Simulated gastrointestinal digestion/Caco-2 cell transport: Effects on biological activities and toxicity of a Brazilian propolis

[Display omitted] •Antioxidant activity of propolis remained after digestion and epithelial transport.•Propolis attenuates nuclear factor kappa B activation after epithelial transport.•Propolis reduces the release of cytokines after epithelial transport.•Some lignans and phenolic acids cross Caco-2 cell monolayers.•Acute toxicity was very low for propolis extract and small intestinal fraction. The objective was to assess the effect of gastrointestinal digestion/Caco-2 cell transport on biological activities and toxicity of the ethanolic extract of organic propolis from southern Brazil (EEOP1). As principal results, the EEOP1 deactivated the ROO•, HOCl and O2•- reactive oxygen species, attenuated NF-κB transcription factor activation, and decreased the release of TNF-α and IL-6 in macrophages after Caco-2 cell transport, while CXCL2/MIP-2 release was reduced after gastrointestinal digestion. Furthermore, the phytochemical profile monitored by HPLC-ESI-QTOF-MS changed, especially for lignans, lignan-precursors and phenolic acids. Conversely, the antimicrobial activity was observed only in the non-digested EEOP1. The EEOP1 lethal dose to kill 50 % of the Galleria mellonella larvae was 1.1 g/kg, and its digested fraction had no toxic effect. Hence, there is indication that some phytochemicals present in the EEOP1 are resistant to the gastrointestinal tract and maintain their biological activities, as expected for a functional food ingredient.