Cyclization Reactions of In Situ-Generated Acyl Ketene with Ynones to Form Oxacycles

Acyl ketenes react with polar unsaturated functional groups to give unique heterocyclic rings, yet reactions with unpolarized unsaturated functional groups have not been reported. Herein, we describe two effective ring-forming reactions between acetyl ketene and electron-deficient alkynes. The first reaction involves in situ tethering between acetyl ketene and nucleophile-containing 1,3-diynones, which promotes sequential intramolecular 1,6/1,4-additions to generate 2-methylene-2H-pyrans in various yields (24-91%). The other involves a zwitterionic intermediate generated from acetyl ketene and DABCO, which undergoes a Michael addition with terminal alkynyl ketones to generate 3-acyl-4-pyrones (11-79%).

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.

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

Funicone-like compounds are a homogeneous group of polyketides that, so far, have only been reported as fungal secondary metabolites. In particular, species in the genus Talaromyces seem to be the most typical producers of this group of secondary metabolites. The molecular structure of funicone, the archetype of these products, is characterized by a γ-pyrone ring linked through a ketone group to a α-resorcylic acid nucleus. This review provides an update on the current knowledge on the chemistry of funicone-like compounds, with special emphasis on their classification, occurrence, and diverse biological activities. In addition, their potential relevance as mycotoxins is discussed.

Characterization of a bioactive meroterpenoid isolated from the marine-derived fungus Talaromyces sp

A new meroterpenoid, taladrimanin A (1), was isolated from a marine-derived fungus Talaromyces sp. HM6-1-1, together with eleven biogenetically related compounds (2-12). A plausible biosynthetic pathway for the meroterpenoids (1-4) was proposed. The planar structure of 1 was assigned by HRESIMS and NMR. Its relative configuration was established by quantum chemical NMR calculation of two possible isomers and analyzed by DP4 + method. Finally, X-ray diffraction unambiguously confirmed the relative configuration and revealed the absolute configuration of compound 1. 2-12 were assigned by comparing their NMR data with those reported in the literature. 1 was the first drimane-type meroterpenoid with a C10 polyketide unit bearing an 8R-configuration. In the bioactive assay, 1 exhibited antitumor activity against gastric cancer cells MGC803 and MKN28; it also inhibited the colony formation and induced apoptosis in MGC803 cells both in a concentration-dependent manner. Additionally, 1 displayed selective antibacterial activity against Staphylococcus aureus 6538P, and low activities towards strains of Vibrio parahaemolyticus and Escherichia coli in this study. KEY POINTS: • Twelve compounds were obtained from Talaromyces sp., including four meroterpenoids, one of which was new. • The new compound taladrimanin A (1) inhibits the growth of gastric cancer cells MGC803 and MKN28 as well as the pathogenic bacteria Staphylococcus aureus 6538P. • The biosynthetic pathway of the meroterpenoids was proposed.

Genetic Characteristics and Metabolic Interactions between Pseudocercospora fijiensis and Banana: Progress toward Controlling Black Sigatoka

The international importance of banana and severity of black Sigatoka disease have led to extensive investigations into the genetic characteristics and metabolic interactions between the Dothideomycete Pseudocercospora fijiensis and its banana host. P. fijiensis was shown to have a greatly expanded genome compared to other Dothideomycetes, due to the proliferation of retrotransposons. Genome analysis suggests the presence of dispensable chromosomes that may aid in fungal adaptation as well as pathogenicity. Genomic research has led to the characterization of genes and metabolic pathways involved in pathogenicity, including: secondary metabolism genes such as PKS10-2, genes for mitogen-activated protein kinases such as Fus3 and Slt2, and genes for cell wall proteins such as glucosyl phosphatidylinositol (GPI) and glycophospholipid surface (Gas) proteins. Studies conducted on resistance mechanisms in banana have documented the role of jasmonic acid and ethylene pathways. With the development of banana transformation protocols, strategies for engineering resistance include transgenes expressing antimicrobial peptides or hydrolytic enzymes as well as host-induced gene silencing (HIGS) targeting pathogenicity genes. Pseudocercospora fijiensis has been identified as having high evolutionary potential, given its large genome size, ability to reproduce both sexually and asexually, and long-distance spore dispersal. Thus, multiple control measures are needed for the sustainable control of black Sigatoka disease.

