In Vitro and in Silico Evaluation of Bikaverin as a Potent Inhibitor of Human Protein Kinase CK2

1,2,3-Triazole-totarol conjugates as potent PIP5K1α lipid kinase inhibitors

The human phosphatidylinositol 4-phosphate 5-kinase type I α (hPIP5K1α) plays a key role in the development of prostate cancer. In this work, seventeen derivatives of the natural diterpene totarol were prepared by copper(I)-catalysed Huisgen 1,3-dipolar cycloaddition reaction of the correspondingO-propargylated totarol with aryl or alkyl azides and screened for their inhibitory activities toward hPIP5K1α. Five compounds, 3a, 3e, 3f, 3i, and 3r, strongly inhibited the enzyme activity with IC50 values of 1.44, 0.46, 1.02, 0.79, and 3.65 µM, respectively, with the most potent inhibitor 3e 13-[(1-(3-nitrophenyl)triazol-4yl)methoxy]-totara-8,11,13-triene). These compounds were evaluated on their antiproliferative effects in a panel of prostate cancer cell lines. Compound 3r inhibited the proliferation of LNCaP, PC3 and DU145 cells at 20 µM, strongly, but also has strong cytotoxic effects on all tested cells.

Neuronal-type-specific epigenome editing to decrease SNCA expression: Implications for precision medicine in synucleinopathies

Overexpression of SNCA has been implicated in the pathogenesis of synucleinopathies, particularly Parkinson's disease (PD) and dementia with Lewy bodies (DLB). While PD and DLB share some clinical and pathological similarities, each disease presents distinct characteristics, including the primary affected brain region and neuronal type. We aimed to develop neuronal-type-specific SNCA-targeted epigenome therapies for synucleinopathies. The system is based on an all-in-one lentiviral vector comprised of CRISPR-dSaCas9 and guide RNA (gRNA) targeted at SNCA intron 1 fused with a synthetic repressor molecule of Krüppel-associated box (KRAB)/ methyl CpG binding protein 2 (MeCp2) transcription repression domain (TRD). To achieve neuronal-type specificity for dopaminergic and cholinergic neurons, the system was driven by tyrosine hydroxylase (TH) and choline acetyltransferase (ChAT) promoters, respectively. Delivering the system into human induced pluripotent stem cell (hiPSC)-derived dopaminergic and cholinergic neurons from a patient with the SNCA triplication resulted in efficient and neuronal-type-specific downregulation of SNCA-mRNA and protein. Furthermore, the reduction in SNCA levels by the gRNA-dSaCas9-repressor system rescued disease-related cellular phenotypes including Ser129-phophorylated α-synuclein, neuronal viability, and mitochondrial dysfunction. We established a novel neuronal-type-specific SNCA-targeted epigenome therapy and provided in vitro proof of concept using human-based disease models. Our results support the therapeutic potential of our system for PD and DLB and provide the foundation for further preclinical studies in animal models toward investigational new drug (IND) enablement and clinical trials.

CK2 and protein kinases of the CK1 superfamily as targets for neurodegenerative disorders

Casein kinases are involved in a variety of signaling pathways, and also in inflammation, cancer, and neurological diseases. Therefore, they are regarded as potential therapeutic targets for drug design. Recent studies have highlighted the importance of the casein kinase 1 superfamily as well as protein kinase CK2 in the development of several neurodegenerative pathologies, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. CK1 kinases and their closely related tau tubulin kinases as well as CK2 are found to be overexpressed in the mammalian brain. Numerous substrates have been detected which play crucial roles in neuronal and synaptic network functions and activities. The development of new substances for the treatment of these pathologies is in high demand. The impact of these kinases in the progress of neurodegenerative disorders, their bona fide substrates, and numerous natural and synthetic compounds which are able to inhibit CK1, TTBK, and CK2 are discussed in this review.

Recovery and purification of bikaverin produced by Fusarium oxysporum CCT7620

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Ethyl acetate extraction resulted in the highest bikaverin yield.

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Kinetic study revealed a saturation of bikaverin extraction after 256 min.

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Three sequential ethyl acetate extractions was the most economical to recover bikaverin.

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Open column chromatography or nanofiltration were not suitable to purify bikaverin.

