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 C6‐C3 metabolites excreted, and any benefit accruing from this metabolite will not necessarily be available to all consumers.
It has been reported that the phenolic metabolite 3′‐methoxycinnamic acid‐4′‐sulfate generated from 5‐O‐caffeoylquinic acid may have health‐promoting properties. However, the variation in 3′‐ and 4′‐methylation of 3′,4′‐dihydroxycinnamic acid, as well as its impact on the yield of this sulfate metabolite is unclear and has been poorly studied. After analyzing the excreted urine (24‐h) of 14 volunteers that had intake white‐fleshed or red‐fleshed apple snack, seven 3′‐methoxy and seven 4′‐methoxy metabolites are determined. In only six volunteers, five females and one male, is 4′‐methylation preferred over 3’‐methylation. It is also observed that an individual′s 3′‐ / 4′‐methylation ratio can change over time, and that the concentration of 3′‐methoxycinnamic acid‐4′‐sulfate is extremely variable.