Structurally Diverse Polyketides From the Mangrove-Derived Fungus Diaporthe sp. SCSIO 41011 With Their Anti-influenza A Virus Activities

Influenza A virus (IAV) is a severe worldwide threat to public health and economic development due to its high morbidity and mortality. Marine-derived fungi have been evidenced as a prolific source for the discovery of pharmacologically-active lead compounds. During the course of our search for novel bioactive substances from marine microorganisms, six new polyketides, including two octaketides (1-2), one chromone derivative (13), two highly substituted phthalides (17-18), and one α-pyrone derivative (21) along with 22 known congeners were isolated from a mangrove-associated fungus Diaporthe sp. SCSIO 41011. Their structures were determined by spectroscopic analysis and by comparison with literature data. And the absolute configurations were established according to the specific rotation or electron circular dichroism method. Antiviral evaluation results revealed that compounds 14, 15, 26, and 5-chloroisorotiorin displayed significant anti-IAV activities against three influenza A virus subtypes, including A/Puerto Rico/8/34 H274Y (H1N1), A/FM-1/1/47 (H1N1), and A/Aichi/2/68 (H3N2), with IC₅₀ values in the range of 2.52-39.97 μM. The preliminary structure-activity relationships (SARs) are also discussed. These findings expand the chemical and bioactive diversity of polyketides derived from the genus Diaporthe, and also provide a basis for further development and utilization of chromone, xanthone, and chloroazaphilone derivatives as source of potential anti-viral chemotherapy agents.

An epigenetic modifier induces production of (10'S)-verruculide B, an inhibitor of protein tyrosine phosphatases by Phoma sp. nov. LG0217, a fungal endophyte of Parkinsonia microphylla

Incorporation of the histone deacetylase (HDAC) inhibitor, suberoylanilide hydroxamic acid (SAHA), to a culture broth of the endophytic fungus Phoma sp. nov. LG0217 isolated from Parkinsonia microphylla changed its metabolite profile and resulted in the production of (10'S)-verruculide B (1), vermistatin (2) and dihydrovermistatin (3). When cultured in the absence of the epigenetic modifier, it produced a new metabolite, (S,Z)-5-(3',4'-dihydroxybutyldiene)-3-propylfuran-2(5H)-one (4) together with nafuredin (5). The structure of 4 was elucidated by spectroscopic analyses and its absolute configuration was determined by application of the modified Mosher's ester method. The absolute structure of (10'S)-verruculide B was determined as 5-[(10'S,2'E,6'E)-10',11'-dihydroxy-3',7',11'-trimethyldodeca-2',6'-dien-1'-yl]-(3R)-6,8-dihydroxy-3-methylisochroman-1-one (1) with the help of CD and NOE data. Compound 1 inhibited the activity of protein tyrosine phosphatases (PTPs) 1B (PTP1B), Src homology 2-containing PTP 1 (SHP1) and T-cell PTP (TCPTP) with IC50 values of 13.7±3.4, 8.8±0.6, and 16.6±3.8μM, respectively. Significance of these activities and observed modest selectivity of 1 for SHP1 over PTP1B and TCPTP is discussed.

Anticancer and antifungal compounds from Aspergillus, Penicillium and other filamentous fungi

This review covers important anticancer and antifungal compounds reported from filamentous fungi and in particular from Aspergillus, Penicillium and Talaromyces. The taxonomy of these fungi is not trivial, so a focus of this review has been to report the correct identity of the producing organisms based on substantial previous in-house chemotaxonomic studies.

