Photostimulated Extended Nitric Oxide (NO) Release from Water-Soluble Block Copolymer to Enhance Antibacterial Activity.

N-Nitrosamines are well established motifs to release nitric oxide (NO) under photoirradiation. Herein, a series of amphiphilic N-nitrosamine-based block copolymers (BCPx-NO) are developed to attain controlled NO release under photoirradiation (365 nm, 3.71 mW/cm2). The water-soluble BCPx-NO forms micellar architecture in aqueous medium and exhibits a sustained NO release of 92-160 µM within 11.5 h, which is 36.8-64.0% of the calculated value. To understand the NO release mechanism, a small molecular NO donor (NOD) resembling the NO releasing functional motif of BCPx-NO is synthesized, which displays a burst NO release in DMSO within 2.5 h. The radical nature of the released NO is confirmed by electron paramagnetic resonance (EPR) spectroscopy. The gradual NO release from micellar BCPx-NO enhances antibacterial activity over NOD and exhibits a superior bactericidal effect on Gram-positive Staphylococcus aureus. In relation to biomedical applications, this work offers a comprehensive insight into tuning light-triggered NO release to improve antibacterial activity.

Selective targeting of the inactive state of hematopoietic cell kinase (Hck) with a stable curcumin derivative.

Hck, a Src family nonreceptor tyrosine kinase (SFK), has recently been established as an attractive pharmacological target to improve pulmonary function in COVID-19 patients. Hck inhibitors are also well known for their regulatory role in various malignancies and autoimmune diseases. Curcumin has been previously identified as an excellent DYRK-2 inhibitor, but curcumin's fate is tainted by its instability in the cellular environment. Besides, small molecules targeting the inactive states of a kinase are desirable to reduce promiscuity. Here, we show that functionalization of the 4-arylidene position of the fluorescent curcumin scaffold with an aryl nitrogen mustard provides a stable Hck inhibitor (Kd = 50 ± 10 nM). The mustard curcumin derivative preferentially interacts with the inactive conformation of Hck, similar to type-II kinase inhibitors that are less promiscuous. Moreover, the lead compound showed no inhibitory effect on three other kinases (DYRK2, Src, and Abl). We demonstrate that the cytotoxicity may be mediated via inhibition of the SFK signaling pathway in triple-negative breast cancer and murine macrophage cells. Our data suggest that curcumin is a modifiable fluorescent scaffold to develop selective kinase inhibitors by remodeling its target affinity and cellular stability.

Rituximab in the treatment of systemic sclerosis-related interstitial lung disease: a systematic review and meta-analysis.

OBJECTIVES: To assess the effect of rituximab (RTX) on the lung function parameters in SSc interstitial lung disease (SSc-ILD) patients. METHODS: PubMed and Embase were searched to identify studies on SSc-ILD treated with RTX, confined to a predefined inclusion and exclusion criteria. A systematic review and meta-analysis were performed on the included studies on changes in forced vital capacity (FVC) and diffusion capacity of carbon monoxide (DLCO) from baseline to 6 and 12 months of follow-up. RESULTS: A total of 20 studies (2 randomized controlled trials, 6 prospective studies, 5 retrospective studies and 7 conference abstracts) were included (n = 575). RTX improved FVC from baseline by 4.49% (95% CI 0.25, 8.73) at 6 months and by 7.03% (95% CI 4.37, 9.7) at 12 months. Similarly, RTX improved DLCO by 3.47% (95% CI 0.99, 5.96) at 6 months and 4.08% (95% CI 1.51, 6.65) at 12 months. In the two studies comparing RTX with other immunosuppressants, improvement of FVC by 6 months in the RTX group was 1.03% (95% CI 0.11, 1.94) greater than controls. At the 12 month follow-up, RTX treatment was similar to controls in terms of both FVC and DLCO. Patients treated with RTX had a lower chance of developing infections compared with controls [odds ratio 0.256 (95% CI 0.104, 0.626), I2 = 0%, P = 0.47). CONCLUSIONS: Treatment with RTX in SSc-ILD was associated with a significant improvement of both FVC and DLCO during the first year of treatment. RTX use was associated with lower infectious adverse events.

