Human intestinal microbial metabolism of naringin.

Naringin, a major flavonoid in citrus fruits, has been proved to be a promising antitussive candidate. It undertakes complicated metabolism. In this study, human intestinal microbial metabolism of naringin was studied in vitro. Six persons' fecal water, which have intestinal microbial enzyme, were used in the first experiment. Naringin was metabolized by fecal water into naringenin. Subsequently, 3-(4-hydroxyphenyl)propionic acid (4-HPPA) was produced with naringenin degradation by a person's fecal water. However, 4-HPPA was not detected after naringenin degradation by the other 5 subjects' fecal water and the reason might be that the degrading velocity of 4-HPPA exceeded the producing velocity. To confirm the difference in degrading 4-HPPA among human feces, 22 healthy persons' feces were used for incubation. In this second experiment, 15 persons' feces could degrade 4-HPPA, but the other 7 subjects' could not. Human feces showed different ability of degrading 4-HPPA, and there are no gender differences. These results may be helpful for explaining findings in pharmacological and toxicological studies and are groundwork for clinical studies.