Detection of aflatoxin B1 in chili powder using attenuated total reflectance-Fourier transform infrared spectroscopy.

Aflatoxin B1, a major global food safety concern, is produced by toxigenic fungi during crop growing, drying, and storage, and shows increasing annual prevalence. This study aimed to detect aflatoxin B1 in chili samples using ATR-FTIR coupled with machine learning algorithms. We found that 83.6% of the chili powder samples were contaminated with Aspergillus and Penicillium species, with aflatoxin B1 levels ranging from 7.63 to 44.32 µg/kg. ATR-FTIR spectroscopy in the fingerprint region (1800-400 cm-1) showed peak intensity variation in the bands at 1587, 1393, and 1038 cm-1, which are mostly related to aflatoxin B1 structure. The PCA plots from samples with different trace amounts of aflatoxin B1 could not be separated. Vibrational spectroscopy combined with machine learning was applied to address this issue. The logistic regression model had the best F1 score with the highest %accuracy (73%), %sensitivity (73%), and %specificity (71%), followed by random forest and support vector machine models. Although the logistic regression model contributed significant findings, this study represents a laboratory research project. Because of the peculiarities of the ATR-FTIR spectral measurements, the spectra measured for several batches may differ, necessitating running the model on multiple spectral ranges and using increased sample sizes in subsequent applications. This proposed method has the potential to provide rapid and accurate results and may be valuable in future applications regarding toxin detection in foods when simple onsite testing is required.

Sorbremnoids A and B: NLRP3 Inflammasome Inhibitors Discovered from Spatially Restricted Crosstalk of Biosynthetic Pathways.

Crosstalk-oriented chemical evolution of natural products (NPs) is an efficacious strategy for generating novel skeletons through coupling reactions between NP fragments. In this study, two NOD-like receptor protein 3 (NLRP3) inflammasome inhibitors, sorbremnoids A and B (1 and 2), with unprecedented chemical architectures were identified from a fungus Penicillium citrinum. Compounds 1 and 2 exemplify rare instances of hybrid NPs formed via a major facilitator superfamily (MFS)-like enzyme by coupling reactive intermediates from two separate biosynthetic gene clusters (BGCs), pcisor and pci56. Both sorbremnoids A and B are NLRP3 inflammasome inhibitors. Sorbremnoid A demonstrated strong inhibition of IL-1ß by directly binding to the NLRP3 protein, inhibiting the assembly and activation of the NLRP3 inflammasome in vitro, with potential application in diabetic refractory wound healing through the suppression of excessive inflammatory responses. This research will inspire the development of anti-NLRP3 inflammasome agents as lead treatments and enhance knowledge pertaining to NPs derived from biosynthetic crosstalk.

New steroids from mangrove-associated fungus Trichoderma asperellum SCNU-F0048.

Chemical investigation of the fungus Trichoderma asperellum SCNU-F0048 led to the discovery of two new steroids, ergosta-4,6,8 (14),22-tetraen-3-(3'-methyl-4'-hydroxyl-γ-butenolide) (1) and camphosterol B (2), as well as two known compounds, i.e. stigmasta-4,6,8(14),22-tetraen-3-one (3) and 4-hydroxy-17- methylincisterol (4). Their structures were elucidated by extensive nuclear mangnetic resonance, spectrum analysis and single crystal X-ray diffraction analysis. Bioassay disclosed that compound 1 showed strong cytotoxicity to a panel of tumor cell lines. Moreover, compounds 1 and 2 showed excellent antifungal activity against Penicillium italicum with IC50 values of 0.016 and 0.022 µM, respectively.

Andrastin-type meroterpenoids, α-pyrone polyketides, and sesquicarane derivatives from Penicillium sp., a fungus isolated from Pinus koraiensis seed.