Nitric Oxide Releasing Delivery Platforms: Design, Detection, Biomedical Applications, and Future Possibilities.

Gasotransmitters belong to the subfamily of endogenous gaseous signaling molecules, which find a wide range of biomedical applications. Among the various gasotransmitters, nitric oxide (NO) has an enormous effect on the cardiovascular system. Apart from this, NO showed a pivotal role in neurological, respiratory, and immunological systems. Moreover, the paradoxical concentration-dependent activities make this gaseous signaling molecule more interesting. The gaseous NO has negligible stability in physiological conditions (37 °C, pH 7.4), which restricts their potential therapeutic applications. To overcome this issue, various NO delivering carriers were reported so far. Unfortunately, most of these NO donors have low stability, short half-life, or low NO payload. Herein, we review the synthesis of NO delivering motifs, development of macromolecular NO donors, their advantages/disadvantages, and biological applications. Various NO detection analytical techniques are discussed briefly, and finally, a viewpoint about the design of polymeric NO donors with improved physicochemical characteristics is predicted.

Effect of an Imidazole-Containing Schiff Base of an Aromatic Sulfonamide on the Cytotoxic Efficacy of N,N-Coordinated Half-Sandwich Ruthenium(II) p-Cymene Complexes.

Sulfonamides have a broad range of therapeutic applications, which include the inhibition of various isoforms of carbonic anhydrases (CAs). Among the various CA isoforms, CA IX is overexpressed in tumors and regulates the pH of the tumor microenvironment. Herein we present five new ruthenium(II) p-cymene complexes (1-5) of Schiff base ligands (L1-L4) of 4-(2-aminoethyl)benzenesulfonamide by varying the aldehyde to enhance the selective cytotoxicity toward cancer cells. All of the complexes are stable to aquation for the observed period of 24 h except 1, which aquated within 1 h, but the monoaquated species is stable for 24 h. The two imidazole derivatives, 1 and 2, are cytotoxic to the cancer cells MDA-MB-231 and MIA PaCa-2 but not to the noncancerous cells CHO and MDCK. The enhanced toxicity in hypoxia against MDA-MB-231 may be due to the greater expression of CA IX in hypoxia, as per the immunofluorescence data. The most cytotoxic complexes, 1 and 2, are lipophilic, whereas 3-5 show high hydrophilicity and are not cytotoxic up to 200 µM. Complexes 1 and 2 also show a higher cellular accumulation in MDA-MB-231 than the nontoxic yet solution-stable complex 5. The cytotoxic complexes bind with the model nucleobase 9-ethylguanine but have slow reactivity toward cellular tripeptide glutathione. Both 1 and 2 induce apoptosis by depolarizing the mitochondrial membrane potential and arrest the cell cycle in the SubG1 phase.

Synthesis, Characterization, and Cytotoxicity of Morpholine-Containing Ruthenium(II) p-Cymene Complexes.

