# Identification and characterization of a novel broad-spectrum antifungal compound targeting the Aspergillus fumigatus cell wall and cell membrane and inducing oxidative stress

## TL;DR

A new antifungal compound from soil microbes shows strong activity against dangerous fungi by damaging cell walls and causing oxidative stress.

## Contribution

A novel polyene macrolide from Kitasatospora melanogena with broad-spectrum antifungal activity and a multifaceted mechanism of action is identified.

## Key findings

- Compound 1 disrupts the cell wall and membrane of Aspergillus fumigatus and other fungal pathogens.
- Transcriptomic analysis reveals downregulation of genes involved in cell wall and membrane biogenesis.
- Compound 1 induces oxidative stress, increasing reactive oxygen species levels in treated fungi.

## Abstract

The substantial increase in fungal diseases, the limited availability of antifungal drugs, and rising resistance to existing treatments highlight the urgent need for developing novel antifungal drugs. Natural products, known for their diverse bioactivities and unique structures, remain critical sources for antifungal drug discovery. In this study, we aimed to identify novel antifungal compounds from soil microbes and isolated a novel 28-membered polyene macrolide, compound 1, from Kitasatospora melanogena. This compound demonstrated potent antifungal activity, with MICs of 4–16 μg/mL against Aspergillus fumigatus, Aspergillus flavus, Candida albicans, and Cryptococcus neoformans. Treatment with compound 1 led to significant growth reduction and disruption of the cell wall and membrane in A. fumigatus compared to the wild-type. To understand the underlying mechanism, we performed a transcriptomic analysis of A. fumigatus exposed to compound 1, revealing a substantial downregulation of genes involved in cell wall and membrane biogenesis, as well as those encoding integral membrane proteins and multidrug transporters. Additionally, compound 1 induced oxidative stress, leading to elevated reactive oxygen species levels. These multifaceted mechanisms highlight the potential of K. melanogena natural products in the development of novel antifungal agents.

Fungal infections cause substantial morbidity and mortality worldwide, yet current treatments are limited and increasingly undermined by resistance. Natural products remain a proven source of antifungal agents, but few new scaffolds have been introduced in recent decades. We identified a novel polyene macrolide from Kitasatospora melanogena with potent activity against major fungal pathogens. This compound disrupts both the fungal cell wall and membrane while inducing oxidative stress, revealing a multifaceted mechanism of action. Our findings highlight soil microbes as valuable reservoirs for antifungal discovery and provide a promising lead for the development of next-generation therapies against life-threatening fungal diseases.