The genus Penicillium has provided us with the household antibiotic penicillin and the well-known lipid-lowering agent mevastatin. The strain Penicillium sp. SZ-1 was found to grow vigorously in an intact Pinus koraiensis seed, it is inferred that the strain may develop unique mechanisms associated with the biosynthesis of rare metabolites. Further fermentation of the strain on solid rice medium yielded thirteen undescribed compounds, including three andrastin-type meroterpenoids (1-3), two α-pyrone polyketides (4 and 5), and eight sesquicarane derivatives (6-13), along with seven known compounds (14-20). Their structures were determined by detailed analysis of the spectroscopic and spectrometric data (NMR and HRESIMS), in addition to comparisons of the experimental and calculated ECD data for absolute configurational assignments. The hemiacetal moiety in compounds 1 and 2 and the 3α-hydroxy group in compound 3 were rarely found in the andrastin-type meroterpenoid family. The sesquicaranes belong to a small group of sesquiterpenoid that are rarely reported. Bioassay study showed that compound 1 exhibited inhibitory effects against Staphylococcus aureus ATCC 29213 and Escherichia coli ATCC 25922 with MIC values of 64 and 32 µg/mL, respectively. In addition, compounds 1 and 3 displayed weak DPPH radical scavenging activities. The andrastins and sesquicaranes in this study enriched the structural diversity of these classes of terpenoids. Of note, this study is the first report on the metabolites of a fungus isolated from P. koraiensis seed.

Peniapyrones A-I, Cytotoxic Tricyclic-Fused α-Pyrone Derivatives from an Endophytic Penicillium brefeldianum F4a.

Five cyclopenta[d]pyrano[4,3-b]pyran-1,7(6H)-dione 6/6/5-fused tricyclic ring system containing metabolites peniapyrones A-E (1-5), and four previously undescribed cyclopenta[4,5]furo[3,2-c]pyran-1-one 6/5/5-fused tricyclic ring system containing compounds peniapyrones F-I (6-9), were isolated from the endophytic Penicillium brefeldianum F4a. Their structures, including absolute configurations, were determined through spectroscopic analysis and quantum chemical calculations. Peniapyrones D (4) and E (5) were a pair of diastereoisomers. Compounds 1, 3, and 5-9 showed cytotoxic activity against AsPC-1, CRL-2234, and MCF-7 cancer cell lines. Compounds 1, 3, 6, 8, and 9 inhibited the Kirsten rat sarcoma viral oncogene homologue (KRAS) mutant AsPC-1 cell line.

Penifuranone A: A Novel Alkaloid from the Mangrove Endophytic Fungus Penicillium crustosum SCNU-F0006.

One previously undescribed alkaloid, named penifuranone A (1), and three known compounds (2-4) were isolated from the mangrove endophytic fungus Penicillium crustosum SCNU-F0006. The structure of the new alkaloid (1) was elucidated based on extensive spectroscopic data analysis and single-crystal X-ray diffraction analysis. Four natural isolates and one new synthetic derivative of penifuranone A, compound 1a, were screened for their antimicrobial, antioxidant, and anti-inflammatory activities. Bioassays revealed that penifuranone A (1) exhibited strong anti-inflammatory activity in vitro by inhibiting nitric oxide (NO) production in lipopolysaccharide-activated RAW264.7 cells with an IC50 value of 42.2 µM. The docking study revealed that compound 1 exhibited an ideal fit within the active site of the murine inducible nitric oxide synthase (iNOS), establishing characteristic hydrogen bonds.

Characterization and antioxidant properties of three exopolysaccharides produced by the Cyclocarya paliurus endophytic fungus.

