Exploring the potential of tannin-rich tree bark extracts in combating foodborne diseases and gastric cancer

The objective of this study was to perform chemical characterization of tannin-rich extracts obtained from the bark of woody species and to assess their bioactive potential for the treatment of foodborne diseases and gastric cancer. The barks of Anacardium occidentale, Stryphnodendron adstringens, and a commercial tannin from Acacia mearnsii were used to prepare the extracts. HPLC was employed to determine the profile and quantity of phenolic compounds present in the extracts, while FTIR was utilized to identify their functional groups. The antioxidant activity was assessed using the DPPH assay, while the antimicrobial activity was evaluated by the disk diffusion method and measurement of minimum inhibitory concentration and minimum bactericidal concentration. Additionally, the antitumor activity was evaluated using the MTT-tetrazolium assay. The phenolic profile of the extracts revealed the presence of ten compounds, with gallic acid and catechin being the most abundant for all species. Hydroxyl (OH) was the recurrent functional group in all the analyzed extracts. At a concentration of 25 μg/mL, the extracts exhibited DPPH free radical scavenging activity of 90%. The extracts had significant antitumor potential, inhibiting the growth of human gastric adenocarcinoma cells (AGS) by 90% at 200 μg/mL. Listeria monocytogenes was the most sensitive bacterium to the use of the extracts, while Escherichia coli was the most resistant. In conclusion, the results obtained in this study demonstrated the promising potential of tannin-rich extracts from the studied species as antioxidant, antimicrobial, and anticancer agents.