Efeito analgésico e anti-inflamatório do extrato aquoso das folhas de trevo-roxo (Scutellaria agrestis A. St. -Hil. ex Benth. - Lamiaceae) em roedores / Analgesic and anti-inflammatory effect of the aqueous extract of "trevo-roxo" (Scutellaria agrestis A. St. -Hil. ex Benth. - Lamiaceae) leaves in rodents

Scutellaria agrestis é utilizada por comunidades ribeirinhas do Amazonas principalmente para o tratamento de otites por via tópica utilizando-se o extrato bruto obtido por maceração. O presente trabalho visou investigar preliminarmente o perfil fitoquímico, a segurança toxicológica e as ações analgésica, anti-inflamatória e antiedematogência do extrato aquoso das folhas de S. agrestis. Foram coletados 80 indivíduos da espécie no horto medicinal da Universidade Nilton Lins, Manaus, Brasil. O perfil fitoquímico foi obtido por meio de prospecção da droga vegetal para heterosídeos cianogênicos, terpenos, compostos fenólicos e alcaloides. A toxicologia foi avaliada pelo teste de toxicidade aguda. As atividades analgésicas/ anti-inflamatórias foram analisadas por meio dos testes de formalina em camundongos e a atividade antiedematogência, pelo teste de edema de pata em ratos. Os metabólitos detectados foram fenóis (taninos hidrolisáveis, cumarinas e várias classes de flavonoides) e terpenos (esteroides livres, saponinas). Não foi possível estabelecer DL50, haja visto que o extrato não provocou a morte de nenhum animal durante o teste de toxicidade aguda, provavelmente devido à ausência de heterosídeos cianogênicos na sua composição. Apesar de não provocar morte, considerou-se que o extrato apresenta uma discreta toxicidade, uma vez que foi observada a ocorrência de espasmos na primeira hora de observação dos animais. O extrato apresentou ainda efeito analgésico e anti-inflamatório significativo nas doses de 30, 100 e 300 mg/kg pelo teste da formalina, sendo o resultado na maior dose equivalente ao obtido com a droga padrão (fentanil). No entanto, não observamos efeito antiedematogênico nas doses testadas durante as 5 horas de registro do edema de pata. Os resultados obtidos nesta pesquisa conferem base científica preliminar quanto à segurança e ao efeito analgésico e antiinflamatório da droga vegetal, o que indica que tal espécie é promissora e expressamente recomendada para maiores estudos farmacológicos in vitro e in vivo.

The Scutellaria agrestis is used by Amazonas riverine communities, especially for otitis externa topical treatment, by using the crude extract obtained by maceration. This study aimed to investigate the preliminary phytochemical profile, the safety/toxicity and the analgesic, anti-inflammatory and antiedematogenic activities of the aqueous extract of the S. agrestis leaves. Eighty individuals were collected at the Nilton Lins University medicinal garden, Manaus, Brazil. The phytochemical profile was obtained through a plant drug survey for cyanogenic heterosides, terpenes, alkaloids and phenolic compounds. The extract safety was evaluated by acute toxicity test. Analgesic and anti-inflammatory activities were accessed using formalin test in mice and the antiedematogenic activity, using paw edema test in mice. We detected phenolic (hydrolysable tannins, coumarins and several classes of flavonoids) and terpenoid (free steroids, saponins) metabolites. We could not establish LD50 because no animals died during the acute toxicity test, probably because of the absence of cyanogenic glycosides on the composition of the extract. However, we found that the extract is slightly toxic as animal spasms were observed in the first hour of the test. The extract showed significant analgesic and anti-inflammatory activity on the formalin test (30, 100 and 300 mg/kg p.o.), and the highest dose result was equivalent to the standard drug (Fentanyl). However, no significant antiedematogenic effect was observed during the paw edema test. The results obtained in this study provide preliminary scientific basis about the safety and analgesic/anti-inflammatory actions of the aqueous extract of S. agrestis, which indicates that this species is a promising option for further in vitro and in vivo pharmacological studies.

Anatomy of vegetative organs of Scutellaria agrestis, a medicinal plant cultivated by riverine populations of the Brazilian Amazon

Scutellaria agrestis A. St. -Hil. ex Benth. , Lamiaceae (trevo-roxo) is cultivated for medicinal purposes by residents of the riverine communities in the State of Amazonas, Brazil. This study aimed to characterize the anatomy and to make histochemical analysis on vegetative organs of S. agrestis. Samples of the leaf, stem and root were collected from five plants cultivated by the communities located in the Solimões river, Amazon. These samples were fixed and prepared following standard techniques for scanning electron microscopy and for light microscopy. Histochemical tests were carried out on sections to detect the main classes of compounds present in the secretion. Numerous glandular trichomes are seen in both leaf and stem of S. agrestis. The leaves are amphi-hypostomatics and show dorsiventral mesophyll. Hydathodes are present at the tip of the marginal teeth. Anthocyanin pigments occur into the epidermal cells of the stem, petiole, and abaxial leaf surface. The petiole is concave-convex shaped and bears collateral vascular bundles. The stem showed square-shaped, evident endoderm, collateral vascular bundles and parenchymatous pith. The root displays a typical protostelic structure. Idioblasts containing mucilage and phenolic compounds occur in the cortex. These data are important, as they can be useful to identify this species, contributing to the quality control of the medicinal plant.