The Effect of<i>Schinus terebinthifolius</i>Raddi (Anacardiaceae) Bark Extract on Histamine‐Induced Paw Edema and Ileum Smooth Muscle Contraction

Abstract

<i>Schinus terebinthifolius</i> Raddi (Anacardiaceae), popularly known as red aroeira, is used in traditional medicine to treat inflammatory, gastric, and respiratory disorders. The aim of this study was to evaluate the antihistaminic activity of <i>S. terebinthifolius (St)</i> bark extract by using in vivo and in vitro experimental models. The effects of <i>St</i> were investigated on contractions induced by histamine, carbachol, and potassium chloride in isolated guinea pig ileum. <i>St</i> was also studied in response to hind paw edema induced by histamine in rats. Experiments revealed that although <i>St</i> (250, 500, and 1,000 <i>µ</i>g/mL) reduced the histamine-induced contractions by 9.1 ± 1.8, 50.2 ± 2.0, and 68.9 ± 2.0%, respectively, it did not inhibit contractions induced by carbachol or KCl. The association of <i>St</i> (250 and 500 <i>µ</i>g/mL) with hydroxyzine, an H₁-antihistamine (0.125 and 0.250 <i>µ</i>M), increased the inhibitory effect to 67.0 ± 3.2 and 85.1 ± 2.1%, respectively. Moreover, <i>St</i> (100, 200, and 400 mg/kg) decreased paw edema from its peak by 33.9, 48.4, and 54.8%, respectively, whereas hydroxyzine (70 mg/kg) inhibited the peak edema by 56.5%. Altogether, the results suggest that the bark extract of <i>S. terebinthifolius</i> has an antihistaminic effect (H₁).