Effects of saline extract and lectin from Punica granatum seed sarcotesta on Aedes aegypti larvae

Abstract

• Salin extract contained lectin, ellagic acid, α and β punicalagins, ellagic acid derivatives, and cinnamic acid derivatives. • The extract was able to induce mortality in A. aegypti larvae. • The lectin PgTeL did not show larvicidal activity. • The extract altered midgut morphology and inhibited amylase and trypsin activity in the larval gut. Currently, one of the main strategies to reduce the incidence of the arboviruses such as Zika, dengue, and chikungunya is through the population control of their vector, Aedes aegypti . Lectins are carbohydrate-binding proteins with several biological properties, including insecticidal activity against A. aegypti. Punica granatum sarcotesta contains a chitin-binding lectin (PgTeL), which prompted our evaluation of its toxicity against A. aegypti . Here, we analyzed the effects of saline extract from P. granatum sarcotesta and PgTeL on the survival of A. aegypti larvae. Saline extract of P. granatum was evaluated for the presence of secondary metabolites; PgTeL was further isolated and purified from this extract. Larvicidal assay was performed using P. granatum saline extract (0.17–1.20 mg/mL of protein) and isolated PgTeL (0.1–1.0 mg/mL). Histological analysis was performed to evaluate the effects of the extract on the larvae midgut morphophysiology. Additionally, the activity of digestive enzymes in midgut extracts of the larvae was determined. P. granatum extract, containing protein (17.1 mg/mL), ellagic acid (2.1 mg/mL), α-punicalagin (2.2 mg/mL), β-punicalagin (2.3 mg/mL), ellagic acid derivatives (2.2 mg/mL), and cinnamic acid derivatives (3.9 mg/mL), caused larvae mortality (LC 50/48 h : 0.67 mg/mL of protein) and altered the midgut morphology; midgut cells were affected, showing protrusions in the apical region and a thickening of the peritrophic matrix. P. granatum extract inhibited amylase and trypsin activities in the larval gut. However, PgTeL did not display larvicidal activity. In conclusion, the sarcotesta saline extract from pomegranate shows larvicidal activity against A. aegypti, and the mode of action may involve disruption of the digestive processes of the larvae. These findings may represent a first step towards the availability of a new tool to control A. aegypti .