Study of the effect of dryness and storage on Ceratonia siliqua L. stem extracts and evaluation of their insecticidal activity

Vector-borne diseases continue to transmit many dangerous pathogens to humans. After decades of continuous use of insecticides, many types of vectors have shown the ability to build resistance to them. This has necessitated the development of more efficient and environmentally friendly alternatives in the form of bioinsecticides. Plants contain a wide range of phytochemicals with specific targeting, rapid biodegradability, environmental sustainability and a variety of medicinal properties, making them a valuable source of biologicals. Moreover, this has led to the development of highly effective new drugs. This study aimed to identify the active ingredients in Ceratonia siliqua L., gathered from two consecutive fruiting seasons which were then divided into C. siliqua fresh (CSF), dry (CSd), and old (stored) stem (CSO) extracts Ceratonia siliqua. Metabolomics profiling was performed using UPLC/MS and multivariate data analysis. The UPLC/MS study resulted in the tentative identification of 54 secondary metabolites. These compounds included flavonoids, phenolic acids, withanolides, terpenoids, phenylpropanoids, etc. CSd showed the highest number of identified components followed by CSO and CSF. The % identification was nearly equal in the negative ion mode for the three extracts while for the positive ion mode it followed the order of CSF > CSd > CSO. After several exposure periods, the plant methanol extracts in this research showed significant insecticidal activity against mosquito larvae, Cx. pipiens, and housefly larvae M. domestica. (CSd) demonstrated the highest insecticidal activity (100 MO%) against Cx. pipiens (LC₅₀ = 0.09 and 0.07 mg/ml) following 24- and 48-hour post-treatments at 1.0 mg/ml. The (CSF) was the most effective on M. domestica larvae (LC₅₀ = 2.32 and 1.80 mg/ml), 24 and 48 h post-treatment with 25 mg/ml concentration. Both CSd and CSF extracts were the most effective at killing mosquito and house fly larvae, followed by the CSO extract. Therefore, C. siliqua extracts may serve as an effective bio-agent for specific vector-borne infection control.