Chemical Composition and Antifungal, Insecticidal and Repellent Activity of Essential Oils From Origanum compactum Benth. Used in the Mediterranean Diet.

Ahmad Mohammad Salamatullah,El Abdali Youness,Abdulhakeem Alzahrani,Hiba-Allah Nafidi,Heba Khalil Alyahya,Mohammed Bourhia,Lahcen Ouahmane,Allali Aimad,Abdelfattah El Moussaoui,Fadli Mohamed,Nawal A Albadr,Rezouki Sanae

doi:10.3389/fpls.2022.798259

Abstract

Essential oils (EO) of Origanum compactum Benth. (O. compactum) are well known for their biological and pharmacological activities. This study aimed to assess the chemical composition, antifungal, insecticidal and repellent activities of EO of O. compactum used in the Mediterranean diet. Phytochemical screening was conducted using gas chromatography-mass spectrometry (GC/MS). Antifungal activity was tested by the disc diffusion method followed by a minimal inhibitory concentration (MIC) assay against Candida albicans (C. albicans), Aspergillus flavus (A. flavus), Aspergillus niger (A. nige), and Fusarium oxysporum (F. oxysporum). Repellent potential and toxicity of EO by contact and inhalation were tested against Callosobruchus maculatus (C. maculatus). The yield of essential oil obtained by hydrodistillation of O. compactum was 4.41 ± 0.35%, mainly composed of Carvacrol (38%) and Thymol (31.46%). Regarding antifungal activity, the results revealed a wide antifungal spectrum of the studied EO against the tested strains, which reached 100% growth inhibition, especially against A. niger and C. albicans even at the lowest MIC values (3.125 μg/mL). Concerning insecticidal activity, the EO caused total mortality of C. maculatus adults at a dose of 20 μL/L air with LC50 value of 5.3 μL/L air. A significant reduction in the number of eggs and emergence was proportionally recorded with increasing doses up to 100% at 20 μL/L air. For repellent activity, the studied EO showed a moderate repellent activity with an average percentage of 39.16%. The outcome of this work revealed that O. Compactum EO could be a sustainable and environmentally friendly alternative bioinsecticide and bio-fungicide to replace the chemically synthesized forms.

Highlights

Medicinal and aromatic plants are important sources of Essential oils (EO) that find applications in various areas of life
In current study, we investigated the chemical composition of EO of O. compactum from Taounate, as well as their insecticidal and repellent activities against Callosobruchus maculatus, major pests of chickpea grains in Morocco, and the antifungal activity against some pathogenic strains of fungi implicated in the contamination of leguminous and nosocomial infections
The results revealed a high antifungal potential of the studied EOs against the tested strains, marked by a maximum growth inhibition rate (100%)

Summary

Introduction

Medicinal and aromatic plants are important sources of EO that find applications in various areas of life. EO is mainly used as a food flavoring but can be successfully used for various non-food applications, as it exhibits many biological properties, including antifungal, antimicrobial, antioxidant, and insecticidal activity (Mssillou et al, 2020; Allali et al, 2021; El Moussaoui et al, 2021). Chickpea (Cicer arietinum L.), is one of the most nutrientdense seed legumes available for human consumption. It is a good source of protein, vitamins, and minerals (Allali et al, 2020a). Fungi in the field and during storage cause considerable crop losses and deterioration of seed quality (Santos et al, 2016). Invasive candidiasis caused by the candida fungus is frequently associated with high mortality rates, and the emergence of resistant strains (El Moussaoui et al, 2021)

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