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.

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.

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.

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.

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.

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.

Alkaloid-metabolites from the mangrove-derived fungus Penicillium robsamsonii HNNU0006.

Nine metabolites, including three undescribed alkaloids pyripyropenes VW (1-2), penicioxa A (4), two previously reported pyripyropene A (3), oxaline (5), three grisephenone-type xanthone derivatives (6-8), and a diphenyl ether derivative 4-chloro-7,4'-dihydroxy-5,2'-dimethoxy-2-methylformate-6'-methybenzophone (9), were isolated from cultures of the mangrove-derived fungus Penicillium robsamsonii HNNU0006. Their structures were determined by spectroscopic analysis, ECD calculations, together with DP4+ probability analysis. Furthermore, all the isolated compounds were tested for cytotoxicity and anti-phytopathogenic fungal activities. Compounds 6-8 showed moderate cytotoxicity against tumor cell lines A549, with IC50 values ranging from 5.68 ± 0.21 to 9.71 ± 0.34 µg/mL, respectively.

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.

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.

Antioxidant compounds produced by endolichenic fungus Penicillium sp.-strain 1322P isolated from Pyxine subcinerea.

Endolichenic fungi are expecting for new bioresources of pharmacological compounds. However, the number of investigations targeting antioxidant compounds produced by endolichenic fungi remains limited. To discover new antioxidant compounds, we analyzed the antioxidant activity of the methanol extracts derived from isolated lichen mycobionts or endolichenic fungi induced from Pyxine subcinerea. We performed this analysis using the oxygen radical absorbance capacity (ORAC) method. As a result, we isolated from an endolichenic fungus identified as Penicillium sp.-stain 1322P in Pyxine subcinerea. This fungus produced a red pigment, and its chemical structure was determined to be sclerotioramine based on the analytical data obtained from NMR, LC-MS/MS, and HPLC-PDA. Sclerotioramine exhibited high antioxidant activity, and the ORAC values (mean ± SD) of sclerotioramine and sclerotiorin were 11.4 ± 0.36 and 4.86 ± 0.70 mmol TE per gram of the respective pure compound. Thus, the antioxidant activity of sclerotioramine was greater than twice that of sclerotiorin. This work represents the first report that the antioxidant activity of sclerotioramine is higher than that of the sclerotiorin.

Five previously undescribed citrinin derivatives from the endophytic fungus Penicillium citrinum GZWMJZ-836.

Penicillium citrinum GZWMJZ-836 is an endophytic fungus from Drynaria roosii Nakaike. Five previously undescribed citrinin derivatives (1-5) and six intermediates related to their biosynthesis (6-11) were obtained from the extract of this strain's solid fermentation using multiple column chromatography separations, including high-performance liquid chromatography. The structures of these compounds were determined through comprehensive spectroscopic analyses, primarily using NMR and HRESIMS data. The stereochemistry was mainly confirmed by ECD calculations, and the configurations of C-7' in compounds 4 and 5 were determined using 13C NMR calculations. Compounds 4-5 and 8 showed antibacterial activity against five strains, with minimum inhibitory concentration values ranging from 7.8 to 125 µM. Compounds 4 and 7 exhibited inhibitions against three plant pathogenic fungi, with IC50 values ranging from 66.6 to 152.1 µM. Additionally, a putative biosynthetic pathway for compounds 1-5 derived from citrinin was proposed.

Penigrines A-E: Five undescribed azepine-indole alkaloids from Penicillium griseofulvum.

Penigrines A-E (1-5), five undescribed azepine-indole alkaloids, were isolated from the fungus Penicillium griseofulvum. Their structures with absolute configurations were determined by NMR, HRESIMS, ECD calculation, and X-ray diffraction experiments. Penigrine C (3) possesses an undescribed 6-oxa-8-azabicyclo[3.2.2]nonane-7,9-dione moiety that fused to an indole core, and penigrines D and E (4 and 5) are a pair of epimers. The plausible biosynthetic pathways of 1-5 are proposed. Penigrine A (1) shows the potential for heart failure treatment.