In recent years, the considerable potential of endophytic bacteria and fungi as prolific producers of exopolysaccharides (EPSs) have attracted interest. In this study, 56 endophytes were isolated from Cyclocarya paliurus, and the secondary metabolites of EPSs were extracted from Monascus purpureus, Penicillium citrinum and Aspergillus versicolor, screened, and named MPE, PCE and AVE, respectively. In this work, the physicochemical properties and antioxidant activities of three EPSs, their cell proliferation activity on IEC-6 and RAW264.7 were investigated. The three EPSs were mainly composed of neutral sugar and differ in microstructure. However, MPE had a loose structure, and PCE exhibited a dense and sheet-like structure. In addition, the three EPSs performed ordinary antioxidant activity in vitro but showed excellent cell proliferation activity on IEC-6 and RAW264.7. The cell proliferation activity of PCE was 1.4-fold that of the controls at a concentration of 800 µg/mL on IEC-6, and MPE exhibited 1.3-fold increase on RAW264.7. This study provided scientific evidence and insights into the application of endophytes as a novel plant resource possessing huge application potential.

Hot off the Press.

A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products, such as penihemeroterpenoid A from Penicillium herquei.

Novel Bioactive Natural Products from Marine-Derived Penicillium Fungi: A Review (2021-2023).

Marine-derived Penicillium fungi are productive sources of structurally unique and diverse bioactive secondary metabolites, representing a hot topic in natural product research. This review describes structural diversity, bioactivities and statistical research of 452 new natural products from marine-derived Penicillium fungi covering 2021 to 2023. Sediments are the main sources of marine-derived Penicillium fungi for producing nearly 56% new natural products. Polyketides, alkaloids, and terpenoids displayed diverse biological activities and are the major contributors to antibacterial activity, cytotoxicity, anti-inflammatory and enzyme inhibitory capacities. Polyketides had higher proportions of new bioactive compounds in new compounds than other chemical classes. The characteristics of studies in recent years are presented.

Azaphilone pigments from the marine-derived Penicillium sclerotium UJNMF 0503 and their neuroprotective potential against H2O2-induced cell apoptosis through modulating PI3K/Akt pathway.

Azaphilones represent a particular group of fascinating pigments from fungal source, with easier industrialization and lower cost than the traditional plant-derived pigments, and they also display a wide range of pharmacological activities. Herein, 28 azaphilone analogs, including 12 new ones, were obtained from the fermentation culture of a marine fungus Penicillium sclerotium UJNMF 0503. Their structures were elucidated by MS, NMR and ECD analyses, together with NMR and ECD calculations and biogenetic considerations. Among them, compounds 1 and 2 feature an unusual natural benzo[d][1,3]dioxepine ring embedded with an orthoformate unit, while 3 and 4 represent the first azaphilone examples incorporating a novel rearranged 5/6 bicyclic core and a tetrahydropyran ring on the side chain, respectively. Our bioassays revealed that half of the isolates exhibited neuroprotective potential against H2O2-induced injury on RSC96 cells, while compound 13 displayed the best rescuing capacity toward the cell viability by blocking cellular apoptosis, which was likely achieved by upregulating the PI3K/Akt signaling pathway.

The cryptic metabolites and anti-phytopathogenic activities from Nigrospora lacticolonia and Penicillium rubens uncovered by the synergism with host Paris polyphylla, monoculture, and co-culture.

The synergism of host Paris polyphylla medium, the monoculture, and the coculture led to seventeen new metabolites, including eight sesquiterpenes, 1-7 having uncommon structural motifs compared to similar caryophyllene derivatives, 8 with an unprecedented bicyclic framework, and three xyloketals (13-15) with unprecedented frameworks from Nigrospora lacticolonia; one polyketide, 17 with novel bicyclo [2.2.2] undecane skeleton, and five polyketide-terpenoid hybrids, 20 (one novel sulfated), 21-24 from Penicillium rubens. The structures were determined mainly by the NMR, HRESIMS, ECD calculation, and single-crystal X-ray diffraction. Nine cryptic compounds (2-4, 5, 12-15, 17) were produced by the inductions of host medium and the coculture. The compounds 13 from N. lacticolonia, 24-26, 28, 29, and 31 from P. rubens indicated significant antiphytopathogenic activities against N. lacticolonia with MICs at 2-4 µg/mL. Moreover, compounds 22-26, 28, 29, and 31 from P. rubens showed antifungal activities against P. rubens with MICs at 2-4 µg/mL. The synergistic effects of host medium and the coculture can induce the structural diversity of metabolites.

