Caffeic acid has a variety of potential pharmacological effects in in vitro studies and in animal models, and the inhibitory effect of caffeic acid on cancer cell proliferation by an oxidative mechanism in the human HT-1080fibrosarcoma cell line has recently been established.
Caffeic acid is an antioxidantin vitro and also in vivo. Caffeic acid also shows immunomodulatory and anti-inflammatory activity. Caffeic acid outperformed the other antioxidants, reducing aflatoxin production by more than 95 percent. The studies are the first to show that oxidative stress that would otherwise trigger or enhance Aspergillus flavus aflatoxin production can be stymied by caffeic acid. This opens the door to use as a natural fungicide by supplementing trees with antioxidants.
Studies of the carcinogenicity of caffeic acid have mixed results. Some studies have shown that it inhibits carcinogenesis, and other experiments show carcinogenic effects. Oral administration of high doses of caffeic acid in rats has caused stomachpapillomas. In the same study, high doses of combined antioxidants, including caffeic acid, showed a significant decrease in growth of colontumors in those same rats. No significant effect was noted otherwise. Caffeic acid is listed under some Hazard Data sheets as a potential carcinogen, as has been listed by the International Agency for Research on Cancer as a Group 2B carcinogen ("possibly carcinogenic to humans"). More recent data show that bacteria in the rats' guts may alter the formation of metabolites of caffeic acid. Other than caffeic acid being a thiamine antagonist (antithiamine factor), there have been no known ill effects of caffeic acid in humans.
Also, caffeic acid treatment attenuated LPS-induced sickness behaviour in experimental animals by decreasing both peripheral and central cytokine levels along with oxidative stress inflicted by LPS.
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