Morpholine motif is an important pharmacophore and, depending on the molecular design, may localize in cellular acidic vesicles. To understand the importance of the presence of pendant morpholine in a metal complex, six bidentate N,O-donor ligands with or without a pendant morpholine unit and their corresponding ruthenium(II) p-cymene complexes (1-6) are synthesized, purified, and structurally characterized by various analytical methods including X-ray diffraction. Complexes 2-4 crystallized in the P21/c space group, whereas 5 and 6 crystallized in the P1̅ space group. The solution stability studies using 1H NMR support instantaneous hydrolysis of the native complexes to form monoaquated species in a solution of 3:7 (v/v) dimethyl sulfoxide-d6 and 20 mM phosphate buffer (pH* 7.4, containing 4 mM NaCl). The monoaquated complexes are stable for at least up to 24 h. The complexes display excellent in vitro antiproliferative activity (IC50 ca. 1-14 µM) in various cancer cell lines, viz., MDA-MB-231, MiaPaCa2, and Hep-G2. The presence of the pendant morpholine does not improve the dose efficacy, but rather, with 2-[[(2,6-dimethylphenyl)imino]methyl]phenol (HL1) and its pendant morpholine analogue (HL3) giving complexes 1 and 3, respectively, the antiproliferative activity was poorer with 3. MDA-MB-231 cells treated with the complexes show that the acidic vesicles remain acidic, but the population of acidic vesicles increases or decreases with time of exposure, as observed from the dispersed red puncta, depending on the complex used. The presence of the 2,6-disubstituted aniline and the naphthyl group seems to improve the antiproliferative dose. The complex treated MDA-MB-231 cells show that cathepsin D, which is otherwise present in the cytosolic lysosomes, translocates to the nucleus as a result of exposure to the complexes. Irrespective of the presence of a morpholine motif, the complexes do not activate caspase-3 to induce apoptosis and seem to favor the necrotic pathway of cell killing.

Hypoxia Active Platinum(IV) Prodrugs of Orotic Acid Selective to Liver Cancer Cells.

Platinum(IV) complexes of orotic acid selectively target liver cancer cells displaying enhanced activity and higher uptake in Hep G2. The comparatively higher expression of Organic Anion Transporter 2 (OAT2) in Hep G2 and decrease in toxicity in the presence of OAT2 inhibitor suggest its involvement in the uptake of the complexes. They are resistant to sequestration by the copper transporter ATP7B, unlike cisplatin and oxaliplatin.

Disruption of the Microtubule Network and Inhibition of VEGFR2 Phosphorylation by Cytotoxic N,O-Coordinated Pt(II) and Ru(II) Complexes of Trimethoxy Aniline-Based Schiff Bases.

Platinum-based complexes are one of the most successful chemotherapeutic agents having a significant ground in cancer chemotherapy despite their side effects. During the past few decades, Ru(II) complexes have been emerging as efficient alternatives owing to their promising activities against platinum-resistant cancer. The pathway of action, lipophilicity, and cytotoxicity of a Pt or Ru complex may be tuned by varying the attached ligands, the coordination mode, and the leaving group. In this work, we report a family of Pt(II) and Ru(II) complexes (1-5) of three N,O and N,N donor-based trimethoxyanilines containing Schiff bases with the general formula [PtII(L)(DMSO)Cl], [RuII(L)(p-cymene)Cl], [RuII(L)(p-cymene)Cl]+, and [PtII(L)Cl2]. All of the complexes are characterized by different analytical techniques. 1H NMR and electrospray ionization mass spectrometry (ESI-MS) data suggest that the N,O-coordinated Pt(II) complexes undergo slower aquation compared to the Ru(II) analogues. The change of the coordination mode to N,N causes the Ru complexes to be more inert to aquation. The N,O-coordinating complexes show superiority over N,N-coordinating complexes by displaying excellent in vitro antiproliferative activity against different aggressive cancer cells, viz., triple-negative human metastatic breast adenocarcinoma MDA-MB-231, human pancreatic carcinoma MIA PaCa-2, and hepatocellular carcinoma Hep G2. In vitro cytotoxicity studies suggest that Pt(II) complexes are more effective than their corresponding Ru(II) analogues, and the most cytotoxic complex 3 is 10-15 times more toxic than the clinical drugs cisplatin and oxaliplatin against MDA-MB-231 cells. Cellular studies show that all of the N,O-coordinated complexes (1-3) initiate disruption of the microtubule network in MDA-MB-231 cells in a dose-dependent manner within 6 h of incubation and finally lead to the arrest of the cell cycle in the G2/M phase and render apoptotic cell death. The disruption of the microtubule network affects the agility of the cytoskeleton rendering inhibition of tyrosine phosphorylation of vascular endothelial growth factor receptor 2 (VEGFR2), a key step in angiogenesis. Complexes 1 and 2 inhibit VEGFR2 phosphorylation in a dose-dependent fashion. Among the Pt(II) and Ru(II) complexes, the former displays higher cytotoxicity, a stronger effect on the cytoskeleton, better VEGFR2 inhibition, and strong interaction with the model nucleobase 9-ethylguanine (9-EtG).

