Abstract
Himatanthus drasticus (Mart.) Plumel belongs to the Apocynaceae family and the latex from its trunk bark (Hd) is known as "janaguba milk". This latex is widely used in Northeast Brazil, mainly in the Cariri region, for its gastroprotective, anti-inflammatory, and antitumor properties. The objective of this study was to investigate a triterpene-rich fraction (FJNB) from H. drasticus latex on acute models of nociception and inflammation and to clarify its mechanisms of action. Wistar rats or Swiss mice were subjected to the carrageenan-induced paw edema test or the formalin test, respectively, after the acute oral treatment with FJNB. The inflamed paws from the carrageenan-induced paw edema and formalin tests were processed for histological and immunohistochemical assays, respectively. The results were analyzed by ANOVA and considered significant at P<0.05. FJNB (10 mg/kg) decreased the paw edema by 25% at the 3rd h after the carrageenan injection. Indomethacin, used as reference, inhibited the paw edema by 59% at the same time-point. In the formalin test, FJNB inhibited the 1st phase by 27, 49, and 52% and the 2nd phase by 37, 50, and 67%, at the doses of 1, 5, and 10 mg/kg, respectively. In addition, FJNB significantly inhibited the expressions of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and the inflammatory cytokine tumor necrosis factor (TNF)-alpha. The histone deacetylase (HDAC) expression and the transcription factor nuclear factor kappa (NF-kB) were also inhibited at the same doses. In conclusion, the FJNB inhibitory actions on iNOS, COX-2, TNF-α, HDAC, and NF-kB could be involved with the drug anti-inflammatory activity.