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

Talarostatin, a vermistatin derivative from the soil-derived fungus Talaromyces thailandensis PSU-SPSF059

The soil-derived fungus Talaromyces thailandensis PSU-SPSF059 produced one new vermistatin derivative, talarostatin, and seven known compounds including two vermistatins, two chrodrimanins, two diphenyl ethers and one penicillide derivative. Extensive spectroscopic analysis was performed to identify their structures. The absolute configuration of talarostatin was determined by comparing the experimental and calculated electronic circular dichroism data. The antimicrobial and cytotoxic activities of the isolated secondary metabolites were also evaluated.

Talaromyces sp. Ethyl Acetate Crude Extract as Potential Mosquitocide to Control Culex pipiens quinquefasciatus

Vector control is considered an effective approach to controlling diseases spread by mosquito bites. Entomopathogenic fungi are widely used in agriculture to control insect pests, and fungal metabolites can potentially be developed as effective mosquitocides. In this study, a high-throughput screening method was used to search for potential mosquitocides in the Global Fungal Extract Library (GFEL). We tested the larvicidal activity of 264 fungal ethyl acetate crude extracts against Culex pipiens quinquefasciatus. Nine fungal extracts caused moderate to high mortality rates (>50%), with two fungal extracts (58A7 and 101H12) causing a 100% mortality rate. The lethal concentrations for 50% of the population (LC50) were 44.27 mg/L and 31.90 mg/L, respectively. Fraction 14 had a high mortality rate, with an LC50 value of 12.13 mg/L, and was isolated from 58A7 (Fractions 1-11) and 101H12 (Fractions 12-15). Further analyses showed that Fraction 14 was made up of vermistatin and dihydrovermistatin. In a Cx. p. quinquefasciatus larvicidal bioassay, vermistatin (LC50 = 28.13 mg/L) was more toxic than dihydrovermistatin (LC50 = 83.87 mg/L). Our findings suggested that the active fungal extract 101H12 from Talaromyces sp. and its compound vermistatin could be developed as mosquitocides.

The Cytotoxic Properties of Extreme Fungi's Bioactive Components-An Updated Metabolic and Omics Overview

Fungi are the most diverse living organisms on planet Earth, where their ubiquitous presence in various ecosystems offers vast potential for the research and discovery of new, naturally occurring medicinal products. Concerning human health, cancer remains one of the leading causes of mortality. While extensive research is being conducted on treatments and their efficacy in various stages of cancer, finding cytotoxic drugs that target tumor cells with no/less toxicity toward normal tissue is a significant challenge. In addition, traditional cancer treatments continue to suffer from chemical resistance. Fortunately, the cytotoxic properties of several natural products derived from various microorganisms, including fungi, are now well-established. The current review aims to extract and consolidate the findings of various scientific studies that identified fungi-derived bioactive metabolites with antitumor (anticancer) properties. The antitumor secondary metabolites identified from extremophilic and extremotolerant fungi are grouped according to their biological activity and type. It became evident that the significance of these compounds, with their medicinal properties and their potential application in cancer treatment, is tremendous. Furthermore, the utilization of omics tools, analysis, and genome mining technology to identify the novel metabolites for targeted treatments is discussed. Through this review, we tried to accentuate the invaluable importance of fungi grown in extreme environments and the necessity of innovative research in discovering naturally occurring bioactive compounds for the development of novel cancer treatments.

Cytotoxic indole alkaloids and polyketides produced by a marine-derived fungus Aspergillus flavipes DS720

Marine-derived microorganisms possess the unique metabolic pathways to produce structurally novel secondary metabolites with potent biological activities. In this study, bioactivity-guided isolation of the marine deep-sea-derived fungus Aspergillus flavipes DS720 led to the characterization of four indole alkaloids (compounds 1–4) and four polyketides (compounds 5–8), such as two new indoles, flavonoids A (1) and B (2) with a C-6 reversed prenylation, and a new azaphilone, flaviazaphilone A (5). Their chemical structures were unambiguously established by an extensive interpretation of spectroscopic data, such as 1D/2D NMR and HRESIMS data. The absolute configurations of the new compound 5 were solved by comparing the experimental and calculated Electronic Circular Dichroism (ECD) spectra. Since sufficient amount of flavonoids A (1) was obtained, 1 was subjected to a large-scale cytotoxic activity screening against 20 different human tumor cell lines. The results revealed that 1 showed broad-spectrum cytotoxicities against HeLa, 5637, CAL-62, PATU8988T, A-375, and A-673 cell lines, with the inhibition rates of more than 90%. This study indicated that the newly discovered indole alkaloid 1 may possess certain potential for the development of lead compounds in the future.

