Activation of the silent secondary metabolite production by introducing neomycin-resistance in a marine-derived Penicillium purpurogenum G59

Advances on anticancer fungal metabolites: sources, chemical and biological activities in the last decade (2012-2023)

Among microorganisms, fungi are the ones that have the most imagination in producing secondary metabolites with the most varied structural differences, which are produced through different biosynthetic pathways. Therefore, they synthesize secondary metabolites classifiable into numerous families of natural compounds such as amino acids, alkaloids, anthraquinones, aromatic compounds, cyclohexene epoxides, furanones, macrolides, naphthoquinones, polyketides, pyrones, terpenes, etc. They also produced metabolites with very complex structures that can not be classified in the known families of natural compounds. Many fungal metabolites show different biological activities with potential applications in agriculture, food chemistry, cosmetics, pharmacology and medicine. This review is focused on the fungal secondary metabolites with anticancer activity isolated in the last ten years. For some metabolites, when described, their biosynthetic origin, the mode of action and the results of structure activity relationships studies are also reported.

Immunosuppressive steroids quadrilisteroids A-C and derivatives from the terrestrial fungus Aspergillus quadrilineatus

Seven undescribed compounds (1-7) along with six known compounds (8-13) were isolated from Eurotiaceae Aspergillus quadrilineatus. Their structures and absolute configurations were elucidated by NMR, HRESIMS, and ECD calculations. Quadrilisteroids A (1) and B (2) possessed an unprecedented 6/5/6/6/6/5 hexacyclic ring system in conjugation with a highly fused benzene ring, while quadrilisteroid C (3) featured a surprising 6/6/6/5/5-fused carbocyclic skeleton. Quadrilisteroid C (3) exhibited potent inhibitory activity against LPS-induced proliferation of B lymphocyte cells with an IC50 value of 1.03 μM. Compound 4, demonstrated inhibitory activity against Con A-induced proliferation of T lymphocyte cells with IC50 values of 6.42 μM.

Secondary metabolites and their bioactivities from Paecilomyces gunnii YMF1.00003

Four new polyketides (1-4) and seven known compounds (5-11) including three polyketides and four sterols were isolated from the fermented extracts of Paecilomyces gunnii YMF1.00003. The new chemical structures were determined through the analysis of the nuclear magnetic resonance and high-resolution electrospray ionization mass spectrometry, and their configurations were subsequently confirmed by nuclear overhauser effect spectroscopy, the calculated electronic circular dichroism (ECD) spectra, and quantum chemical calculations of the NMR data (qcc NMR). Based on the results of pre-activity screening and compound structure target prediction, certain metabolites were assayed to evaluate their cytotoxic and protein kinase Cα inhibitory activities. Results indicated that 3β-hydroxy-7α-methoxy-5α,6α-epoxy-8(14),22E-dien-ergosta (8) exhibited potent cytotoxic activity, with half-maximal inhibitory concentration values of 3.00 ± 0.27 to 15.69 ± 0.61 μM against five tumor cells, respectively. The new compound gunniiol A (1) showed weak cytotoxic activity at a concentration of 40 μM. At a concentration of 20 μg/mL, compounds 1, 6, and 7 exhibited protein kinase Cα inhibition by 43.63, 40.93, and 57.66%, respectively. This study is the first to report steroids demonstrating good cytotoxicity and polyketides exhibiting inhibitory activity against protein kinase Cα from the extracts of P. gunnii.

Penicimides A and B, two novel diels-alder [4 + 2] cycloaddition ergosteroids from Penicillium herquei

