Ginkgo biloba L. exocarp petroleum ether extract inhibits methicillin-resistant Staphylococcus aureus by modulating ion transport, virulence, and biofilm formation in vitro and in vivo.

ETHNOPHARMACOLOGICAL RELEVANCE: As reported in the Ancient Chinese Medicinal Books, Ginkgo biloba L. fruit has been used as a traditional Chinese medicine for the treatment asthma and cough or as a disinfectant. Our previous study demonstrated that G. biloba exocarp extract (GBEE), an extract of a traditional Chinese herb, inhibits the formation of methicillin-resistant Staphylococcus aureus (MRSA) biofilms. However, GBEE is a crude extract that contains many components, and the underlying mechanisms of purified GBEE fractions extracted with solvents of different polarities are unknown. AIM OF THE STUDY: This study aimed to investigate the different components in GBEE fractions extracted with solvents of different polarities and their antibacterial effects and mechanisms against MRSA and Staphylococcus haemolyticus biofilms both in vitro and in vivo. METHODS: The components in different fractions were detected by high-performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS). Microbroth dilution assays and time growth curves were used to determine the antibacterial effects of the fractions on 15 clinical bacterial isolates. Crystal violet staining, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were utilized to identify the fractions that affected bacterial biofilm formation. The potential MRSA targets of the GBEE fraction obtained with petroleum ether (PE), denoted GBEE-PE, were screened by transcriptome sequencing, and the gene expression profile was verified by quantitative polymerase chain reaction (qPCR). RESULTS: HPLC-HRMS analysis revealed that the four GBEE fractions (extracted with petroleum ether, ethyl acetate, n-butanol, and water) contained different ginkgo components, and the antibacterial effects decreased as the polarity of the extraction solvent increased. The antibacterial activity of GBEE-PE was greater than that of the GBEE fraction extracted with ethyl acetate (EA). GBEE-PE improved H. illucens survival and reduced MRSA colonization in model mouse organs. Crystal violet staining and SEM and TEM analyses revealed that GBEE-PE inhibited MRSA and S. haemolyticus biofilm formation. Transcriptional analysis revealed that GBEE-PE inhibits MRSA biofilms by altering ion transport, cell wall metabolism and virulence-related gene expression. In addition, the LO2 cell viability and H. illucens toxicity assay data showed that GBEE-PE at 20 mg/kg was nontoxic. CONCLUSION: The GBEE fractions contained different components, and their antibacterial effects decreased with increases in the polarity of the extraction solvent. GBEE-PE limited MRSA growth and biofilm formation by affecting ion transport, cell wall synthesis, and virulence-related pathways. This research provides a more detailed overview of the mechanism by which GBEE-PE inhibits MRSA both in vitro and in vivo and suggests that GBEE-PE is a new prospective antimicrobial with the potential to be used in MRSA therapeutics in the future.

The effect and mechanism of iodophors on the adhesion and virulence of Staphylococcus aureus biofilms attached to artificial joint materials.

BACKGROUND: Iodophors are known to be a treatment for biofilm-related periprosthetic joint infection. However, the efficacy and mechanism of eradicating biofilms from different artificial joint materials after iodophor treatment are unknown. This study was conducted to understand the effect and mechanism of iodophors with respect to the adhesion and virulence of Staphylococcus aureus biofilms attached to artificial joint materials. METHODS: Biofilms of Staphylococcus aureus strains were grown on titanium alloy, cobalt chromium molybdenum and polyethylene coupons, which are commonly used materials for artificial joints, for 24 h. Afterward, all coupons were divided into experimental and control groups: (1) exposed to a 0.5 ± 0.05% iodophor for 5 min and (2) exposed to phosphate-buffered saline for 5 min. To gauge the level of biofilm, colony forming units (CFU), live/dead staining confocal microscopy and crystal violet staining were used. Meanwhile, the expression of icaACDR and clfA, which are related to virulence and adhesion, was examined in both the experimental and control groups. RESULTS: A roughly three-log decrease in CFU/cm2 was seen in the viable plate count compared to the control group. Confocal imaging and crystal violet staining verified the CFU data. Moreover, the expression of icaACDR was reduced on three different orthopaedic implant materials, and the expression of clfA was also inhibited on titanium alloy coupons exposed to the iodophor. CONCLUSIONS: Our results indicated that exposure to an iodophor for 5 min could significantly eliminate biofilms. When Staphylococcus aureus that had adhered to these three materials, which were used for artificial joints, was treated with an iodophor for 5 min, the expression of icaACDR was significantly reduced. This provides strong evidence for clinically clearing periprosthetic joint infections without removing the artificial joints.