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.

Cancer Chemotherapy via Natural Bioactive Compounds

BACKGROUND

Cancer-induced mortality is increasingly prevalent globally which skyrocketed the necessity to discover new/novel safe and effective anticancer drugs. Cancer is characterized by the continuous multiplication of cells in the human which is unable to control. Scientific research is drawing its attention towards naturally-derived bioactive compounds as they have fewer side effects compared to the current synthetic drugs used for chemotherapy.

OBJECTIVE

Drugs isolated from natural sources and their role in the manipulation of epigenetic markers in cancer are discussed briefly in this review article.

METHODS

With advancing medicinal plant biotechnology and microbiology in the past century, several anticancer phytomedicines were developed. Modern pharmacopeia contains at least 25% herbal-based remedy including clinically used anticancer drugs. These drugs mainly include the podophyllotoxin derivatives vinca alkaloids, curcumin, mistletoe plant extracts, taxanes, camptothecin, combretastatin, and others including colchicine, artesunate, homoharringtonine, ellipticine, roscovitine, maytanasin, tapsigargin,andbruceantin.

RESULTS

Compounds (psammaplin, didemnin, dolastin, ecteinascidin,and halichondrin) isolated from marine sources and animals such as microalgae, cyanobacteria, heterotrophic bacteria, invertebrates. They have been evaluated for their anticancer activity on cells and experimental animal models and used chemotherapy.Drug induced manipulation of epigenetic markers plays an important role in the treatment of cancer.

CONCLUSION

The development of a new drug from isolated bioactive compounds of plant sources has been a feasible way to lower the toxicity and increase their effectiveness against cancer. Potential anticancer therapeutic leads obtained from various ethnomedicinal plants, foods, marine, and microorganisms are showing effective yet realistically safe pharmacological activity. This review will highlight important plant-based bioactive compounds like curcumin, stilbenes, terpenes, other polyphenolic phyto-compounds, and structurally related families that are used to prevent/ ameliorate cancer. However, a contribution from all possible fields of science is still a prerequisite for discovering safe and effective anticancer drugs.

Absolute configuration of azaphilones from Monascus kaoliang KB9 and solvent effects on their keto and enol forms

Monascus fermented rice, also known as red yeast rice, exhibits a broad spectrum of biological activities due to its chemical constituents, such as monacolins and azaphilone pigments. Here, we cultured Monascus kaoliang KB9 in a liquid malt medium instead of on rice as a carbon source. Eleven known compounds (1-11) containing azaphilones and their early intermediate were isolated and identified. However, this was the first time that angular tricyclic azaphilones, monasfluols A (4) and B (7), acetyl-monasfluol A (5) and monasfluore A (6), were isolated from this species. Interestingly, all isolated tricyclic azaphilones existed exclusively in enol form in CD₃OD, as evidenced by NMR spectroscopy. The absolute configuration of compounds 4-7 was also first experimentally identified based on ECD spectroscopy combined with conformational analyses using computational techniques. The assigned stereochemistry of Monascus azaphilones in this work provides essential structural information that will benefit future biological and pharmaceutical investigations.

Cryptic Biosynthesis of the Berkeleypenostatins from Coculture of Extremophilic Penicillium sp

Coculture fermentation of Penicillium fuscum and P. camembertii/clavigerum yielded berkeleypenostatins A-G (1-7) as well as the previously reported berkeleylactones A-H, the known macrolide A26771B, citrinin, and patulin. As was true with the berkeleylactones, there was no evidence of the berkeleypenostatins in either axenic culture. The structures were deduced from analyses of spectral data, and the absolute configuration of berkeleypenostatin A (1) was determined by single-crystal X-ray crystallography. Berkeleypenostatins A (1) and E (5) inhibited migration of human pancreatic carcinoma cells (HPAF-II). Both compounds were tested by the NCI Developmental Therapeutics Program. In the NCI 60 cell five-dose screen, berkeleypenostatin E (5) was the more active of the two, with 1-10 μM total growth inhibition (TGI) of all leukemia cell lines, as well as the majority of colon, CNS, melanoma, ovarian, prostate, renal, and breast cancer cell lines.

