Flavone acetic acid suppresses human peripheral blood lymphocyte and human colonic lamina propria lymphocyte DNA synthesis

Influence of OH group and sugar bonded to flavonoids on flavonoid-mediated suppression of tumor growth in vitro

Many flavonoids extracted from higher plants, synthesized or purified flavonoids, and their aglycones showed anti-tumor activity. Using purified or synthesized flavonoids, we studied the effect of the chemical structure of 2-benzoic flavone on the growth of human tumor cells (HCT-15 in vitro. The type of sugar combined with the A phenol of flavonoids played an important role in the tumor suppression; i.e., glucose attachment at the A phenol caused suppression of tumor cell growth, but other sugars such as rhamnose and lutinoside at that position did not suppress the growth of the cells. OH groups bonded to the B phenol also had a great effect on the growth. Flavonoids with OH groups conjugated to the 3', 4', and 5' of B phenol were stronger in anti-tumor effect than those with the OH groups attached at the 3' and 4' or 4' only, although anthocyanins were generally more effective than the other flavonoids.

Suppression of tumor cell growth by anthocyanins in vitro

Bioflavonoids, extracted from flower petals, were examined for their growth inhibitory effect on cells in culture. They were found to significantly suppress the growth of the cultured cells. Anthocyanins tended to show greater inhibitory effect than other flavonoids. Commercially synthesized or purified aglycones of flavonoids were also studied for their suppression of tumor cells. The anthocyanins were more effective than other flavonoid aglycones, although the aglycones were easily inactivated under the culture conditions.

Reversion of the transformed phenotypes of v-H-ras NIH3T3 cells by flavonoids through attenuating the content of phosphotyrosine

Fifteen flavonoids were employed to examine their effects on the morphological changes, foci formation in soft agar and cellular growth in v-H-ras-transformed NIH3T3 cells. The data presented here demonstrated that only three specific flavonoids--apigenin, kaempferol, and genistein--exhibited the reverting effect on the transformed phenotypes of ras-3T3 cells. For example, treatment with 25 microM of these flavonoids could effectively reverse the transformed morphology of ras-3T3 cells into flatter cells with contact inhibition. Colony formation in soft agar was decreased to 0.11%, 0.15%, and 0.35% by 25 microM apigenin, kaempferol, and genistein, respectively, as compared with control (0.92%). It was also found that the proliferation of ras-3T3 cells was significantly inhibited by these compounds in a dose-dependent manner. Finally, two biochemical parameters, the content of phosphotyrosine and cAMP, were examined to see whether affected by these compounds. The results showed the phosphotyrosine content in ras-3T3 cells was dramatically decreased by apigenin and kaempferol, but that was slightly reduced by genistein. By contrast, these three flavonoids all failed to significantly alter the level of cAMP within this transformant. Based on these observations, we suggest that some specific flavonoids are capable of reverting the transforming properties of v-H-ras transformed cells. The possible mechanism of this reversion is not mediated by activating the protein kinase A or its associated pathways, but rather inhibiting tyrosine kinases, subsequently leading to the blockage of p21ras-mediated signal transduction circuitry.

Inhibition of ornithine decarboxylase activity decreases polyamines and suppresses DNA synthesis in human colonic lamina propria lymphocytes

Ornithine decarboxylase (ODC) and the polyamines are essential for cell proliferation in a variety of cells including lymphocytes. In this study, we investigated the potential role of ODC and polyamines in human colonic lamina propria lymphocytes (LPL) compared to peripheral blood lymphocytes (PBL). Our results show that con A stimulation of LPL and PBL was associated with marked increases in ODC and polyamines. The specific inhibitor of ODC, alpha-difluoromethylornithine (DFMO), resulted in a complete inhibition of ODC activity and depletion of putrescine, spermidine and spermine levels. DFMO also suppressed DNA synthesis of LPL and PBL by up to 48% and 62% respectively. This antiproliferative effect was reversed by adding back the polyamines putrescine (1 mM), spermidine (10 microM) or spermine (10 microM) to the culture medium. We conclude that ODC and the polyamines are important for human LPL proliferation, and hence may play a role in human mucosal immune function.