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Bikaverin was successfully purified on semi-preparative HPLC.

Microbial pigments have a distinguished potential for applications in food and pharmaceutical industries, stimulating the research in this field. The present study evaluated the ideal conditions for extracting bikaverin (red pigment) from the biomass of Fusarium oxysporum CCT7620. Among the solvents tested, ethyl acetate extraction resulted in the highest bikaverin concentration and the kinetic study revealed a saturation in bikaverin concentration from 256 min on. Based on a preliminary economic study, three sequential extractions with ethyl acetate was considered the ideal protocol to recover bikaverin. After extraction, chromatographic methods were tested to purify bikaverin. The use of silica gel or Sephadex (open column) could not successfully purify bikaverin, but the semi-preparative HPLC resulted in a bikaverin-enriched fraction with a purity degree equivalent to the commercial analytical standard. This work provides relevant information regarding the extraction and purification of bikaverin, which may be useful for other downstraming processes.

Practical Enzymatic Production of Carbocycles

The Pd-catalyzed carbon-carbon bond formation pioneered by Heck in 1969 has dominated medicinal chemistry development for the ensuing fifty years. As the demand for more complex three-dimensional active pharmaceuticals continues to increase, preparative enzyme-mediated assembly, by virtue of its exquisite selectivity and sustainable nature, is poised to provide a practical and affordable alternative for accessing such compounds. In this minireview, we summarize recent state-of-the-art developments in practical enzyme-mediated assembly of carbocycles. When appropriate, background information on the enzymatic transformation is provided and challenges and/or limitations are also highlighted.

Natural Compounds Isolated from Stachybotrys chartarum Are Potent Inhibitors of Human Protein Kinase CK2

A large number of secondary metabolites have been isolated from the filamentous fungus Stachybotrys chartarum and have been described before. Fourteen of these natural compounds were evaluated in vitro in the present study for their inhibitory activity towards the cancer target CK2. Among these compounds, stachybotrychromene C, stachybotrydial acetate and acetoxystachybotrydial acetate turned out to be potent inhibitors with IC₅₀ values of 0.32 µM, 0.69 µM and 1.86 µM, respectively. The effects of these three compounds on cell proliferation, growth and viability of MCF7 cells, representing human breast adenocarcinoma as well as A427 (human lung carcinoma) and A431 (human epidermoid carcinoma) cells, were tested using EdU assay, IncuCyte^® live-cell imaging and MTT assay. The most active compound in inhibiting MCF7 cell proliferation was acetoxystachybotrydial acetate with an EC₅₀ value of 0.39 µM. In addition, acetoxystachybotrydial acetate turned out to inhibit the growth of all three cell lines completely at a concentration of 1 µM. In contrast, cell viability was impaired only moderately, to 37%, 14% and 23% in MCF7, A427 and A431 cells, respectively.

In Silico and In Vitro Studies of Natural Compounds as Human CK2 Inhibitors

BACKGROUND

Casein Kinase 2 (CK2) is a ubiquitous cellular serine-threonine kinase with broad spectrum of substrates. This enzyme is widely expressed in eukaryotic cells and is overexpressed in different human cancers. Thus, the inhibition of CK2 can induce the physiological process of apoptosis leading to tumor cell death.

OBJECTIVES

Selecting natural inhibitors toward the target enzyme using database mining.

METHODS

With our continuous effort to discover new compounds with CK2 inhibitory effect, several commercial natural databases were searched using molecular modeling approach and the selected compounds were evaluated in vitro.

RESULTS

Three compounds were selected as candidates and evaluated in vitro using CK2 holoenzyme, their effect on three cancer cell lines was determined. The selected candidates were weak inhibitors toward the target enzyme, only one compound showed moderate effect on cell viability.

CONCLUSION

Several natural databases were screened, compounds were selected and tested in vitro. Despite the unexpected low inhibitory activity of the tested compounds, this study can help in directing the search of potent CK2 inhibitors and better understand the binding requirements of the ATP competitive inhibitors.

