Inhibition of histamine-induced bronchospasm in guinea pigs treated with Cecropia glaziovi Sneth and correlation with the in vitro activity in tracheal muscles.
A standardized aqueous extract (AE) and a purified fraction (BuF) of Cecropia glaziovi Sneth leaves were tested in unrestrained guinea pigs challenged with histamine. Changes of the respiratory pressure and rate were recorded in a whole body plethysmograph before and after treatment. The concentration of histamine necessary to produce bronchospasm was increased by five-fold following administration of AE (1.0 g/kg p.o.), and by two-fold after treatment with the semi-purified procyanidin/flavonoids enriched BuF (0.1 g/kg p.o.). Both effects were blocked by previous treatment with propranolol (10.0 mg/kg i.p.). In vitro incubation of BuF (0.1-1.0 mg/ml) decreased by 13-55% the maximal response of guinea pig tracheal muscle to histamine, without significant change of EC50. The results confirmed old reports on the useful pulmonary effects of Cecropia extracts. The bronchodilation observed in vivo seems to be related to beta-adrenergic activity observed in vitro only with high concentrations of the purified extract.
Delarcina
S
S
Natural Products Section, Department of Pharmacology, UNIFESP/Escola Paulista de Medicina, 04044-020, São Paulo, SP, Brazil.
Lima-Landman
M T R
MT
Souccar
C
C
Cysneiros
R M
RM
Tanae
M M
MM
Lapa
A J
AJ
D000284:Administration, Oral; D000818:Animals; D001986:Bronchial Spasm / Q000139:chemically induced / Q000517:prevention & control*; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D006632:Histamine; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D008517:Phytotherapy; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D018515:Plant Leaves; D014132:Trachea / Q000187:drug effects*; D027003:Urticaceae
D001993:Bronchodilator Agents; D010936:Plant Extracts; D006632:Histamine