The anthracenedione compound bostrycin induces mitochondria-mediated apoptosis in the yeast Saccharomyces cerevisiae

Marine anticancer drugs in modulating miRNAs and antioxidant signaling

Several marine drugs exert anticancer effects by inducing oxidative stress, which becomes overloaded and kills cancer cells when redox homeostasis is imbalanced. The downregulation of antioxidant signaling induces oxidative stress, while its upregulation attenuates oxidative stress. Marine drugs have miRNA-modulating effects against cancer cells. However, the potential antioxidant targets of such drugs have been rarely explored. This review aims to categorize the marine-drug-modulated miRNAs that downregulate their antioxidant targets, causing oxidative stress in anticancer treatments. We also categorize the downregulation of oxidative-stress-inducing miRNAs in antioxidant protection among non-cancer cells. We summarize the putative antioxidant targets of miRNA-modulating marine drugs by introducing a bioinformatics tool (miRDB). Finally, the marine drugs affecting antioxidant targets are surveyed. In this way, the connections between marine drugs and their modulating miRNA and antioxidant targets are innovatively categorized to provide a precise network for exploring their potential anticancer functions and protective effects on non-cancer cells.

Biochemical and metabolomic insights into antifungal mechanism of berberine against Candida glabrata

An unprecedented expansion of antifungal therapy failure incidences in healthcare settings of Candida glabrata is the matter of global concern that needs to be addressed efficiently and effectively. In this pursuit, the present study has investigated the antifungal mechanism of benzylisoquinoline alkaloid berberine using biochemical, metabolic, and gene expression analysis, with the aim to delineate its therapeutic activity against C. glabrata and differentially fluconazole-responsive clinical isolates. Interestingly, the clinical isolates were found to be highly susceptible to berberine. Berberine was found to control the surface properties like hydrophobicity and charge of the cells. The cell membrane composition was altered by berberine, where the ergosterol and fatty acids were affected. The efflux pump activity was inhibited, and osmotic stress was generated in C. glabrata cells upon berberine exposure. The berberine has also generated oxidative stress and activated antioxidant system in C. glabrata cells. Furthermore, these observations were supported by the transcriptional expression study of C. glabrata cell genes (CDR1, RLM1, SLT2, SUR4, KRE1) and metabolomics analysis. Based on fold change analysis, the study identified 20 differential metabolites upon berberine treatment, which belong to central carbon, amino acids, and nucleotide pathways. The checkerboard analysis revealed the potentiation of some classically used antifungal drugs by berberine, thus suggesting it as a combinatorial nutraceutical adjuvant for the eradication of fungal infections. KEY POINTS: • Berberine exhibited better potency against azole-resistant clinical isolates • Berberine modulated metabolites of different pathways • Berberine generated oxidative stress and blocked efflux pump activity.

Anthraquinones and Their Analogues from Marine-Derived Fungi: Chemistry and Biological Activities

Anthraquinones are an interesting chemical class of polyketides since they not only exhibit a myriad of biological activities but also contribute to managing ecological roles. In this review article, we provide a current knowledge on the anthraquinoids reported from marine-derived fungi, isolated from various resources in both shallow waters such as mangrove plants and sediments of the mangrove habitat, coral reef, algae, sponges, and deep sea. This review also tentatively categorizes anthraquinone metabolites from the simplest to the most complicated scaffolds such as conjugated xanthone-anthraquinone derivatives and bianthraquinones, which have been isolated from marine-derived fungi, especially from the genera Apergillus, Penicillium, Eurotium, Altenaria, Fusarium, Stemphylium, Trichoderma, Acremonium, and other fungal strains. The present review, covering a range from 2000 to 2021, was elaborated through a comprehensive literature search using the following databases: ACS publications, Elsevier, Taylor and Francis, Wiley Online Library, MDPI, Springer, and Thieme. Thereupon, we have summarized and categorized 296 anthraquinones and their derivatives, some of which showed a variety of biological properties such as enzyme inhibition, antibacterial, antifungal, antiviral, antitubercular (against Mycobacterium tuberculosis), cytotoxic, anti-inflammatory, antifouling, and antioxidant activities. In addition, proposed biogenetic pathways of some anthraquinone derivatives are also discussed.