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.

Molecules derived from the extremes of life: a decade later

Covering: Early 2008 until the end of 2019Microorganisms which survive (extreme-tolerant) or even prefer (extremophilic) living at the limits of pH, temperature, salinity and pressure found on earth have proven to be a rich source of novel structures. In this update we summarise the wide variety of new molecules which have been isolated from extremophilic and extreme-tolerant microorganisms since our original 2009 review, highlighting the range of bioactivities these molecules have been reported to possess.

Epigenetic manipulation of filamentous fungi for biotechnological applications: a systematic review

The study of the epigenetic regulation of gene function has reached pivotal importance in life sciences in the last decades. The mechanisms and effects of processes such as DNA methylation, histone posttranslational modifications and non-coding RNAs, as well as their impact on chromatin structure and dynamics, are clearly involved in physiology homeostasis in plants, animals and microorganisms. In the fungal kingdom, studies on the model yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe contributed enormously to the elucidation of the eukaryote epigenetic landscape. Epigenetic regulation plays a central role in the expression of virulence attributes of human pathogens such as Candida albicans. In this article, we review the most recent studies on the effects of drugs capable of altering epigenetic states and on the impact of chromatin structure-related genes deletion in filamentous fungi. Emphasis is given on plant and insect pathogens, endophytes, secondary metabolites and cellulases/xylanases producing species.

Extreme environments: microbiology leading to specialized metabolites

The prevalence of multidrug-resistant microbial pathogens due to the continued misuse and overuse of antibiotics in agriculture and medicine is raising the prospect of a return to the preantibiotic days of medicine at the time of diminishing numbers of drug leads. The good news is that an increased understanding of the nature and extent of microbial diversity in natural habitats coupled with the application of new technologies in microbiology and chemistry is opening up new strategies in the search for new specialized products with therapeutic properties. This review explores the premise that harsh environmental conditions in extreme biomes, notably in deserts, permafrost soils and deep-sea sediments select for micro-organisms, especially actinobacteria, cyanobacteria and fungi, with the potential to synthesize new druggable molecules. There is evidence over the past decade that micro-organisms adapted to life in extreme habitats are a rich source of new specialized metabolites. Extreme habitats by their very nature tend to be fragile hence there is a need to conserve those known to be hot-spots of novel gifted micro-organisms needed to drive drug discovery campaigns and innovative biotechnology. This review also provides an overview of microbial-derived molecules and their biological activities focusing on the period from 2010 until 2018, over this time 186 novel structures were isolated from 129 representatives of microbial taxa recovered from extreme habitats.

New Azaphilones from Nigrospora oryzae Co-Cultured with Beauveria bassiana

In this study, the co-culture of Nigrospora oryzae and Beauveria bassiana, the endophytes in the seeds of Dendrobium officinale, were examined for metabolite diversity. Five new azaphilones were isolated, and their structures were determined by spectral analysis. In terms of azaphilones, compound 2 had an unprecedented skeleton, with a bicyclic oxygen bridge. The antifungal selectivities of the metabolite produced by N. oryzae against its co-culture fungus, B. bassiana, and common pathogens exhibited competitive interaction in this mix-culture. Compounds 1 and 2 showed obvious nitric oxide (NO) inhibitory activity with ratios of 37%, and 39%, respectively, at a concentration of 50 μM.

Hypoxia-Protective Azaphilone Adducts from Peyronellaea glomerata

Peyronellones A and B (1 and 2), a pair of rare tetracyclic caged adducts of azaphilone with pyruvic acid, along with four new analogues (3-6), were isolated from solid cultures of the endophytic fungus Peyronellaea glomerata. Their structures were elucidated through spectroscopic analysis, and their absolute configurations were unambiguously determined by a combination of single-crystal X-ray crystallography, Rh₂(OCOCF₃)₄-induced ECD experiments, ECD calculations, and modified Mosher methods. Compound 2 (5 μM) was found to have a significant hypoxia-protective effect that improved the survival rate of hypoxia/reoxygenation-treated human umbilical vein endothelial cells from 35% to 70%, which was equal to the potency of the positive control, verapamil. Flow cytometry analysis suggested 2 could inhibit H/R-induced late-stage apoptosis of this cell line.