Cytotoxic Ruthenium(II) Complexes of Pyrazolylbenzimidazole Ligands That Inhibit VEGFR2 Phosphorylation.

Eight new ruthenium(II) complexes of N,N-chelating pyrazolylbenzimidazole ligands of the general formula [RuII(p-cym)(L)X]+ [where the ligand L is 2-(1H-pyrazol-1-yl)-1H-benzo[d]imidazole (L1) substituted at the 4 position of the pyrazole ring by Cl (L2), Br (L3), or I (L4) and X = Cl- and I-] were synthesized and characterized using various analytical techniques. Complexes 1 and 3 were also characterized by single-crystal X-ray crystallography, and they crystallized as a monoclinic crystal system in space groups P21/n and P21/c, respectively. The complexes display good solution stability at physiological pH 7.4. The iodido-coordinated pyrazolylbenzimidazole ruthenium(II) p-cymene complexes (2, 4, 6, and 8) are more resistant toward hydrolysis and have less tendency to form monoaquated complexes in comparison to their chlorido analogues (1, 3, 5, and 7). The halido-substituted 2-(1H-pyrazol-1-yl)-1H-benzo[d]imidazole ligands, designed as organic-directing molecules, inhibit vascular endothelial growth factor receptor 2 (VEGFR2) phosphorylation. In addition, the ruthenium(II) complexes display a potential to bind to DNA bases. The cytotoxicity profile of the complexes (IC50 ca. 9-12 µM for 4-8) against the triple-negative breast cancer cells (MDA-MB-231) show that most of the complexes are efficient. The lipophilicity and cellular accumulation data of the complexes show a good correlation with the cytotoxicity profile of 1-8. The representative complexes 3 and 7 demonstrate the capability of arresting the cell cycle in the G2/M phase and induce apoptosis. The inhibition of VEGFR2 phosphorylation with the representative ligands L2 and L4 and the corresponding metal complexes 3 and 7 in vitro shows that the organic-directing ligands and their complexes inhibit VEGFR2 phosphorylation. Besides, L2, L4, 3, and 7 inhibit the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) and proto-oncogene tyrosine-protein kinase (Src), capable of acting downstream of VEGFR2 as well as independently. Compounds L2, L4, 3, and 7 have a lesser effect on ERK1/2 and more prominently affect Src phosphorylation. We extended the study for L2 and 3 in the Tg(fli1:gfp) zebrafish model and found that L2 is more effective in vivo compared to 3 in inhibiting angiogenesis.

Effect of N,N Coordination and RuII Halide Bond in Enhancing Selective Toxicity of a Tyramine-Based RuII (p-Cymene) Complex.

Ruthenium compounds are promising anticancer candidates owing to their lower side-effects and encouraging activities against resistant tumors. Half-sandwich piano-stool type RuII compounds of general formula [(L)RuII(η6-arene)(X)]+ (L = chelating bidentate ligand, X = halide) have exhibited significant therapeutic potential against cisplatin-resistant tumor cell lines. In RuII (p-cymene) based complexes, the change of the halide leaving group has led to several interesting features, viz., hydrolytic stability, resistance toward thiols, and alteration in pathways of action. Tyramine is a naturally occurring monoamine which acts as a catecholamine precursor in humans. We synthesized a family of N,N and N,O coordinated RuII (p-cymene) complexes, [(L)RuII(η6-arene)(X)]+ (1-4), with tyramine and varied the halide (X = Cl, I) to investigate the difference in reactivity. Our studies showed that complex 2 bearing N,N coordination with an iodido leaving group shows selective in vitro cytotoxicity against the pancreatic cancer cell line MIA PaCa-2 (IC50 ca. 5 µM) but is less toxic to triple-negative breast cancer (MDA-MB-231), hepatocellular carcinoma (Hep G2), and the normal human foreskin fibroblasts (HFF-1). Complex 2 displays stability toward hydrolysis and does not bind with glutathione, as confirmed by 1H NMR and ESI-HRMS experiments. The inert nature of 2 leads to enhancement of cytotoxicity (IC50 = 5.3 ± 1 µM) upon increasing the cellular treatment time from 48 to 72 h.