The racemic trimeric quinone and polycyclic quinones isolated from the aerial parts of Morinda umbellata L

Four undescribed racemic quinones, umbellatas Q-T, were isolated from the aerial parts of Morinda umbellata L. All enantiomers were separated on a chiral HPLC column, and their structures were elucidated by UV spectroscopy, IR spectroscopy, HR-ESI-MS, 1D and 2D NMR spectroscopy, DP4+ NMR calculations, ECD spectroscopy, and X-ray diffraction. Three of the racemes are polycyclic anthraquinones, and one is a rare racemic trimer of naphthoquinone-bisnaphthohydroquinones. (+)-Umbellata S exhibited potent cytotoxicity (IC₅₀: 6.2-9.3 μM) against the A2780, HeLa, H7420, Ketr3 and SW 1990 human cancer cell lines.

Antifungal activity of β-lapachone against azole-resistant Candida spp. and its aspects upon biofilm formation

Aim: The purpose of this study was to assess the antifungal effect of β-lapachone (β-lap) on azole-resistant strains of Candida spp. in both planktonic and biofilm form. Materials & methods: The antifungal activity of β-lap was evaluated by broth microdilution, flow cytometry and the comet assay. The cell viability of the biofilms was assessed using the MTT assay. Results: β-lap showed antifungal activity against resistant strains of Candida spp. in planktonic form. In addition, β-lap decreased the viability of mature biofilms and inhibited the formation of biofilms in vitro. Conclusion: β-lap showed antifungal activity against Candida spp., suggesting that the compound can be utilized as an adjunct agent in the treatment of candidiasis.

Simulation of electrochemical properties of naturally occurring quinones

Quinones are produced in organisms and are utilized as electron transfer agents, pigments and in defence mechanisms. Furthermore, naturally occurring quinones can also be cytotoxins with antibacterial properties. These properties can be linked to their redox properties. Recent studies have also shown that quinones can be utilized in flow battery technology, though naturally occurring quinones have not yet been investigated. Here, we have analyzed the properties of 990 different quinones of various biological sources through a computation approach to determine their standard reduction potentials and aqueous solubility. The screening was performed using the PBE functional and the 6-31G** basis set, providing a distribution of reduction potentials of the naturally occurring quinones varying from - 1.4 V to 1.5 V vs. the standard hydrogen electrode. The solvation energy for each quinone, which indicates the solubility in aqueous solution, was calculated at the same level. A large distribution of solubilities was obtained, containing both molecules that show tendencies of good solubilities and molecules that do not. The solubilities are dependent on the nature of the side groups and the size of the molecules. Our study shows that the group containing the quinones of fungal origin, which is also the largest of the groups considered, has the largest antimicrobial and electrochemical potential, when considering the distribution of reduction potentials for the compounds.

Ocotea glomerata (Nees) Mez Extract and Fractions: Chemical Characterization, Anti-Candida Activity and Related Mechanism of Action

Background: Opportunistic fungal infections are increasingly common, with Candida albicans being the most common etiological agent; however, in recent years, episodes of candidiasis caused by non-albicansCandida species have emerged. Plants belonging to the Lauraceae family have shown remarkable antifungal effects. This study assessed the anti-Candida activity of Ocotea glomerata extracts and fractions, time of death and the synergistic effects with conventional antifungals. The possible mechanism of action was also addressed. Methods: Minimal inhibitory concentrations (MIC) were determined by broth microdilution technique, and the mechanism of action was assessed by ergosterol, sorbitol, cell viability, reactive oxygen species (ROS) generation and phosphatidylserine externalization tests. Results: All the tested extracts evidenced antifungal activity, but the methanol extract was revealed to be the most effective (MIC = 3.12 μg/mL) on C. krusei. The combination of methanol extract with ketoconazole and fluconazole revealed a synergistic effect for C. krusei and C. albicans, respectively. Fractions 1 and 5 obtained from the methanol extract had fungicidal activity, mainly against C. krusei. Methanol extract did not reveal effects by ergosterol and sorbitol assays; however, it led to an increase in intracellular ROS levels, decreased cell viability, and consequently, cell death. Conclusion: O. glomerata methanol extract may be viewed as a rich source of biomolecules with antifungal activity against Candida spp.