Inhibition of proliferation, migration, and adhesion of skin fibroblasts by enzymatic poly(gallic acid) grafted with L-Arginine, migration, and adhesion of skin fibroblasts by enzymatic poly(gallic acid) grafted with L-Arginine.

Psoriasis and atopic dermatitis (AD) are characterized by enhanced skin inflammation, which results in hyperproliferation and the recruitment of immune cells into the skin. For that reason, it is needed a chemical capable to reduce cell proliferation and the recruitment of cells. The search for new molecules for therapeutic skin treatment mainly focuses on the antioxidant and anti-inflammatory properties, highlighting the rheological properties of polymeric polypeptides. We studied L-arginine (L-Arg) grafted (-g-) to enzymatic poly(gallic acid) (PGAL). The latter is a multiradical antioxidant with greater properties and thermal stability. The derivative was enzymatically polymerized in an innocuous procedure. The poly(gallic acid)-g-L-Arg molecule (PGAL-g-L-Arg) inhibits bacterial strains which also have been involved in the progression of psoriasis and AD. However, it is important to analyze their biological effect on skin cells. The cell viability was analyzed by calcein/ethidium homodimer assays and crystal violet. The proliferation and cell attachment were determined by a curve of time and quantitation of the optical density of crystal violet. To analyze the cell migration a wound-healing assay was performed. This synthesis demonstrates that it is not cytotoxic at high concentrations (250 µg/mL). We observed a decrease in the proliferation, migration, and adhesion of dermal fibroblasts in vitro but the compound could not avoid the increase of reactive oxygen species in the cell. Based on our findings, PGAL-g-L-Arg is a promising candidate for treating skin diseases such as psoriasis and AD where decreasing the proliferation and cell migration could help to avoid inflammation.

The effect of hypergravity, hyperbaric pressure, and hypoxia on osteogenic differentiation of adipose stem cells.

Human adipose stem cells (ASCs) hold great potential for regenerative medicine approaches, including osteogenic regeneration of bone defects, that fail to heal autonomously. Osteogenic differentiation of stem cells is dependent on the stimulation of biophysical factors. In the present study, the effects of hypergravity, hypoxia, and hyperbaric treatment were investigated on adipose stem cell (ASC) metabolic activity, quantified by PrestoBlue conversion, and cell numbers, evaluated by crystal violet staining. Osteogenic differentiation was assessed by alkaline phosphatase (ALP) activity and cresolphthalein staining of calcium deposition. Differentiation was performed for 12 days, which was accompanied by periodical stimulation. Increasing gravity forces up to 50x g did not affect ASC viability, but it enhanced osteogenic markers with a strongest effect between 20 and 30x g. Hyperbaric stimulation at 3 bar decreased ASC cell numbers but increased ALP activity and calcium deposition. Hypoxia at 8 % atmospheric oxygen did not affect ASC proliferation, while cell numbers were reduced at 3 % oxygen. Furthermore, hypoxic conditions produced opposing results on osteogenic markers, as ALP activity increased whereas cresolphthalein staining decreased upon stimulation. These data demonstrated that intermittent short duration of basal physical or chemical impulses interfere with the osteogenic differentiation of ASCs. Our findings could be of specific relevance in ASC based therapies for regenerative medicine and bone tissue engineering approaches.

Naringenin suppresses epithelial ovarian cancer by inhibiting proliferation and modulating gut microbiota.

BACKGROUND: Ovarian cancer has the highest mortality among all gynecological malignancies; currently, no effective therapeutics are available for its treatment. Naringenin has been shown to inhibit the progression of various cancers, but its inhibitory effect on ovarian cancer remains unknown. PURPOSE: This study aimed to evaluate the inhibitory effects of naringenin on ovarian cancer and elucidate the underlying mechanisms. METHODS: Cancer cell proliferation was detected by cell counting kit-8 and crystal violet assays, and the migration capability was determined by wound healing and transwell assays. Western blotting and immunohistochemistry assays were employed to determine the expression levels of the epidermal growth factor receptor, phosphatidylinositol 3-kinase (PI3K) and cyclin D1 in vitro and in vivo, respectively. An ES-2 xenograft nude mouse model was established for the in vivo experiments, and fecal samples were collected for intestinal microbiota analysis by 16S rDNA sequencing. RESULTS: Naringenin suppressed the proliferation and migration of A2780 and ES-2 cancer cell lines and downregulated PI3K in vitro. In animal experiments, naringenin treatment significantly decreased the tumor weight and volume, and oral administration exhibited greater effects than intraperitoneal injection. Additionally, naringenin treatment ameliorated the population composition of the microbiota in animals with ovarian cancer and significantly increased the abundances of Alistipes and Lactobacillus. CONCLUSION: Naringenin suppresses epithelial ovarian cancer by inhibiting PI3K pathway expression and ameliorating the gut microbiota, and the oral route is more effective than parenteral administration.