Differences in Stability, Cytotoxicity, and Mechanism of Action of Ru(II) and Pt(II) Complexes of a Bidentate N,O Donor Ligand.

We report [RuII(L)(η6-p-cym)Cl] (1 and 2) and [PtII(L)(DMSO)Cl] (3 and 4) complexes, where L is a chelate imine ligand derived from chloroethylamine and salicylaldehyde (HL1) or o-vanillin (HL2). The complexes were characterized by single-crystal X-ray diffraction and other analytical techniques. The 1H nuclear magnetic resonance data show that both the Ru(II) and Pt(II) complexes start forming the aquated complex within an hour. The aquated complexes are stable at least up to 24 h. The complexes bind to the N7 of the model nucleobase 9-ethylguanine (9-EtG). Interaction with calf thymus (CT) DNA shows moderate binding interactions with binding constants, Kb (3.7 ± 1.2) × 103 M-1 and (4.3 ± 1.9) × 103 M-1 for 1 and 3, respectively. The complexes exhibit significant antiproliferative activity against human pancreas ductal adenocarcinoma (Mia PaCa-2), triple negative metastatic breast adenocarcinoma (MDA-MB-231), hepatocellular carcinoma (Hep G2), and colorectal adenocarcinoma (HT-29) cell lines. The studies show that with the same ligand the Pt(II) complexes are more potent than the Ru(II) complexes. The in vitro potencies of all the complexes toward pancreatic cancer cell line MIA PaCa-2 are more than cisplatin (CDDP). The Pt(II) and Ru(II) complexes show similar binding constants with CT-DNA, but the reactivity of the Pt(II) complex 3 with 9-EtG is faster and their overall cell killing pathways are different. This is evident from the arrest of the cell cycle by the Ru(II) complex 1 in the G2/M phase in contrast to the SubG1 phase arrest by the Pt(II) complex 3. The immunoblot study shows that 3 increases cyclin D and Bcl-2 expression in MDA-MB-231 due to the SubG1 phase arrest where these proteins express in greater quantities. However, both 1 and 3 kill in the apoptotic pathway via dose-dependent activation of caspase 3. Complex 3 depolarizes the mitochondria more efficiently than 1, suggesting its higher preference for the intrinsic pathway of apoptosis. Our work reveals that the same bidentate ligand with a change of the metal center, viz, Pt(II) or Ru(II), imparts significant variation in cytotoxic dosage and pathway of action due to specific intrinsic properties of a metal center (viz, coordination geometry, solution stability) manifested in a complex.

ATP7B Binds Ruthenium(II) p-Cymene Half-Sandwich Complexes: Role of Steric Hindrance and Ru-I Coordination in Rescuing the Sequestration.

Ruthenium(II/III) complexes are predicted to be efficient alternatives to platinum drug-resistant cancers but have never been investigated for sequestration and efflux by Cu-ATPases (ATP7A or ATP7B) overexpressed in resistant cancer cells, although a major cause of platinum drug resistance is found to be sequestration of platinum chemotherapeutic agents by thiol donors glutathione (GSH) or the Cys-X-X-Cys (CXXC) motifs in the Cu-ATPases in cytosol. Here, we show for the first time that ATP7B efficiently sequesters ruthenium(II) η6-p-cymene complexes. We present seven complexes, [RuII(η6-p-cym)(L)X](PF6) (1-7; L = L1-L3, X = Cl, Br, and I), out of which two resists deactivation by the cellular thiol, glutathione (GSH). The results show that Ru-I coordination and a moderate steric factor increase resistance to GSH and the CXXC motif. RuII-I-coordinated 3 and 7 showed resistance to sequestration by ATP7B. 3 displays highest resistance against GSH and does not trigger ATP7B trafficking in the liver cancer cell line. It escapes ATP7B-mediated sequestration and triggers apoptosis. Thus, with a suitable bidentate ligand and iodido leaving group, RuII(η6-p-cym) complexes may display strong kinetic inertness to inhibit the ATP7B detoxification pathway. Inductively coupled plasma mass spectrometry data show higher retention of 3 and 7 inside the cell with time compared to 4, supporting ATP7B-mediated sequestration.

