Sementes de Lonchocarpus sericeus (Poir) Kunth ex Dc como repositório de inibidores de proteases: purificação e seus efeitos sobre o ciclo de vida do mosquito Aedes aegypti

Abstract

Arboviroses such as chikungunya, dengue and zika represent a serious issue in public health due to the absence of an approved vaccine or specific antiviral drugs for its prevention and treatment. One of the ways to avoid the occurrence of these diseases is by combating the mosquito vector, Aedes aegypti. This insect belongs to Diptera order, which commonly has digestive enzymes similar to trypsin and chymotrypsin. Protease inhibitors are molecules that can block enzymatic activity leading to an impairment of digestion and nutrition. Together, these factors can lead the insects to death. In this context, we purified a new protease inhibitor from seeds of an underexploited plant, Lonchocarpus sericeus. This inhibitor was subjected to a biochemical characterization, evaluated for the inbitory activity upon the digestive proteases from Aedes aegypti larvae and its insecticidal effect upon egg hatchability and larvae development. The purified inhibitor (LsCTI) showed a single protein band on SDS-PAGE, the molecular mass determined by MALDI-TOF-MS was 8,870.45 Da. LsCTI was able to inhibit more than one serine protease. Kinetics analyzes revealed the type of noncompetitive inhibition and a low Ki for chymotrypsin (8.24 x 10-8 M). The stability of the inhibitory activity was remarkable for the thermal resistance, LsCTI supported heating at 100 ° C for 180 min without losing its activity. The IC50 value of LsCTI was 4.7 x 10-7 M. for Ae. aegypti midgut enzymes. LsCTI did not affect egg hatchability when tested at 0.3 mg.mL-1, but caused a high larval mortality rate (77%) and developmental delay (37%). Thus, LsCTI is a novel protease inhibitor with remarkable biochemical characteristics and a novel potential tool to control the Ae. Aegypti development.