Effect of Syzygium aromaticum extract on immediate hypersensitivity in rats.
J Ethnopharmacol. 1998 Mar;60(2):125-31. PMID: 9582002
We investigated the effect of aqueous extract of Syzygium aromaticum (L.) Merr. et Perry (Myrtaceae) flower bud (SAFB) on immediate hypersensitivity. SAFB inhibited compound 48/80-induced systemic anaphylaxis in rats (IC50 = 31.25 mg/kg, i.p.). SAFB also inhibited local immunoglobulin E (IgE)-mediated passive cutaneous anaphylactic reaction (IC50 = 17.78 mg/kg, i.v.; IC50 = 19.81 mg/kg, p.o.). When SAFB was pretreated at concentrations ranging from 25 to 1000 mg/kg, the serum histamine levels were reduced in a dose-dependent manner. Moreover, SAFB dose-dependently inhibited histamine release from rat peritoneal mast cells (RPMC) by compound 48/80 or anti-dinitrophenyl IgE. When SAFB was added, the level of cAMP in RPMC transiently and significantly increased about 47-fold at 10 s compared with that of basal cells. These results indicate that SAFB inhibits immediate hypersensitivity by inhibition of histamine release from mast cells in vivo and in vitro.