Synthesis, Structure, Stability, and Inhibition of Tubulin Polymerization by RuII-p-Cymene Complexes of Trimethoxyaniline-Based Schiff Bases.

Four trimethoxy- and dimethoxyphenylamine-based Schiff base (L1-L4)-bearing RuII-p-cymene complexes (1-4) of the chemical formula [RuII(η6-p-cymene)(L)(Cl)] were synthesized, isolated in pure form, and structurally characterized using single-crystal X-ray diffraction and other analytical techniques. The complexes showed excellent in vitro antiproliferative activity against various forms of cancer that are difficult to cure, viz., triple negative human metastatic breast carcinoma MDA-MB-231, human pancreatic carcinoma MIA PaCa-2, and hepatocellular carcinoma Hep G2. The 1H nuclear magnetic resonance data in the presence of 10% dimethylformamide-d7 or dimethyl sulfoxide-d6 in phosphate buffer (pD 7.4, containing 4 mM NaCl) showed that the complexes immediately generate the aquated species that is stable for at least 24 h. Electrospray ionization mass spectrometry data showed that they do not bind with guanine nitrogen even in the presence of 5 molar equivalents of 9-EtG, during a period of 24 h. The best complex in the series, 1, exhibits an IC50 of approximately 10-15 µM in the panel of tested cancer cell lines. The complexes do not enhance the production of reactive oxygen species in the cells. Docking studies with a tubulin crystal structure (Protein Data Bank entry 1SAO ) revealed that 1 and 3 as well as L1 and L3 have a high affinity for the interface of the α and ß tubulin dimer in the colchicine binding site. The immunofluorescence studies showed that 1 and 3 strongly inhibited microtubule network formation in MDA-MB-231 cells after treatment with an IC20 or IC50 dose for 12 h. The cell cycle analysis upon treatment with 1 showed that the complexes inhibit the mitotic phase because the arrest was observed in the G2/M phase. In summary, 1 and 3 are RuII half-sandwich complexes that are capable of disrupting a microtubule network in a dose-dependent manner. They depolarize the mitochondria, arrest the cell cycle in the G2/M phase, and kill the cells by an apoptotic pathway.

Multiple myeloma presenting as acute pancreatitis.

A 36 year old male presented to the emergency department with severe epigastric pain, nausea, vomiting without hematemesis, diarrhea and anorexia. He presented with respiratory distress, shock and fever at the emergency. He was intubated and shifted to the intensive care unit with the diagnosis of acute pancreatitis with hypercalcemia and an elevated amylase and lipase's well as thrombocytopenia and elevated creatinine. CT scan of abdomen was done which showed lytic bone lesions in the spine and necrosis of the pancrease. He was evaluated for multiple myeloma and it was confirmed in a bone marrow biopsy. Multiple myeloma usually is seen in patients aged more than 60 yrs. The typical presentation of multiple myeloma is anemia, back pain, and an elevated sedimentation rate. Patients with multiple myeloma have hypercalcemia but it's rarely manifested as acute pancreatitis. This case shows a rare presentation of multiple myeloma as acute pancreatitis in a younger adult.

Human serum transferrin fibrils: nanomineralisation in bacteria and destruction of red blood cells.