Two novel naturally occurring [4 + 2] Diels-Alder cycloaddition ergosteroids (1 and 2), three undescribed oxidized ergosteroids (3-5), and eleven known analogs (6-16) were isolated from Penicillium herquei. Compounds 1 and 2 represent the first reported cycloadducts of a steroid with 1,4,6-trimethyl-1,6-dihydropyridine-2,5-dione or 4,6-dimethyl-1,6-dihydropyridine-2,5-dione to date. Compound 3 is the C-15 epimer of (22E,24R)-9α,11β-dihydroxyergosta-4,6,8(14),22-tetraen-3-one (14). The chemical structures of these compounds were elucidated through widespread spectroscopic analyses, mainly including HRESIMS and 1D and 2D NMR data, calculated 13C NMR-DP4+ analysis, and electronic circular dichroism (ECD) data analyses. Biological evaluations of Compounds 1-16 revealed that 3, 9-11, and 15 inhibited the production of NO in LPS-induced RAW264.7 cells with an IC50 value from 7.37 ± 0.69 to 38.9 ± 2.25 μM (the positive control dexamethasone IC50: 9.54 ± 0.71 μM). In addition, Compound 3 exhibited a potent inhibitory effect on the secretion of the proinflammatory cytokines TNF-α and IL-6, the transcription level of the proinflammatory macrophage markers TNF-α, and the expression of the iNOS protein.

Citrinin as a potential anti-cancer therapy: A comprehensive review

Citrinin (CIT) is a polyketide-derived mycotoxin, which is produced by many fungal strains belonging to the gerena Monascus, Aspergillus, and Penicillium. It has been postulated that mycotoxins have several toxic mechanisms and are potentially used as antineoplastic agents. Therefore, the present study carried out a systematic review, including articles from 1978 to 2022, by collecting evidence in experimental studies of CIT antiplorifactive activity in cancer. The Data indicate that CIT intervenes in important mediators and cell signaling pathways, including MAPKs, ERK1/2, JNK, Bcl-2, BAX, caspases 3,6,7 and 9, p53, p21, PARP cleavage, MDA, reactive oxygen species (ROS) and antioxidant defenses (SOD, CAT, GST and GPX). These factors demonstrate the potential antitumor drug CIT in inducing cell death, reducing DNA repair capacity and inducing cytotoxic and genotoxic effects in cancer cells.

Rare Carbon-Bridged Citrinin Dimers from the Starfish-Derived Symbiotic Fungus Penicillium sp. GGF16-1-2

Four novel, rare carbon-bridged citrinin dimers, namely dicitrinones G–J (1–4), and five known analogs (5–9) were isolated from the starfish-derived fungus Penicillium sp. GGF 16-1-2. Their structures were elucidated by extensive spectroscopic analysis and quantum chemical calculations. Compounds 1–9 exhibited strong antifungal activities against Colletotrichum gloeosporioides with LD₅₀ values from 0.61 μg/mL to 16.14 μg/mL. Meanwhile, all compounds were evaluated for their cytotoxic activities against human pancreatic cancer BXPC-3 and PANC-1 cell lines; as a result, compound 1 showed more significant cytotoxicities than the positive control against both cell lines. In addition, based on the analyses of the protein-protein interaction (PPI) network and Western blot, 1 could induce apoptosis by activating caspase 3 proteins (CASP3).

Penicillium genus as a source for anti-leukemia compounds: an overview from 1984 to 2020

Penicillium is a widely explored genus due to its chemical diversity and associated biological properties; in addition, it represents an important source for cytotoxic compounds with good application perspectives. Based on these aspects, in this review, Penicillium compounds that presented activity against human leukemia cell lines are being listed and discussed. For this, a careful bibliographic survey was carried out in the main electronic databases, i.e. Scopus, SciFinder, Web of Science and Pubmed. Between 1984 and 2020, thirty seven original papers were selected, when using the search terms Penicillium and leukemia. The occurrence of l-asparaginase produced by some Penicillium spp. was also highlighted since this enzyme is being employed for acute lymphoblastic leukemia and lymphosarcoma therapies. Therefore, this overview aims to demonstrate the potential of metabolites biosynthesized by Penicillium fungi which can be applied in human leukemia therapies and opportunities for designing new lead compounds.

