Estudo fitoquímico e potencial como biodenfensor de Piper tuberculatum contra mosquitos vetores da dengue

Abstract

The mosquito Aedes aegypti is an important vector in the transmission of the dengue virus, responsible for causing serious health problems, especially in tropical and subtropical regions. It is crucial to adopt vector control and prevention measures to prevent the proliferation of these mosquitoes and minimize the transmission of these diseases. The use of plants for mosquito control is a promising alternative, especially in Amazonian areas, due to the high biodiversity and abundance of plant species with chemical compounds exhibiting larvicidal activity, such as Piper tuberculatum Jacq. Therefore, the aim of this study was to conduct phytochemical investigation and evaluate the larvicidal activity of extracts, fractions, and isolated compounds from P. tuberculatum leaves against A. aegypti. The crude extract from the leaves was obtained by exhaustive maceration in methanol with ultrasound assistance, followed by fractionation using a column filter. The chemical profile of the extract and its fractions was investigated using mass spectrometry. The 100% ethyl acetate fraction (EMFPT-3) underwent purification by semi-preparative HPLC, resulting in the isolation of cis-piplartine, piplartine, and 4,5-dihydropiperlonguminine amides, whose structures were determined by spectroscopic and spectrometric methods (1D and 2D NMR; MS). The methanolic extract and fractions from the column filter were tested for larvicidal activity against A. aegypti following the World Health Organization (WHO, 2005) protocol, with some modifications. The Hex/EtOAc 1:1 (EMFPT-2), 100% EtOAc (EMFPT-3), and EtOAc/MeOH 1:1 (EMFPT-4) fractions exhibited larvicidal activity with mortality rates between 92% and 100% against A. aegypti after 24 hours of exposure, demonstrating to be a viable alternative for vector control. Meanwhile, the isolated amides cis-piplartine, piplartine, and 4,5-dihydropiperlonguminine showed larvicidal activity against A. aegypti, causing mortality ranging from 2 ± 0 to 97 ± 2% and LC50 values of 23.77 and 30.18 μg/mL. Therefore, the results reinforce the larvicidal potential previously reported for P. tuberculatum and other species of the genus, as well as demonstrating the potential of amides as promising chemical agents for the control of tropical diseases such as dengue.