Urinary metabolites from mango (Mangifera indica L. cv. Keitt) galloyl derivatives and in vitro hydrolysis of gallotannins in physiological conditions.

SCOPE: The absorption, metabolism, and excretion of mango galloyl derivatives (GD) has not yet been investigated in humans, and studies investigating repeated dosages of polyphenols are limited. METHODS AND RESULTS: In this human pilot trial, healthy volunteers (age = 21-38 y, n = 11) consumed 400 g/day of mango-pulp (cv. Keitt) for 10 days, and seven metabolites of gallic acid (GA) were characterized and quantified in urine excreted over a 12 h period. Pyrogallol-O-sulfate and deoxypyrogallol-O-sulfate were found to be significantly more excreted between days 1 and 10 (p < 0.05) from 28.5 to 55.4 mg and 23.6 to 47.7 mg, respectively. Additionally, the in vitro hydrolysis of gallotannins (GTs) was monitored at physiological pH and temperature conditions, and after 4 h a significant (p < 0.05) shift in composition from relativity high to low molecular weight GTs was observed. CONCLUSION: Seven metabolites of GA were identified in the urine of healthy volunteers, and two microbial metabolites were found to be significantly more excreted following 10 days of mango consumption. Mango GTs were also found to release free GA in conditions similar to the intestines. GTs may serve as a pool of pro-GA compounds that can be absorbed or undergo microbial metabolism.

Phytochemical composition and effects of commercial enzymes on the hydrolysis of gallic acid glycosides in mango (Mangifera indica L. cv. 'Keitt') pulp.

A detailed characterization of mango pulp polyphenols and other minor phytochemicals was accomplished for the first time in the cultivar 'Keitt' whereby the identification and semiquantification of five hydroxybenzoic acids, four cinnamic acids, two flavonoids, and six apocarotenoids was accomplished. Among the most abundant compounds were two monogalloyl glucosides (MGG) identified as having an ester- or ether-linked glucose, with the ester-linked moiety present in the highest concentration among nontannin polyphenolics. Additionally, the impact of side activities of three commercial cell-wall degrading enzymes during 'Keitt' mango pulp processing was evaluated to determine their role on the hydrolysis of ester- and ether-linked phenolic acids. The use of Crystalzyme 200XL reduced the concentration of ester-linked MGG by 66%, and the use of Rapidase AR 2000 and Validase TRL completely hydrolyzed ether-linked MGG after 4 h of treatment at 50 °C. Fruit quality, in vivo absorption rate, and bioactivity of mango phytochemicals rely on their chemical characterization, and characterizing changes in composition is critical for a complete understanding of in vivo mechanisms.