Antifungal Activity of Spent Coffee Ground Extracts

Area of Science:

• Mycology
• Pharmacognosy
• Biotechnology

Background:

• Spent coffee grounds (SCG) represent a significant waste stream from global coffee consumption, rich in bioactive compounds.
• Investigating waste valorization for sustainable product development is crucial in addressing environmental and economic challenges.
• Fungal infections, particularly those affecting the skin and mucosa, pose a persistent public health concern, necessitating novel therapeutic agents.

Purpose of the Study:

• To evaluate the antifungal and fungicidal efficacy of ethanolic extracts derived from spent coffee grounds (SCG) obtained from caffeinated and decaffeinated coffee capsules.
• To elucidate the mechanism of action of SCG extracts against fungal pathogens by analyzing their impact on fungal cell membrane and cell wall integrity.
• To assess the cytotoxic profile of SCG extracts against tumoral and non-tumoral cell lines and identify key phenolic compounds responsible for the observed bioactivity.

Main Methods:

• Preparation of ethanolic extracts from spent coffee grounds (SCG) sourced from caffeinated and decaffeinated coffee capsules.
• Antifungal susceptibility testing against a panel of yeasts and filamentous fungi, including skin fungal agents like *Candida krusei*, *Candida parapsilosis*, *Trichophyton mentagrophytes*, and *Trichophyton rubrum*.
• Quantification of fungal cell membrane (ergosterol) and cell wall (chitin, β-(1,3)-glucan) components following treatment with SCG extracts.
• Cytotoxicity assays using tumoral and non-tumoral cell lines (PLP2) and phytochemical analysis to identify phenolic compounds.

Main Results:

• Ethanolic SCG extracts demonstrated significant antifungal activity against *Candida krusei*, *Candida parapsilosis*, *Trichophyton mentagrophytes*, and *Trichophyton rubrum*.
• SCG extracts exhibited fungicidal effects against *T. mentagrophytes* and *T. rubrum*.
• SCG extracts significantly reduced ergosterol, chitin, and β-(1,3)-glucan content in *C. parapsilosis*, indicating disruption of membrane and cell wall synthesis.
• Extracts showed selective cytotoxicity, being toxic to tumoral cell lines but not to the non-tumoral PLP2 cell line, and contained caffeoylquinic acid, feruloylquinic acid, and caffeoylshikimic acid derivatives.

Conclusions:

• Spent coffee grounds (SCG) possess significant antifungal and fungicidal properties, offering a sustainable valorization pathway.
• SCG extracts target fungal cell membrane and cell wall synthesis, presenting a promising mechanism for novel antifungal drug development.
• These findings support the development of SCG-derived antifungal formulations for treating skin and mucosal fungal infections, enhancing the sustainability of coffee waste management.