Neuroprotective azaphilones from a deep-sea derived fungus Penicillium sp. SCSIO41030.

Ten azaphilones including one pair of new epimers and three new ones, penineulones A-E (1-5) with the same structural core of angular deflectin, were obtained from a deep-sea derived Penicillium sp. SCSIO41030 fermented on a liquid medium. Their structures including absolute configurations were elucidated using chiral-phase HPLC analysis, extensive NMR spectroscopic and HRESIMS data, ECD and NMR calculations, and by comparing NMR data with literature data. Biological assays showed that the azaphilones possessed no antitumor and anti-viral (HSV-1/2) activities at concentrations of 5.0 µM and 20 µM, respectively. In addition, azaphilones 8 and 9 showed neuroprotective effects against Aß25-35-induced neurotoxicity in primary cultured cortical neurons at a concentration of 10 µM. Azaphilones 8 and 9 dramatically promoted axonal regrowth against Aß25-35-induced axonal atrophy. Our study indicated that azaphilones could be promising lead compounds for neuroprotection.

A New Quinazolinone Alkaloid along with Known Compounds with Seed-Germination-Promoting Activity from Rhodiola tibetica Endophytic Fungus Penicillium sp. HJT-A-6.

A new quinazolinone alkaloid named peniquinazolinone A (1), as well as eleven known compounds, 2-(2-hydroxy-3-phenylpropionamido)-N-methylbenzamide (2), viridicatin (3), viridicatol (4), (±)-cyclopeptin (5a/5b), dehydrocyclopeptin (6), cyclopenin (7), cyclopenol (8), methyl-indole-3-carboxylate (9), 2,5-dihydroxyphenyl acetate (10), methyl m-hydroxyphenylacetate (11), and conidiogenone B (12), were isolated from the endophytic Penicillium sp. HJT-A-6. The chemical structures of all the compounds were elucidated by comprehensive spectroscopic analysis, including 1D and 2D NMR and HRESIMS. The absolute configuration at C-13 of peniquinazolinone A (1) was established by applying the modified Mosher's method. Compounds 2, 3, and 7 exhibited an optimal promoting effect on the seed germination of Rhodiola tibetica at a concentration of 0.01 mg/mL, while the optimal concentration for compounds 4 and 9 to promote Rhodiola tibetica seed germination was 0.001 mg/mL. Compound 12 showed optimal seed-germination-promoting activity at a concentration of 0.1 mg/mL. Compared with the positive drug 6-benzyladenine (6-BA), compounds 2, 3, 4, 7, 9, and 12 could extend the seed germination period of Rhodiola tibetica up to the 11th day.

Lipid-Lowering Meroterpenoids Penihemeroterpenoids A-F from Penicillium herquei GZU-31-6 via Targeting the AMPK/ACC/SREBP-1c Signaling Pathway.

Penihemeroterpenoids A-C, the first meroterpenoids with an unprecedented 6/5/6/5/5/6/5 heptacyclic ring system, together with precursors penihemeroterpenoids D-F, were co-isolated from the fungus Penicillium herquei GZU-31-6. Among them, penihemeroterpenoids C-F exhibited lipid-lowering effects comparable to those of the positive control simvastatin by the activation of the AMPK/ACC/SREBP-1c signaling pathway, downregulated the mRNA levels of lipid synthesis genes FAS and PNPLA3, and increased the level of mRNA expression of the lipid export gene MTTP.

Genome Mining of a Deep-Sea-Derived Penicillium allii-sativi Revealed Polyketide-Terpenoid Hybrids with Antiosteoporosis Activity.

