Janus-Faced Molecules against Plant Pathogenic Fungi.

The high cytotoxicity of the secondary metabolites of mycotoxins is capable of killing microbes and tumour cells alike, similarly to the genotoxic effect characteristic of Janus-faced molecules. The "double-edged sword" effect of several cytotoxins is known, and these agents have, therefore, been utilized only reluctantly against fungal infections. In this review, consideration was given to (a) toxins that could be used against plant and human pathogens, (b) animal models that measure the effect of antifungal agents, (c) known antifungal agents that have been described and efficiently prevent the growth of fungal cells, and (d) the chemical interactions that are characteristic of antifungal agents. The utilization of apoptotic effects against tumour growth by agents that, at the same time, induce mutations may raise ethical issues. Nevertheless, it deserves consideration despite the mutagenic impact of Janus-faced molecules for those patients who suffer from plant pathogenic fungal infections and are older than their fertility age, in the same way that the short-term cytotoxicity of cancer treatment is favoured over the long-term mutagenic effect.

Discovery and Characterization of 4-Hydroxy-2-pyridone Derivative Sambutoxin as a Potent and Promising Anticancer Drug Candidate: Activity and Molecular Mechanism.

Sambutoxin, a representative derivative of 4-hydroxy-2-pyridone, was isolated from Hericium alpestre for the first time in this study. The possible correlation between the sambutoxin-induced suppression of tumor growth and its influence on cell-cycle arrest and apoptosis was investigated. The effects of sambutoxin on reactive oxygen species (ROS) production, DNA damage, mitochondrial transmembrane potential, cell apoptosis, and the expression of related proteins were evaluated. An in vitro cell viability study demonstrated that sambutoxin could inhibit the proliferation of various cancer cells. Treatment with sambutoxin induced the production of ROS, which caused DNA damage. Furthermore, the subsequent sambutoxin-induced activation of ATM and Chk2 resulted in G2/M arrest, accompanied by decreased expression of cdc25C, cdc2, and cyclin B1. Sambutoxin induced apoptosis by activating the mitochondrial apoptosis pathway through an increased Bax/Bcl-2 ratio, loss of mitochondrial membrane potential (ΔΨm), cytochrome (Cyt) c release, caspase-9 and caspase-3 activation, and poly(ADP-ribose) polymerase (PARP) degradation. The ROS elevation induced the sustained phosphorylation of c-Jun N-terminal kinase (JNK), while SP600125, a JNK inhibitor, nearly completely reversed sambutoxin-induced apoptosis. Accordingly, an in vivo study showed that sambutoxin exhibited potential antitumor activity in a BALB/c nude mouse xenograft model without significant systemic toxicity. Moreover, the expression changes in proteins related to the G2/M phase, DNA damage, and apoptosis in vivo were consistent with those in vitro. Importantly, sambutoxin has remarkable antiproliferative effects and is a promising anticarcinogen candidate for cancer treatment.

A novel moniliformin derivative as pan-inhibitor of histone deacetylases triggering apoptosis of leukemia cells.

New and potent agents that evade multidrug resistance (MDR) and inhibit epigenetic modifications are of great interest in cancer drug development. Here, we describe that a moniliformin derivative (IUPAC name: 3-(naphthalen-2-ylsulfanyl)-4-{[(2Z)-1,3,3-trimethyl-2,3-dihydro-1H-indol-2-ylidene]methyl}cyclobut-3-ene-1,2-dione; code: MCC1381) bypasses P-gp-mediated MDR. Using transcriptomics, we identified a large number of genes significantly regulated in response to MCC1381, which affected the cell cycle and disturbed cellular death and survival. The potential targets of MCC1381 might be histone deacetylases (HDACs) as predicted by SwissTargetPrediction. In silico studies confirmed that MCC1381 presented comparable affinity with HDAC1, 2, 3, 6, 8 and 11. Besides, the inhibition activity of HDACs was dose-dependently inhibited by MCC1381. Particularly, a strong binding affinity was observed between MCC1381 and HDAC6 by microscale thermophoresis analysis. MCC1381 decreased the expression of HDAC6, inversely correlated with the increase of acetylated HDAC6 substrates, acetylation p53 and α-tubulin. Furthermore, MCC1381 arrested the cell cycle at the G2/M phase, induced the generation of reactive oxygen species and collapse of the mitochondrial membrane potential. MCC1381 exhibited in vivo anti-cancer activity in xenografted zebrafish. Collectively, MCC1381 extended cytotoxicity towards P-gp-resistant leukemia cancer cells and may act as a pan-HDACs inhibitor, indicating that MCC1381 is a novel candidate for cancer therapy.