The Berkeleylactones, Antibiotic Macrolides from Fungal Coculture

A carefully timed coculture fermentation of Penicillium fuscum and P. camembertii/clavigerum yielded eight new 16-membered-ring macrolides, berkeleylactones A-H (1, 4, 6-9, 12, 13), as well as the known antibiotic macrolide A26771B (5), patulin, and citrinin. There was no evidence of the production of the berkeleylactones or A26771B (5) by either fungus when grown as axenic cultures. The structures were deduced from analyses of spectral data, and the absolute configurations of compounds 1 and 9 were determined by single-crystal X-ray crystallography. Berkeleylactone A (1) exhibited the most potent antimicrobial activity of the macrolide series, with low micromolar activity (MIC = 1-2 μg/mL) against four MRSA strains, as well as Bacillus anthracis, Streptococcus pyogenes, Candida albicans, and Candida glabrata. Mode of action studies have shown that, unlike other macrolide antibiotics, berkeleylactone A (1) does not inhibit protein synthesis nor target the ribosome, which suggests a novel mode of action for its antibiotic activity.

Extremely Acidic Soils are Dominated by Species-Poor and Highly Specific Fungal Communities

Highly acidic soils (pH < 3) represent an environment which might potentially offer new biotechnologically interesting fungi. Nevertheless, only little data on fungal communities in highly acidic habitats are available. Here, we focused on the diversity of cultivable filamentous microfungi in highly acidic soils (pH < 3) in the Czech Republic. Altogether, 16 soil samples were collected from four sampling sites and were processed by various approaches. In total, 54 fungal taxa were isolated and identified using classical as well as molecular markers. All dominant species were found both as living mycelia and as resistant stages. Numerous recently described or unknown taxa were isolated. The core of the fungal assemblage under study consisted of phylogenetically unrelated and often globally distributed fungi exclusively inhabiting highly acidic habitats like Acidiella bohemica, Acidomyces acidophilus, and unidentified helotialean fungus, as well as taxa known from less acidic and often extreme environments like Acidea extrema, Penicillium simplicissimum s.l., and Penicillium spinulosum. The large number of identified specialized species indicates that highly acidic environments provide suitable conditions for the evolution of specialist species. The occurrence of ubiquitous fungi in highly acidic substrates points to the principal role of competition in the colonization of such environments. The detected taxa did not require low pH to survive, because they can grow in a broad range of pH.

Azaphilones from an Acid Mine Extremophile Strain of a Pleurostomophora sp

An extremophilic fungus identified as a Pleurostomophora sp. was isolated from the Berkeley Pit, an acid mine waste lake. When grown in liquid culture, the fungus produced berkchaetoazaphilones A-C (1, 2, and 5), the red pigment berkchaetorubramine (6), and the known compound 4-(hydroxymethyl)quinoline. These compounds were evaluated as inhibitors of matrix metalloproteinase-3, caspase-1, and proinflammatory cytokine production in induced THP-1 cells. Berkchaetoazaphilone B (2) inhibited IL-1β, TNFα, and IL-6 production in the induced inflammasome assay and was cytotoxic toward human retinoblastoma cell line Y79 (IC50 = 1.1 μM), leukemia cell lines CCRF-CEM and SR, and the melanoma cell line LOX IMVI (IC50 = 10 μM).

