Efficacy of Hot Capsicum annuum Extracts Against the Biological Activity of Culex pipiens and Musca domestica Larvae with their Phytochemical Profiles.

Abstract

Purpose: The extensive use of chemical pesticides poses risks to the environment and human health due to the toxicity and poor biodegradability. Alternative natural practices, including the use of natural molecules, are needed to achieve more sustainable production methods to meet consumer and societal expectations. Plants contain a wide range of potential phytochemicals that target a specific target, are rapidly biodegradable, are environmentally friendly, and have a variety of therapeutic effects, making them a treasure trove of biological materials.

Methods: Toxicity of hot Capsicum annuum extracts was tested against 3^rd instar larvae of Culex pipiens and Musca domestica. LC₅₀ values were determined using serial concentrations, and phytochemical profiling was performed to identify active compounds with molecular docking studies.

Results: In this study, different exposure periods of various Capsicum annuum extracts showed high insecticidal activity against mosquito and housefly larvae. The petroleum ether (CAPe) extract from C. annuum was the most effective (100 MO%) against Culex pipiens (LC₅₀ = 150.46 ppm) and Musca domestica larvae (LC₅₀ = 0.18 mg/ml) 24 h after treatment. The LC₅₀ dose of the CAPe extract led to a negative effect on the insect metabolism process represented by a significant decrease in the activity level of protease, lipase, α-amylase, and invertase enzymes in both mosquito and fly larvae. Antimicrobial activity tests showed that the CAPe extract killed all of the microbes that were tested, except for Penicillium glabrum. The UPLC/MS comparison of the four Capsicum extracts led to the possible identification of eighty metabolites. The large amounts of flavonoids, phenolic acids, and capsaicinoids were in line with what has been written about the genus Capsicum. Moreover, the multivariate data analysis showed that capsaicinoids, sophorolipids, triterpenoids, and phenolic acids were abundant in the methanol extract compared to flavonoids, triterpenoids, and fatty acids for the petroleum ether extract. Simultaneously, the docking results showed that all of the docked compounds could fit into the digestive lysosome active site of M. domestica (2H5Z).

Conclusions: The major compounds in petroleum ether extract were able to interact with essential amino acids at the target sites of both Cx. pipiens and M. domestica, and therefore the insects' life-supporting functions were negatively affected. Overall, CAPe extract from Capsicum annuum could be a promising ecofriendly bioinsecticide.