Leucinostatin A inhibits prostate cancer growth through reduction of insulin-like growth factor-I expression in prostate stromal cells.

Targeting stroma in tumor tissues is an attractive new strategy for cancer treatment. We developed in vitro coculture system, in which the growth of human prostate cancer DU-145 cells is stimulated by prostate stromal cells (PrSC) through insulin-like growth factor I (IGF-I). Using this system, we have been searching for small molecules that inhibit tumor growth through modulation of tumor-stromal cell interactions. As a result, we have found that leucinostatins and atpenins, natural antifungal antibiotics, inhibit the growth of DU-145 cells cocultured with PrSC more strongly than that of DU-145 cells alone. In this study we examined the antitumor effects of these small molecules in vitro and in vivo. When DU-145 cells were coinoculated with PrSC subcutaneously in nude mice, leucinostatin A was found to significantly suppress the tumor growth more than atpenin B. The antitumor effect of leucinostatin A in vivo was not obtained against the tumors of DU-145 cells alone. RT-PCR experiments revealed that leucinostatin A specifically inhibited IGF-I expression in PrSC without effect on expressions of other IGF axis molecules. Leucinostatins and atpenins are known to abrogate mitochondrial functions. However, when we used mitochondrial DNA-depleted, pseudo-rho(0) cells, we found that one of leucinostain A actions certainly depended on mitochondrial function, but it actually inhibited the growth of DU-145 cells more strongly in coculture with pseudo-rho(0) PrSC and reduced IGF-I expression in pseudo-rho(0) PrSC. Taken together, our results suggested that leucinostatin A inhibited prostate cancer cell growth through reduction of IGF-I expression in PrSC.

Natural toxins and their therapeutic potential.

Plants have been extensively investigated for exploring their therapeutic potentials, but there are comparatively scanty reports on drugs derived from animal kingdom, except for hormones. During last decade, the toxins that are used for defense by the animals, have been isolated and found useful tools for physiological and pharmacological studies, besides giving valuable leads to drug development. Toxins with interesting results have been isolated from the venoms of snakes, scorpions, spiders, snails, lizards, frogs and fish. The present review describe about some toxins as drugs and their biological activities. Some fungal, bacterial and marine toxins have also been covered in this article.

Chetomin, a Hsp90/HIF1α pathway inhibitor, effectively targets lung cancer stem cells and non-stem cells.

Non-small cell lung cancer (NSCLC) remains recalcitrant to effective treatment due to tumor relapse and acquired resistance. Cancer stem cells (CSCs) are believed to be one mechanism for relapse and resistance and are consequently considered promising drug targets. We report that chetomin, an active component of Chaetomium globosum, blocks heat shock protein 90/hypoxia-inducible factor 1 alpha (Hsp90/HIF1α) pathway activity. Chetomin also attenuated sphere-forming, a stem cell-like characteristic, of NSCLC CSCs (at ~ nM range) and the proliferation of non-CSCs NSCLC cultures and chemoresistant sublines (at ~ µM range). At these concentrations, chetomin exerted a marginal influence on noncancerous cells originating from several organs. Chetomin markedly decreased in vivo tumor formation in a spontaneous KrasLA1 lung cancer model, flank xenograft models, and a tumor propagation flank implanted model at doses that did not produce an observable toxicity to the animals. Chetomin blocked Hsp90/HIF1α pathway activity via inhibiting the Hsp90-HIF1α binding interaction without affecting Hsp90 or Hsp70 protein levels. This study advocates chetomin as a Hsp90/HIF1α pathway inhibitor and a potent, nontoxic NSCLC CSC-targeting molecule.

Roseotoxin B alleviates cholestatic liver fibrosis through inhibiting PDGF-B/PDGFR-ß pathway in hepatic stellate cells.

