Extratos de Tephrosia toxicaria (Sw.) Pers.: prospecção de atividades Anti-Aedes, antioxidante, antimicrobiana e leishmanicida, e biossegurança

Abstract

Tephrosia toxicaria (Sw.) Pers. is a legume occurring in the Northeast Brazil that has attracted the attention of researchers because it serves as a matrix to obtain numerous adjuvant formulations for integrated management strategies of vectors and diseases, such as plant extracts, due to its selective toxicity and environmental compatibility. The search for new natural adjuvant formulations for the management of diseases, vectors and pathogens shows that plant extracts are still promising, especially considering the great Brazilian biodiversity, they are obtained from renewable sources, their toxic selectivity to target organisms and environmental compatibility. The development of the present research was stimulated by the possibility of expanding the repertoire of options for natural adjuvants, which aimed to investigate the bioactive potential and biosecurity of aqueous and hydroethanolic extracts from seeds, roots, stems and leaves of T. toxicaria. The first chapter of this thesis deals with a bibliographic review of the current state of art on the use of botanical insecticides in the integrated management of arbovirus vectors, with emphasis on species belonging to the genera Aedes, Culex and Anopheles. The second chapter describes the versatility of T. toxicaria extracts in the Aedes control, highlighting the hydroethanolic root extract (RHA) as the most promising larvicidal extract, demonstrating the lowest lethal concentration for 50% (300 µg/mL) and 90% (840 µg/mL) of Aedes larvae, observed at 24 h post-exposure. In field tests, RHA (840 µg/mL) is a promising oviposition deterrent agent, reducing Aedes egg laying by approximately 90%. In addition to manifesting insecticidal properties, RHA manifests antioxidant activity, mainly in control of metal ion homeostasis and restoration of the metabolic activity of cells under oxidative stress conditions, under low concentrations (100 µg/mL). Although leishmanicidal molecules are also expressed in RHA, its solubilization was less pronounced, requiring a higher concentration of extract to inhibit the growth of Leishmania amazonensis promastigotes (IC50 = 3.53 mg/mL). In the concentration range of 1024 – 32 μg/mL, RHA was not able to inhibit the growth of the bacterial and fungal strains investigated. RHA concentrates carbohydrates, phenolic compounds and proteins, with estimated molecular masses between 10 and 24 kDa. Protein analyzes suggest the expression of protease inhibitors and lectins in RHA. In the concentration range of 300 – 1 μg/mL, RHA does not compromise the initial development and biomass of Lactuca sativa; and in the concentration range of 1000 – 1 μg/mL, RHA does not compromise the metabolic activity of HepG2 (CC50 = 2.68 mg/mL) and 3T3 (CC50 = 5.07 mg/mL). The promising bioinsecticidal and antioxidant effects, associated with the absence of toxicity events against non-target organisms and cell lines, suggest T. toxicaria as a natural source to be sustainably exploited to obtain extracts with wide biological and pharmacological use.