Evaluation of the antimicrobial function of Ginkgo biloba exocarp extract against clinical bacteria and its effect on Staphylococcus haemolyticus by disrupting biofilms.

ETHNOPHARMACOLOGICAL RELEVANCE: The fruit of Ginkgo biloba L. (Ginkgo nuts) has been used for a long time as a critical Chinese medicine material to treat cough and asthma, as well as a disinfectant. Similar records were written in the Compendium of Materia Medica (Ben Cao Gang Mu, pinyin in Chinese) and Sheng Nong's herbal classic (Shen Nong Ben Cao Jing, pinyin in Chinese). Recent research has shown that Ginkgo biloba exocarp extract (GBEE) has the functions of unblocking blood vessels and improving brain function, as well as antitumour activity and antibacterial activity. GBEE was shown to inhibit methicillin-resistant Staphylococcus aureus (MRSA) biofilm formation as a traditional Chinese herb in our previous report in this journal. AIM OF THE STUD: yThe antibiotic resistance of clinical bacteria has recently become increasingly serious. Thus, this study aimed to investigate the Ginkgo biloba exocarp extract (GBEE) antibacterial lineage, as well as its effect and mechanism on S. haemolyticus biofilms. This study will provide a new perspective on clinical multidrug resistant (MDR) treatment with ethnopharmacology herbs. METHODS: The microbroth dilution assay was carried out to measure the antibacterial effect of GBEE on 13 types of clinical bacteria. Bacterial growth curves with or without GBEE treatment were drawn at different time points. The potential targets of GBEE against S. haemolyticus were screened by transcriptome sequencing. The effects of GBEE on bacterial biofilm formation and mature biofilm disruption were determined by crystal violet staining and scanning electron microscopy. The metabolic activity of bacteria inside the biofilm was assessed by colony-forming unit (CFU) counting and (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2HY-tetrazolium bromide (MTT) assay. Quantitative polymerase chain reaction (qPCR) was used to measure the gene expression profile of GBEE on S. haemolyticus biofilm-related factors. RESULTS: The results showed that GBEE has bacteriostatic effects on 3 g-positive (G+) and 2 g-negative (G-) bacteria among 13 species of clinical bacteria. The antibacterial effect of GBEE supernatant liquid was stronger than the antibacterial effect of GBEE supernviaould-like liquid. GBEE supernatant liquid inhibited the growth of S. epidermidis, S. haemolyticus, and E. faecium at shallow concentrations with minimum inhibitory concentrations (MICs) of 2 µg/ml, 4 µg/ml and 8 µg/ml, respectively. Genes involved in quorum sensing, two-component systems, folate biosynthesis, and ATP-binding cassette (ABC) transporters were differentially expressed in GBEE-treated groups compared with controls. Crystal violet, scanning electron microscopy (SEM) and MTT assays showed that GBEE suppressed S. haemolyticus biofilm formation in a dose-dependent manner. Moreover, GBEE supernatant liquid downregulated cidA, cidB and atl, which are involved in cell lysis and extracellular DNA (eDNA) release, as well as downregulated the cbp, ebp and fbp participation in encoding cell-surface binding proteins. CONCLUSIONS: GBEE has an excellent antibacterial effect on gram-positive bacteria and also inhibits the growth of gram-negative bacteria, such as A. baumannii (carbapenem-resistant Acinetobacter baumannii) CRABA and S. maltophilia. GBEE inhibits the biofilm formation of S. haemolyticus by altering the regulation and biofilm material-related genes, including the release of eDNA and cell-surface binding proteins.

Asian Sand Dust Particles Enhance the Development of Aspergillus fumigatus Biofilm on Nasal Epithelial Cells.

