Antifungal assessment, synergistic activity and molecular docking studies of essential oils as potential fungal inhibitor candidates against Alternaria alternata

The management of plant pathogens has become a challenge due to increasing pesticide resistance. Recent studies have focused on developing alternatives to chemical pesticides, enabling effective control of crop pathogens with reduced environmental impact and minimal effects on human health. This study examines the chemical composition and the antifungal activity of four essential oils extracted from Origanum compactum , Thymus leptobotrys , Laurus nobilis , and Rosmarinus officinalis in individual and combined forms against Alternaria alternata causal agent of olive leaf diseases. The most potent inhibitors of A. alternata were oregano and Thyme essential oils, distinguished by the predominance of carvacrol (59% and 75.05%), respectively. Furthermore, essential oil combinations such as oregano/thyme and oregano/thyme/laurel reduced the MIC values and showed synergistic effects (FICI ≤ 0.5). In silico analysis by molecular docking was performed to study the anticipated ligands of these essential oils against Ubiquitin E3 Ligase responsible for H2B monoubiquitination in Alternaria alternata . These results suggest that, as part of the search for sustainable ways to reduce fungicide use in agriculture, essential oils, combinations, and even chemical compounds may be effective against Alternaria alternata .