Synthesis of Indolyl Isothiocyanate and Its Inhibitory Activity against Fungi

Area of Science:

• Agricultural Science
• Organic Chemistry
• Mycology

Background:

• Fungal diseases pose a significant threat to crop yields worldwide.
• Developing novel fungicides is crucial for sustainable agriculture and food security.
• Indolyl and isothiocyanate moieties are known pharmacophores with potential biological activity.

Purpose of the Study:

• To synthesize novel indolyl isothiocyanate compounds.
• To evaluate the in vitro and in vivo antifungal activity of these compounds.
• To investigate the mechanism of action of promising antifungal agents.

Main Methods:

• Synthesis of 24 indolyl isothiocyanate derivatives.
• In vitro antifungal screening against *Alternaria alternata*, *Phytophthora capsici*, *Botrytis cinerea*, and *Valsa mali*.
• Determination of EC50 values and potted plant antifungal assays.
• Physiological and biochemical analysis of fungal targets.
• Theoretical calculations of charge distribution.

Main Results:

• Compounds 8, 13, 14, and 17 demonstrated over 80% inhibition against *P. capsici*, *B. cinerea*, and *V. mali* at 100 μg/mL.
• EC50 values for compounds 13 and 14 were determined to be 0.64 and 2.08 μg/mL, respectively.
• Compounds 13 and 14 exhibited approximately 80% protective effect against *B. cinerea* in potted assays.
• Compound 13 induced cell wall thickening and mitochondrial vacuolization in *B. cinerea*.
• Theoretical analysis highlighted the importance of charge distribution in fungicidal activity.

Conclusions:

• The synthesized indolyl isothiocyanate compounds show potent fungicidal properties.
• Compounds 13 and 14 are promising candidates for further development as agricultural fungicides.
• The study provides valuable insights into the structure-activity relationships and mechanism of action for this class of compounds.