Apigenin

Apigenin is a flavonoid found in parsley, artichoke, basil, celery and other plants. Over the last three years, a large number of published studies have demonstrated the anti-cancer properties of apigenin.

To study the effects of various plant constituents, an examination was made of 21 different flavonoids on the growth of human breast cancer cells. Apigenin was shown to the most effective anti-proliferative flavonoid tested.(114) A related study showed that flavonoids such as apigenin bind to estrogen receptor sites on cell membranes in order to prevent over-proliferation of these cells in response to estrogen.(115)

A study assessed the antioxidant potencies of several dietary flavonoids compared with vitamin C. Pretreatment with all flavonoids and vitamin C produced dose-dependent reductions in oxidative DNA damage. When ranked in order of potency, only apigenin, rutin and quercetin were more effective than vitamin C in reducing DNA oxidative damage.(116)

Apigenin was tested to ascertain its effect on human leukemia cells. Apigenin was shown to induce apoptosis more effectively than quercetin and other flavonoids tested. The researchers attributed a unique mechanism of inducing apoptosis to the cancer preventive activity of apigenin.(117) Another study showed that apigenin and another flavonoid called luteolin strongly inhibited the growth of human leukemia cells and induced these cells to differentiate.(118) Topoisomerases are involved in many aspects of leukemic cell DNA metabolism such as replication and transcription reactions. In one study, quercetin or apigenin were shown to inhibit topoisomerase-catalyzed DNA irregularities.(119) In a study of various agents used to induce differentiation of human promyelocytic leukemia cells, apigenin and luteolin were among the flavonoids shown to cause these leukemia cells to mature into healthy moncytes and macrophages.(120)

In studies against thyroid cancer cell lines, apigenin and luteolin were the most effective inhibitors found. Apigenin was shown to inhibit cancer cell signal transduction and induce apoptosis. The scientists concluded that apigenin may provide a new approach for the treatment of human anaplastic thyroid carcinoma for which no effective therapy is presently available.(121) Another study compared the effects genistein, apigenin, luteolin, chrysin and other flavonoids on human thyroid carcinoma cell lines. Among the flavonoids tested, apigenin and luteolin were shown to be the most potent inhibitors of these cancer cell lines. The scientists noted that because these thyroid cancer cells lacked an anti-estrogen receptor binding site and an estrogen receptor, that apigenin and luteolin are inhibiting these cancer cells via previously unknown mechanisms. The scientists concluded that apigenin and luteolin may represent a new class of therapeutic agents in the management of thyroid cancer.(122)