BACKGROUND: Asian sand dust (ASD) and Aspergillus fumigatus are known risk factors for airway mucosal inflammatory diseases. Bacterial and fungal biofilms commonly coexist in chronic rhinosinusitis and fungus balls. We evaluated the effects of ASD on the development of A. fumigatus biofilm formation on nasal epithelial cells. METHODS: Primary nasal epithelial cells were cultured with A. fumigatus conidia with or without ASD for 72 h. The production of interleukin (IL)-6, IL-8, and transforming growth factor (TGF)-ß1 from nasal epithelial cells was determined by the enzyme-linked immunosorbent assay. The effects of ASD on A. fumigatus biofilm formation were determined using crystal violet, concanavalin A, safranin staining, and confocal scanning laser microscopy. RESULTS: ASD and A. fumigatus significantly enhanced the production of IL-6 and IL-8 from nasal epithelial cells. By coculturing A. fumigatus with ASD, the dry weight and safranin staining of the fungal biofilms significantly increased in a time-dependent manner. However, the increased level of crystal violet and concanavalin A stain decreased after 72 h of incubation. CONCLUSIONS: ASD and A. fumigatus induced the production of inflammatory chemical mediators from nasal epithelial cells. The exposure of A. fumigatus to ASD enhanced the formation of biofilms. The coexistence of ASD and A. fumigatus may increase the development of fungal biofilms and fungal inflammatory diseases in the sinonasal mucosa.

Water-Repellent TiO2-Organic Dye-Based Air Filters for Efficient Visible-Light-Activated Photochemical Inactivation against Bioaerosols.

Recently, bioaerosols, including the 2019 novel coronavirus, pose a serious threat to global public health. Herein, we introduce a visible-light-activated (VLA) antimicrobial air filter functionalized with titanium dioxide (TiO2)-crystal violet (CV) nanocomposites facilitating abandoned visible light from sunlight or indoor lights. The TiO2-CV based VLA antimicrobial air filters exhibit a potent inactivation rate of ∼99.98% and filtration efficiency of ∼99.9% against various bioaerosols. Under visible-light, the CV is involved in overall inactivation by inducing reactive oxygen species production both directly (CV itself) and indirectly (in combination with TiO2). Moreover, the susceptibility of the CV to humidity was significantly improved by forming a hydrophobic molecular layer on the TiO2 surface, highlighting its potential applicability in real environments such as exhaled or humid air. We believe this work can open a new avenue for designing and realizing practical antimicrobial technology using ubiquitous visible-light energy against the threat of infectious bioaerosols.

Review of the use of gentian violet in dermatology practice.

OBJECTIVE: To review the use of gentian violet in dermatology. DESIGN: A comprehensive literature search on gentian violet in dermatology practice was performed through PubMed. RESULTS: Gentian violet is effective in treating methicillin-resistant Staphylococcus aureus-colonized skin lesions; mean number of days for complete eradication was 9.1 days. Gentian violet is almost as effective as ketoconazole and more effective than nystatin in the treatment of oral thrush in AIDS patients. In an in vitro study on cutaneous T cell lymphoma cell lines, there was no difference between nitrogen mustard and gentian violet in stimulating apoptosis. When comparing gentian violet to silver sulfadiazine dressings in healing burn wounds, the gentian violet treatment group reported less pain, fewer febrile episodes, and decreased bacterial growth compared to control. In atopic dermatitis subjects, gentian violet decreased Staphylococcus aureus colonization and improved disease severity in lesional skin compared to non-lesional skin. CONCLUSION: Studies have investigated gentian violet's antibacterial, antifungal, antiviral, antiparasitic, anti-angiogenic, antitumor, and wound healing properties. Gentian violet is a low cost and well-tolerated topical agent with the potential for widespread applications in dermatology.

Antibacterial Surfaces with Activity against Antimicrobial Resistant Bacterial Pathogens and Endospores.

Hospital-acquired bacterial infections are a significant burden on healthcare systems worldwide causing an increased duration of hospital stays and prolonged patient suffering. We show that polyurethane containing crystal violet (CV) and 3-4 nm zinc oxide nanoparticles (ZnO NPs) possesses excellent bactericidal activity against hospital-acquired pathogens including multidrug resistant Escherichia coli (E. coli), Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA), and even highly resistant endospores of Clostridioides (Clostridium) difficile. Importantly, we used clinical isolates of bacterial strains, a protocol to mimic the environmental conditions of a real exposure in the healthcare setting, and low light intensity equivalent to that encountered in UK hospitals (∼500 lux). Our data shows that ZnO NPs enhance the photobactericidal activity of CV under low intensity light even with short exposure times, and we show that this involves both Type I and Type II photochemical pathways. Interestingly, polyurethane containing ZnO NPs alone showed significant bactericidal activity in the dark against one strain of E. coli, indicating that the NPs possess both light-activated synergistic activity with CV and inherent bactericidal activity that is independent of light. These new antibacterial polymers are potentially useful in healthcare facilties to reduce the transmission of pathogens between people and the environment.