Antimicrobial Resistance in ESKAPE Pathogens

Antimicrobial-resistant ESKAPE ( Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens represent a global threat to human health. The acquisition of antimicrobial resistance genes by ESKAPE pathogens has reduced the treatment options for serious infections, increased the burden of disease, and increased death rates due to treatment failure and requires a coordinated global response for antimicrobial resistance surveillance. This looming health threat has restimulated interest in the development of new antimicrobial therapies, has demanded the need for better patient care, and has facilitated heightened governance over stewardship practices.

Berberine Antifungal Activity in Fluconazole-Resistant Pathogenic Yeasts: Action Mechanism Evaluated by Flow Cytometry and Biofilm Growth Inhibition in Candida spp

The incidence of fungal infections and, in particular, the incidence of fungal antibiotic resistance, which is associated with biofilm formation, have significantly increased, contributing to morbidity and mortality. Thus, new therapeutic strategies need to be developed. In this context, natural products have emerged as a major source of possible antifungal agents. Berberine is a protoberberine-type isoquinoline alkaloid isolated from the roots, rhizomes, and stem bark of natural herbs, such as Berberis aquifolium, Berberis vulgaris, Berberis aristata, and Hydrastis canadensis, and of Phellodendron amurense. Berberine has been proven to have broad antibacterial and antifungal activity. In the present study, the potential antifungal effect of berberine against fluconazole-resistant Candida and Cryptococcus neoformans strains, as well as against the biofilm form of Candida spp., was assessed. The antifungal effect of berberine was determined by a broth microdilution method (the M27-A3 method of the Clinical and Laboratory Standards Institute) and flow cytometry techniques, in which the probable mechanism of action of the compound was also assessed. For biofilm assessment, a colorimetric 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was used to determine the susceptibility of sessile cells. The isolates used in the study belonged to the Laboratory of Bioprospection and Experiments in Yeast (LABEL) of the Federal University of Ceará. After 24 and 72 h, fluconazole-resistant Candida and Cryptococcus neoformans strains showed berberine MICs equal to 8 μg/ml and 16 μg/ml, respectively. Cytometric analysis showed that treatment with berberine caused alterations to the integrity of the plasma and mitochondrial membranes and DNA damage, which led to cell death, probably by apoptosis. Assessment of biofilm-forming isolates after treatment showed statistically significant reductions in biofilm cell activity (P < 0.001).

Anthraquinones and Derivatives from Marine-Derived Fungi: Structural Diversity and Selected Biological Activities

Anthraquinones and their derivatives constitute a large group of quinoid compounds with about 700 molecules described. They are widespread in fungi and their chemical diversity and biological activities recently attracted attention of industries in such fields as pharmaceuticals, clothes dyeing, and food colorants. Their positive and/or negative effect(s) due to the 9,10-anthracenedione structure and its substituents are still not clearly understood and their potential roles or effects on human health are today strongly discussed among scientists. As marine microorganisms recently appeared as producers of an astonishing variety of structurally unique secondary metabolites, they may represent a promising resource for identifying new candidates for therapeutic drugs or daily additives. Within this review, we investigate the present knowledge about the anthraquinones and derivatives listed to date from marine-derived filamentous fungi's productions. This overview highlights the molecules which have been identified in microorganisms for the first time. The structures and colors of the anthraquinoid compounds come along with the known roles of some molecules in the life of the organisms. Some specific biological activities are also described. This may help to open doors towards innovative natural substances.

Can Some Marine-Derived Fungal Metabolites Become Actual Anticancer Agents?

Marine fungi are known to produce structurally unique secondary metabolites, and more than 1000 marine fungal-derived metabolites have already been reported. Despite the absence of marine fungal-derived metabolites in the current clinical pipeline, dozens of them have been classified as potential chemotherapy candidates because of their anticancer activity. Over the last decade, several comprehensive reviews have covered the potential anticancer activity of marine fungal-derived metabolites. However, these reviews consider the term "cytotoxicity" to be synonymous with "anticancer agent", which is not actually true. Indeed, a cytotoxic compound is by definition a poisonous compound. To become a potential anticancer agent, a cytotoxic compound must at least display (i) selectivity between normal and cancer cells (ii) activity against multidrug-resistant (MDR) cancer cells; and (iii) a preferentially non-apoptotic cell death mechanism, as it is now well known that a high proportion of cancer cells that resist chemotherapy are in fact apoptosis-resistant cancer cells against which pro-apoptotic drugs have more than limited efficacy. The present review thus focuses on the cytotoxic marine fungal-derived metabolites whose ability to kill cancer cells has been reported in the literature. Particular attention is paid to the compounds that kill cancer cells through non-apoptotic cell death mechanisms.

