Low Cellular Activity Research Articles

Structure-Based Discovery of a Series of Covalent, Orally Bioavailable, and Selective BFL1 Inhibitors.

BFL1, a member of the antiapoptotic BCL2 family, has been relatively understudied compared to its counterparts despite evidence of its overexpression in various hematological malignancies. Across two articles, we describe the development of BFL1 in vivo tools. The first article describes the hit identification from a covalent fragment library and the subsequent evolution from the hit to compound 6.22 This work reports the structure-based optimization of compound 6 into a series of BFL1 inhibitors selective over the other BCL2 family members, with low nanomolar cellular activity when combined with AZD5991, exemplified by compound 20. Compound 20 demonstrated a cell death phenotype in SUDHL1 and OCILY10 cell lines and in the in vivo study, BFL1 stabilization and cleaved caspase 3 activation were observed in a dose-dependent manner. In addition, the enzymatic turnover studies with the BFL1 protein showed that compound 20 stabilized the protein, extending the half-life to 10.8 h.

Discovery and structure-activity relationship study of nicotinamide derivatives as DNA demethylase ALKBH2 inhibitors

AlkB homolog 2 (ALKBH2) is a Fe (II) and 2-oxoglutarate (2OG)-dependent DNA demethylase. It has been reported to be highly expressed in many cancers including glioblastoma (GBM) and affected disease progression by regulating gene expression. Small molecule inhibitors of ALKBH2 might be used as disease intervention reagents or chemical tools for bio-functional studies of ALKBH2, but currently no potent and selective ALKBH2 inhibitors are reported. We herein disclose a new potent and selective ALKBH2 inhibitor (AH2-15c), which showed an IC50 value of 0.031 ± 0.001 μM in a fluorescence polarization (FP) assay and exhibited more than 200-fold selectivity towards ALKBH2 versus other AlkB subfamily members. Since AH2-15c showed very low cellular activity due to its poor cell membrane permeability originating from the carboxyl group, we investigated the un-hydrolyzed counterpart AH2-14c. AH2-14c could directly bind to ALKBH2 and increase the abundance of DNA N3-methylcytosine (3meC) modifications in GBM U87 cells, with a superior effect to AH2-15c. In addition, AH2-14c exhibited much better activities of anti-viability, anti-proliferation and anti-migration against U87 cells. Collectively, we discovered the first potent and selective ALKBH2 inhibitor, which could be taken as a foundation for future drug development and mechanism of action studies.

Thymus spp. Aqueous Extracts and Their Constituent Salvianolic Acid A Induce Nrf2-Dependent Cellular Antioxidant Protection Against Oxidative Stress in Caco-2 Cells.

The increasing incidence of colorectal cancer and inflammatory diseases poses a major health concern, with oxidative stress playing a significant role in the onset of these pathologies. Factors such as excessive consumption of sugar-rich and fatty foods, synthetic food additives, pesticides, alcohol, and tobacco contribute to oxidative stress and disrupt intestinal homeostasis. Functional foods arise as a potential tool to regulate redox balance in the intestinal tract. Herbs (such as Thymus spp.) have long been screened for their antioxidant properties, but their use as antioxidants for medicinal purposes requires validation in biological models. In this study, we addressed the potential antioxidant protection and preventive effects of extracts from two thyme species at the intestinal level, as well as their molecular mechanisms of action. Caco-2 cells were pre-exposed (4 h) to aqueous (AD) and hydroethanolic (HE) extracts of Thymus carnosus and Thymus capitellatus, followed by a recovery period in culture medium (16 h), and then treated with tert-butyl-hydroperoxide (TBHP; 4 h), before analyzing cell viability. The effect of the extracts' main components was also analysed. Cellular oxidative stress, cell-death markers, and the expression of antioxidant-related proteins were evaluated using flow cytometry on cells pre-exposed to the AD extracts and salvianolic acid A (SAA). Results showed that pre-exposure to AD extracts or SAA reduced TBHP-induced oxidative stress and cell death, mediated by increased levels of nuclear factor erythroid 2-related factor 2 (Nrf2) protein. The protective activity of T. capitellatus AD extract was shown to be dependent on NAD(P)H quinone dehydrogenase 1 (NQO1) protein expression and on increased glutathione (GSH) content. Furthermore, ursolic acid induced cytotoxicity and low cellular antioxidant activity, and thus the presence of this triterpenoid impaired the antioxidant effect of HE extracts. Thus, AD extracts show high potential as prophylactic dietary agents, while HE extracts arise as a source of nutraceuticals with antioxidant potential.

