New Insights into Chemical and Biological Properties of Funicone-like Compounds

In Vitro Evaluation of Antiviral Activities of Funicone-like Compounds Vermistatin and Penisimplicissin against Canine Coronavirus Infection

Recent studies have demonstrated that 3-O-methylfunicone (OMF), a fungal secondary metabolite from Talaromyces pinophilus belonging to the class of funicone-like compounds, has antiviral activity against canine coronaviruses (CCoV), which causes enteritis in dogs. Herein, we selected two additional funicone-like compounds named vermistatin (VER) and penisimplicissin (PS) and investigated their inhibitory activity towards CCoV infection. Thus, both compounds have been tested for their cytotoxicity and for antiviral activity against CCoV in A72 cells, a fibrosarcoma cell line suitable for investigating CCoV. Our findings showed an increase in cell viability, with an improvement of morphological features in CCoV-infected cells at the non-toxic doses of 1 μM for VER and 0.5 μM for PS. In addition, we observed that these compounds caused a strong inhibition in the expression of the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor which is activated during CCoV infection. Our results also showed the alkalinization of lysosomes in the presence of VER or PS, which may be involved in the observed antiviral activities.

The Outstanding Chemodiversity of Marine-Derived Talaromyces

Fungi in the genus Talaromyces occur in every environment in both terrestrial and marine contexts, where they have been quite frequently found in association with plants and animals. The relationships of symbiotic fungi with their hosts are often mediated by bioactive secondary metabolites, and Talaromyces species represent a prolific source of these compounds. This review highlights the biosynthetic potential of marine-derived Talaromyces strains, using accounts from the literature published since 2016. Over 500 secondary metabolites were extracted from axenic cultures of these isolates and about 45% of them were identified as new products, representing a various assortment of chemical classes such as alkaloids, meroterpenoids, isocoumarins, anthraquinones, xanthones, phenalenones, benzofurans, azaphilones, and other polyketides. This impressive chemodiversity and the broad range of biological properties that have been disclosed in preliminary assays qualify these fungi as a valuable source of products to be exploited for manifold biotechnological applications.

Effectiveness of the Fungal Metabolite 3-O-Methylfunicone towards Canine Coronavirus in a Canine Fibrosarcoma Cell Line (A72)

Canine coronavirus (CCoV), an alphacoronavirus, may cause self-limiting enteric disease in dogs, especially in puppies. The noteworthy plasticity of coronaviruses (CoVs) occurs through mutation and recombination processes, which sometimes generate new dangerous variants. The ongoing SARS-CoV-2 pandemic and the isolation of a novel canine-feline recombinant alphacoronavirus from humans emphasizes the cross-species transmission ability of CoVs. In this context, exploring antiviral compounds is essential to find new tools for fighting against CoVs infections. Fungi produce secondary metabolites, which are often developed as antibiotics, fungicides, hormones, and plant growth regulators. Previous examinations of benzo-γ-pyrone 3-O-methylfunicone (OMF), obtained from Talaromyces pinophilus, showed that it reduces the infectivity of hepatitis C virus and bovine herpesvirus 1. Based on this evidence, this study evaluated the antiviral ability of OMF against CCoV infection in a canine fibrosarcoma (A72) cell line. During CCoV infection, a non-toxic dose of OMF markedly increased features of cell viability. Moreover, OMF induced a significant reduction in virus yield in the presence of an intense downregulation of the viral nucleocapsid protein (NP). These findings occurred in the presence of a marked reduction in the aryl hydrocarbon receptor (AhR) expression. Taken together, preliminary findings suggest that OMF inhibiting AhR shows promising activity against CCoV infection.