Orabase-formulated gentian violet effectively improved oral potentially malignant disorder in vitro and in vivo.

Oral cancer is a prevalent cancer in male worldwide. Oral potentially malignant disorders (OMPDs) are the oral mucosa lesions that have high malignant transformation rate to oral cancer. The mainstay for OMPDs treatment includes carbon dioxide (CO2) laser and surgery, which may lead to the side effects of scarring and impaired function of oral cavity in the patients and reduced their willingness to receive curative therapy. Therefore, developing a non-invasive and function-preserving therapy is clinically important. Since development of a novel chemotherapeutic drug requires a lot of time and cost, we applied the high-throughput screening (HTS) approach to identify new bioactivities for FDA-approved drugs, known as drug repurposing. Through this drug repurposing approach, we discovered that gentian violet (GV), which is well known for its antibacterial, antifungal, antihelminthic, antitrypanosomal and antiviral activities, was able to induce significant cell death in DOK oral precancerous cells through ROS production. Moreover, decreased phosphorylation of p53(Ser15) and NFκB(Ser536) was required for GV-induced cell death. In vivo, 3% GV orabase effectively suppressed the progression of DMBA-induced oral precancerous lesions. In conclusion, this new formulation of GV through drug repurposing has the potential to be further developed as a therapeutic drug for OPMD clinically.

Photoactivable Polymers Embedded with Cadmium-Free Quantum Dots and Crystal Violet: Efficient Bactericidal Activity against Clinical Strains of Antibiotic-Resistant Bacteria.

The rising incidence of antibiotic-resistant infections from contaminated surfaces in hospitals or implanted medical devices has led to increasing interest in new antibacterial surfaces. Photoactivatable surfaces that can generate cytotoxic reactive oxygen species under exposure to ambient light is a promising approach to inactivation of surface-borne microorganisms. There is growing interest in the use of quantum dots (QDs) as light-harvesting agents for photobactericidal applications, but the cadmium in commonly used QDs will restrict clinical application. Herein, the photobactericidal activity of novel polyurethane substrates containing cadmium-free QDs was tested against clinical multidrug-resistant Gram-positive and Gram-negative bacterial strains: methicillin-resistant Staphylococcus aureus (MRSA) and a carbapenemase-producing strain of Escherichia coli ( E. coli). To enhance the capacity for reactive oxygen species generation, QDs were incorporated into the polymer with a photosensitizing dye, crystal violet. Close proximity between the QD and dye enables electron and energy transfer processes leading to generation of cytotoxic singlet oxygen and superoxide radicals. A QD solution in cyclohexane was premixed with a solution of CV in the more polar solvent, dichloromethane, to promote the formation of QD-CV nanocomposite complexes via CV adsorption. This solution was then used to embed the QDs and crystal violet into medical grade polyurethane via swell-encapsulation. The combination of QD and CV elicited significant synergistic antibacterial activity under visible light against MRSA within 1 h (99.98% reduction) and E. coli within 4 h (99.96% reduction). Photoluminescence lifetime and singlet oxygen phosphorescence measurements demonstrated that interaction between the QDs and the crystal violet occurs within the polymer and leads to enhanced generation of reactive oxygen species. Strong inhibition of kill was observed using the superoxide scavenger, superoxide dismutase. The efficacy of these QD-CV polymer substrates, that can harvest light across the visible spectrum, against multidrug-resistant bacteria demonstrates the feasibility of this approach.

Analysis of the Effect of Gentian Violet on Apoptosis and Proliferation in Cutaneous T-Cell Lymphoma in an In Vitro Study.