Agonist Discovery for Membrane Proteins on Live Cells by Using DNA-encoded Libraries.

Identifying biologically active ligands for membrane proteins is an important task in chemical biology. We report an approach to directly identify small molecule agonists against membrane proteins by selecting DNA-encoded libraries (DELs) on live cells. This method connects extracellular ligand binding with intracellular biochemical transformation, thereby biasing the selection toward agonist identification. We have demonstrated the methodology with three membrane proteins: epidermal growth factor receptor (EGFR), thrombopoietin receptor (TPOR), and insulin receptor (INSR). A ∼30 million and a 1.033 billion-compound DEL were selected against these targets, and novel agonists with subnanomolar affinity and low micromolar cellular activities have been discovered. The INSR agonists activated the receptor by possibly binding to an allosteric site, exhibited clear synergistic effects with insulin, and activated the downstream signaling pathways. Notably, the agonists did not activate the insulin-like growth factor 1 receptor (IGF-1R), a highly homologous receptor whose activation may lead to tumor progression. Collectively, this work has developed an approach toward "functional" DEL selections on the cell surface and may provide a widely applicable method for agonist discovery for membrane proteins.

Monascus pigment-protected bone marrow-derived stem cells for heart failure treatment

Mesenchymal stem cells (MSCs) have demonstrated significant therapeutic potential in heart failure (HF) treatment. However, their clinical application is impeded by low retention rate and low cellular activity of MSCs caused by high inflammatory and reactive oxygen species (ROS) microenvironment. In this study, monascus pigment (MP) nanoparticle (PPM) was proposed for improving adverse microenvironment and assisting in transplantation of bone marrow-derived MSCs (BMSCs). Meanwhile, in order to load PPM and reduce the mechanical damage of BMSCs, injectable hydrogels based on Schiff base cross-linking were prepared. The PPM displays ROS-scavenging and macrophage phenotype-regulating capabilities, significantly enhancing BMSCs survival and activity in HF microenvironment. This hydrogel demonstrates superior biocompatibility, injectability, and tissue adhesion. With the synergistic effects of injectable, adhesive hydrogel and the microenvironment-modulating properties of MP, cardiac function was effectively improved in the pericardial sac of rats. Our results offer insights into advancing BMSCs-based HF therapies and their clinical applications.

Low protein adsorption and high cellular activity of PEG-based silicone polyurethane for artificial heart valves

Polyurethane have the advantages of convenient structural design, low production cost, and excellent mechanical compatibility, and is expected to be used as a polymer heart valve material. However, its development in biomaterials is limited because it is prone to hydrolysis and coagulation after long-term implantation in organisms. In this study, "PEG-MDI-PEG" macromolecular diol was prepared by structural design of the soft segment of polyurethane. Copolymerization with telechelic α,ω-bis(6-hydroxyethoxypropyl)-PDMS as mixed soft segment, prepolymer solution was prepared by solution polymerization, and the biocompatibility of silicone-based polyurethane obtained by casting was characterized. By adjusting the feed ratio to control the silicon content in the copolymer, when the silicon content was 60 %, the protein adsorption capacity was 75 % lower than that of unmodified polyurethane, and the cell activity was more than 80 %, which was a useful characteristic for silicon-based polyurethane as a potential polymer valve material.