Phylogeny and nomenclature of the genus Talaromyces and taxa accommodated in Penicillium subgenus Biverticillium

The taxonomic history of anamorphic species attributed to Penicillium subgenus Biverticillium is reviewed, along with evidence supporting their relationship with teleomorphic species classified in Talaromyces. To supplement previous conclusions based on ITS, SSU and/or LSU sequencing that Talaromyces and subgenus Biverticillium comprise a monophyletic group that is distinct from Penicillium at the generic level, the phylogenetic relationships of these two groups with other genera of Trichocomaceae was further studied by sequencing a part of the RPB1 (RNA polymerase II largest subunit) gene. Talaromyces species and most species of Penicillium subgenus Biverticilliumsensu Pitt reside in a monophyletic clade distant from species of other subgenera of Penicillium. For detailed phylogenetic analysis of species relationships, the ITS region (incl. 5.8S nrDNA) was sequenced for the available type strains and/or representative isolates of Talaromyces and related biverticillate anamorphic species. Extrolite profiles were compiled for all type strains and many supplementary cultures. All evidence supports our conclusions that Penicillium subgenus Biverticillium is distinct from other subgenera in Penicillium and should be taxonomically unified with the Talaromyces species that reside in the same clade. Following the concepts of nomenclatural priority and single name nomenclature, we transfer all accepted species of Penicillium subgenus Biverticillium to Talaromyces. A holomorphic generic diagnosis for the expanded concept of Talaromyces, including teleomorph and anamorph characters, is provided. A list of accepted Talaromyces names and newly combined Penicillium names is given. Species of biotechnological and medical importance, such as P. funiculosum and P. marneffei, are now combined in Talaromyces. Excluded species and taxa that need further taxonomic study are discussed. An appendix lists other generic names, usually considered synonyms of Penicillium sensu lato that were considered prior to our adoption of the name Talaromyces.

TAXONOMIC NOVELTIES

Taxonomic novelties:New species - Talaromyces apiculatus Samson, Yilmaz & Frisvad, sp. nov. New combinationsand names - Talaromyces aculeatus (Raper & Fennell) Samson, Yilmaz, Frisvad & Seifert, T. albobiverticillius (H.-M. Hsieh, Y.-M. Ju & S.-Y. Hsieh) Samson, Yilmaz, Frisvad & Seifert, T. allahabadensis (B.S. Mehrotra & D. Kumar) Samson, Yilmaz & Frisvad, T. aurantiacus (J.H. Mill., Giddens & A.A. Foster) Samson, Yilmaz, & Frisvad, T. boninensis (Yaguchi & Udagawa) Samson, Yilmaz, & Frisvad, T. brunneus (Udagawa) Samson, Yilmaz & Frisvad, T. calidicanius (J.L. Chen) Samson, Yilmaz & Frisvad, T. cecidicola (Seifert, Hoekstra & Frisvad) Samson, Yilmaz, Frisvad & Seifert, T. coalescens (Quintan.) Samson, Yilmaz & Frisvad, T. dendriticus (Pitt) Samson, Yilmaz, Frisvad & Seifert, T. diversus (Raper & Fennell) Samson, Yilmaz & Frisvad, T. duclauxii (Delacr.) Samson, Yilmaz, Frisvad & Seifert, T. echinosporus (Nehira) Samson, Yilmaz & Frisvad, comb. nov. T. erythromellis (A.D. Hocking) Samson, Yilmaz, Frisvad & Seifert, T. funiculosus (Thom) Samson, Yilmaz, Frisvad & Seifert, T. islandicus (Sopp) Samson, Yilmaz, Frisvad & Seifert, T. loliensis (Pitt) Samson, Yilmaz & Frisvad, T. marneffei (Segretain, Capponi & Sureau) Samson, Yilmaz, Frisvad & Seifert, T. minioluteus (Dierckx) Samson, Yilmaz, Frisvad & Seifert, T. palmae (Samson, Stolk & Frisvad) Samson, Yilmaz, Frisvad & Seifert, T. panamensis (Samson, Stolk & Frisvad) Samson, Yilmaz, Frisvad & Seifert, T. paucisporus (Yaguchi, Someya & Udagawa) Samson & Houbraken T. phialosporus (Udagawa) Samson, Yilmaz & Frisvad, T. piceus (Raper & Fennell) Samson, Yilmaz, Frisvad & Seifert, T. pinophilus (Hedgcock) Samson, Yilmaz, Frisvad & Seifert, T. pittii (Quintan.) Samson, Yilmaz, Frisvad & Seifert, T. primulinus (Pitt) Samson, Yilmaz & Frisvad, T. proteolyticus (Kamyschko) Samson, Yilmaz & Frisvad, T. pseudostromaticus (Hodges, G.M. Warner, Rogerson) Samson, Yilmaz, Frisvad & Seifert, T. purpurogenus (Stoll) Samson, Yilmaz, Frisvad & Seifert, T. rademirici (Quintan.) Samson, Yilmaz & Frisvad, T. radicus (A.D. Hocking & Whitelaw) Samson, Yilmaz, Frisvad & Seifert, T. ramulosus (Visagie & K. Jacobs) Samson, Yilmaz, Frisvad & Seifert, T. rubicundus (J.H. Mill., Giddens & A.A. Foster) Samson, Yilmaz, Frisvad & Seifert, T. rugulosus (Thom) Samson, Yilmaz, Frisvad & Seifert, T. sabulosus (Pitt & A.D. Hocking) Samson, Yilmaz & Frisvad, T. siamensis (Manoch & C. Ramírez) Samson, Yilmaz & Frisvad, T. sublevisporus (Yaguchi & Udagawa) Samson, Yilmaz & Frisvad, T. variabilis (Sopp) Samson, Yilmaz, Frisvad & Seifert, T. varians (G. Sm.) Samson, Yilmaz & Frisvad, T. verruculosus (Peyronel) Samson, Yilmaz, Frisvad & Seifert, T. viridulus Samson, Yilmaz & Frisvad.