Importance: Triggering the extrinsic apoptotic pathway is an effective way to kill cutaneous T-cell lymphoma (CTCL) cells in vitro and ex vivo. Objective: To compare small molecules that induce extrinsic apoptosis in CTCL to identify and analyze compounds that induce high levels of tumor cell death and block tumor cell growth. Design, Setting, and Participants: From November 5, 2014, to January 30, 2018, this study performed high-throughput small molecule screening of 1710 compounds followed by detailed analysis of the ability of gentian violet (GV) to promote apoptosis and inhibit proliferation of CTCL cells. Exposures: In vitro and ex vivo analyses using enzyme-linked immunosorbent assays, flow cytometry, and immunoblotting. Main Outcomes and Measures: Apoptosis, cleaved caspases, extrinsic apoptotic death receptors and ligands, cell proliferation, nuclear factor-κB expression, and other factors. Results: This study used high-throughput screening to detect cleaved caspase 8 induced in CTCL cells by 1710 unique compounds. The nonprescription, topical antimicrobial remedy GV induced more total apoptosis than did nitrogen mustard (mechlorethamine). Furthermore, GV induced 4 to 6 times greater apoptosis in CTCL lines than in normal keratinocytes, suggesting a favorable topical toxicity profile. In addition to increasing caspase 8, GV also upregulated death receptors 4 and 5, tumor necrosis factor (TNF)-related apoptosis-inducing ligand, and Fas ligand but not the Fas receptor, TNF receptor, or TNF-α ligand. These results are consistent with induction of extrinsic apoptosis via the Fas and TNF-related apoptosis-inducing ligand pathways. Increased phosphorylation of phospholipase C-γ1, Ca2+ influx, and reactive oxygen species were also detected, indicating that the mechanism of Fas ligand upregulation involves key elements of the activation-induced cell death pathway. In ex vivo studies, 1-µmol/L GV induced up to 90% CTCL apoptosis in Sézary blood cells. In addition, GV reduced expression of antiapoptotic myeloid cell leukemia 1 and proproliferative nuclear factor-κB components and increased inhibitory κB levels. This finding was associated with cell cycle arrest and reduced CTCL tumor cell proliferation. Furthermore, the CTCL killing associated with GV was augmented when used in combination with methotrexate. Conclusions and Relevance: This study found that GV attacked tumor viability and growth in CTCL. Although purple at neutral pH, GV can be rendered colorless by altering its pH. These preclinical findings may help to broaden knowledge of the antineoplastic features of GV and provide a rationale for clinical studies of its use as a novel, inexpensive, topical therapy for CTCL that is available worldwide.

The effect of subinhibitory concentrations of gentian violet on the germ tube formation by Candida albicans and its adherence to oral epithelial cells.

OBJECTIVE: This study investigated the effect of subinhibitory concentrations of gentian violet on the germ tube formation by Candida albicans and its adherence ability to oral epithelial cells. METHODS: Thirty strains of C. albicans isolated from denture wearers, normal healthy individuals and HIV positive patients were used in the study. The antifungal property (Minimum Fungicidal Concentration) of gentian violet was determined at various time intervals using a microdilution technique. The effect of subinhibitory concentrations of gentian violet on the adherence ability (0.000244%) and on germ tube formation ((0.000244%, 0.000122%, 0.000061% and 0.000031%) was determined. In both experiments, water was used as a control. The test results were compared using the Kruskal-Wallis test. RESULTS: At 60min a high concentration (0.0078%) of gentian violet was required to completely kill C. albicans. Subinhibitory concentrations of gentian violet significantly reduced the adherence ability of C. albicans by 57% (p<0.01) and equally inhibited germ tube formation (p<0.01) compared with the controls. The inhibition was concentration dependent, with up to 98% reduction at a concentration of 0.000244%. Germ tube reduction was significantly higher in the isolates from the HIV positive patients than in the isolates from denture wearers. CONCLUSION: At high concentrations, gentian violet killed C. albicans, whereas at subinhibitory concentrations it reduced its virulence by preventing the adherence ability and germ tube formation. This suggests that the beneficial effects of gentian violet would last beyond the fungicidal concentrations in the treatment of candidiasis.

Down-Regulation of SOX2 Underlies the Inhibitory Effects of the Triphenylmethane Gentian Violet on Melanoma Cell Self-Renewal and Survival.

