Nitrosamine formation from different Catha edulis leaves extracts under simulated gastric condition

Abstract

Nitrosamines are well-known carcinogenic and toxic compounds for humans and animals. The aim of this study was to investigate the possible formation of nitrosamine compounds from aqueous extracts of five different types of Catha edulis leaves using nitrite as a nitrosation agent, either in aqueous solution or under simulated normal fasting stomach conditions (at 37 °C and pH 2) for 1 h. Nitrosoephedrine was used as a reference compound in this study. Nitrosation of aqueous extracts of the different types of Catha edulis leaves with constant concentration of nitrite (14.4 mM) in aqueous solution showed total apparent nitrosamine compounds to be in the range 94–319 mg/100 g DM (dry matter) of CE ( Catha edulis) leaves. In contrast, nitrosamines formed in simulated gastric fluid were much lower, in the range 23–79 mg/100 g DM of CE leaves. Based on the moderate formation of nitrosamines with the Sabri Catha edulis leaves, the latter was selected for investigating the effect of varying levels of nitrite in aqueous solution and simulated gastric juice. The nitrosation of aqueous extracts of Sabri Catha edulis with different levels of nitrite in aqueous solution yielded a dose-dependent amount of total apparent nitrosamine compounds, these being undetected at ⩽0.5 mM sodium nitrite in aqueous solution and ⩽1 mM in simulated gastric juice. This raises the question of whether the observed high incidence of esophageal and forestomach carcinomas in Yemen could be attributed to the formation of nitrosamines in vivo from the secondary amines present in Catha edulis leaves.