Natural Products as a Vital Source for the Discovery of Cancer Chemotherapeutic and Chemopreventive Agents

Throughout history, natural products have played a dominant role in the treatment of human ailments. For example, the legendary discovery of penicillin transformed global existence. Presently, natural products comprise a large portion of current-day pharmaceutical agents, most notably in the area of cancer therapy. Examples include Taxol, vinblastine, and camptothecin. These structurally unique agents function by novel mechanisms of action; isolation from natural sources is the only plausible method that could have led to their discovery. In addition to terrestrial plants as sources for starting materials, the marine environment (e.g., ecteinascidin 743, halichondrin B, and dolastatins), microbes (e.g., bleomycin, doxorubicin, and staurosporin), and slime molds (e.g., epothilone B) have yielded remarkable cancer chemotherapeutic agents. Irrespective of these advances, cancer remains a leading cause of death worldwide. Undoubtedly, the prevention of human cancer is highly preferable to treatment. Cancer chemoprevention, the use of vaccines or pharmaceutical agents to inhibit, retard, or reverse the process of carcinogenesis, is another important approach for easing this formidable public health burden. Similar to cancer chemotherapeutic agents, natural products play an important role in this field. There are many examples, including dietary phytochemicals such as sulforaphane and phenethyl isothiocyanate (cruciferous vegetables) and resveratrol (grapes and grape products). Overall, natural product research is a powerful approach for discovering biologically active compounds with unique structures and mechanisms of action. Given the unfathomable diversity of nature, it is reasonable to suggest that chemical leads can be generated that are capable of interacting with most or possibly all therapeutic targets.

Talaromycolides A-C, Novel Phenyl-Substituted Phthalides Isolated from the Green Chinese Onion-Derived Fungus Talaromyces pinophilus AF-02

The green Chinese onion (Allium fistulosum L.), which is widely cultivated and has been naturalized in many places, is an important spice and vegetable in East and Southeast Asia. It is used to treat the common cold in China. In the ongoing search for antibacterial activity in fungi derived from natural, pungently scented vegetables, the secondary metabolites of Talaromyces pinophilus AF-02, which was isolated from the stem of the green Chinese onion, were investigated. The genus Talaromyces (Trichocomaceae) is an important fungal genus because of its ubiquity and the role of many of its species in food and agriculture production. Three new phthalide derivatives, talaromycolides A-C, 1-3; a new long-chain dicarboxylic acid, 11; and 12 known compounds were isolated from methanolic extracts of this fungus. Their structures were determined via extensive NMR, HR-ESI-MS, and CD spectroscopic analyses. Compounds 1-3 are rare phthalide derivatives with a novel linkage position between the phenyl and phthalide moieties. The biological properties of 1-16 were evaluated using six different bacteria, and 1-3, 5, and 11 exhibited significant antibacterial activity in response to some of the tested strains.

Bioactive secondary metabolites from acid mine waste extremophiles

The extremophilic microbes of the Berkeley Pit Lake are a valuable source of new and interesting secondary metabolites. It is of particular interest that these acidophilic microbes produce small molecule inhibitors of pathways associated with low pH and high Eh. These same small molecules also inhibit molecular pathways induced by reactive oxygen species (ROS) and inflammation in mammalian cells. Low pH is a hallmark of inflammation and high Eh is one of ROS, so the suitability of this collection as a source of bioactive metabolites is actually quite biorational. Compound isolation was guided by inhibition of caspase-1 and matrix metalloproteinase-3, and active compounds were sent to the National Cancer Institute-Developmental Therapeutics Program and Memorial Sloan Kettering Cancer center for evaluation as either antiproliferative or cytotoxic agents.

Bioactive Secondary Metabolites from Acid Mine Waste Extremophiles

The extremophilic microbes of the Berkeley Pit Lake are a valuable source of new and interesting secondary metabolites. It is of particular interest that these acidophilic microbes produce small molecule inhibitors of pathways associated with low pH and high Eh. These same small molecules also inhibit molecular pathways induced by reactive oxygen species (ROS) and inflammation in mammalian cells. Low pH is a hallmark of inflammation and high Eh is one of ROS, so the suitability of this collection as a source of bioactive metabolites is actually quite biorational. Compound isolation was guided by inhibition of caspase-1 and matrix metalloproteinase-3, and active compounds were sent to the National Cancer Institute-Developmental Therapeutics Program and Memorial Sloan Kettering Cancer center for evaluation as either antiproliferative or cytotoxic agents.

Marine natural products

This review covers the literature published in 2012 for marine natural products, with 1035 citations (673 for the period January to December 2012) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1241 for 2012), together with the relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.

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.