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Published on: February 13, 2019
Synthesis, Structure-Activity Considerations and Histopathological Effects of Diborane Derivatives as Mosquito
Yüksel Şahin1, Fatma Bursali2, Yücel Basimoglu Koca2
1Department of Chemistry, Faculty of Sciences, Aydın Adnan Menderes University, 09010, Aydın, Turkey. ysahin@adu.edu.tr.
Background:
Boron-based compounds are attracting increasing interest due to their antimicrobial, cytotoxic, and bioactive properties. However, the insecticidal potential and mechanism of action of 1,2-diborane derivatives have not yet been investigated. This study investigated the effects of these compounds on the larvae of Aedes aegypti, Aedes albopictus, and Culex pipiens. A new 1,3,2-diazaborinane derivative (comp. 6) was synthesized and characterized.
Methods:
The effects of compound 6 and five previously synthesized diborane/diborolane derivatives were evaluated against the mosquito vectors Ae. aegypti, Ae. albopictus and Cx. pipiens.
Results:
All compounds exhibited significant larvicidal activity against late 3rd-4th instar larvae. Probit analysis revealed LC₅₀ values ranging from 16.712 to 30.087 μg/mL for Ae. aegypti, 17.417-32.636 μg/mL for Ae. albopictus, and 17.789-28.582 μg/mL for Cx. pipiens. Compounds 1 and 2 showed the highest larvicidal potency, whereas compounds 3, 4 and 6 were comparatively less active. Histopathological examination demonstrated that the primary target tissues were the gastric caeca and midgut epithelium. Compared with untreated controls, exposed larvae exhibited epithelial disruption, cytoplasmic vacuolization, cellular swelling, degeneration of microvilli, and damage to the peritrophic membrane. The severity of tissue injury differed among species, with severe alterations observed in Ae. aegypti, moderate alterations in Cx. pipiens, and relatively mild changes in Ae. albopictus.
Conclusion:
The findings demonstrate that diborane derivatives, particularly those bearing specific substituents on boron atoms, exhibit significant biological activity against mosquito larvae, with their toxic effects primarily targeting the larval digestive system. The findings demonstrate larvicidal activity of selected diborane derivatives and support further investigation of these compounds as potential mosquito larvicidal candidates. However, studies on selectivity toward non-target organisms and mechanisms of action under laboratory and field-relevant conditions are required.
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01:26Physical Properties of Amines
02:36Regioselectivity and Stereochemistry of Hydroboration
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.