Human melanomas contain a population of tumor-initiating cells that are able to maintain the growth of the tumor. We previously showed that the embryonic transcription factor SOX2 is essential for self-renewal and tumorigenicity of human melanoma-initiating cells. However, targeting a transcription factor is still challenging. Gentian violet (GV) is a cationic triphenylmethane dye with potent antifungal and antibacterial activity. Recently, a combination therapy of imiquimod and GV has shown an inhibitory effect against melanoma metastases. Whether and how GV affects melanoma cells remains unknown. Here we show that GV represses melanoma stem cell self-renewal through inhibition of SOX2. Mechanistically, GV hinders EGFR activation and inhibits the signal transducer and activator of transcription-3 [(STAT3)/SOX2] axis. Importantly, we show that GV treatment decreases STAT3 phosphorylation at residue tyrosine 705, thus preventing the translocation of STAT3 into the nucleus and its binding to SOX2 promoter. In addition, GV affects melanoma cell growth by promoting mitochondrial apoptosis and G2 cell cycle arrest. This study shows that in melanoma, GV affects both the stem cell and the tumor bulk compartments, suggesting the potential use of GV in treating human melanoma alone or in combination with targeted therapy and/or immunotherapy.

Gentian violet inhibits MDA-MB-231 human breast cancer cell proliferation, and reverses the stimulation of osteoclastogenesis and suppression of osteoblast activity induced by cancer cells.

Gentian violet (GV) is a cationic triphenylmethane dye, with potent antifungal and antibacterial activity. We recently reported that in vitro GV suppresses the differentiation of bone resorbing osteoclasts while stimulating the differentiation and activity of bone forming osteoblasts. Breast cancer is highly metastatic to bone and drives bone turnover that further promotes cancer engraftment and expansion, the so-called vicious cycle. In humans, breast cancer metastases cause osteolytic lesions and skeletal damage that leads to bone fractures, an additional source of patient morbidity. The MDA-MB-231 human breast cancer cell line is a commonly used model of human breast cancer that when injected into mice metastasizes to bone causing osteolytic lesions by promoting osteoclastic bone resorption and/or suppressing osteoblastic bone formation. In the present study, we investigated the direct action of GV on MDA-MB-231 proliferation, and the capacity of GV to reverse the negative impact of MDA-MB-231 cells on osteoclast and osteoblast differentiation. Our data reveal for the first time that GV suppresses proliferation, and induces apoptosis, of MDA-MB-231 cells. We further demonstrated the capacity of GV to reverse the pro-osteoclastogenic and anti-osteoblastic activities of MDA-MB-231 cells in vitro. These data suggest that GV has important applications in the treatment of breast cancer through multiple actions including direct suppression of cancer cell proliferation, breaking the vicious cycle between cancer and bone, and alleviating the skeletal defects induced by bone metastasis.

Redox-modulating agents target NOX2-dependent IKKε oncogenic kinase expression and proliferation in human breast cancer cell lines.

Oxidative stress is considered a causative factor in carcinogenesis, but also in the development of resistance to current chemotherapies. The appropriate usage of redox-modulating compounds is limited by the lack of knowledge of their impact on specific molecular pathways. Increased levels of the IKKε kinase, as a result of gene amplification or aberrant expression, are observed in a substantial number of breast carcinomas. IKKε not only plays a key role in cell transformation and invasiveness, but also in the development of resistance to tamoxifen. Here, we studied the effect of in vitro treatment with the redox-modulating triphenylmethane dyes, Gentian Violet and Brilliant Green, and nitroxide Tempol on IKKε expression and cell proliferation in the human breast cancer epithelial cell lines exhibiting amplification of IKKε, MCF-7 and ZR75.1. We show that Gentian Violet, Brilliant Green and Tempol significantly decrease intracellular superoxide anion levels and inhibit IKKε expression and cell viability. Treatment with Gentian Violet and Brilliant Green was associated with a reduced cyclin D1 expression and activation of caspase 3 and/or 7. Tempol decreased cyclin D1 expression in both cell lines, while activation of caspase 7 was only observed in MCF-7 cells. Silencing of the superoxide-generating NOX2 NADPH oxidase expressed in breast cancer cells resulted in the significant reduction of IKKε expression. Taken together, our results suggest that redox-modulating compounds targeting NOX2 could present a particular therapeutic interest in combination therapy against breast carcinomas exhibiting IKKε amplification.

A bivalent cationic dye enabling selective photo-inactivation against Gram-negative bacteria.

A piperazine-modified Crystal Violet was found to be able to selectively inactivate Gram-negative bacteria upon visible light irradiation but left Gram-positive bacteria less damaged, which can serve as a blueprint for the development of novel narrow-spectrum agents to replenish the current arsenal of photodynamic antimicrobial chemotherapy (PACT).