Two novel meroterpenoids, alliisativins A and B (1, 2) were discovered through a genome-based exploration of the biosynthetic gene clusters of the deep-sea-derived fungus Penicillium allii-sativi MCCC entry 3A00580. Extensive spectroscopic analysis, quantum calculations, chemical derivatization, and biogenetic considerations were utilized to establish their structures. Alliisativins A and B (1, 2) possess a unique carbon skeleton featuring a drimane sesquiterpene with a highly oxidized polyketide. Noteworthily, alliisativin A (1) showed dual activity in promoting osteogenesis and inhibiting osteoclast, indicating an antiosteoporosis potential.

Secondary metabolites from Penicillium sp. HS-11, a fungal endophyte of Huperzia serrata.

Three new sorbicillinoids sorbicatechols E-G (1-3), along with seven known compounds 4-10, were obtained from the ethanol extract of Penicillium sp. HS-11, a fungal endophyte of the medicinal plant Huperzia serrata. The structures of 1-3 were established by detailed interpretation of the spectroscopic data and their absolute configurations were established by comparative analyses of the ECD spectra. Sorbicatechol G (3) represented the first hybrid sorbicillinoid bearing a tetralone skeleton. In the in-vitro bioassay, trichodimerol (5) exhibited moderate inhibitory activity against the Escherichia coli ß-glucuronidase (EcGUS) with an IC50 value of 92.0 ± 9.4 µM.

Purification of andibenin and a chromanone analogue from rhizospheric Aspergillus flavus and soil-borne Penicillium notatum exhibiting cytotoxic and antibacterial properties.

The discovery of bioactive compounds from fungal natural sources holds immense potential for the development of novel therapeutics. The present study investigates the extracts of soil-borne Penicillium notatum and rhizosphere-inhabiting Aspergillus flavus for their antibacterial, antifungal, and cytotoxic potential. Additionally, two compounds were purified using chromatographic and spectroscopic techniques. The results demonstrated that the ethyl acetate fraction of A. flavus exhibited prominent cytotoxic activity against Artemia salina, whereas the ethyl acetate fraction of P. notatum displayed promising antibacterial potential. At dose concentrations of 10, 100, and 1000 µg mL-1, the ethyl acetate fraction of A. flavus showed mortality percentages of 7.6%, 66.4%, and 90%, respectively. The ethyl acetate fraction of P. notatum extract exhibited significant antibacterial activity, forming inhibition zones measuring 41, 38, 34, 34, and 30 mm against B. subtilis, S. flexneri, E. coli, K. pneumoniae, and S. aureus, respectively, at 1000 µg mL-1. At this concentration, inhibition zones of 28, 27, and 15 mm were recorded for P. vulgaris, S. typhi, and X. oryzae. Using bioassay-guided approach, one compound each was purified from the fungal extracts. The initial purification involved mass spectroscopic analysis, followed by structural elucidation using 500 MHz nuclear magnetic resonance (NMR) spectroscopy. Compound 1, derived from A. flavus, was identified as ethyl 2-hydroxy-5,6-dimethyl-4-oxocyclohex-2-ene-1-carboxylate, with a mass of 212, whereas compound 2, isolated from P. notatum, was identified as 3-amino-2-(cyclopenta-2,4-dien-1-ylamino)-8-methoxy-4H-chromen-4-one, with an exact mass of 270. Based on bioassay results, compound 1 was subjected to brine shrimp lethality assay and compound 2 was tested for its antibacterial potential. Compound 1 exhibited 30% lethality against brine shrimp larvae at a concentration of 100 µg mL-1, whereas at 1000 µg mL-1 the mortality increased to 70%. Compound 2 displayed notable antibacterial potential, forming inhibition zones of 30, 24, 19, and 12 mm against S. aureus, E. coli, B. subtilis, and S. flexneri, respectively. In comparison, the standard antibiotic tetracycline produced inhibition zones of 18, 18, 15, and 10 mm against the respective bacterial strains at the same concentration.

