Abstract: The contents of total polyphenols and total and individual flavonoids in celery juice and two celery extracts (which were adsorbed onto polyamide resin and then eluted with 40% or 60% ethanol) before and after simulated oral, gastric and intestinal digestion were measured and compared. The protective effect of the digests against oxidative stress in cells was studied. Besides, the correlation between polyphenol and flavonoid contents and the protection against oxidative stress was evaluated. The results showed that the contents of total polyphenols, total flavonoids, luteolin-7-O-glucose-2-O-selenoside, luteoloside, apigenin and 3-methoxy apigenin were increased by 6.82, 6.03, 26.18, 8.62, 22.17 and 9.07 times for the extract eluted with 40% ethanol; 6.54, 6.50, 12.46, 5.21, 17.60 and 4.09 times for the extract eluted with 60% ethanol; 29.26, 26.10, 5.16, 2.63, 8.58, and 4.67 times for celery juice, respectively after in vitro simulated digestion. The antioxidative stress ability of celery juice and both extracts increased first and then decreased during the simulated digestion. Alcohol extraction and normal dietary intake had no significant effect on the in vitro digestion of celery flavonoids, and there was a positive correlation between total phenol and flavonoid contents and antioxidative stress ability.

Key words: celery flavonoids, individual flavonoids, simulated in vitro digestion, oxidative stress