Virtual controls as an alternative to randomized controlled trials for assessing efficacy of interventions

Randomized controlled trials are ubiquitously spoken of as the "gold standard" for testing interventions and establishing causal relations. This article presents evidence for two premises. First: there are often major problems with randomized designs; it is by no means true that the only good design is a randomized design. Second: the method of virtual controls in some circumstances can and should replace randomized designs.Randomized trials can present problems with external validity or generalizability; they can be unethical; they typically involve much time, effort, and expense; their assignments to treatment conditions often can be maintained only for limited time periods; examination of their track record reveals problems with reproducibility on the one hand, and lack of overwhelming superiority to observational methods on the other hand.The method of virtual controls involves ongoing efforts to refine statistical models for prediction of outcomes from measurable variables, under conditions of no treatment or current standard of care. Research participants then join a single-arm study of a new intervention. Each participant's data, together with the formulas previously generated, predict that participant's outcome without the new intervention. These outcomes are the "virtual controls." The actual outcomes with intervention are compared with the virtual control outcomes to estimate effect sizes. Part of the research product is the prediction equations themselves, so that in clinical practice, individual treatment decisions may be aided by quantitative answers to the questions, "What is estimated to happen to this particular patient with and without this treatment?"The method of virtual controls is especially indicated when rapid results are of high priority, when withholding intervention is likely harmful, when adequate data exist for prediction of untreated or standard of care outcomes, when we want to let people choose the treatment they prefer, when tailoring treatment decisions to individuals is desirable, and when real-world clinical information can be harnessed for analysis.

Recent Trends in Enzyme Inhibition and Activation in Drug Design

It is known that enzymes are involved in many pathological conditions, such as inflammation, diabetes, microbial infections, HIV, neoplastic, neglected diseases and others [...]

Pathway engineering in yeast for synthesizing the complex polyketide bikaverin

Fungal polyketides display remarkable structural diversity and bioactivity, and therefore the biosynthesis and engineering of this large class of molecules is therapeutically significant. Here, we successfully recode, construct and characterize the biosynthetic pathway of bikaverin, a tetracyclic polyketide with antibiotic, antifungal and anticancer properties, in S. cerevisiae. We use a green fluorescent protein (GFP) mapping strategy to identify the low expression of Bik1 (polyketide synthase) as a major bottleneck step in the pathway, and a promoter exchange strategy is used to increase expression of Bik1 and bikaverin titer. Then, we use an enzyme-fusion strategy to directly couple the monooxygenase (Bik2) and methyltransferase (Bik3) to efficiently channel intermediates between modifying enzymes, leading to an improved titer of bikaverin at 202.75 mg/L with flask fermentation (273-fold higher than the initial titer). This study demonstrates that the biosynthesis of complex fungal polyketides can be established and efficiently engineered in S. cerevisiae, highlighting the potential for natural product synthesis and large-scale fermentation in yeast.

Bikaverin is a fungal-derived tetracyclic polyketide with antibiotic, antifungal and anticancer properties. Here, the authors employ various pathway engineering strategies to achieve high level production of bikaverin in baker’s yeast.

Natural blue pigments and bikaverin

In last years, the main studied microbial sources of natural blue pigments have been the eukaryotic algae, Rhodophytes and Cryptophytes, and the cyanobacterium Arthrospira (Spirulina) platensis, responsible for the production of phycocyanin, one of the most important blue compounds approved for food and cosmetic use. Recent research also includes the indigoidine pigment from the bacteria Erwinia, Streptomyces and Photorhabdus. Despite these advances, there are still few options of microbial blue pigments reported so far, but the interest in these products is high due to the lack of stable natural blue pigments in nature. Filamentous fungi are particularly attractive for their ability to produce pigments with a wide range of colors. Bikaverin is a red metabolite present mainly in species of the genus Fusarium. Although originally red, the biomass containing bikaverin changes its color to blue after heat treatment, through a mechanism still unknown. In addition to the special behavior of color change by thermal treatment, bikaverin has beneficial biological properties, such as antimicrobial and antiproliferative activities, which can expand its use for the pharmaceutical and medical sectors. The present review addresses the production natural blue pigments and focuses on the properties of bikaverin, which can be an important source of blue pigment with potential applications in the food industry and in other industrial sectors.

