Enhanced In Vitro Bioaccessibility and Anticancer Activity of Brazilian Propolis Extracted with L-Lactic Acid

Abstract

This study aimed to investigate whether L-lactic acid (LA), as a better solvent than ethanol (EtOH), enhances the bioaccessibility of phenolic compounds in red and green Brazilian propolis and to evaluate their potential anticancer effects in vitro. In vitro gastrointestinal digestion was performed by sequentially subjecting propolis extracts to buccal, gastric, and intestinal digestion phases, and samples were collected at each stage for analysis. The total phenolic content (TPC) was determined using the Folin-Ciocalteu reagent with gallic acid as a standard. The total antioxidant capacity was evaluated using the cupric ion reducing antioxidant capacity and 2,2-diphenyl-1-picrylhydrazyl assays. The phenolic compounds of propolis samples were determined by high-performance liquid chromatography with diode-array detection analysis. The anticancer effects of propolis samples were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The results showed that the TPC and antioxidant activity were markedly higher in the gastric and intestinal digestive products of LA propolis extracts than in those of ethanolic extracts. Treatment with red propolis LA extracts (RP-LA) resulted in a dose-dependent reduction in the viability of lung and colon carcinoma cells. Specifically, treatment with 1,750 ppm of RP-LA decreased the survival rate of carcinoma cells by 85% to 90%, whereas treatment with ethanolic propolis extracts at the same concentration did not exhibit any cytotoxic effect on cell viability. These findings suggest that LA is a more effective solvent than EtOH for extracting bioactive compounds from propolis, enhancing its antioxidant and anticarcinogenic potential.