Variation in the Methylation of Caffeoylquinic Acids and Urinary Excretion of 3 '-methoxycinnamic acid-4 '-Sulfate After Apple Consumption by Volunteers

Identifier:  imarina:9226652

Handle: https://hdl.handle.net/20.500.11797/imarina9226652

Authors:  Rubio, Laura; Romero, Maria Paz; Sola, Rosa; Motilva, Maria Jose; Clifford, Michael N; Macia, Alba

Abstract:
Introduction: It has been reported that the phenolic metabolite 3 '-methoxycinnamic acid-4 '-sulfate generated from 5-O-caffeoylquinic acid may have potential benefits in human health. However, the variation in 3 '- and 4 '-methylation of 3 ',4 '-dihydroxycinnamic acid and its impact on the yield of this sulfate metabolite is unclear and has been poorly studied.Methods and Results: To address this aim, the excreted 3 '-methoxy and 4 '-methoxy metabolites in urine samples (24-h) are determined in 14 volunteers after an acute intake of 80 g of red-fleshed apple (RFA) or white-fleshed apple (WFA). These methoxy metabolites are also determined in the same volunteers in a second acute intake after a 6-week sustained consumption of the same products.Conclusion: Seven 3 '-methoxy and seven 4 '-methoxy metabolites are determined, i.e., the free cinnamic and corresponding phenylpropanoic acid, plus their sulfate, glucuronide, and glycine conjugates. In only six volunteers, five females and one male, is 4 '-methylation preferred over 3 '-methylation, but it is observed that an individual ' s 3 '- : 4 '-methylation ratio can change over time, and that the yield of 3 '-methoxycinnamic acid-4 '-sulfate is extremely variable, ranging from undetectable to 71% of the total C-6-C-3 metabolites excreted, and any benefit accruing from this metabolite will not necessarily be available to all consumers.