Abstract 7145: Identification of Debio 0432 as a potent and selective USP1 inhibitor for cancer therapy

Abstract Introduction: Debio 0432 is a Ubiquitin Specific Protease 1 (USP1) inhibitor at preclinical stage. This study presents the first data on this small molecule and its activity as an anti-cancer therapy in multiple preclinical models. USP1 is a deubiquitinase, member of the deubiquitinating enzyme (DUB) family that plays an important role at the replication fork during DNA replication. Its prominent role in DNA repair, targeting Proliferating Cell Nuclear Antigen (PCNA) that regulates polymerase recruitment in the translesion synthesis (TLS), makes it an emergent target in the DNA damage repair (DDR) field. Methods: In silico docking has been used to identify a likely binding site of Debio 0432. Biochemical and cellular assays have been performed to show its activity on the target and in cell lines of different cancer types. In vivo models in cell line derived xenograft (CDX) and patient derived xenograft (PDX) were then used to confirm the activity of the compound and to study PK/PD relationship. Results: Debio 0432 likely binds USP1 in an allosteric pocket and is very selective across the 58 members of the USP family. Furthermore, it does not affect any kinase. Its biochemical activity on USP1 is in the low nanomolar range and cellular activity ranges between from single digit nM to above 1uM. In vivo, Debio 0432 shows antitumor activity in the BRCA mutant breast cancer model MDA-MB-436. The downstream target Ub-PCNA, selected as pharmacodynamic marker, is modulated in a dose and plasma exposure-dependent manner. Further in vivo experiments in PDX models showed dose-dependent activity in different cancer types, in both BRCA wild type and mutant models. Treatments in all in vivo studies were well tolerated. Conclusion: Overall, we show that Debio 0432 is a selective and potent small molecule targeting USP1, an emerging target in the DDR field. It shows good activity in different preclinical models and is well tolerated at active doses. Debio 0432 is currently undergoing IND-enabling studies and in preparation for entry into clinical development. Citation Format: Noemie Luong, Annett Kunze, Nicolas Quesnot, Erin R. Aho, Loren Berry, Scott Boiko, Alex J. Buckmelter, Sebastien Lofek, Selena Vigano, Christophe Chardonnens. Identification of Debio 0432 as a potent and selective USP1 inhibitor for cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7145.

Synthesis and biological evaluation of (2‐aminosulfonylpyridin‐6‐yl)pyrazolopyrimidinone derivatives as Wee1 inhibitors for cancer treatment

AbstractFor an analog‐based design of novel Wee1 inhibitors, we profiled in vitro ADMET and in vivo PK properties of adavosertib. Based on the properties of adavosertib, we aimed to improve its metabolic stability by designing a novel target compound 1a with an aminosulfonyl group instead of the 2‐hydroxypropan‐2‐yl moiety in adavosertib. Derivatives of target compound 1a were synthesized and evaluated for Wee1 enzyme inhibition and liver microsomal phase I stability. We identified compound 1a as a sub‐nanomolar Wee1 inhibitor and 10 additional compounds with one‐digit nanomolar Wee1 inhibitory activity, among which seven compounds including 1a exhibited improved metabolic stabilities compared with adavosertib. However, MDA‐MB‐231 cell growth inhibitory activities of all synthesized compounds and Wee1 substrate phosphorylation inhibitory activities of selected compounds were inferior to adavosertib overall. Moreover, the representative compound 1a exhibited low permeability, which may be the reason for the low cellular activities of compound 1a.

Liquid chromatography-mass spectrometry-based metabolomics and fluxomics reveals the metabolic alterations in glioma U87MG multicellular tumor spheroids versus two-dimensional cell cultures.

Multicellular tumor spheroids (MCTSs) that reconstitute the metabolic characteristics of in vivo tumor tissue may facilitate the discovery of molecular biomarkers and effective anticancer therapies. However, little is known about how cancer cells adapt their metabolic changes in complex three-dimensional (3D) microenvironments. Here, using the two-dimensional (2D) cell model as control, the metabolic phenotypes of glioma U87MG multicellular tumor spheroids were systematically investigated based on static metabolomics and dynamic fluxomics analysis. A liquid chromatography-mass spectrometry-based global metabolomics and lipidomics approach was adopted to survey the cellular samples from 2D and 3D culture systems, revealing marked molecular differences between them. Then, by means of metabolomic pathway analysis, the metabolic pathways altered in glioma MCTSs were found using 13 C6 -glucose as a tracer to map the metabolic flux of glycolysis, the tricarboxylic acid (TCA) cycle, de novo nucleotide synthesis, and de novo lipid biosynthesis in the MCTS model. We found nine metabolic pathways as well as glycerolipid, glycerophospholipid and sphingolipid metabolism to be predominantly altered in glioma MCTSs. The reduced nucleotide metabolism, amino acid metabolism and glutathione metabolism indicated an overall lower cellular activity in MCTSs. Through dynamic fluxomics analysis in the MCTS model, we found that cells cultured in MCTSs exhibited increased glycolysis activity and de novo lipid biosynthesis activity, and decreased the TCA cycle and de novo purine nucleotide biosynthesis activity. Our study highlights specific, altered biochemical pathways in MCTSs, emphasizing dysregulation of energy metabolism and lipid metabolism, and offering novel insight into metabolic events in glioma MCTSs.

