Larvicidal activity of piperovatine and dichloromethane extract from Piper corcovadensis roots against mosquitoes Aedes aegypti L / Actividad larvicida de piperovatina y extracto de diclorometano de las raíces de Piper corcovadensis contra mosquitos vectores del dengue Aedes aegypti L

The research of new substances capable of controlling the Aedes aegypti mosquito is urgent due to the increase in the transmission of the diseases such as dengue, chikungunya and Zika virus by the vector. Thus, the aim of this study was to evaluate the larvicidal activity of crude extract of Piper corcovadensis roots, a native plant from Brazil, and of the isolated compound piperovatine against larvae of A. aegypti by the larval immersion test. The lethal concentration that killed 50% (LC50) and 99% (LC99) of larvae was determined by Probit analysis. The results indicated high larvicidal activity on A. aegypti larvae for crude extract of Piper corcovadensis roots with LC50 of 4.86 µg/mL and LC99 of 15.50 µg/mL and piperovatine with LC50 of 17.78 µg/mL and LC99 of 48.55 µg/mL. This work opens new perspectives to the development of future products with crude extract of Piper corcovadensis roots and piperovatine that can be applied to mosquito control.

La investigación de nuevas sustancias capaces de controlar el mosquito Aedes aegypti es urgente debido al aumento en la transmisión de enfermedades como el dengue, el chikungunya y el virus Zika por el vector. Por lo tanto, el objetivo de este estudio fue evaluar la actividad larvicida del extracto crudo de las raíces de Piper corcovadensis, una planta nativa de Brasil, y del compuesto aislado piperovatine contra larvas de A. aegypti mediante la prueba de inmersión larvaria. La concentración letal que mató al 50% (LC50) y al 99% (LC99) de larvas se determinó mediante análisis Probit. Los resultados indicaron una alta actividad larvicida en larvas de A. aegypti para extracto crudo de las raíces de Piper corcovadensis con LC50 de 4.86 µg/mL y LC99 de 15.50 µg/mL y piperovatine con LC50 de 17.78 µg/mL y LC99 de 48.55 µg/mL. Este trabajo abre nuevas perspectivas para el desarrollo de futuros productos con extracto crudo de las raíces de Piper corcovadensis y piperovatine que pueden aplicarse al control de mosquitos.

Contribuição ao estudo farmacognóstico da Piper ovatum Vahl / Contribution to the pharmacognostic study of Piper ovatum Vahl

RESUMO: O presente estudo descreve as características morfo-anatômicas dos órgãos vegetativos e do pó da Piper ovatum Vahl de modo que os dados obtidos possam ser utilizados como referência em análises de controle de qualidade de amostras de fármacos, a fim de verificar sua autenticidade. As raízes, caules, pecíolos e folhas foram fixadas, seccionadas à mão livre e coradas, as secções transversais e paradérmicas foram analisadas por microscopia óptica e a superfície do limbo foi observada, também, por microscopia eletrônica de varredura (MEV). Os órgãos vegetativos da P. ovatum apresentam morfologia e anatomia similar às outras espécies de Piper. No entanto, não foram observadas inclusões celulares nas folhas de P. ovatum. Análises por MEV mostraram a presença de tricomas glandulares constituídos de pedúnculo unicelular e porção secretora globóide igualmente unicelular recoberto por cutícula, na epiderme abaxial das folhas. Também foi observada a presença de uma cutícula espessa e que origina crostas no limite entre uma célula e outra, em ambas as superfícies foliares. No mesófilo foi observada a presença de idioblastos oleíferos característica marcante de outras espécies de Piperaceae. Além disso, na microscopia do pó foram observados hipoderme e idioblastos oleíferos em fragmentos do limbo, fragmentos de fibras esclerenquimáticas do caule, além de células esclerosas isoladas ou em grupos no pecíolo. O perfil cromatográfico do extrato hidroetanólico das folhas de P. ovatum foi obtido por cromatografia líquida de alta eficiência (CLAE). Nas análises por CLAE foram identificados como substâncias majoritárias do extrato as amidas piperovatina e piperlonguminina nos tempos de retenção de 10,25 e 10,81 min., respectivamente.

ABSTRACT: The present study describes the morphological and anatomical characteristics of vegetative organs and powder of the Piper ovatum Vahl, in order to use the obtained data as reference in the quality control tests of pharmaceutical samples, investigating their authenticity. The roots, stems, petioles and leaves were fixed, freehand sectioned and stained according to usual microtechniques. The transverse and paradermal sections were analyzed by optical microscopy and the leaf surface was also observed by scanning electron microscopy (SEM). The vegetative organs of the P. ovatum show morphology and anatomy similar to other species of Piper. However, cellular inclusions were not observed in the P. ovatum leaves. The SEM analysis showed the presence of glandular trichomes consisting of a unicellular stalk and globular secretory portion covered by cuticle on the abaxial surface of the leaves. The SEM also had shown one thick cuticle forming crusts in the limit of the epidermal cells, on both leaf surfaces. In the mesophyll, we observed oil idioblasts, which are typical features of other species of Piperaceae. Moreover, in the powder of the P. ovatum we observed hypodermis and oil idioblasts in leaf fragments, fragments of sclerenchyma fibers from the stem and isolated sclereids or in petiole groups. The chromatographic profile of the hydroethanolic extract of the P. ovatum leaves was obtained by high performance liquid chromatography (HPLC). In this analysis, we identified the amides piperovatine and piperlonguminine in the retention times of 10.25 and 10.81 min., respectively, as majority compounds present in the extract.