Two new polyketides from the fungus Penicillium oxalicum MHZ153

Several secondary metabolite gene clusters in the genomes of ten Penicillium spp. raise the risk of multiple mycotoxin occurrence in chestnuts

Penicillium spp. produce a great variety of secondary metabolites, including several mycotoxins, on food substrates. Chestnuts represent a favorable substrate for Penicillium spp. development. In this study, the genomes of ten Penicillium species, virulent on chestnuts, were sequenced and annotated: P. bialowiezense. P. pancosmium, P. manginii, P. discolor, P. crustosum, P. palitans, P. viridicatum, P. glandicola, P. taurinense and P. terrarumae. Assembly size ranges from 27.5 to 36.8 Mb and the number of encoded genes ranges from 9,867 to 12,520. The total number of predicted biosynthetic gene clusters (BGCs) in the ten species is 551. The most represented families of BGCs are non ribosomal peptide synthase (191) and polyketide synthase (175), followed by terpene synthases (87). Genome-wide collections of gene phylogenies (phylomes) were reconstructed for each of the newly sequenced Penicillium species allowing for the prediction of orthologous relationships among our species, as well as other 20 annotated Penicillium species available in the public domain. We investigated in silico the presence of BGCs for 10 secondary metabolites, including 5 mycotoxins, whose production was validated in vivo through chemical analyses. Among the clusters present in this set of species we found andrastin A and its related cluster atlantinone A, mycophenolic acid, patulin, penitrem A and the cluster responsible for the synthesis of roquefortine C/glandicoline A/glandicoline B/meleagrin. We confirmed the presence of these clusters in several of the Penicillium species conforming our dataset and verified their capacity to synthesize them in a chestnut-based medium with chemical analysis. Interestingly, we identified mycotoxin clusters in some species for the first time, such as the andrastin A cluster in P. flavigenum and P. taurinense, and the roquefortine C cluster in P. nalgiovense and P. taurinense. Chestnuts proved to be an optimal substrate for species of Penicillium with different mycotoxigenic potential, opening the door to risks related to the occurrence of multiple mycotoxins in the same food matrix.

Anti-Inflammatory Ergosteroid Derivatives from the Coral-Associated Fungi Penicillium oxalicum HL-44

To obtain the optimal fermentation condition for more abundant secondary metabolites, Potato Dextrose Agar (PDA) medium was chosen for the scale-up fermentation of the fungus Penicillium oxalicum HL-44 associated with the soft coral Sinularia gaweli. The EtOAc extract of the fungi HL-44 was subjected to repeated column chromatography (CC) on silica gel and Sephadex LH-20 and semipreparative RP-HPLC to afford a new ergostane-type sterol ester (1) together with fifteen derivatives (2-16). Their structures were determined with spectroscopic analyses and comparisons with reported data. The anti-inflammatory activity of the tested isolates was assessed by evaluating the expression of pro-inflammatory factors Tnfα and Ifnb1 in Raw264.7 cells stimulated with LPS or DMXAA. Compounds 2, 9, and 14 exhibited significant inhibition of Ifnb1 expression, while compounds 2, 4, and 5 showed strong inhibition of Tnfα expression in LPS-stimulated cells. In DMXAA-stimulated cells, compounds 1, 5, and 7 effectively suppressed Ifnb1 expression, whereas compounds 7, 8, and 11 demonstrated the most potent inhibition of Tnfα expression. These findings suggest that the tested compounds may exert their anti-inflammatory effects by modulating the cGAS-STING pathway. This study provides valuable insight into the chemical diversity of ergosteroid derivatives and their potential as anti-inflammatory agents.

A new cytotoxic phenalenone derivative from Penicillium oxalicum

From the supernatant of the fermentation broth of Penicillium oxalicum, we isolated a previously undescribed peniciphenalenin G (1) and three known compounds 2-4. Their chemical structures were established through spectroscopic analysis as well as comparing with data in the literature. Compound 1 displayed a moderate cytotoxicity with IC₅₀ value 21.4 μM (positive drug regorafenib with IC₅₀ value of 8.2 μM) against Caco2 cells while compounds 2 and 3 showed weak cytotoxicities with IC₅₀ value of 52.1 and 39.2 μM, respectively.