Dorsal striatum c-Fos activity in perseverative ephrin-A2A5-/- mice and the cellular effect of low-intensity rTMS.

Overreliance on habit is linked with disorders, such as drug addiction and obsessive-compulsive disorder, and there is increasing interest in the use of repetitive transcranial magnetic stimulation (rTMS) to alter neuronal activity in the relevant pathways and for therapeutic outcomes. In this study, we researched the brains of ephrin-A2A5-/- mice, which previously showed perseverative behavior in progressive-ratio tasks, associated with low cellular activity in the nucleus accumbens. We investigated whether rTMS treatment had altered the activity of the dorsal striatum in a way that suggested altered hierarchical recruitment of brain regions from the ventral striatum to the dorsal striatum, which is linked to abnormal habit formation. Brain sections from a limited number of mice that underwent training and performance on a progressive ratio task with and without low-intensity rTMS (LI-rTMS) were taken from a previous study. We took advantage of the previous characterization of perseverative behavior to investigate the contribution of different neuronal subtypes and striatal regions within this limited sample. Striatal regions were stained for c-Fos as a correlate of neuronal activation for DARPP32 to identify medium spiny neurons (MSNs) and for GAD67 to identify GABA-ergic interneurons. Contrary to our hypothesis, we found that neuronal activity in ephrin-A2A5-/- mice still reflected the typical organization of goal-directed behavior. There was a significant difference in the proportion of neuronal activity across the striatum between experimental groups and control but no significant effects identifying a specific regional change. However, there was a significant group by treatment interaction which suggests that MSN activity is altered in the dorsomedial striatum and a trend suggesting that rTMS increases ephrin-A2A5-/- MSN activity in the DMS. Although preliminary and inconclusive, the analysis of this archival data suggests that investigating circuit-based changes in striatal regions may provide insight into chronic rTMS mechanisms that could be relevant to treating disorders associated with perseverative behavior.

Design and Optimization of Novel Benzimidazole- and Imidazo[4,5-b]pyridine-Based ATM Kinase Inhibitors with Subnanomolar Activities.

The ATM kinase is a promising target in cancer treatment as an important regulator of the cellular response to DNA double-strand breaks. In this work, we present a new class of specific benzimidazole-based ATM inhibitors with picomolar potency against the isolated enzyme and favorable selectivity within relative PIKK and PI3K kinases. We could identify two promising inhibitor subgroups with significantly different physicochemical properties, which we developed simultaneously. These efforts lead to numerous highly active inhibitors with picomolar enzymatic activities. Furthermore, initial low cellular activities on A549 cells could be increased significantly in numerous examples resulting in cellular IC50 values in the subnanomolar range. Further characterization of the highly potent inhibitors 90 und 93 revealed promising pharmacokinetic properties and strong activities in organoids in combination with etoposide. Additionally, 93 showed no off-target activities within a kinome-representative mini kinase panel, with favorable selectivities within the PIKK- and PI3K-families.