Rare Chromone Derivatives from the Marine-Derived Penicillium citrinum with Anti-Cancer and Anti-Inflammatory Activities

Three new and rare chromone derivatives, epiremisporine C (1), epiremisporine D (2), and epiremisporine E (3), were isolated from marine-derived Penicillium citrinum, together with four known compounds, epiremisporine B (4), penicitrinone A (5), 8-hydroxy-1-methoxycarbonyl-6-methylxanthone (6), and isoconiochaetone C (7). Among the isolated compounds, compounds 2–5 significantly decreased fMLP-induced superoxide anion generation by human neutrophils, with IC₅₀ values of 6.39 ± 0.40, 8.28 ± 0.29, 3.62 ± 0.61, and 2.67 ± 0.10 μM, respectively. Compounds 3 and 4 exhibited cytotoxic activities with IC₅₀ values of 43.82 ± 6.33 and 32.29 ± 4.83 μM, respectively, against non-small lung cancer cell (A549), and Western blot assay confirmed that compounds 3 and 4 markedly induced apoptosis of A549 cells, through Bcl-2, Bax, and caspase 3 signaling cascades.

Two new compounds from a mangrove sediment-derived fungus Penicillium polonicum H175

Two new compounds, 6-acetyl-4-methoxy-3,5-dimethyl-2H-pyran-2-one (1) and (2E,4E)-5-((2S,3S,4R,5R)-3,4-dihydroxy-2,4,5-trimethyltetrahydrofuran-2-yl)-2,4-dimethylpenta-2,4-dienal (2), and 22 known compounds were identified from the mangrove-forest-derived fungus Penicillium polonicum H175. The structures of these compounds were elucidated by analysis of the high-resolution electrospray ionisation mass spectroscopy (HR-ESI-MS), 1 D and 2 D nuclear magnetic resonance (NMR) data. The hypoglycaemic effect of compounds was evaluated by the Tg (Ins: htBidTE-ON; LR) zebrafish model. Compound 3 (aspterric acid) exhibited a significant hypoglycaemic effect equivalent to the positive drug rosiglitazone (RSG) at 10 μmol/L.

Marine-Derived Penicillium purpurogenum Reduces Tumor Size and Ameliorates Inflammation in an Erlich Mice Model

Background: This study addresses the antitumoral properties of Penicillium purpurogenum isolated from a polluted lagoon in Northeastern Brazil. Methods: Ethyl Acetate Extracellular Extract (EAE) was used. The metabolites were studied using direct infusion mass spectrometry. The solid Ehrlich tumor model was used for antitumor activity. Female Swiss mice were divided into groups (n = 10/group) as follows: The negative control (CTL−), treated with a phosphate buffered solution; the positive control (CTL+), treated with cyclophosphamide (25 mg/kg); extract treatments at doses of 4, 20, and 100 mg/kg; animals without tumors or treatments (Sham); and animals without tumors treated with an intermediate dose (EAE20). All treatments were performed intraperitoneally, daily, for 15 days. Subsequently, the animals were euthanized, and the tumor, lymphoid organs, and serum were used for immunological, histological, and biochemical parameter evaluations. Results: The extract was rich in meroterpenoids. All doses significantly reduced tumor size, and the 20 and 100 mg/kg doses reduced tumor-associated inflammation and tumor necrosis. The extract also reduced the cellular infiltration of lymphoid organs and circulating TNF-α levels. The extract did not induce weight loss or renal and hepatic toxic changes. Conclusions: These results indicate that P. purpurogenum exhibits immunomodulatory and antitumor properties in vivo. Thus, fungal fermentation is a valid biotechnological approach to the production of antitumor agents.

The Structural Diversity of Marine Microbial Secondary Metabolites Based on Co-Culture Strategy: 2009-2019

Marine microorganisms have drawn great attention as novel bioactive natural product sources, particularly in the drug discovery area. Using different strategies, marine microbes have the ability to produce a wide variety of molecules. One of these strategies is the co-culturing of marine microbes; if two or more microorganisms are aseptically cultured together in a solid or liquid medium in a certain environment, their competition or synergetic relationship can activate the silent biosynthetic genes to produce cryptic natural products which do not exist in monocultures of the partner microbes. In recent years, the co-cultivation strategy of marine microbes has made more novel natural products with various biological activities. This review focuses on the significant and excellent examples covering sources, types, structures and bioactivities of secondary metabolites based on co-cultures of marine-derived microorganisms from 2009 to 2019. A detailed discussion on future prospects and current challenges in the field of co-culture is also provided on behalf of the authors’ own views of development tendencies.

