration (10 μg GAE/mL), a significant reduction (p < 0,05) in cell viability was observed compared to the control. These variations among the samples may indicate that conditions in the gastrointestinal tract (pH, digestive enzymes, and bile salts) can degrade or biotransform the fruit’s active compounds, highlighting the need for pharmacological protection strategies to enable its potential therapeutic effect.