The potent in vitro antioxidant ellagitannins from pomegranate juice are metabolised into bioavailable but poor antioxidant hydroxy-6H-dibenzopyran-6-one derivatives by the colonic microflora of healthy humans.

摘要: The antiatherogenic activity of pomegranate juice has been attributed to its antioxidant polyphenols. The most potent in vitro antioxidant polyphenol from this juice is the ellagitannin punicalagin. However, the bioavailability ellagitannins, including punicalagin, not been previously described humans. present work aims to evaluate, healthy humans, the and metabolism pomegranate juice ellagitannins, assess their effect on several blood parameters (including cardiovascular risk disease markers) and compare antioxidant activity punicalagin with that vivo generated metabolites. Six healthy subjects (four men two women) consumed 1 L daily (5.58 g/L polyphenols, including 4.37 g/L punicalagin isomers) for 5 days. The polyphenols vivo generated metabolites were measured by HPLC–DAD–MS–MS. Fourteen haematological and twenty serobiochemical parameters including LDL, HDL VLDL as well as cholesterol triglycerides in each lipoprotein were evaluated. In activity of plasma (ABTS FRAP assays) urine and DPPH) determined. Neither punicalagin nor ellagic acid present detected in both urine. Three microbial ellagitannin-derived metabolites detected: 3,8–dihydroxy–6H–dibenzo[b,d] pyran–6–one glucuronide, an unidentified aglycone (tentatively, trihydroxy–6H–dibenzo[b,d]pyran–6–one) hydroxy–6–Hdibenzo[ b,d]pyran–6–one glucuronide. These could reach up 18.6 µM plasma, although a large inter–individual variability was observed. urine, the same corresponding aglycones became evident after day consumption. Total excretion of metabolites ranged 0.7 to 52.7% regarding ingested punicalagin. No relevant effect observed on any parameter. The did not show significant antioxidant activity compared to pomegranate juice. The potential systemic biological effects of ingestion should be colonic microflora rather than to the juice.