Areca catechu L. and gastrointestinal toxicity: Potential mixture effects?

Resumo

Introduction: Relatively unknown in the Western societies, the masticatory Areca nut (Areca catechu L.) features as the fourth most used psychoactive substance worldwide, despite its carcinogenic properties mainly associated with the development of oral submucosal fibrosis and oral cancer. Knowledge of its effects on other organs and physiological functions remains limited, with most toxic effects being attributed exclusively to areca alkaloids[1]. Aims: We aimed to evaluate the impact of A. catechu aqueous extract and relevant phytochemical constituents (arecoline, arecaidine, guvacine, isoguvacine, N-nitrosoguvacine, catechin and epicatechin) on radical stress and gastrointestinal toxicity.  Methods: Viability of human colorectal adenocarcinoma Caco2 and hepatocarcinoma HepG2 cells was evaluated through the MTT and lactate dehydrogenase assays, upon exposure to A. catechu aqueous extract or its single phytochemicals (up to 1000 µg/mL or 200 µM, respectively). Radical neutralizing potential was assessed by the nitric oxide (^•NO) and superoxide (O₂^•-) scavenging assays. Results: Concentration-dependent antiradical activity upon ^•NO and O₂^•- was verified for A. catechu extract (IC₅₀ of 48.99 µg/mL and 36.63 µg/mL, respectively). Although O₂^•- production was increased by 32% at 7.81 µg/mL, the opposite effect was observed at concentrations starting at 31.25 µg/mL, with an almost complete neutralization (96.47%, p<0.0001) being achieved at 250 µg/mL of extract. Increased O₂^•- levels were also observed with guvacine, isoguvacine and N-nitrosoguvacine. As for ^•NO, besides the extract, neutralizing properties were also observed with (+)-catechin and (-)-epicatechin at 3.125 µM upwards. While A. catechu’ extract impaired metabolic competence above 500 µg/mL in intestinal and hepatic cells, leading to cell membrane integrity loss at the highest concentration, no significant effects were found for individual compounds. Conclusions: Although radical stress exacerbation by some compounds, cytotoxicity in intestinal and hepatic cells might stem from minor constituents of A. catechu nut or synergistic effects among tested compounds.