Two New Nor-seco-Isodhilarane-Type Meroterpenoids from the Endophytic Fungus Penicillium purpurogenum

Two new nor-seco isodhilarane meroterpenoids (NSIMs), purpurogenolides F (1) and G (2), along with three known meroterpenoid analogs (3-5), were isolated from the cultures of an endophytic fungus, Penicillium purpurogenum. Structures and absolute configurations of the new NSIMs were determined based on extensive spectroscopic data analyses, including HR-ESI-MS, UV, IR, NMR chemical shift calculations together with DP4+ probability analysis, as well as ECD calculations. All the isolated meroterpenoids were assessed for their anti-inflammatory activities, and compound 4 exhibited moderate inhibitory activity against the nitric oxide (NO) production in lipopolysaccharide (LPS) induced RAW 264.7 cells with an IC₅₀ value of 20.85±2.31 μM.

Seco and Nor-seco Isodhilarane-Type Meroterpenoids from Penicillium purpurogenum and the Configuration Revisions of Related Compounds

Seco and nor-seco isodhilarane-type meroterpenoids (SIMs and NSIMs) are mainly found in Penicillium fungi and have been characterized by highly congested polycyclic skeletons and a broad range of bioactivities. However, the literature reports inconsistent configuration assignments for some SIMs and NSIMs, due to their complex polycyclic systems and multichiral centers. Herein, we described eight SIMs and NSIMs isolated from the EtOAc extract of Penicillium purpurogenum, which led to the configuration revisions of purpurogenolide C (1a), berkeleyacetal B (2a), chrysogenolide F (3a), and berkeleyacetal C (4a) as compounds 1-4, respectively. Furthermore, extensive re-evaluation of the experimental and computational ¹³C NMR chemical shifts of the reported 39 SIMs and NSIMs provided an empirical approach for determining the C-9 relative configuration, according to the ¹³C NMR chemical shifts of C-9, which contributed to the configuration revisions of another three SIMs (5a and 6a) and NSIMs (7a), denoted as compounds 5-7, respectively. Biological assays indicated that compound 3 exhibited cytotoxic activity against HepG2 and A549 cell lines with IC₅₀ values of 5.58 and 6.80 μM, respectively. Compounds 2-4, 8, 9, and 32 showed moderate hepatoprotective activity at 10 μM in the APAP-induced HepG2 cell injury model.

Talaromydien a and talaroisocoumarin A, new metabolites from the marine-sourced fungus Talaromyces sp. ZZ1616

New talaromydien A (1) and talaroisocoumarin A (2), together with nine known compounds (3 - 11), were isolated from a culture of the marine-derived Talaromyces sp. ZZ1616 in potato dextrose broth medium. Structures of the new compounds were elucidated based on their HRESIMS data, NMR spectroscopic analyses, the modified Mosher's method, ECD, ¹³C NMR and optical rotation calculations. Talaroisocoumarin A showed antimicrobial activities with MIC values of 36.0 μg/mL against methicillin-resistant Staphylococcus aureus, 32.0 μg/mL against Escherichia coli, and 26.0 μg/mL against Candida albicans.

Mutation, Chemoprofiling, Dereplication, and Isolation of Natural Products from Penicillium oxalicum

Diethyl sulfate (DES)-based chemical mutagenesis was applied on different fungal strains with the aim of diversifying the secondary metabolites. The mutant strain (VRE-MT1) of Penicillium oxalicum was subjected to dereplication (LCMS-based) and isolation of natural products, resulting in obtaining 10 molecules of bioactive potential. Metabolites, viz. tuckolide, methylpenicinoline, 2-acetyl-3,5-dihydroxy-4,6-dimethylbenzeneacetic acid, penicillixanthone A, brefeldin A 7-ketone, and antibiotic FD 549, were observed for the first time from P. oxalicum. The results of antimicrobial activity reveal that the compounds N-[2-(4-hydroxyphenyl)ethenyl]formamide, methylpenicinoline, and penipanoid A have potent antibacterial activity against Bacillus subtilis (ATCC 6633) with minimum inhibitory concentration (MIC) values of 16, 64, and 16 μM, respectively, and the compounds N-[2-(4-hydroxyphenyl)ethenyl]formamide, methylpenicinoline, and penipanoid A were found active against Escherichia coli (ATCC 25922), with MIC values of 16, 64, and 16 μM, respectively. Also, the metabolites N-[2-(4-hydroxyphenyl)ethenyl]formamide and tuckolide showed effective antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid scavenging assays. The mutant VRE-MT1 was found to have 8.34 times higher quantity of N-[2-(4-hydroxyphenyl)ethenyl]formamide as compared to the mother strain. The DES-based mutagenesis strategy has been found to be a potent tool to diversify the secondary metabolites in fungi.

