Evaluation of total phenols and flavonoids, antioxidant power, and antifungal effect of Mentha spicata essential oil against species causing strawberry’s rot

This study was aimed to investigate the total phenols and flavonoids content, antioxidant activity, and antifungal effect of Mentha spicata essential oil on fungi species causing strawberry’s rot (Aspergillus niger, Botrytis cinerea, and Rhizopus stolonifer). For these purposes, the essential oil of M. spicata was firstly extracted by the Clevenger apparatus. The M. spicata essential oil contained 55.15 mg GAE/g total phenols and 29.25 mg QE/g total flavonoids, which show an important role in its antioxidant and antifungal activities. The antioxidant activity (IC50) of the essential oil was found to be 23.35, 19.80, and 27.11 µg/ml, respectively, based on the DPPH radical scavenging, ABTS radical scavenging, and beta-carotene/linoleic acid assays. The antimicrobial tests (disk diffusion agar, well diffusion agar, minimum inhibitory concentration, and minimum fungicidal concentration) showed that the essential oil of M. spicata had a potentially high antifungal activity; Aspergillus niger and Botrytis cinerea were the most sensitive and resistant fungi species to the essential oil. The minimum inhibitory concentration for Aspergillus niger, Botrytis cinerea, and Rhizopus stolonifer was 12.5, 50 and 25 mg/mL, respectively. The minimum fungicidal concentration for Aspergillus niger, Botrytis cinerea, and Rhizopus stolonifer was 100, 200 and 100 mg/mL, respectively. Based on the results, the M. spicata essential oil can be used as an antioxidant and antimicrobial agent in food products.