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 (AlCl
3) 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 (LD
50 = 11.77 μg/mL), nematicidal (LD
50 = 11.78 μg/mL),
antifeedant (LD
50 > 40 μg/mL), and antifungal activities (minimum inhibitory concentration: 16 μg/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.
