Abstract
Purpose: To evaluate the larvicidal, nematicidal, antifeedant, and antifungal effects of 10 solvent extracts of Mentha spicata root.
Methods: Ten solvent extracts were investigated for their total flavonoid and phenolic content and screened for larvicidal, nematicidal, antifeedant, and antifungal activities. The total phenolic content of the extracts was determined using the Folin-Ciocalteu method, while total flavonoid content was determined by aluminium chloride (AlCl3) colorimetric assay. Four solvents extracts were screened for antifungal activity against Aspergillus niger, Candida albicans, recultured Cryptococcus neoformans, and Microsporum audouinii using the agar diffusion method. The nematicidal activity of the compounds was evaluated against the juvenile Meloidogyne javanica organism, while larvicidal properties were evaluated against the urban mosquito Culex quinquefasciatus using a standard bioassay protocol. The antifeedant activity of marine acclimated Oreochromis mossambicus was used for evaluating ichthyotoxic potential.
Results: The total flavonoid content in the extracts ranged from 18.5 to 83.4 mg/g, and the amount of free phenolic compounds ranged from 14.7 to 91.9 mg/g of extract powder. The water extract of these plants exhibited significant antioxidant activity and significant levels of phenolics and flavonoids. The water extract exhibited higher larvicidal (LD50 = 11.77 mu g/mL), nematicidal (LD50 = 11.78 mu g/mL), antifeedant (LD50 > 40 mu g/mL), and antifungal activities (minimum inhibitory concentration: 16 mu g/mL) against M. audouinii compared with the other extracts.
Conclusion: These results show that the water extract of Mentha spicata may be used as a potential natural alternative source of nutritional and pharmaceutical ingredients.