Transient responses of melatonin to stress

Melatonin and its metabolites are ubiquitous antioxidants that are produced
 in response to reactive oxygen species (ROS) in virtually all cells of the
 body. The highest reported melatonin values in plasma and sweat occur during
 heavy exercise both indoors and outdoors during the day. The advent of sweat
 biosensors with sufficient melatonin sensitivity provides pseudo real-time
 evidence that melatonin is produced throughout the body not just in the pineal
 gland. The role of the pineal gland appears to be to provide cyclic production
 of melatonin for the regulation of circadian rhythms as well as supplemental melatonin
 during periods of low cellular activity. 
 Melatonin from the pineal gland represents only a small fraction of the
 body’s production capacity. Greater than 5 pg/ml min ramp rates for plasma and
 sweat melatonin have been reported during strenuous exercise in sunlight as
 compared to 0.15 pg/ml min ramp rates for plasma melatonin under dim light
 melatonin onset (DLMO) conditions. Sunlight
 and exercise, like fever, generates transient elevated levels of ROS in tissues
 with time constants measured in minutes or even seconds making this systemic
 antioxidant response potentially protective. Based on a simple accounting of
 ROS generated by sunlight, ROS we breathe, ROS we drink, and exercise, it
 appears that the body maintains a heightened basal level of ROS as part of its
 pathogen defense mechanisms. Current
 human lifestyles and modern enclosed spaces have substantially eliminated over
 90% of the ROS which undermines one of the body’s primary defenses. With
 advanced age, the inability to maintain this protective barrier appears to make
 us more susceptible to disease.

Maturation of bovine oocytes under low culture temperature decreased glutathione peroxidase activity of both oocytes and blastocysts.

It is known that the basic variable in the cellular environment is temperature and low temperature decreases cellular metabolism rate. Also, low cellular metabolic activity reduces oxidative stress, resulting in low ROS production. The aim of this study was therefore to investigate the effect of 36.5°C (low) and 38.5°C (conventional) incubation temperatures during IVM on glutathione peroxidase activity of oocytes and blastocysts following fertilization. Bovine oocytes were matured in medium-199 for 22 hours at either 36.5°C or 38.5°C and they were subjected to in vitro fertilization (IVF). Putative zygotes were then transferred randomly into SOFaa embryo culture media with or without antioxidant (a mixture of GSH and SOD) until development to the blastocyst stage. Glutathione peroxidase enzyme (GSH-Px) activity was lower (p⟨0.05) in oocytes matured at low temperature than those of conventional temperature. Similarly, GSH-Px activity was lower (p⟨0.05) in blastocysts, which were obtained from oocytes matured at low temperature and cultured in antioxidants-supplemented embryo media. The GSH-Px activity of blastocysts, obtained from oocytes matured in low temperature, cultured in antioxidants-free embryo media was similar to blastocysts obtained from oocytes matured in conventional temperature, cultured in antioxidants-supplemented embryo media. The results of the present study show that decreasing the in vitro maturation temperature decreases antioxidant enzyme activity in both oocyte and blastocyst. Additionally, maturation of bovine oocytes at 36.5°C incubation temperature may provide an optimal thermal condition for the enzymatic antioxidant system of both oocytes and blastocyst.

Micro Magnetic Field Produced by Fe3O4 Nanoparticles in Bone Scaffold for Enhancing Cellular Activity

The low cellular activity of poly-l-lactic acid (PLLA) limits its application in bone scaffold, although PLLA has advantages in terms of good biocompatibility and easy processing. In this study, superparamagnetic Fe3O4 nanoparticles were incorporated into the PLLA bone scaffold prepared by selective laser sintering (SLS) for continuously and steadily enhancing cellular activity. In the scaffold, each Fe3O4 nanoparticle was a single magnetic domain without a domain wall, providing a micro-magnetic source to generate a tiny magnetic field, thereby continuously and steadily generating magnetic stimulation to cells. The results showed that the magnetic scaffold exhibited superparamagnetism and its saturation magnetization reached a maximum value of 6.1 emu/g. It promoted the attachment, diffusion, and interaction of MG63 cells, and increased the activity of alkaline phosphatase, thus promoting the cell proliferation and differentiation. Meanwhile, the scaffold with 7% Fe3O4 presented increased compressive strength, modulus, and Vickers hardness by 63.4%, 78.9%, and 19.1% compared with the PLLA scaffold, respectively, due to the addition of Fe3O4 nanoparticles, which act as a nanoscale reinforcement in the polymer matrix. All these positive results suggested that the PLLA/Fe3O4 scaffold with good magnetic properties is of great potential for bone tissue engineering applications.

Nanotopographical Coatings Induce an Early Phenotype-Specific Response of Primary Material-Resident M1 and M2 Macrophages.