Identifying effective anti-fibrotic therapies is a major clinical need that remains unmet. In the present study, roseotoxin B was shown to possess an improving effect on cholestatic liver fibrosis in bile duct-ligated mice, as proved by histochemical and immunohistochemical staining, hepatic biochemical parameters, and TUNEL apoptotic cell detection in tissue sections. Using cellular thermal shift assay, computational molecular docking, microscale thermophoresis technology, and surface plasmon resonance biosensor, we confirmed that PDGFR-ß was a direct target of roseotoxin B in fibrotic livers. Of note, human tissue microarrays detected pathologically high expression of p-PDGFR-ß in liver samples of ~80% of patients with liver fibrosis and cirrhosis. PDGF-B/PDGFR-ß pathway promotes transdifferentiation and excessive proliferation of hepatic stellate cells (HSCs), which is a very crucial driver for liver fibrosis. Meaningfully, roseotoxin B blocked the formation of PDGF-BB/PDGFR-ßß complex by targeting the D2 domain of PDGFR-ß, thereby inhibiting the PDGF-B/PDGFR-ß pathway in HSCs. In summary, our study provided roseotoxin B as a unique candidate agent for the treatment of liver fibrosis.

Therapeutic potential of antiidiotypic single chain antibodies with yeast killer toxin activity.

Single chain fragment (ScFv) antiidiotypic antibodies (antilds) of a killer toxin (KT) from the yeast Pichia anomala have been produced by recombinant DNA methodology from the splenic lymphocytes of mice immunized by idiotypic vaccination with a KT-neutralizing monoclonal antibody (Mab KT4). ScFv KT-like antilds (KTIdAb) react with specific Candida albicans KT cell wall receptors (KTR) exerting a candidacidal activity in vitro could be neutralized by adsorption with Mab KT4. ScFv KTIdAb displayed an effective therapeutic activity in an experimental model of rat candidal vaginitis.

Therapy of mucosal candidiasis by expression of an anti-idiotype in human commensal bacteria.

Two recombinant strains of Streptococcus gordonii, secreting or displaying a microbicidal single-chain antibody (H6), and stably colonizing rat vagina, were used to treat an experimental vaginitis caused by Candida albicans. A post-challenge intravaginal delivery of the H6-secreting strain was as efficacious as fluconazole in rapidly abating the fungal burden. Three weeks after challenge, 75% and 37.5% of the rats treated with the H6-secreting or displaying bacteria, respectively, were cured of the infection, which persisted in 100% of the animals treated with a S. gordonii strain expressing an irrelevant single-chain antibody. Thus, a human commensal bacterium can be suitably engineered to locally release a therapeutic antibody fragment.

Ophiobolin A, a sesterpenoid fungal phytotoxin, displays different mechanisms of cell death in mammalian cells depending upon the cancer cell origin.

Herein we have undertaken a systematic analysis of the effects of the fungal derivative ophiobolin A (OphA) on eight cancer cell lines from different tissue types. The LD50 for each cell line was determined and the change in cell size determined. Flow cytometric analysis and western blotting were used to assess the cell death markers for early apoptosis, late apoptosis and necrosis, and the involvement of the caspase signalling pathway. Alterations in calcium levels and reactive oxygen species were assessed due to their integral involvement in intracellular signalling. Subsequently, the endoplasmic reticulum (ER) and mitochondrial responses were investigated more closely. The extent of ER swelling, and the upregulation of proteins involved in the unfolded protein responses (UPR) were seen to vary according to cell line. The mitochondria were also shown to behave differently in response to the OphA in the different cell lines in terms of the change in membrane potential, the total area of mitochondria in the cell and the number of mitochondrial bifurcations. The data obtained in the present study indicate that the cancer cell lines tested are unable to successfully activate the ER stress/UPR responses, and that the mitochondria appear to be a central player in OphA-induced cancer cell death.

A novel and simple cell-based electrochemical impedance biosensor for evaluating the combined toxicity of DON and ZEN.

In this study, a novel and simple cell-based electrochemical biosensor was developed to assess the individual and combined toxicity of deoxynivalenol (DON) and zearalenone (ZEN) on BEL-7402 cells. The sensor was fabricated by modification with AuNPs, p-aminothiophenol, and folic acid in succession. The BEL-7402 cells which had a good activity were adhered on the electrode through the high affinity between the folate receptor and folic acid selectivity. We used the collagen to maintain the cell adhesion and viability. Electrochemical impedance spectroscopy (EIS) was developed to evaluate the individual and combined toxicity of DON and ZEN. Our results indicate that DON and ZEN caused a marked decrease in the cell viability in a dose-dependent manner. The value of electrochemical impedance spectroscopy decreased with the concentration of DON and ZEN in range of 0.1-20, 0.1-50 µg/ml with the detection limit as 0.03, 0.05 µg/ml, respectively, the IC50 for DON and ZEN as obtained by the proposed electrochemical method were 7.1 µg/ml and 24.6 µg/ml, respectively, and the combination of two mycotoxins appears to generate an additive response. The electrochemical cytotoxicity evaluation result was confirmed by biological assays. Compared to conventional methods, this electrochemical test is inexpensive, highly sensitive, and fast to respond, with long-term monitoring and real-time measurements. The proposed method provides a new avenue for evaluating the toxicity of mycotoxins.

