Phytochemical characterization by HS-SPME-GC-MS and exploration of the antifungal, insecticidal and repellent activity of Ptychotis verticillata essential oil

Abstract

The objective of this investigation was to assess the chemical makeup of essential oil derived from Ptychotis verticillata (PVEO), and to examine its antifungal, insecticidal, and repellent properties. PVEO was extracted through hydrodistillation, and its volatile constituents were analyzed using Headspace Solid-Phase Microextraction Gas Chromatography-Mass Spectrometry. Qualitative and quantitative evaluation of antifungal activity was carried out using the agar diffusion method and the minimum inhibitory concentration (MIC) test against Candida glabrata, Saccharomyces cerevisiae, Aspergillus niger and Penicillium digitatum. We evaluated the repellent potential, as well as the contact and inhalation toxicity of PVEO against Callosobruchus maculatus. The results of the study indicated that the essential oil of P. verticillata was composed mainly of γ-Terpinen (25.86%), β-Cymene (18.70%) O-Cymen-5-ol (16.78) and α-Pinene (12.13%). PVEO showed potent antifungal activity against all strains tested. The results of insecticidal activity of this essential oil were promising in adult C. maculatus. At a dose of 20 ml · dm–3 of air, EO caused maximum mortality with an LC50 value of 5.64 ml · dm–3 for the inhalation test and 3.4 ml · dm–3 for the contact test. In addition, a significant decrease in the number of eggs laid and adult emergence was observed as EO doses increased, reaching a reduction of around 95% at a dose of 20 ml · dm–3 of air. In terms of repellent activity, PVEO also showed encouraging results. It demonstrated an average repellent activity of around 92 ± 10.95%. Furthermore, molecular docking simulations corroborated the in vitro results and demonstrated that specific p-Menthen-3-one compounds formed more robust hydrogen bonding interactions with the target receptors. These experiments underscore PVEO’s effectiveness as a fungicide against the tested fungal strains, demonstrating its role as a bio-insecticide against C. maculatus adults, and its potential as an appealing repellent. This suggests that PVEO could serve as a valuable alternative within integrated pest management strategies.

Keywords

• antifungal activity
• essential oil
• hspme-gc-ms
• insecticidal activity
• ptychotis verticillata