Implants elicit an immunological response after implantation that results in the worst case in a complete implant rejection. This biomaterial-induced inflammation is modulated by macrophages and can be influenced by nanotopographical surface structures such as titania nanotubes or fractal titanium nitride (TiN) surfaces. However, their specific impact on a distinct macrophage phenotype has not been identified. By using two different levels of nanostructures and smooth samples as controls, the influence of tubular TiO2 and fractal TiN nanostructures on primary human macrophages with M1 or M2-phenotype was investigated. Therefore, nanotopographical coatings were either, directly generated by physical vapor deposition (PVD) or by electrochemical anodization of titanium PVD coatings. The cellular response of macrophages was quantitatively assessed to demonstrate a difference in biocompatibility of nanotubes in respect to human M1 and M2-macrophages. Depending on the tube diameter of the nanotubular surfaces, low cell numbers and impaired cellular activity, was detected for M2-macrophages, whereas the impact of nanotubes on M1-polarized macrophages was negligible. Importantly, we could confirm this phenotypic response on the fractal TiN surfaces. The results indicate that the investigated topographies specifically impact the macrophage M2-subtype that modulates the formation of the fibrotic capsule and the long-term response to an implant.

Astaxanthin attenuates contrast-induced acute kidney injury through silent mating-type information regulation 2 homolog-1/peroxisome proliferator-activated receptor γ co-activator–α/NRF1 signaling pathway

Objectives: In this study, we established a model of contrast-induced acute kidney injury with iohexol. This model was used to investigate whether astaxanthin (AST) attenuates oxidative stress and apoptosis by activating silent mating-type information regulation 2 homolog-1 (SIRT1) signaling pathway in rat renal tubular epithelial cells (NRK-52E). Materials and Methods: NRK-52E cells were randomly divided into six groups: control group (CON group), vehicle (dimethyl sulfoxide group, iohexol group (I group), AST pretreatment group (AST + I group), AST plus nicotinamide (NA) co-pretreatment group (AST + NA + I group), and NA treatment group (NA + I group). The cellular activity was measured by cell counting kit-8. We estimated the levels of malonaldehyde (MDA) by the thiobarbituric acid method, and the level of intracellular reactive oxygen species (ROS) was measured by flow cytometry. Western blot analysis was conducted to detect the protein levels of SIRT1, peroxisome proliferator-activated receptor γ co-activator–α (PGC-1α), and NRF1. Results: Compared with the CON group, the I group showed suppressed cellular activity; increased levels of MDA and ROS; and decreased levels of SIRT1, PGC-1α, and NRF1 protein. Compared with the I group, AST + I pretreated group showed high cellular activity; low levels of MDA and ROS; and increased levels of SIRT1, PGC-1α, and NRF1 protein. SIRT1 inhibitor NA reversed the protective effect of AST. Compared with the AST + NA + I group, NA + I group showed low cellular activity; high levels of MDA and ROS; and low levels of SIRT1, PGC-1α, and NRF1 protein, which further confirmed the protective effect of AST. Conclusion: AST alleviated iohexol-induced NRK-52E cell injury by decreasing the formation of MDA and ROS and upregulating the SIRT1/PGC-1α/NRF1 signaling pathway.

Potential Adiponectin Receptor Response Modifier Therapeutics.

Many human diseases may benefit from adiponectin replacement therapy, but due to pharmacological disadvantages of the intact protein, druggable options focus on peptidic, and small molecule agonists of the adiponectin receptor. Peptide-based adiponectin replacement drug leads are derived from, or resemble, the active site of globular adiponectin. ADP355, the first-in-class such peptide, exhibits low nanomolar cellular activities, and clinically acceptable efficacies in a series of fibrotic and inflammation-derived diseases. The advantage of small molecule therapies, spearheaded by AdipoRon, is oral availability and extension of utility to a series of metabolic conditions. It is exactly the difficulties in the reliability and readout of the in vitro measures and the wealth of in vivo models that make comparison of the various drug classes complicated, if not impossible. While only a fewer number of maladies could take advantage of adiponectin receptor antagonists, the limited number of these available can be very useful tools in target validation studies. Alternative approaches to direct adiponectin signaling control use upstream adiponectin production inducing therapies but currently these offer relatively limited success compared to direct receptor agonists.