Bioactive isocoumarins isolated from a mangrove-derived fungus Penicillium sp. MGP11

Two new isocoumarins penicimarins L-M (1-2), along with seven known analogues (3-9) were isolated from the mangrove-derived fungus Penicillium sp. MGP11. Compounds 1-2 were established by spectroscopic methods and comparison of their circular dichroism (CD) spectra with the literature. All isolated compounds were evaluated for antioxidant and α-glucosidase inhibitory activities. Compound 8 had better antioxidant activity (IC₅₀ = 4.6 μM) than positive control trolox (IC₅₀ = 12.9 μM). Compounds 5, 8 and 9 exhibited α-glucosidase inhibitory activity with the IC₅₀ values of 776.5, 683.7 and 868.7 μM, respectively.

Phenylhydrazone and Quinazoline Derivatives from the Cold-Seep-Derived Fungus Penicillium oxalicum

Three new phenylhydrazones, penoxahydrazones A-C (compounds 1-3), and two new quinazolines, penoxazolones A (compound 4) and B (compound 5), with unique linkages were isolated from the fungus Penicillium oxalicum obtained from the deep sea cold seep. Their structures and relative configurations were assigned by analysis of 1D/2D NMR and mass spectroscopic data, and the absolute configurations of 1, 4, and 5 were established on the basis of X-ray crystallography or ECD calculations. Compound 1 represents the first natural phenylhydrazone-bearing steroid, while compounds 2 and 3 are rarely occurring phenylhydrazone tautomers. Compounds 4 and 5 are enantiomers that feature quinazoline and cinnamic acid units. Some isolates exhibited inhibition of several marine phytoplankton species and marine-derived bacteria.

New Dihydroisocoumarin Root Growth Inhibitors From the Sponge-Derived Fungus Aspergillus sp. NBUF87

Six new dihydroisocoumarins, aspergimarins A-F (1-6), were discovered together with five known analogs (7-11) from a monoculture of the sponge-derived fungus Aspergillus sp. NBUF87. The structures of these compounds were elucidated through comprehensive spectroscopic methods, and absolute configurations were assigned after X-ray crystallography, use of the modified Mosher's method, and comparison of electronic circular dichroism (ECD) data with literature values for previously reported analogs. Compounds 1-11 were evaluated in a variety of bioassays, and at 100 μM, both 1 and 5 showed significant inhibitory effects on the lateral root growth of Arabidopsis thaliana Columbia-0 (Col-0). Moreover, at 100 μM, 5 also possessed notable inhibition against the primary root growth of Col-0. Meanwhile, 1-11 were all found to be inactive in vitro against acetylcholinesterase (AChE) (IC50 > 100 μM), four different types of human-derived cancer cell lines (IC50 > 50 μM), as well as methicillin-resistant Staphylococcus aureus and Escherichia coli (MIC > 50 μg/mL), and Plasmodium falciparum W2 (EC50 > 100 μg/mL), in phenotypic tests.

Two new dihydroisocoumarins with antimicrobial activities from the fungus Penicillium sp. XR046 collected from Xinren coal area

Two new dihydroisocoumarins (1 and 2), together with six known compounds (3-8), were isolated from the fungus Penicillium sp. XR046 collected from the Xinren coal area of Guizhou province in China. Their structures were elucidated on the basis of spectroscopic analysis. The absolute configurations of C-3 in 1 and 2 were established by comparison of their CD data with those of known compounds. Compounds 1-6 showed anti-microbial activities with MIC values in the range of 50∼100 μg/mL against Candida albicans, Staphylococcus epidermidis, Bacillus subtilis, and Escherichia coli.