Comparative bioactive compounds and antifungal potential evaluation of Mentha longifolia (L.) Hudson (Lamiaceae) extracts against plant pathogenic fungi

Abstract

The present study was design to evaluate the Mentha longifolia stem, flower and leaves infusion, decoction and hydroalcoholic extracts to determine the bioactive molecules and antifungal activities by zone of inhibition technique, Minimum inhibitory concentration (MIC) and minimum fungicidal  concentration (MFC) were assay by broth dilution technique and spore germination assay using Light Compound Microscope against plant pathogenic  fungi (Fusarium oxysporum, Aspergillus parasiticus, Rhizoctonia solani and Alternaria alternata). The Mentha longifolia phytochemicals were found in the  range flavonoids 3.8 - 2.4%, saponins were 5.6-3.4%, alkaloids 0.7-0.1% and total phenolic were 40-15 mg Gallic acid/g. The maximum zone of  inhibition 23±1 mm and 22±1 mm were found by hydroalcoholic leaves extract against Fusarium oxysporum and Aspergillus parasiticus respectively. The  MIC range of hydroalcoholic were 12.5-100 mg/mL, infusion were 25-100 mg/mL and decoction were 25-200 mg/mL. While MFC range of hydroalcoholic  were 25-200 mg/mL, infusion were 50- 200 mg/mL and decoction were 50-200 mg/mL. Spore germination assay reaveled that increse in the extract  concenetration decrese the spore germination. The results revealed that Mentha longifolia chemical composition might be build up as latent bio- fungicides against plant pathogenic fungi.