Prostaglandin E2 is a well-known proinflammatory mediator and promoter of some tumours. To test the potentially anti-inflammatory activity of some phytochemicals commonly found in foods, an in vitro cell culture model using a macrophage cell line RAW264.7 was employed. The PGE2 production in RAW264.7 cells stimulated by LPS was dose-dependently inhibited by apigenin, curcumin, resveratrol, naringenin and quercetin with IC50s of 1.9, 9.7, 13.9, 36.7 and 23.3 micro M, respectively. Some green tea polyphenols, including, (-)epicatechin (-EC), ( plus or minus )catechin, (-)epigallocatechin gallate (-EGCG) and (-)epicatechin gallate (-ECG), also inhibited PGE2 production of RAW264.7 cells stimulated by LPS, while (+)EC and (-)epigallocatechin (-EGC) did not. The IC50s were 11.3 micro M for (-)EGCG, 39.1 micro M for (-)ECG, 151 micro M for (-)EC and 321 micro M for ( plus or minus )catechin. Ascorbic acid exerted a weak inhibition while beta -carotene was not effective. The inhibitory effect was not accompanied by a significant change in COX-2 protein expression, as revealed by Western blot analysis. The water (WE) and ethyl acetate (EAE) extract of onion, a rich source of quercetin, also showed an inhibitory effect on PGE2 production. On the other hand, WE of celery, a rich source of apigenin, enhanced PGE2 production in the absence of LPS, and EAE of celery also enhanced PGE2 production in the presence of LPS. The anti-inflammatory activity of phytochemicals in foods merits further studies to help those suffering from chronic inflammation to ameliorate their inflammatory conditions by a proper selection of foods.
v.3(2):59-71, FOOD SCIENCE AND AGRICULTURAL CHEMISTRY