Caspase-1 inhibitors from an extremophilic fungus that target specific leukemia cell lines

Berkeley Pit Lake, Butte, Montana, is a 540 m deep abandoned open-pit copper mine filled with over 140 billion liters of acidic, metal-sulfate-contaminated water. This harsh environment has yielded several microorganisms that produce interesting biologically active compounds. Several polyketide metabolites including the new berkazaphilones A (1) and B (2) and octadienoic acid derivatives berkedienoic acid (13) and berkedienolactone (15), as well as previously reported azaphilone 4, vermistatin (6), dihydrovermistatin (7), penisimplicissin (8), aldehyde 9, and methylparaconic acid (11), were isolated from a culture broth of Penicillium rubrum taken from a depth of 270 m. The structures of these compounds were deduced by interpretation of spectroscopic data. The compounds were isolated either for their inhibition of the signal transduction enzyme caspase-1 or because of their structural similarity to these inhibitors. Selected compounds were further evaluated for their ability to inhibit interleukin-1β production by inflammasomes in induced THP-1 cells. Berkazaphilones B (2) and C (4) and vermistatin analogue penisimplicissin (8) exhibited selective activity against leukemia cancer cell lines in the National Cancer Institute 60 human cell line assay.

Occurence and bioactivities of funicone-related compounds

Studies on production of secondary metabolites by fungi have received a substantial boost lately, particularly with reference to applications of their biological properties in human medicine. Funicones represent a series of related compounds for which there is accumulating evidence supporting their possible use as pharmaceuticals. This paper provides a review on the current status of knowledge on these fungal extrolites, with special reference to aspects concerning their molecular structures and biological activities.

Penicidones A-C, three cytotoxic alkaloidal metabolites of an endophytic Penicillium sp

Along with the known secondary metabolites lumichrome, physcion, and emodin-1,6-dimethyl ether, three alkaloids named penicidones A-C (1-3) were isolated from the culture of Penicillium sp. IFB-E022, an endophytic fungal strain residing in the stem of Quercus variabilis (Fagaceae). The structures of penicidones A-C were established by a correlative interpretation of spectroscopic data including IR, UV and HR-ESI-MS, as well as by analysis of a set of 1D and 2D NMR experiments. The stereochemistry of compounds 1 and 2 was obtained by comparison of the optical rotation with those of vermistatin and its analogues. Penicidones A-C were the first group of natural products possessing a penicidone framework. Compounds 1-3 exhibited moderate cytotoxicity against four cancer cell lines.