Isolation and identification of the active constituent β-isocostic acid from the hexane extract of the leaves of Sphaeranthus indicus against mosquito vectors

• Published in: Toxicon (Oxford) 2025-01, Vol.253, p.108200, Article 108200
• Main Authors: Yagoo, Alex, Milton, M.C. John, Vilvest, Jelin, Arokia Ahino Jessie, A., Shirota, Osamu, Balakrishna, Kedike
• Format: Article
• Language: English
• Subjects: Aedes - drug effects; Animals; Asteraceae - chemistry; Culex - drug effects; Hexanes; Insecticides - pharmacology; Larva - drug effects; Mosquito Vectors - drug effects; Mosquitocidal agents; Natural insecticides; Plant Extracts - chemistry; Plant Extracts - pharmacology; Plant Leaves - chemistry; Pupa - drug effects; Sphaeranthus indicus; Vector control; β-isocostic acid
• ISSN: 0041-0101; 1879-3150; 1879-3150
• DOI: 10.1016/j.toxicon.2024.108200

Mosquitoes, as hematophagous ectoparasites, are significant pests and vectors of numerous pathogens, causing diseases such as dengue, lymphatic filariasis, malaria, chikungunya, and Japanese encephalitis in India. This study investigates the potential of natural insecticides derived from plants to combat mosquito populations, focusing on botanical extract from the leave of Sphaeranthus indicus. Specifically, the hexane extract of S. indicus exhibited notable efficacy against Aedes aegypti and Culex quinquefasciatus mosquitoes. The research entailed the extraction, fractionation, and structural identification of active compounds through spectroscopic analysis. Among ten fractions isolated, fraction 4 demonstrated the highest mosquitocidal activity, leading to the identification of β-isocostic acid as the primary active compound. The study's biological assays included ovicidal, larvicidal, and pupicidal tests, revealing that β-isocostic acid exhibited significant efficacy, with ovicidal activity rates of 75.2% and 78.2% at 2 ppm against Ae. aegypti and Cx. quinquefasciatus, respectively. Larvicidal and pupicidal assays further confirmed the potent activity of β-isocostic acid, with LC50 values of 1.02 ppm and 0.96 ppm against Ae. aegypti and Cx. quinquefasciatus larvae, and 1.20 ppm and 1.14 ppm against Ae. aegypti and Cx. quinquefasciatus pupae respectively. The isolated compound demonstrated comparable efficacy to azadirachtin and temephos, indicating its potential as a natural mosquitocidal agent. This research underscores the importance of exploring botanical sources for developing effective and environmentally sustainable mosquito control strategies, particularly in light of increasing resistance to synthetic insecticides. The findings suggest that β-isocostic acid could serve as a viable alternative to chemical mosquitocides, contributing to integrated vector management programs. [Display omitted] •First report on larvicidal, pupicidal, and ovicidal effects of β-isocostic acid.•β-isocostic acid was isolated from the leaves of Spharanthus indicus.•Characterized using IR, NMR, and GC-MS techniques.•The compound exhibited promising ovicidal, larvicidal and pupicidal efficacy.•Supports natural products as promising alternatives to synthetic insecticides.