Phytochemical analysis and antifungal activity of Mentha against Phytophthora infestans.

The present study evaluated modified solvent evaporation-assisted methanolic Mentha extracts for their antifungal efficacy against Phytophthora infestans. Mentha extracts showed significantly (p < 0.05) higher total tannin content (2193.5 ± 7.5 mg) in the root extract of Mentha citrate , followed by total flavonoid content (1777± 8 mg) in the leaf extract of Mentha piperta and total phenolic content (1710±4 mg) in the leaf extract of Mentha piperta. A significant amount of variability was found for bioactive compounds in Mentha varieties by using qualitative descriptors. Statistically, Mentha extracts and artificial antioxidants showed a significant (p < 0.05) difference in terms of percentage inhibition during DPPH, nitric acid scavenging, reducing power, phosphomolybdenum, chelating power, and hydroxyl radical scavenging assays, from which it was observed that the leaves, stem, and root of wild Mentha showed better antioxidant values. During the antifungal assay, the leaf extract of wild Mentha showed a significantly (p < 0.05) higher inhibition percentage, i.e., 33.2%, followed by the leaf extract of Mentha piperita , i.e., 31.9%. In contrast, the minimum percentage was found in Mentha arvensis (Kosi). Mentha varieties and ascorbic acid are also effective against P. infestans. The HPLC chromatogram of wild Mentha revealed a significantly (p < 0.05) higher eriocitrin level in the leaves, i.e., 7.92 mg, as compared to the stem i.e., 7.63 mg. This study identified Mentha as an alternative treatment against P. infestans as compared to traditional chemical pesticides and also reduced the impact of chemical pesticides on the environment. [Display omitted] • Eight Mentha varieties, i.e., Mentha arvensis (Unti), Mentha arvensis (Kranti), Mentha arvensis (Kosi), Mentha citrata (Kiran), Mentha piperita (Kukurel), Mentha spicata (Supriya), Mentha spicata L. Var. Viridis (MSS-5), and Wild Mentha were subjected to in vitro antifungal activity against P. infestans. • Phytochemical tests were performed for qualitative and quantitative analysis. • The inhibitory of 2,2-Diphenyl-1-picrylhydrazyl (DPPH), nitric oxide scavenging, reducing power, phosphomolybdenum assay, chelating power and hydroxyl radical scavenging assays were investigated, indicating antioxidant properties. • The extracts showed good antifungal activity against P. infestans, while leaf extract of wild Mentha gave the maximum inhibition percentage, i.e., 33.2 %. • High performance liquid chromatography (HPLC) revealed the presence of eriocitrin in the leaves and stem of wild Mentha. [ABSTRACT FROM AUTHOR]