The Application of Ribosome Engineering to Natural Product Discovery and Yield Improvement in Streptomyces

Microbial natural product drug discovery and development has entered a new era, driven by microbial genomics and synthetic biology. Genome sequencing has revealed the vast potential to produce valuable secondary metabolites in bacteria and fungi. However, many of the biosynthetic gene clusters are silent under standard fermentation conditions. By rational screening for mutations in bacterial ribosomal proteins or RNA polymerases, ribosome engineering is a versatile approach to obtain mutants with improved titers for microbial product formation or new natural products through activating silent biosynthetic gene clusters. In this review, we discuss the mechanism of ribosome engineering and its application to natural product discovery and yield improvement in Streptomyces. Our analysis suggests that ribosome engineering is a rapid and cost-effective approach and could be adapted to speed up the discovery and development of natural product drug leads in the post-genomic era.

From genomics to metabolomics, moving toward an integrated strategy for the discovery of fungal secondary metabolites

Fungal secondary metabolites are defined by bioactive properties that ensure adaptation of the fungus to its environment. Although some of these natural products are promising sources of new lead compounds especially for the pharmaceutical industry, others pose risks to human and animal health. The identification of secondary metabolites is critical to assessing both the utility and risks of these compounds. Since fungi present biological specificities different from other microorganisms, this review covers the different strategies specifically used in fungal studies to perform this critical identification. Strategies focused on the direct detection of the secondary metabolites are firstly reported. Particularly, advances in high-throughput untargeted metabolomics have led to the generation of large datasets whose exploitation and interpretation generally require bioinformatics tools. Then, the genome-based methods used to study the entire fungal metabolic potential are reported. Transcriptomic and proteomic tools used in the discovery of fungal secondary metabolites are presented as links between genomic methods and metabolomic experiments. Finally, the influence of the culture environment on the synthesis of secondary metabolites by fungi is highlighted as a major factor to consider in research on fungal secondary metabolites. Through this review, we seek to emphasize that the discovery of natural products should integrate all of these valuable tools. Attention is also drawn to emerging technologies that will certainly revolutionize fungal research and to the use of computational tools that are necessary but whose results should be interpreted carefully.

Four new antitumor metabolites isolated from a mutant 3-f-31 strain derived from Penicillium purpurogenum G59

Penicimutanolones A (1) and B (2), penicimutanolone A methyl ether (3), and penicimumide (4), four new antitumor metabolites, were isolated from a neomycin-resistant mutant of the marine-derived fungus Penicillium purpurogenum G59. The structures of the compounds were elucidated by spectroscopic methods, and the absolute configurations were determined by X-ray crystallography and calculated ECD. In MTT and SRB assays, compounds 1-3 showed strong inhibitory effects on 14 human cancer cell lines. Compounds 1 and 2 maybe induce apoptosis of cancer cells mainly due to the inhibition of the expression of survivin, a client protein of HSP90. In addition, in vivo antitumor activity was observed for compound 1 in murine sarcoma HCT116 tumor-bearing Kunming mice, using docetaxel as a positive control.

Strategies to diversify natural products for drug discovery

Natural product libraries contain specialized metabolites derived from plants, animals, and microorganisms that play a pivotal role in drug discovery due to their immense structural diversity and wide variety of biological activities. The strategies to greatly extend natural product scaffolds through available biological and chemical approaches offer unique opportunities to access a new series of natural product analogues, enabling the construction of diverse natural product-like libraries. The affordability of these structurally diverse molecules has been a crucial step in accelerating drug discovery. This review provides an overview of various approaches to exploit the diversity of compounds for natural product-based drug development, drawing upon a series of examples to illustrate each strategy.

Penicimutamides D–E: two new prenylated indole alkaloids from a mutant of the marine-derived Penicillium purpurogenum G59

Two new prenylated indole alkaloids, penicimutamides D–E (1–2), were discovered via activating silent pathways in a marine-derived fungus.

