New Fungal Compounds Curb H5N1 Neuraminidase in Lab Tests

Two previously unknown p-terphenyl compounds, named curtisians W and X, have been isolated from the methanolic extract of the fruiting bodies of the fungus Pseudomerulius curtisii, formerly known as Paxillus curtisii. The discovery, published in The Journal of Antibiotics, also reports that both molecules block the neuraminidase enzyme of the H5N1 influenza virus in laboratory assays.

The research team, led by Byung Soon Hwang and Bong-Sik Yun with colleagues including Dae-Won Ki, Dae-Cheol Choi, In-Kyoung Lee and Jaehoon Bae, worked out the structures of the two compounds using high-resolution mass spectrometry along with one- and two-dimensional nuclear magnetic resonance measurements.

In enzyme inhibition tests, curtisians W and X suppressed H5N1 neuraminidase in a dose-dependent manner. Curtisian W showed an IC50 value of 15.4 micromolar, while curtian X was more potent at 9.3 micromolar. Kinetic analysis indicated that both compounds act as non-competitive inhibitors, with Ki values of 31.8 micromolar for curtisian W and 15.6 micromolar for curtisian X.

The non-competitive mechanism reported here distinguishes these compounds from substrate-competitive inhibitors, although the findings come from in vitro enzyme assays and do not establish antiviral efficacy in cells, animals, or patients.

The authors note that the data supporting the study are available from the corresponding author upon reasonable request. The report appears as a Brief Report in the journal’s 2026 volume, published on 23 October 2026.

Subject of Research: Isolation of two new p-terphenyl compounds from the fungus Pseudomerulius curtisii and their in vitro inhibition of H5N1 influenza neuraminidase.

Article Title: Curtisians W and X, two new p-terphenyls from the fruiting bodies of Pseudomerulius curtisii, and their neuraminidase inhibitory activity

Article References: Hwang, B. S., Ki, D.-W., Choi, D.-C., Lee, I.-K., Bae, J., & Yun, B.-S. (2026). Curtisians W and X, two new p-terphenyls from the fruiting bodies of Pseudomerulius curtisii, and their neuraminidase inhibitory activity. The Journal of Antibiotics. https://doi.org/10.1038/s41429-026-00959-3

Image Credits: AI Generated

DOI: 10.1038/s41429-026-00959-3

Keywords: curtisians, p-terphenyls, Pseudomerulius curtisii, neuraminidase, H5N1 influenza, natural products, fungal metabolites, enzyme inhibition, non-competitive inhibitor, NMR structure elucidation, The Journal of Antibiotics, fruiting