Phytochemical Profiling, Antioxidant, and Antifungal Activities of Ethyl Acetate and Chloroformic Extracts from Three Mentha Species

Phytopathogenic fungi remain the main infectious agents in plants, causing severe damage to the environment and human health. Thus, to reduce the usage of synthetically derived fungicides and perform agricultural crop production, the search for new control strategies including plant extracts constitutes an eco-friendly and safe alternative. This study aimed to quantify the phytochemical constituents of the three plant ( Mentha pulegium L., Mentha spicata L., and Mentha longifolia L.) extracts and to screen their phytochemical composition including total phenolic (TPC), flavonoids (TFC) and condensed tannins contents (TCTC), and to evaluate their antioxidant activities. The efficacy of all mint extracts will be investigated against phytopathogenic fungal species. The three plant extracts were screened to assess their total phenolic, flavonoids, and condensed tannin contents using spectrophotometric assays. The antioxidant activities include 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric ion reducing antioxidant power (FRAP), and β-carotene assays. The antifungal activities were investigated on phytopathogenic species including Botrytis cinerea, Fusarium culmorum, Fusarium oxysporum, Aspergillus niger, Aspergillus flavus, and Trichoderma sp. Quantitative analyses of phytochemical constituents of Mentha genus extracts revealed that both ethyl acetate (EtAc) and chloroformic (Chl) extracts are a rich source of phenols, flavonoids, and condensed tannins. Ethyl acetate extract of M. longifolia (EtAc L) displayed the highest content of phenols (69.9 ± 1.35 mg GAE/g DW) and flavonoids (53.26 ± 2.11 mg CE/g DW), while M. pulegium ethyl acetate extract (EtAc P) has the highest condensed tannins content (2.13 ± 0.4 mg CE/g DW). Moreover, the tested extracts exhibited potent antioxidant activities at low concentrations for EtAc L, followed by M. spicata (EtAc S), and EtAc P (IC50 = 35.76 ± 1.32 µg/mL for scavenging DPPH free radicals; EC50 527.96 ± 5.45 µg/mL for FRAP, and IC50 = 106.3 ± 3.75 µg/mL for β-carotene bleaching test). Finally, all tested extracts were able to inhibit the growth of several phytopathogenic micro-organisms on both agar and broth media. The Mentha extracts derived from the three mint species (i.e., L, P, and S) could be used for their antifungal activities to provide sustainable crop pest management.