Anticancer, antifungal and antibacterial potential of bis(β-ketoiminato)ruthenium(II) carbonyl complexes

Herein we report a library of new ruthenium(II) complexes which incorporate a range of functionalised β-ketoiminate ligands. The complexes undergo an unusual reduction from Ru(III) to Ru(II), and consequently incorporate carbonyl ligands from the 2-ethoxyethanol solvent, forming ruthenium(II) dicarbonyl complexes. In order to address the potential applications of these complexes, we have screened the library against a range of tumour cell lines, however, all compounds exhibit low cellular activity and this is tentatively assigned to the decomposition of the compounds in aqueous media. Studies to establish the antifungal and antibacterial potential of these complexes was addressed and show increased growth inhibitions for C. neoformans and S. aureus species.

Properties of vaterite-containing tricalcium silicate composited graphene oxide for biomaterials

The properties of vaterite-containing tricalcium silicate (referred as V-C3S) bone cement can be significantly affected by the addition of graphene oxide (GO). The composited bone cement can overcome the problems of calcium silicate-based bone cement, such as poor mechanical properties and low cellular activity. The material properties, mineralization and cell compatibility were characterized. The results demonstrated that GO/V-C3S had good curing ability, mechanical properties and high injectability. In general, V-C3S adding with 0.04 wt% GO is better due to its advanced compressive strength (17.14% higher than pure V-C3S) and lower pH value. In vitro immersion experiments could show its admirable mineralization ability. Cell experiments confirmed its low cytotoxicity and favorable ability of cell proliferation. In addition, enhanced antibacterial property (2–3 times higher compared with pure V-C3S) was also verified by antibacterial experiments. These results suggest that GO/V-C3S bone cement is a promising material for biomedical applications.

Melatonin and the Optics of the Human Body

Melatonin is fundamental to the lighting, display, and architectural industries as the primary biomarker used in circadian theory. Billions of dollars are being spent on research, product development, and marketing based on the impact of visible light on melatonin produced by the pineal gland. It has now been shown that the mitochondria produce melatonin in many cells in quantities which are orders of magnitude higher than that produced in the pineal gland. This subcellular melatonin does not necessarily fluctuate with our circadian clock or release into the circulation system, but instead has been proposed to be consumed locally in response to the free radical density within each cell, in particular in response to Near Infrared (NIR) exposure. The main point of this review hypothesizes that the subcellular melatonin is being produced in response to the NIR photons which make up the majority of natural sunlight. Given the number of cells and quantity of subcellular melatonin identified to date, it is reasonable to propose that the body produces and maintains a melatonin reservoir that is separate and apart from the circulatory melatonin generated by the pineal gland. To understand how sunlight may support or stimulate this antioxidant reservoir, it becomes necessary to quantify the free radical density in various parts of the human body. To do this, it is necessary to move away from two-dimensional empirical approaches and develop three-dimensional bio-optical models based on the underlying biological processes at play. Three-dimensional Mechanistic Bio-optical Models (MBM) of the skin, eye, and brain based on non-sequential optical ray tracing and Electron Spin Resonance (ESR) data clearly indicate that the NIR portion of natural sunlight provides the primary stimulus during the day to the majority of the cells in the human body, impacting over 60% of the cells in an adult body and 100% of the cells in the fetus and young children. It is also shown that optically, the human body, under the assumption of natural sunlight, has developed optical mechanisms to gather and localize NIR photons in the most sensitive areas of the human body: blood vessels, retina, brain, skin, and even the fetus. That assumption is no longer valid in modern societies where the majority of our time is spent exposed to visible only lighting and displays, which emit zero NIR photons. Based on an optical and biological review of the literature and the MBM results, it is proposed that the NIR portion of natural sunlight stimulates an excess of antioxidants in each of our healthy cells and that the cumulative effect of this antioxidant reservoir is to enhance the body’s ability to rapidly and locally deal with changing conditions throughout the day. In this approach the role of circulatory melatonin produced by the pineal gland is to provide an efficient method of delivering supplemental melatonin during periods of low cellular activity and solar stimulus to damaged or aging cells in both diurnal and nocturnal animals. While circulatory melatonin may be the “Hormone of Darkness”, subcellular melatonin may be the “Hormone of Daylight”.