Modeling bikaverin production by Fusarium oxysporum CCT7620 in shake flask cultures

Bikaverin is a fungal red pigment that presents antimicrobial and antitumor activities. Therefore, this substance could be used as an alternative additive in the food and pharmaceutical industries. The aim of this work was to use response surface methodology to optimize the fermentation conditions and maximize the production of bikaverin in shake flasks. The variables investigated were agitation speed (71–289 rpm), temperature (21–35 °C), and substrate (rice) concentration in the culture medium (16.4–83.6 g/L). The agitation speed had a positive effect on red pigment production, while substrate concentration and temperature had the opposite effect. Maximum bikaverin production was predicted to occur using 289 rpm, 24.3 °C, and 16.4 g/L rice concentration. Experimental validation using 289 rpm, 28 °C, and 20 g/L rice concentration was 6.2% higher than predicted by the model. The present investigation was important for defining the best conditions for the production of bikaverin.

QSAR Model of Indeno[1,2-b]indole Derivatives and Identification of N-isopentyl-2-methyl-4,9-dioxo-4,9-Dihydronaphtho[2,3-b]furan-3-carboxamide as a Potent CK2 Inhibitor

Casein kinase II (CK2) is an intensively studied enzyme, involved in different diseases, cancer in particular. Different scaffolds were used to develop inhibitors of this enzyme. Here, we report on the synthesis and biological evaluation of twenty phenolic, ketonic, and para-quinonic indeno[1,2-b]indole derivatives as CK2 inhibitors. The most active compounds were 5-isopropyl-1-methyl-5,6,7,8-tetrahydroindeno[1,2-b]indole-9,10-dione 4h and 1,3-dibromo-5-isopropyl-5,6,7,8-tetrahydroindeno[1,2-b]indole-9,10-dione 4w with identical IC₅₀ values of 0.11 µM. Furthermore, the development of a QSAR model based on the structure of indeno[1,2-b]indoles was performed. This model was used to predict the activity of 25 compounds with naphtho[2,3-b]furan-4,9-dione derivatives, which were previously predicted as CK2 inhibitors via a molecular modeling approach. The activities of four naphtho[2,3-b]furan-4,9-dione derivatives were determined in vitro and one of them (N-isopentyl-2-methyl-4,9-dioxo-4,9-dihydronaphtho[2,3-b]furan-3-carboxamide) turned out to inhibit CK2 with an IC₅₀ value of 2.33 µM. All four candidates were able to reduce the cell viability by more than 60% after 24 h of incubation using 10 µM.

Putative metabolic pathway for the bioproduction of bikaverin and intermediates thereof in the wild Fusarium oxysporum LCP531 strain

Fungal naphthoquinones, like red bikaverin, are of interest due to their growing applications in designing pharmaceutical products. Though considerable work has been done on the elucidation of bikaverin biosynthesis pathway in Fusarium fujikuroi, very few reports are available regarding its bioproduction in F. oxysporum. We are hereby proposing a putative metabolic pathway for bikaverin bioproduction in a wild F. oxysporum strain by cross-linking the pigment profiles we obtained under two different fermentation conditions with literature. Naphthoquinone pigments were extracted with a pressurized liquid extraction method, and characterized by HPLC–DAD and UHPLC-HRMS. The results led to the conclusions that the F. oxysporum LCP531 strain was able to produce bikaverin and its various intermediates, e.g., pre-bikaverin, oxo-pre-bikaverin, dinor-bikaverin, me-oxo-pre-bikaverin, and nor-bikaverin, in submerged cultures in various proportions. To our knowledge, this is the first report of the isolation of these five bikaverin intermediates from F. oxysporum cultures, providing us with steady clues for confirming a bikaverin metabolic pathway as well as some of its regulatory patterns in the F. oxysporum LCP531 strain, based on the previously reported model in F. fujikuroi. Interestingly, norbikaverin accumulated along with bikaverin in mycelial cells when the strain grew on simple carbon and nitrogen sources and additional cofactors. Along bikaverin production, we were able to describe the excretion of the toxin beauvericin as main extrolite exclusively in liquid medium containing complex nitrogen and carbon sources, as well as the isolation of ergosterol derivate in mycelial extracts, which have potential for pharmaceutical uses. Therefore, culture conditions were also concluded to trigger some specific biosynthetic route favoring various metabolites of interest. Such observation is of great significance for selective production of pigments and/or prevention of occurrence of others (aka mycotoxins).