Possible involvement of protein kinase c inhibition in the reduction of phorbol ester-induced neutrophil aggregation by magnolol in the rat.
The influence of the plant product magnolol on neutrophil aggregation has been investigated in the rat. Magnolol inhibited phorbol 12-myristate 13-acetate (PMA)-activated rat neutrophil aggregation in a concentration-dependent manner with an IC50 (concentration resulting in 50% inhibition) of 24.2 +/- 1.7 microM. Magnolol suppressed the enzyme activity of neutrophil cytosolic and rat brain protein kinase C (PKC) over the same range of concentrations at which it inhibited the aggregation. Magnolol did not affect PMA-induced cytosolic PKC-alpha and -delta membrane translocation or trypsin-treated rat-brain PKC activity, but attenuated [3H]phorbol 12,13-dibutyrate binding to neutrophil cytosolic PKC. These results suggest that the inhibition of PMA-induced rat neutrophil aggregation by magnolol is probably attributable, at least in part, to the direct suppression of PKC activity through blockade of the regulatory region of PKC.
Wang
J P
JP
Department of Medical Research, Taichung Veterans General Hospital, Republic of China.
Lin
P L
PL
Hsu
M F
MF
Chen
C C
CC
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001713:Biphenyl Compounds / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D066298:In Vitro Techniques; D017705:Lignans; D009504:Neutrophils / Q000187:drug effects* / Q000502:physiology; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014316:Tritium; D014357:Trypsin / Q000378:metabolism
D001713:Biphenyl Compounds; D004791:Enzyme Inhibitors; D017705:Lignans; D010975:Platelet Aggregation Inhibitors; C005498:magnolol; D014316:Tritium; D011493:Protein Kinase C; D014357:Trypsin; D013755:Tetradecanoylphorbol Acetate