Peniditerpenoids A and B: Oxidized Indole Diterpenoids with Osteoclast Differentiation Inhibitory Activity from a Mangrove-Sediment-Derived Penicillium sp.

An unprecedented di-seco-indole diterpenoid, peniditerpenoid A (1), and a rare N-oxide-containing indole diterpenoid derivative, peniditerpenoid B (2), together with three known ones (3-5), were obtained from the mangrove-sediment-derived fungus Penicillium sp. SCSIO 41411. Their structures were determined by the analysis of spectroscopic data, quantum chemical calculations, and X-ray diffraction analyses. Peniditerpenoid A (1) inhibited lipopolysaccharide-induced NF-κB with an IC50 value of 11 µM and further effectively prevented RANKL-induced osteoclast differentiation in bone marrow macrophages. In vitro studies demonstrated that 1 exerted significant inhibition of NF-κB activation in the classical pathway by preventing TAK1 activation, IκBα phosphorylation, and p65 translocation. Furthermore, 1 effectively reduced the level of NFATc1 activation, resulting in the attenuation of osteoclast differentiation. Our findings suggest that 1 holds promise as an inhibitor with significant potential for the treatment of diseases related to osteoporosis.

Penicilloneines A and B, Quinolone-Citrinin Hybrids from a Starfish-Derived Penicillium sp.

Penicilloneines A (1) and B (2) are the first reported quinolone-citrinin hybrids. They were isolated from the starfish-derived fungus Penicillium sp. GGF16-1-2, and their structures were elucidated using spectroscopic, chemical, computational, and single-crystal X-ray diffraction methods. Penicilloneines A (1) and B (2) share a common 4-hydroxy-1-methyl-2(1H)-quinolone unit; however, they differ in terms of citrinin moieties, and these two units are linked via a methylene bridge. Penicilloneines A (1) and B (2) exhibited antifungal activities against Colletotrichum gloeosporioides, with lethal concentration 50 values of 0.02 and 1.51 µg/mL, respectively. A mechanistic study revealed that 1 could inhibit cell growth and promote cell vacuolization and consequent disruption of the fungal cell walls via upregulating nutrient-related hydrolase genes, including putative hydrolase, acetylcholinesterase, glycosyl hydrolase, leucine aminopeptidase, lipase, and beta-galactosidase, and downregulating their synthase genes 3-carboxymuconate cyclase, pyruvate decarboxylase, phosphoketolase, and oxalate decarboxylase.

The role of glycosylation in non-productive adsorption of cellulase to lignin isolated from pretreated corn stover.

Glycosylation, a general post-translational modification for fungal cellulase, has been shown to affect cellulase binding to its substrate. However, the exact impact of glycosylation on cellulase-lignin interaction remain unclear. Here, we demonstrated that the lignin isolated from tetrahydrofuran-pretreated corn stover exhibits strong adsorption capability to cellulase due to its negatively charged and porous structure. For the cellulases with varying glycosylation levels, the less-glycosylated protein showed high adsorption capability to lignin, and that trend was observed for the main cellulase components secreted by Penicillium oxilicum, including endoglucanase PoCel5B, cellobiohydrolase PoCel7A-2, and ß-glucosidase PoBgl1. Additionally, N-glycan sites and motifs were examined using mass spectrometry, and protein structures with N-glycans were constructed, where PoBgl1 and PoCel7A-2 contained 13 and 1 glycosylated sites respectively. The results of molecular dynamics simulations indicated that the N-glycans impacted on the solvent-accessible surface area and secondary structure of protein, and the binding conformation of lignin fragment on cellulase, resulting in a decrease in binding energy (14 kcal/mol for PoBgl1 and 13 kcal/mol for PoCel7A-2), particularly for van der Waals and electrostatic interaction. Those findings suggested that glycosylation negatively impacted the lignin-cellulase interaction, providing a theoretical basis for the rational engineering of enzymes to reduce lignin-enzyme interaction.