Anti-diabetic and anti-inflammatory indole diterpenes from the marine-derived fungus Penicillium sp. ZYX-Z-143.

Seven new indole-diterpenoids, penpaxilloids A-E (1-5), 7-methoxypaxilline-13-ene (6), and 10-hydroxy-paspaline (7), along with 20 known ones (8-27), were isolated from the marine-derived fungus Penicillium sp. ZYX-Z-143. Among them, compound 1 was a spiro indole-diterpenoid bearing a 2,3,3a,5-tetrahydro-1H-benzo[d]pyrrolo[2,1-b][1,3]oxazin-1-one motif. Compound 2 was characterized by a unique heptacyclic system featuring a rare 3,6,8-trioxabicyclo[3.2.1]octane unit. The structures of the new compounds were established by extensive spectroscopic analyses, NMR calculations coupled with the DP4 + analysis, and ECD calculations. The plausible biogenetic pathway of two unprecedented indole diterpenoids, penpaxilloids A and B (1 and 2), was postulated. Compound 1 acted as a noncompetitive inhibitor against protein tyrosine phosphatase 1B (PTP1B) with IC50 value of 8.60 ± 0.53 µM. Compound 17 showed significant α-glucosidase inhibitory activity with IC50 value of 19.96 ± 0.32 µM. Moreover, compounds 4, 8, and 22 potently suppressed nitric oxide production on lipopolysaccharide-stimulated RAW264.7 macrophages.

Structure-Guided Discovery of Diverse Cytotoxic Dimeric Xanthones/Chromanones from Penicillium chrysogenum C-7-2-1 and Their Interconversion Properties.

Xanthone-chromanone homo- or heterodimers are regarded as a novel class of topoisomerase (Topo) inhibitors; however, limited information about these compounds is currently available. Here, 14 new (1-14) and 6 known tetrahydroxanthone chromanone homo- and heterodimers (15-20) are reported as isolated from Penicillium chrysogenum C-7-2-1. Their structures and absolute configurations were unambiguously demonstrated by a combination of spectroscopic data, single-crystal X-ray diffraction, modified Mosher's method, and electronic circular dichroism analyses. Plausible biosynthetic pathways are proposed. For the first time, it was discovered that tetrahydroxanthones can convert to chromanones in water, whereas chromone dimerization does not show this property. Among them, compounds 5, 7, 8, and 16 exhibited significant cytotoxicity against H23 cell line with IC50 values of 6.9, 6.4, 3.9, and 2.6 µM, respectively.

Penisimplicins A and B: Novel Polyketide-Peptide Hybrid Alkaloids from the Fungus Penicillium simplicissimum JXCC5.

In this study, two previously undescribed nitrogen-containing compounds, penisimplicins A (1) and B (2), were isolated from Penicillium simplicissimum JXCC5. The structures of 1 and 2 were elucidated on the basis of comprehensive spectroscopic data analysis, including 1D and 2D NMR and HRESIMS data. The absolute configuration of 2 was determined by Marfey's method, ECD calculation, and DP4+ analysis. Both structures of 1 and 2 feature an unprecedented manner of amino acid-derivatives attaching to a polyketide moiety by C-C bond. The postulated biosynthetic pathways for 1 and 2 were discussed. Additionally, compound 1 exhibited significant acetylcholinesterase inhibitory activity, with IC50 values of 6.35 µM.

HPPO-Derived Meroterpenoids from the Marine-Derived Fungus Penicillium sp. SCSIO 41691.

