Antifungal Activity of Thymus Fontanesii Boiss. & Reut. Essential Oil Against the Main Phytopathogenic Fungi of Tomato (Solanum Lycopersicum L.): Study of Effects on Alternaria Spp., Fusarium Oxysporum F. P. Lycopersici and Aspergillus Niger

Abstract

This study investigated the chemical composition and the antifungal, antioxidant, and anti-inflammatory properties of the essential oil obtained from Thymus fontanesii Boiss. & Reut., an endemic Algerian aromatic species with promising value in sustainable crop protection. The essential oil was extracted from the aerial parts by hydrodistillation using a Clevenger-type apparatus, giving a yield of 1.36 ± 0.01%, and was subsequently characterized by gas chromatography-mass spectrometry (GC-MS). The analysis led to the identification of twenty-eight compounds, with p-cymene (11.68%), a terpinen-related compound (6.02%), β-caryophyllene (5.72%), and myrcene (1.93%) as the main detected constituents. The biological activity of the oil was evaluated in vitro against three important tomato phytopathogens, namely Fusarium oxysporum, Alternaria spp., and Aspergillus niger. Antioxidant activity was determined using the DPPH radical-scavenging assay, whereas anti-inflammatory potential was assessed through inhibition of protein denaturation. The essential oil exhibited a clear dose-dependent antifungal effect against all tested fungi. Complete inhibition of mycelial growth was observed at 5 µL/50 mL for F. oxysporum, 10 µL/50 mL for A. niger, and 25 µL/50 mL for Alternaria spp. In the antioxidant assay, the oil reached 83.5 ± 2.1% inhibition at 200 µg/mL, compared with 89.1 ± 2.2% for vitamin C. Anti-inflammatory activity also increased with concentration and reached 81.5 ± 2.4% inhibition at 400 µg/mL, showing values comparable to the reference drugs under the same conditions. These findings indicate that T. fontanesii essential oil is a valuable natural source of bioactive compounds and support its potential use in eco-friendly formulations for plant protection and related biological applications.