COMPARISON OF TOMATO PHENOLIC AND ASCORBATE FRACTIONS ON THE INHIBITION OF N-NITROSO COMPOUND FORMATION

Whole tomato juice has previously been shown to inhibit N-nitrosoamino acid formation in vivo to a greater extent than expected on the basis of its ascorbate content. The present work compares in vitro inhibition of nitrosation by ascorbate and phenolic fractions from tomatoes. Tomato extracts were separated into phenolic and ascorbate portions, and the phenolic portion was further fractionated. Fractions were tested for inhibition of N-nitrosomorpholine (NMOR) formation. Several phenolic fractions as well as the ascorbate fraction inhibited NMOR formation. Most of the inhibition from the phenolic fraction was due to p-coumaric and chlorogenic acids. The ascorbate fraction contained unidentified compounds that inhibited nitrosation. While both fractions substantially inhibited nitrosation, the ascorbate fraction was more inhibitory than the phenolic fraction.