Transepithelial transport of isoflavonoids from Brazilian red propolis in Caco-2 cell monolayers

• Autor(a) principal: Morais, Daniel Vieira de
• Data de Publicação: 2021
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/64/64135/tde-26042023-140330/
• topic: Antioxidant compounds; Compostos antioxidantes; Digestão in vitro; in vitro digestion; Propolis; Própolis

The study of natural products in Brazil provides relevant information on plant species and raw materials, which can be used sustainably to benefit society while supporting several development programs for biodiversity conservation. Over the past years, several studies have elucidated the mechanisms underlying the overproduction of free radicals and oxidative stress in systemic diseases. To overcome this issue, naturally-occurring bioactive compounds (e.g., polyphenols) have been shown to be effective as ROS/RNS scavengers. Among them, Brazilian Red Propolis (BRP) extract and its isolated isoflavones were shown to have a remarkable antioxidant capacity, even though their potential bioactivity after human consumption remains largely unknown. In the first study, we investigated the best extraction conditions for recovery of phenolic compounds with antioxidant activity from BRP extracts. LC-QTOF-ESI-MS/MS analysis was used in negative mode to identify the extract composition. In the second study, the optimized BRP extract was examined for its ROS/RNS scavenging capacity throughout gastrointestinal digestion and absorption across Caco-2 cell monolayers. Our findings revealed that the optimal extraction conditions were 90 % ethanol at 80 °C for 30 min. Interestingly, thirteen substances were tentatively identified for the first time in BRP, including four flavones (tricin; genkwanin; hispidulin and 8-Hydroxy-5-methoxyflavanone), one flavanol (7-Hydroxy-6-methoxydihydroflavonol), two flavanones (5,6-Dihydroxy-3,4-dimethoxyflavanone and 6-Hydroxyflavanone), two chalcones (2,4-Dihydroxychalcone and 2,6-dihydroxy-4-methoxydihydrochalcone) and four isoflavonoids (dihydrobiochanin A, dimethyl medicarpin, 5,4Dihydroxy7methoxyisoflavone and 3,9-Dimethoxypterocarpan). In the gastrointestinal model, a significant decrease in the amount of phenolic compounds in the BRP extract was observed throughout different digestion phases as well as in the antioxidant capacity. Eleven compounds could be absorbed through Caco-2 monolayers, which showed significant peroxyl radical (ROO) scavenging activity. Due to the complexity of the human gastrointestinal system, further studies will be necessary to understand the contribution of other variables, such as the presence of colonic bacteria, to the absorption of the flavonoids present in the BRP extract. This is a pioneer study using an in vitro digestion/Caco-2 cell model to evaluate the antioxidant activity of an optimized BRP extract. Collectively, our findings provide important insights to understand the bioavailability of bioactive compounds from propolis and other natural products