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Mefenoxam and pyraclostrobin: toxicity and in vitro inhibitory activity against Pythium insidiosum

P C Stibbe1, L B Ianiski1, C Weiblen2

  • 1Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil.

Letters in Applied Microbiology
|August 16, 2022
PubMed

Insights

Agricultural fungicides mefenoxam and pyraclostrobin show in vitro efficacy against the pathogen Pythium insidiosum. These compounds demonstrated no toxicity in vivo, suggesting potential for pythiosis treatment with further research.

Area of Science:

  • Agricultural Science
  • Mycology
  • Veterinary Medicine

Background:

  • Pythium insidiosum is an oomycete pathogen causing pythiosis, a serious disease in animals.
  • Limited treatment options exist for pythiosis, necessitating the exploration of novel therapeutic agents.

Purpose of the Study:

  • To determine the in vitro susceptibility of Pythium insidiosum to agricultural fungicides mefenoxam and pyraclostrobin.
  • To evaluate the in vivo toxicity of mefenoxam and pyraclostrobin using a Caenorhabditis elegans model.

Main Methods:

  • Broth microdilution method to determine minimum inhibitory and oomicidal concentrations.
  • Scanning electron microscopy (SEM) to visualize fungicide effects on P. insidiosum hyphae.
  • In vivo toxicity assessment using the Caenorhabditis elegans model.

Main Results:

  • Mefenoxam and pyraclostrobin exhibited significant in vitro inhibitory effects against 21 P. insidiosum isolates.
  • SEM revealed morphological changes on P. insidiosum hyphae treated with sublethal fungicide concentrations.
  • No significant toxicity was observed in the Caenorhabditis elegans model at the evaluated doses.

Conclusions:

  • Mefenoxam and pyraclostrobin possess inhibitory activity against Pythium insidiosum and are not toxic at tested doses.
  • Further research into pharmacokinetics, toxicity in different species, and potential drug interactions is required for clinical application in pythiosis.
Keywords:
Pythium insidiosumOomycetesagricultural fungicidessusceptibility testtoxicity

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