Estudos morfoanatômico, fitoquímico e de atividades biológicas de folha e caule de Eugenia Pyriformis Cambess., Myrtaceae.

Abstract

Resumo: A especie Eugenia pyriformis Cambess., conhecida popularmente como uvaia, e uma Myrtaceae nativa do Brasil. Suas folhas sao utilizadas na medicina popular para o tratamento de gota, pois possui a propriedade de baixar os niveis de acido urico. Este trabalho teve como objetivo realizar estudos morfoanatomico, fitoquimico e de atividades biologicas de folha e caule da especie, acrescentando dados ao conhecimento dessa planta medicinal e potencial droga vegetal. O material vegetal foi coletado, identificado e devidamente preparado para as diferentes analises. Quanto a morfoanatomia, observou-se que a folha e simples, oposta e elipticolanceolada. Possui epiderme uniestratificada, estomatos anomociticos restritos a face abaxial, tricomas tectores unicelulares, mesofilo dorsiventral e nervura central com seccao plano-convexa, com um feixe vascular bicolateral. No caule, o felogenio tem instalacao superficial e ha floema interno, fibras e celulas petreas. Compostos fenolicos, prismas e drusas de oxalato de calcio ocorrem nos orgaos vegetativos analisados. Na prospeccao fitoquimica, verificaram-se glicosideos flavonicos e esteroides e/ou triterpenoides no extrato hidroalcoolico de folha, enquanto que saponinas, taninos e acidos fixos foram detectados no extrato aquoso, tanto de folha como de caule. No oleo essencial, foram encontrados os monoterpenos oxigenados 1,8-cineol, linalol e terpinen-4-ol. Tres substancias foram identificadas e relatadas pela primeira vez na especie, o triterpeno ƒÀ-amirina e os derivados porfirinicos feofitina a e feofitina b. Com relacao a atividade antioxidante no ensaio com DPPH, constatou-se que a fracao de acetato de etila de folha possui atividade antioxidante maior em relacao as demais. Para o complexo fosfomolibdenio, o extrato etanolico bruto de folha e caule, e a fracao de acetato de etila de folha tem atividade antioxidante um pouco superior a da rutina. Com referencia a acao antimicrobiana, demonstrou-se que o extrato etanolico bruto de folha apresenta atividade contra Staphylococcus aureus e Escherichia coli, e as fracoes de acetato de etila e hidroalcoolica de folha apresentam efeito inibitorio frente a S. aureus e Enterococcus faecalis. Esses tres microrganismos sofreram inibicao de crescimento pelo extrato etanolico bruto de caule. O extrato acetonico bruto de folha e caule revelou atividade contra Pseudomonas aeruginosa e E. faecalis. No teste de toxicidade frente a Artemia salina, verificou-se que as fracoes cloroformica e de acetato de etila de folha e as fracoes hexanica, de acetato de etila e hidroalcoolica de caule apresentam citotoxicidade com DL50 inferiores a 1000 ƒÊg/mL. No teste alelopatico, as amostras nao mostraram influencia sobre a germinacao das sementes de Lactuca sativa, exceto a fracao hexanica de caule que inibiu o crescimento da radicula em proporcao maior. Os resultados obtidos contribuiram para acrescentar dados ao conhecimento botanico, fitoquimico e de atividades biologicas dessa especie medicinal.

Abstract: Eugenia pyriformis Cambess., known as uvaia in Portuguese, is a Myrtaceae species native to Brazil. Its leaves are used in folk medicine for the treatment of gout, due to the property of lowering the uric acid levels. This work has aimed to study the morpho-anatomy, phytochemistry and biological activities of the leaf and stem of E. pyriformis, adding datato knownlege to this medicinal plant and potential vegetal drug. The plant material was collected, identified and properly prepared for the different analyses. With respect to the morpho-anatomy, it was observed that the leaf is simple, opposite and elliptic-lanceolate. It has uniseriate epidermis, anomocytic stomata exclusively on the abaxial surface, unicellular non-glandular trichomes, dorsiventral mesophyll and plano-convex midrib with a bicollateral vascular bundle. In the stem, the phellogen is installed superficially and it is found internal phloem, fibres and stone cells. Phenolic compounds, prisms and druses of calcium oxalate are present in the vegetative parts examined. In the phytochemical screening, it was found flavonoid glycosides and steroids and/or triterpenoids in the leaf hydroalcoholic extract, while saponins, tannins and fixed acids were detected in the leaf and stem aqueous extracts. In the essential oil, it was encountered the oxygenated monoterpenes 1,8-cineole, linalool and terpinen-4-ol. Three substances were identified and reported for the first time for the species, the triterpene £]-amyrin and the porphyrin derivatives pheophytin a and pheophytin b. Related to the antioxidant activity with DPPH essay, the ethyl acetate fraction of the leaf has presented higher antioxidant activity than the other samples. Regarding the phosphomolybdenum complex, the crude ethanol extract of the leaf and stem, and the ethyl acetate fraction of the leaf have shown a little higher effect than rutin. Considering the antimicrobial activity, the crude ethanol extract of the leaf inhibits Staphylococcus aureus and Escherichia coli, and the ethyl acetate and hydroalcoholic fractions of the leaf exhibit effect against S. aureus and Enterococcus faecalis. These three microorganisms have undertaken growth inhibition by the crude ethanol extract of the stem. The crude acetone extract of the leaf and stem has shown activity against Pseudomonas ay, it was observed that the chloroform and ethyl acetate fractions of the leaf and the hexane, ethyl acetate and hydroalcoholic fractions of the stem have cytotoxicity with LD50 less than 1000ƒÝg/mL. Considering the allelopathic test, the samples have not influenced the growth of the Lactuca sativa seeds, except for the hexane fraction of the stem which inhibits the root growth in higher proportion. The results of this work have contributed to expand the knowledge on the botanical, phytochemical and biological activities of this medicinal species.