Endophytic fungi: a reservoir of antibacterials

Multidrug drug resistant bacteria are becoming increasingly problematic particularly in the under developed countries of the world. The most important microorganisms that have seen a geometric rise in numbers are Methicillin resistant Staphylococcus aureus, Vancomycin resistant Enterococcus faecium, Penicillin resistant Streptococcus pneumonia and multiple drug resistant tubercule bacteria to name a just few. New drug scaffolds are essential to tackle this every increasing problem. These scaffolds can be sourced from nature itself. Endophytic fungi are an important reservoir of therapeutically active compounds. This review attempts to present some data relevant to the problem. New, very specific and effective antibiotics are needed but also at an affordable price! A Herculean task for researchers all over the world! In the Asian subcontinent indigenous therapeutics that has been practiced over the centuries such as Ayurveda have been effective as "handed down data" in family generations. May need a second, third and more "in-depth investigations?"

Antifungal activity of naphthoquinoidal compounds in vitro against fluconazole-resistant strains of different Candida species: a special emphasis on mechanisms of action on Candida tropicalis

In recent decades, the incidence of candidemia in tertiary hospitals worldwide has substantially increased. These infections are a major cause of morbidity and mortality; in addition, they prolong hospital stays and raise the costs associated with treatment. Studies have reported a significant increase in infections by non-albicans Candida species, especially C. tropicalis. The number of antifungal drugs on the market is small in comparison to the number of antibacterial agents available. The limited number of treatment options, coupled with the increasing frequency of cross-resistance, makes it necessary to develop new therapeutic strategies. The objective of this study was to evaluate and compare the antifungal activities of three semisynthetic naphthofuranquinone molecules against fluconazole-resistant Candida spp. strains. These results allowed to us to evaluate the antifungal effects of three naphthofuranquinones on fluconazole-resistant C. tropicalis. The toxicity of these compounds was manifested as increased intracellular ROS, which resulted in membrane damage and changes in cell size/granularity, mitochondrial membrane depolarization, and DNA damage (including oxidation and strand breakage). In conclusion, the tested naphthofuranquinones (compounds 1-3) exhibited in vitro cytotoxicity against fluconazole-resistant Candida spp. strains.

Phenoptosis in yeasts

The current view on phenoptosis and apoptosis as genetic programs aimed at eliminating potentially dangerous organisms and cells, respectively, is given. Special emphasis is placed on apoptosis (phenoptosis) in yeasts: intracellular defects and a plethora of external stimuli inducing apoptosis in yeasts; distinctive morphological and biochemical hallmarks accompanying apoptosis in yeasts; pro- and antiapoptotic factors involved in yeast apoptosis signaling; consecutive stages of apoptosis from external stimulus to the cell death; a prominent role of mitochondria and other organelles in yeast apoptosis; possible pathways for release of apoptotic factors from the intermembrane mitochondrial space into the cytosol are described. Using some concrete examples, the obvious physiological importance and expediency of altruistic death of yeast cells is shown. Poorly known aspects of yeast apoptosis and prospects for yeast apoptosis study are defined.

Differences of cytotoxicity of orthodontic bands assessed by survival tests in Saccharomyces cerevisiae

The aim of this study was to evaluate the cytotoxicity induced by orthodontic bands through survival tests on Saccharomyces cerevisiae, a microorganism that presents several genetic and biochemical characteristics similar to human cells. Three groups of bands were evaluated: silver soldered (SSB), laser soldered (LSB), and bands without any solder (WSB). Yeast cells were directly exposed to the bands and indirectly, when a previous elution of the metals in artificial saliva was performed. The negative control was composed of yeast cells or artificial saliva not exposed to any kind of metal. In the direct exposure experiments, all tested groups of bands induced a slight reduction in yeast viability compared to the control. This effect was more intense for the SSB, although not statistically significant. For the indirect exposure experiments, the SSB induced a statistically significant decrease in cell viability compared to the LSB. There were no significant differences between the survival rates of the negative control and the LSB group in both direct and saliva tests. SSBs were cytotoxic, whilst LSBs were not, confirming that laser soldering may be a more biocompatible alternative for use in connecting wires to orthodontic appliances.

