# Manganese‐Induced Production of Antioxidant Polyene Steroids in the Extremophile Fungus Talaromyces fuscoviridis Isolated From Copper‐Mine Soil

## TL;DR

A fungus from copper-mine soil produces antioxidant steroids, especially when exposed to manganese, and one steroid is newly discovered.

## Contribution

Discovery of a new antioxidant steroid and its enhanced production via manganese supplementation in an extremophile fungus.

## Key findings

- A new steroid, Ergosta-5(6),7(8),14(15),22(23)-tetraen-3-ol, was identified and confirmed by single-crystal X-ray diffraction.
- Manganese chloride significantly increased the biosynthesis of antioxidant polyene steroids in Talaromyces fuscoviridis.
- The steroids showed strong in vitro antioxidant activity, with over 80% scavenging capacity compared to β-carotene at low concentrations.

## Abstract

The fungus Talaromyces fuscoviridis was isolated from soil collected in a copper‐mine tailings basin in Pará State, Brazil, an extreme environment that can induce the production of bioactive secondary metabolites. Extracts and fractions obtained after cultivation were analyzed by liquid chromatography coupled to high‐resolution mass spectrometry (LC–HRMS) and compared using Global Natural Products Social molecular networking (GNPS), which revealed a family of seven putative polyunsaturated steroids. Isolation led to the characterization of two major steroids: the known Ergosta‐3(4),5(6),7(8),14(15),22(23)‐pentaene (1a) and a previously unreported metabolite, Ergosta‐5(6),7(8),14(15),22(23)‐tetraen‐3‐ol (2a). Their structures were elucidated through comprehensive spectroscopic and spectrometric methods (e.g., UV–Vis, NMR, and high‐resolution mass spectrometric [HRMS]), with the structure of steroid 2a being unequivocally confirmed by single‐crystal x‐ray diffraction (SCXRD). Notably, the biosynthesis of these steroids was significantly enhanced when the cultivation medium was supplemented with manganese chloride (MnCl2). Furthermore, the steroids were tested for their in vitro antioxidant activity against the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) free radical using an adapted UHPLC–DAD method, showing over 80% of the scavenging capacity of β‐carotene at the lowest tested concentrations.