Time Dependency of Chemodiversity and Biosynthetic Pathways: An LC-MS Metabolomic Study of Marine-Sourced Penicillium

This work aimed at studying metabolome variations of marine fungal strains along their growth to highlight the importance of the parameter “time” for new natural products discovery. An untargeted time-scale metabolomic study has been performed on two different marine-derived Penicillium strains. They were cultivated for 18 days and their crude extracts were analyzed by HPLC-DAD-HRMS (High Performance Liquid Chromatography-Diode Array Detector-High Resolution Mass Spectrometry) each day. With the example of griseofulvin biosynthesis, a pathway shared by both strains, this work provides a new approach to study biosynthetic pathway regulations, which could be applied to other metabolites and more particularly new ones. Moreover, the results of this study emphasize the interest of such an approach for the discovery of new chemical entities. In particular, at every harvesting time, previously undetected features were observed in the LC-MS (Liquid Chromatography-Mass Spectrometry) data. Therefore, harvesting times for metabolite extraction should be performed at different time points to access the hidden metabolome.

Dung-inhabiting fungi: a potential reservoir of novel secondary metabolites for the control of plant pathogens

Coprophilous fungi are a large group of saprotrophic fungi mostly found in herbivore dung. The number of these fungi undergoing investigation is continually increasing, and new species and genera continue to be described. Dung-inhabiting fungi play an important ecological role in decomposing and recycling nutrients from animal dung. They produce a large array of bioactive secondary metabolites and have a potent enzymatic arsenal able to utilise even complex molecules. Bioactive secondary metabolites are actively involved in interaction with and defence against other organisms whose growth can be inhibited, resulting in an enhanced ecological fitness of producer strains. Currently, these antibiotics and bioactive secondary metabolites are of interest in medicine in particular, while very little information is available concerning their potential use in agriculture. This review introduces the ecology of dung-inhabiting fungi, with particular emphasis on the production of antibiotic compounds as a means to compete with other microorganisms. Owing to the fast pace of technological progress, new approaches to predicting the biosynthesis of bioactive metabolites are proposed. Coprophilous fungi should be considered as elite candidate organisms for the discovery of novel antifungal compounds, above all in view of their exploitation for crop protection.

A novel oxaphenalenone, penicimutalidine: activated production of oxaphenalenones by the diethyl sulphate mutagenesis of marine-derived fungus Penicillium purpurogenum G59

One new (1) and three known oxaphenalenones (2–4) were obtained by activating silent pathways in a marine-derived fungus.

Chromosulfine, a novel cyclopentachromone sulfide produced by a marine-derived fungus after introduction of neomycin resistance

The discovery of chromosulfine, a novel cyclopentachromone sulfide generated by activating silent fungal pathways in a marine-derived fungus, was reported.

Penicimutamides A–C: rare carbamate-containing alkaloids from a mutant of the marine-derived Penicillium purpurogenum G59

Three new and rare carbamate-containing penicimutamides A–C (1–3) were discovered via activating silent pathways in a marine-derived fungus.

Rare Chromones from a Fungal Mutant of the Marine-Derived Penicillium purpurogenum G59

Three new and rare chromones, named epiremisporine B (2), epiremisporine B1 (3) and isoconiochaetone C (4), along with three known remisporine B (1), coniochaetone A (5) and methyl 8-hydroxy-6-methyl-9-oxo-9H-xanthene-1-carboxylate (6) were isolated from a mutant from the diethyl sulfate (DES) mutagenesis of a marine-derived Penicillium purpurogenum G59. The structures of 2–4 including the absolute configurations were determined by spectroscopic methods, especially by NMR analysis and electronic circular dichroism (ECD) experiments in conjunction with calculations. The absolute configuration of the known remisporine B (1) was determined for the first time. Compounds 2 and 3 have a rare feature that has only been reported in one example so far. The compounds 1–6 were evaluated for their cytotoxicity against several human cancer cell lines. The present work explored the great potential of our previous DES mutagenesis strategy for activating silent fungal pathways, which has accelerated the discovery of new bioactive compounds.