Advances in the study of the structures and bioactivities of metabolites isolated from mangrove-derived fungi in the South China Sea

Many metabolites with novel structures and biological activities have been isolated from the mangrove fungi in the South China Sea, such as anthracenediones, xyloketals, sesquiterpenoids, chromones, lactones, coumarins and isocoumarin derivatives, xanthones, and peroxides. Some compounds have anticancer, antibacterial, antifungal and antiviral properties, but the biosynthesis of these compounds is still limited. This review summarizes the advances in the study of secondary metabolites from the mangrove-derived fungi in the South China Sea, and their biological activities reported between 2008 and mid-2013.

The role of mitochondria in yeast programmed cell death

Mammalian apoptosis and yeast programmed cell death (PCD) share a variety of features including reactive oxygen species production, protease activity and a major role played by mitochondria. In view of this, and of the distinctive characteristics differentiating yeast and multicellular organism PCD, the mitochondrial contribution to cell death in the genetically tractable yeast Saccharomyces cerevisiae has been intensively investigated. In this mini-review we report whether and how yeast mitochondrial function and proteins belonging to oxidative phosphorylation, protein trafficking into and out of mitochondria, and mitochondrial dynamics, play a role in PCD. Since in PCD many processes take place over time, emphasis will be placed on an experimental model based on acetic acid-induced PCD (AA-PCD) which has the unique feature of having been investigated as a function of time. As will be described there are at least two AA-PCD pathways each with a multifaceted role played by mitochondrial components, in particular by cytochrome c.

Oxidative stress and programmed cell death in yeast

Yeasts, such as Saccharomyces cerevisiae, have long served as useful models for the study of oxidative stress, an event associated with cell death and severe human pathologies. This review will discuss oxidative stress in yeast, in terms of sources of reactive oxygen species (ROS), their molecular targets, and the metabolic responses elicited by cellular ROS accumulation. Responses of yeast to accumulated ROS include upregulation of antioxidants mediated by complex transcriptional changes, activation of pro-survival pathways such as mitophagy, and programmed cell death (PCD) which, apart from apoptosis, includes pathways such as autophagy and necrosis, a form of cell death long considered accidental and uncoordinated. The role of ROS in yeast aging will also be discussed.

Studies on the synthesis of derivatives of marine-derived bostrycin and their structure-activity relationship against tumor cells

A series of new derivatives (5–29) of marine-derived bostrycin (1) were synthesized. The in vitro cytotoxic activities of all compounds were evaluated against MCF-7, MDA-MB-435, A549, HepG2, HCT-116 and MCF-10A cells using the MTT method. The compounds 7, 8, 22, 23, 25, 28 and 29 of the total showed comparable activity to epirubicin, the positive control, against the tested cancer cell lines. However, these compounds also exhibited cytotoxicity towards MCF-10A cells. The structure-activity relationship (SAR) of bostrycin derivatives was also discussed based on the obtained experimental data.

Mitochondrial dynamics in yeast cell death and aging

Mitochondria play crucial roles in programmed cell death and aging. Different stimuli activate distinct mitochondrion-dependent cell death pathways, and aging is associated with a progressive increase in mitochondrial damage, culminating in oxidative stress and cellular dysfunction. Mitochondria are highly dynamic organelles that constantly fuse and divide, forming either interconnected mitochondrial networks or separated fragmented mitochondria. These processes are believed to provide a mitochondrial quality control system and enable an effective adaptation of the mitochondrial compartment to the metabolic needs of the cell. The baker's yeast, Saccharomyces cerevisiae, is an established model for programmed cell death and aging research. The present review summarizes how mitochondrial morphology is altered on induction of cell death or on aging and how this correlates with the induction of different cell death pathways in yeast. We highlight the roles of the components of the mitochondrial fusion and fission machinery that affect and regulate cell death and aging.