Clin Chim Acta. 2002 Dec; 326(1-2): 169-75.

Effect of five flavonoid compounds isolated from leaves of Diospyros kaki on stimulus-induced superoxide generation and tyrosyl phosphorylation of proteins in human neutrophils.

Chen G, Lu H, Wang C, Yamashita K, Manabe M, Meng Z, Xu S, Kodama H.

Department of Phytochemistry, Shenyang Pharmaceutical University, No. 103, Wenhua Road, Shenyang 110015, China.

BACKGROUND: The crude drug "kaki-yÃ´" is a traditional medicine used in Japan as a hypotensive drug. METHODS: The effect of five flavonoid compounds isolated from the leaves of Diospyros kaki was investigated on the stimulus-induced superoxide generation and phosphorylation of tyrosine residues of protein in human neutrophils. The five compounds examined were kaempferol 3-O-beta-D-galactopyranoside (TR), kaempferol 3-O-beta-D-glucopyranoside (AS), isorhamnetin 3-O-beta-D-glucopyranoside (IS), quercetin 3-O-beta-D-galactopyranoside (HY), quercetin 3-O-beta-D-glucopyranosyl-(6-->1)-alpha-L-rhamnopyranoside (RU). RESULTS: When the cells were preincubated with these five compounds, the superoxide generation induced by N-formyl-methionyl-leucyl-phenylalanine (fMLP) was significantly suppressed in a concentration-dependent manner. The arachidonic acid (AA)-induced superoxide generation was suppressed by TR, AS, HY and RU. On the other hand, the superoxide generation was weakly enhanced by IS in low concentration (5-20 micromol/l), but was suppressed in high concentration (50 micromol/l). The superoxide generation induced by phorbol 12-myristate 13-acetate (PMA) suppressed the TR, IS, HY and RU, but AS gave no effect. When the cells were incubated with fMLP in the presence of TR, IS and RU, fMLP-induced tyrosyl phosphorylation of 45-kDa proteins of the cells was dose-dependently suppressed in parallel to the suppression of fMLP-induced superoxide generation. These five flavonoids showed almost no hemolytic effect even at a concentration of 500 micromol/l. CONCLUSION: Flavonoid compounds suppressed stimulus-induced superoxide generation and tyrosyl phosphorylation and may have pharmaceutical application.