Prevention of graft-versus-host disease by treatment of bone marrow with gliotoxin in fully allogeneic chimeras and their cytotoxic T cell repertoire.

Gliotoxin, a secondary fungal metabolite, at nanomolar concentrations, irreversibly inhibits murine T cell proliferation to mitogen. Treatment of allogeneic spleen cells with gliotoxin allows their transfer into sublethally irradiated recipients without inducing a GVH reaction. Gliotoxin treatment of bone marrow allows the establishment of fully allogenic bone marrow chimeras free of GVH disease. The cytotoxic T cell repertoire against influenza virus in these animals is restricted to both host- and donor-type MHC. However, their immune competence is severely compromised by their lack of host MHC-type stimulator cells.

A transphyletic anti-infectious control strategy based on the killer phenomenon.

A strategy for the prevention and control of candidiasis, pneumocystosis, and tuberculosis, based on the idiotypic network of the yeast killer effect has been envisaged. Anti-idiotypic antibodies representing the internal image of a candidacidal, pneumocysticidal, and mycobactericidal killer toxin from Pichia anomala and idiotypes of killer toxin-neutralizing monoclonal antibodies mimicking the specific cell wall receptor of sensitive microorganisms might provide a unique approach for engineering innovative antibiotics and vaccines active against taxonomically unrelated pathogenic microorganisms. The rationale of the strategy relies on a phenomenon of microbial competition which has been mutated by the immune system in the response to natural infections.

Effect of ochratoxin A on Salmonella typhimurium-challenged layer chickens.

Eleven-day-old chickens received 10(8) colony-forming units Salmonella typhimurium orally for 2 consecutive days. The next day, the 13-day-old chickens were given a high dose of ochratoxin A (3 mg/kg) orally. The number of S. typhimurium in both the duodenal and cecal contents of chickens administered with high doses of ochratoxin A increased significantly when compared with control birds. Ochratoxin A was shown to be one of numerous factors that affect the susceptibility of chickens to salmonellae colonization.

[Medical importance of yeast killer toxin]. / Maya öldürücü toksinin tibbi önemi.

Yeast killer toxins (YKT) are exotoxins produced by several yeasts including certain Candida species. They can kill fungi, bacteria and even protozoa by binding to the specific receptors on their cell surfaces. On the basis of their killer effect, studies have been carried out on the differentiation of fungi and some bacteria by using YKT as epidemiological tools. Following biotyping procedures, idiotypic and anti-idiotypic antibodies produced against YKT have been shown to exhibit great potential in protection and immunotherapy against several microorganisms, promising as novel approaches to fight against microbial diseases. In this review article, the structural properties, ecologic and epidemiologic importance, therapeutic, prophylactic and immunotherapy studies of yeast killer toxins, have been discussed.

[Kojic acid and its derivatives as potential therapeutic agents]. / Kyselina kojová a jej deriváty ako potenciálne liecivá.

The review paper studies kojic acid, a secondary metabolite of fibrous fungi, as a carrier chemical structure of potential pharmaceuticals. The examined preparative procedures, physico-chemical and biologic properties, and especially the antifungal and antileukemic effects of the parent kojic acid indicate that novel potential drugs can be developed on its basis.

Dissecting influenza virus pathogenesis uncovers a novel chemical approach to combat the infection.

The cytokine storm is an aggressive immune response characterized by the recruitment of inflammatory leukocytes and exaggerated levels of cytokines and chemokines at the site of infection. Here we review evidence that cytokine storm directly contributes to the morbidity and mortality resulting from influenza virus infection and that sphingosine-1-phosphate (S1P) receptor agonists can abort cytokine storms providing significant protection against pathogenic human influenza viral infections. In experiments using murine models and the human pathogenic 2009 influenza viruses, S1P1 receptor agonist alone reduced deaths from influenza virus by over 80% as compared to lesser protection (50%) offered by the antiviral neuraminidase inhibitor oseltamivir. Optimal protection of 96% was achieved by combined therapy with the S1P1 receptor agonist and oseltamivir. The functional mechanism of S1P receptor agonist(s) action and the predominant role played by pulmonary endothelial cells as amplifiers of cytokine storm during influenza infection are described.