Efeito dos terpenos ácidos centipédico e lactona do ácido hawtriwaico em modelos de dermatite de contato induzida por TPA e oxazolona em camundongos

Abstract

The terpens centipedic acid (CA) and lactone of hawtriwaic acid (LAH) isolated from the flowers chapters of Egletes viscosa Less, popularly known as macela or macela da terra, were evaluated on 13-acetate-12-o-tetradecanoil-forbol (TPA) induced irritative contact dermatitis model and on oxazolone induced allergic contact dermatitis in mice. The centipedic acid and LAH on the following dosage of 0,125; 0,25 and 0,5 mg/ear using the skin surface as a via reduced in a significative way the ear oedema induced by application of TPA (2,5 μg/ear). The values of reduction are the following respectively: 45,5; 55,1; 61,1% and 33,3; 42,2 and 63,3%. When the oral administration was used the doses of 12,5; 25 and 50 mg/kg had showed a significative oedema reduction of 46,6; 59,3; 67,9% and 58,7; 59,7; 71%, respectively. Dexametasone through skin surface administration on dosage of 0,05 mg/ear and oral dosage of 1mg/kg have reduced in a significative way the ear oedema in 90 and 73,1%, respectively. The centipedic acid and LAH using the dosage of 0,05 mg/ear through the skin surface had reduced the mieloperoxydase activity in 90,1 and 94,6%, respectively, while dexametasone (0,05 mg/ear) had reduced in 96,2% when compared to the group treated only with the vehicle. The terpens on the topic dosage of 0,05 mg/ear were capable to reduce the tecidual levels of TNF-α as well as dexametasone. The antiinflamatory action of the terpens on TPA induced dermatitis model was confirmed through histological analysis of the tissue. The oxazolone induced contact dermatitis model (OXA 1%/ear) had promoted an epidermic hyperplasia in which INF-γ have a central role. The products under evaluation centipedic acid (0,25 and 0,5 mg/ear) and LAH (0,5 mg/ear) through skin surface reduced in a significative way the epidermic hyperplasia Throughout the observation period (4°- 19° day). Centipedic acid and LAH on the following dosage 0,5/mg reduced in a significative way the tecidual levels of INF-γ (92,2 and 99,4%, respectively) after 19 days of treatment. When using oral administration the centipedic acid (12,5; 25 e 50 mg/kg) reduced the epidermic hyperplasia from seventh through tenth ninth day. Dexametasone through skin surface administration on dosage of 0,05 mg/ear and oral dosage of 1mg/kg have reduced the epidermic hyperplasia in 100 and 75%, respectively The data that were found plus the histological analysis have showed the antiinflammatory effect, mainly through topic administration, of these terpens on allergic contact dermatitis models in which epidermic hyperplasia and increased tecidual levels of INF-γ are important features, such as psoriasis.