Unveiling the antifungal mechanisms of Helichrysum essential oils through phytochemical characterization, predictive modeling, and molecular docking

Abstract

Postharvest losses and concerns over synthetic preservatives have intensified interest in natural, sustainable alternatives. Hence, essential oils (EOs) from indigenous South African Helichrysum species were investigated for their potential to control fungal spoilage. Essential oils from H. odoratissimum, H. patulum, H. petiolare, and H. splendidum were characterized by GC-MS and FTIR, and their antioxidant activities were evaluated using DPPH and ABTS assays. Antifungal efficacy was assessed against Penicillium sp. and Botrytis sp. through minimum inhibitory and fungicidal concentrations (MIC and MFC) determinations. The antifungal mechanisms of the most active EO were further explored using Scanning Electron Microscopy (SEM), molecular docking, and inactivation kinetics modeling (Gompertz, logistic, and exponential equations). All EOs contained diverse monoterpenes and sesquiterpenes, though composition varied by species. H. splendidum exhibited the strongest antioxidant (IC50 = 4.09 µL/mL) and antifungal activity, with the lowest MIC (16 µL/mL) and MFC (128 µL/mL) values. SEM revealed hyphal collapse and disrupted spore formation, while molecular docking showed several EO compounds had stronger binding affinities to fungal enzymes than propiconazole. The Gompertz model provided the best fit (R2 = 0.9852) for describing fungal inactivation dynamics. Overall, Helichrysum EOs, particularly H. splendidum, demonstrate strong potential as natural antifungal agents for postharvest preservation. This study integrates phytochemical profiling, SEM, molecular docking, and predictive modeling to highlight the promise of EOs from indigenous South African plants as eco-friendly alternatives to chemical preservatives.