Seven new 4-hydroxy-6-phenyl-2H-pyran-2-one (HPPO) derived meroterpenoids, 1-methyl-12a,12b-epoxyarisugacin M (1), 1-methyl-4a,12b-epoxyarisugacin M (2), 2,3-dihydroxy-3,4a-epoxy-12a-dehydroxyisoterreulactone A (3), 2-hydroxy-12a-dehydroxyisoterreulactone A (4), 3'-demethoxyterritrems B' (5), 4a-hydroxyarisugacin P (6), and 1-epi-arisugacin H (7), together with two known analogues (8 and 9), were isolated from the marine-derived fungal strain Penicillium sp. SCSIO 41691. Their structures were elucidated by spectroscopic methods, and the absolute configurations of compounds 1 and 3 were determined by single-crystal X-ray diffraction. Among them, 1 and 2 had a unique methyl migration in the basic meroterpenoid skeleton with a 12a,12b-epoxy or 4a,12b-epoxy group, and 3 was a highly oxygenated HPPO-derived meroterpenoid featuring a rare 6/5/6/6/6/6 hexacyclic system with a 3,4a-epoxy group. Biologically, 5 exhibited inhibitory activity against lipopolysaccharide-induced nitric oxide production in RAW 264.7 cells with an IC50 value of 21 µM, more potent than the positive control indomethacin.

Bialorastins A-F, highly oxygenated and polycyclic andrastin-type meroterpenoids with proangiogenic activity from the deep-sea cold-seep-derived fungus Penicillium bialowiezense CS-283.

Six new highly oxygenated and polycyclic andrastin-type meroterpenoids, namely, bialorastins A-F (1-6), were discovered from the culture of Penicillium bialowiezense CS-283, a fungus isolated from the deep-sea cold seep squat lobster Shinkaia crosnieri. The planar structures and absolute configurations of these compounds were determined by detailed analysis of spectroscopic data, single crystal X-ray diffraction, and TDDFT-ECD calculations. Structurally, bialorastin A (1) represents a rare 17-nor-andrastin that possesses an unusual 2-oxaspiro[4.5]decane-1,4-dione moiety with a unique 6/6/6/6/5 polycyclic system, while bialorastin B (2) is also a 17-nor-andrastin featuring a gem-propane-1,2-dione moiety. Additionally, bialorastins C-E (3-5) possess a 6/6/6/6/5/5 fused hexacyclic skeleton, characterized by distinctive 3,23-acetal/lactone-bridged functionalities. All isolated compounds were evaluated for their proangiogenic activities in transgenic zebrafish. Compound 3 exhibited significant proangiogenic activity, which notably increased the number and length of intersegmental blood vessels in model zebrafish in a dose-dependent manner at concentrations of 20 and 40 µM. On a molecular scale, the tested compounds were modeled through molecular docking to have insight into the interactions with the possible target VEGFR2. Mechanistically, RT-qPCR results revealed that compound 3 could promote angiogenesis via activating VEGFR2 and subsequently activating the downstream PI3K/AKT and MAPK signaling pathways. These findings indicate that 3 could be a potential lead compound for developing angiogenesis agents.

Curvularin derivatives from the marine mangrove derived fungus Penicillium sumatrense MA-325.

Sumalarins D-G (1-4), four previously undescribed curvularin derivatives, along with two known related metabolites, curvularin (5) and dehydrocurvularin (6), were isolated and identified from the mangrove-derived fungus Penicillium sumatrense MA-325. Among them, sumalarin D (1) represents a unique example of curvularin derivative featuring a 5-methylfuran-2-yl-methyl group. Their structures were elucidated based on analysis of NMR and MS data as well as comparison of ECD spectra and quantum chemical calculations of NMR, and compound 1 was confirmed by X-ray crystallographic analysis. Compounds 1, 2, 5, and 6 are active against aquatic pathogenic bacteria Vibrio alginolyticus and V. harveyi with MIC values ranging from 4 to 64 µg/mL, while compound 6 is cytotoxic against tumor cell lines 5673, HCT 116, 786-O, and Hela with IC50 values of 3.5, 10.6, 10.9, and 14.9 µM, respectively.