Objectives: Secondary bioactive metabolites from plants may be realistic alternatives to conventional synthetic chemicals. The aim of the present research was to test the Tanacetum falconeri Hook. f. in different bioassays to evaluate its potential as nematocidal, insecticidal, antibacterial, cytotoxic, and phytotoxic agent. The plant T. falconeri was further studied for its chemical constituents.
Materials and methods: The methanolic extract from T. falconeri was fractionated into various solvent fractions. All solvent fractions were further subjected to different bioassays. Antibacterial activity and cytotoxicity were determined by broth micro-dilution method and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, respectively. Nematocidal activity was evaluated by using second-stage juvenile of Meloidogyne incognita. Insecticidal activity and phytotoxicity were measured with the help of Rhyzopertha dominica and Tribolium castaneum and fronds of Lemna minor L., respectively. Compound-1 was isolated by using liquid chromatography and its structure was determined by spectroscopic data as cis-dehydromatricaria ester.
Results: The excellent nematocidal activity (reduction in 100% motility) of the compound-1 against a root-knot nematode was obtained at 1% concentration after 72 h incubation time, whereas the reductions in motilities were 95% and 75% at concentrations 0.5% (w/v) and 0.125% (w/v), respectively. Similarly, the mortalities were 90% and 82% at 1% and 0.5% concentrations, respectively, after 24 h of the treatment. Compound-1 also exhibited the excellent insecticidal activity against Sitophilus oryzae at 1% concentration (providing 100% mortality) with effective dose 50 (EC50) of 0.08 mg/L. The EC50 of phosphine, which was used as standard, was 0.07 mg/L. Two fractions of T. falconeri showed a moderate cytotoxic activity against 3T3 cells lines at the concentration of 30 mg/mL with inhibitory concentration 50 values of 22.4 and 25.8 mg/L corresponding to TfP and TfM, respectively.
Conclusion: This study demonstrates that cis-dehydromatricaria ester-1 provides nematocidal activity (100% mortality) against the root-knot nematodes. Its insecticidal activity against S. oryzae may enable its use as marketable insecticide.
Keywords: Pesticides; Tanacetum falconeri; root-knot nematodes; secondary metabolites; toxicity.