Volatile profile of Calicotome spinosa (L.) Link. revealed by SPME-GC-MS: Phytotoxic and insecticidal activities supported by in silico analysis

Abstract

In the search for eco-friendly alternatives to synthetic agrochemicals, the volatile organic compounds (VOCs) of Calicotome spinosa (L.) Link, a Mediterranean shrub valued for its medicinal and ecological significance, were investigated. Molecular identification using ITS sequencing showed high similarity to reference material (accession PX285687). The study aimed to characterize the plant’s volatiles through solid-phase microextraction coupled with gas chromatography–mass spectrometry (SPME-GC–MS) and to evaluate their phytotoxic and insecticidal properties, supported by in silico molecular docking. SPME-GC–MS analysis identified 20 VOCs, with hexahydrofarnesyl acetone (33.6%), dihydroactinidiolide (13.4%), trans-β-ionone (12.7%), farnesane (6.0%), and 3,5-di-tert-butylphenol (5.6%) as major constituents. Bioassays showed that hexane and dichloromethane extracts exhibited strong, dose-dependent phytotoxicity against Lens culinaris , significantly inhibiting germination and seedling growth. Insecticidal assays demonstrated potent fumigant activity: dichloromethane extract caused up to 100% mortality of Stegobium paniceum and 90% of Ephestia kuehniella within 72 hours, while n-hexane showed slightly lower efficacy. Residual toxicity confirmed consistent mortality across treatments. Molecular docking indicated strong binding of hexahydrofarnesyl acetone and 3,5-di-tert-butylphenol to acetylcholinesterase (AChE) and the octopamine receptor (Oamb) in Drosophila melanogaster , suggesting a dual neurotoxic mode of action. Overall, C. spinosa VOCs represent promising natural candidates for sustainable bioherbicide and bioinsecticide development. • The volatile constituents of Calicotome spinosa were profiled using the SPME–GC–MS approach. • Twenty VOCs were detected, predominantly hexahydrofarnesyl acetone, dihydroactinidiolide, and trans-β-ionone. • n -Hexane and dichloromethane extracts displayed marked phytotoxicity against Lens culinaris and the weeds Euphorbia peplus and Oxalis corniculata. • Both extracts exerted significant fumigant and residual insecticidal effects on Ephestia kuehniella and Stegobium paniceum. • Molecular docking evidenced strong binding affinities of the main volatiles to AChE and Oamb targets, suggesting a dual neurotoxic mode of action.