Evaluation of chemical activity and antifungal effect of Vitex agnus-castus essential oil on Penicillium digitatum and Penicillium italicum causing orange rot

Plant essential oils are frequently used as natural preservatives to decrease the toxicity of synthetic fungicides and environmental pollution. This study was aimed to investigate the antifungal effect of Vitex agnus-castus essential oil on Penicillium digitatum and Penicillium italicum causing orange rot. The essential oil of V. agnus-castus was extracted by the hydrodistillation method and the extraction yield was 0.95% w/w. The total phenol and flavonoids content of the essential oil were also measured and the results showed that the essential oil is rich in phenolics (91.74 mg GAE/g) and flavonoids (52.32 mg QE/g). The evaluation of antioxidant activity of the V. agnus-castus essential oil showed that the bioactive compound is able to effectively scavenge DPPH (IC50 = 48.62 μg/mL) and ABTS (IC50 = 40.50 μg/mL) free radicals. The antifungal activity of the V. agnus-castus essential oil was evaluated against P. digitatum and P. italicum, based on disk diffusion agar, well diffusion agar, and minimum inhibitory/fungicidal concentration methods. And P. digitatum was more sensitive to the essential oil and lower concentration of the bioactive compound was able to inhibit the growth of or kill the species. In general, the results of this study showed that the V. agnus-castus essential oil is rich in bioactive compounds with remarkable antioxidant and antifungal activities, and it could be applied as a natural preservative to increase the shelf-life of food products.