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


CONCLUSIONS
Flavonoid compounds suppressed stimulus-induced superoxide generation and tyrosyl phosphorylation and may have pharmaceutical application.
Chen
Guang
G
Department of Phytochemistry, Shenyang Pharmaceutical University, No. 103, Wenhua Road, Shenyang 110015, China.
Lu
Huangwei
H
Wang
Chunlei
C
Yamashita
Koichi
K
Manabe
Masanobu
M
Meng
Zhiyun
Z
Xu
Suixu
S
Kodama
Hiroyuki
H
D000959:Antihypertensive Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D001798:Blood Proteins / Q000378:metabolism*; D029788:Diospyros / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D008970:Molecular Weight; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D018515:Plant Leaves / Q000737:chemistry; D028321:Plant Preparations / Q000737:chemistry*; D010946:Plants, Medicinal / Q000737:chemistry; D013481:Superoxides / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000031:analogs & derivatives / Q000494:pharmacology; D014443:Tyrosine / Q000378:metabolism*
D000959:Antihypertensive Agents; D001798:Blood Proteins; D005419:Flavonoids; D028321:Plant Preparations; D013481:Superoxides; D014443:Tyrosine; C016658:phorbolol myristate acetate; D009240:N-Formylmethionine Leucyl-Phenylalanine; D013755:Tetradecanoylphorbol Acetate