Flavanones, the main
polyphenols of citrus fruits, are thought to contribute to the protective effects of these fruits against
cardiovascular diseases and
cancer. The metabolism of
naringin (naringenin 7-O-neohesperidoside) is studied here in healthy (
sham-operated, ShO) and
tumor-bearing (TuB) rats. The
tumor was induced by implanting Yoshida's
sarcoma in hindlimb. Both groups received for 7 days a semi-synthetic diet containing 0.5%
naringin in per feeding conditions.
Flavanones were analyzed in plasma, liver, kidney and urine by tandem mass spectrometry.
Naringenin conjugates (essentially
glucuronides) accounted for up to 98% of the total
flavanones in plasma. Low amounts of
hesperetin (4'-O-methyl naringénine) and
isosakuranetin (3'-hydroxy-4'-O-methylnaringenin) were also detected in all
biological samples and accounted for 2% of the total
flavanones in plasma. They were largely present as aglycones. The in vivo hydroxylation of
flavanones is described here for the first time. Total concentrations of
naringenin metabolites reached 17.3+/-2.7 microM in plasma 6 hours after the beginning of the meal in healthy rats and only 10.6+/-1.3 microM in TuB rats. The nature of metabolites was similar in both healthy and TuB rats and in plasma, tissues and urine. The lower concentration of
flavanones in the TuB rats suggests that disease and more particularly
cancer, may affect the bioavailability of
flavonoids.