Fibrils formed by human serum transferrin [(1-3 µM) apo-Tf, partially iron-saturated (Fe0.6 -Tf) and holo-Tf (Fe2 -Tf) forms], from dilute bicarbonate solutions, were deposited on formvar surfaces and studied by electron microscopy. We observed that possible bacterial contamination appears to give rise to long, pea-pod-like (PPL) structures for Fe2 -Tf, attributable to the formation of polyhydroxybutyrate (PHB) storage granules, under the nutrient-limiting conditions used. These PPL structures contained periodic nanomineralisation sites susceptible to uranyl stain. Extended incubation of transferrin solutions (about four days) gave rise to extensive transferrin fibril structures. Optical microscopy and AFM studies showed that red blood cells (RBCs) readily adhere to these fibrils. Moreover, the fibrils appear to penetrate RBC membranes and to induce rapid cell destruction (within about 5 h). It is speculated that in situations in vivo where transferrin fibrils can form, such interactions might have adverse physiological consequences, and further studies could aid the understanding of related pathological events.

Photocleavable Visible Light-Triggered Anthraquinone-Derived Water-Soluble Block Copolymer for Peroxynitrite Generation in Cancer Therapy.

We report a facile stimuli-responsive strategy to generate reactive oxygen and nitrogen species (ROS and RNS) in the biological milieu from a photocleavable water-soluble block copolymer under visible light irradiation (427 nm, 2.25 mW/cm2). An anthraquinone-based water-soluble polymeric nitric oxide (NO) donor (BCPx-NO) is synthesized, which exhibits NO release in the range of 40-65 µM within 10 h of photoirradiation with a half-life of 30-103 min. Additionally, BCPx-NO produces peroxynitrite (ONOO-) and singlet oxygen (1O2) under photoirradiation. To understand the mechanism of NO release and photolysis of the functional group under blue light, we prepared a small-molecule anthraquinone-based N-nitrosamine (NOD). The cellular investigation of the effect of spatiotemporally controlled ONOO- and 1O2 generation from the NO donor polymeric nanoparticles in a triple negative breast adenocarcinoma (MDA-MB-231) under visible light irradiation (white light, 5.83 mW/cm2; total dose 31.5 J/cm2) showed an IC50 of 0.6 mg/mL. The stimuli-responsive strategy using a photolabile water-soluble block copolymer employed to generate ROS and RNS in a biological setting widens the horizon for their potential in cancer therapy.

Inhibition of NF-κB-Mediated Proinflammatory Transcription by Ru(II) Complexes of Anti-Angiogenic Ligands in Triple-Negative Breast Cancer.

Nuclear factor kappa beta (NF-κB) plays a pivotal role in breast cancer, particularly triple-negative breast cancer, by promoting inflammation, proliferation, epithelial-mesenchymal transition, metastasis, and drug resistance. Upregulation of NF-κB boosts vascular endothelial growth factor (VEGF) expression, assisting angiogenesis. The Ru(II) complexes of methyl- and dimethylpyrazolyl-benzimidazole N,N donors inhibit phosphorylation of ser536 in p65 and translocation of the NF-κB heterodimer (p50/p65) to the nucleus, disabling transcription to upregulate inflammatory signaling. The methyl- and dimethylpyrazolyl-benzimidazole inhibit VEGFR2 phosphorylation at Y1175, disrupting downstream signaling through PLC-γ and ERK1/2, ultimately suppressing Ca(II)-signaling. Partial release of the antiangiogenic ligand in a reactive oxygen species-rich environment is possible as per our observation to inhibit both NF-κB and VEGFR2 by the complexes. The complexes are nontoxic to zebrafish embryos up to 50 µM, but the ligands show strong in vivo antiangiogenic activity at 3 µM during embryonic growth in Tg(fli1:GFP) zebrafish but no visible effect on the adult phase.

Antioxidant Polymers with Enhanced Neuroprotection Against Insulin Fibrillation.

Lipoic acid (LA) and dihydrolipoic acid (DHLA) are well established antioxidants to scavenge reactive oxygen species (ROS). However, they are carboxylates with ≈4.7 pKa making them negatively charged at physiological pH (7.4) reducing their passive diffusion through cell membranes. LA is known to be capable of reducing protein fibrillation. Incorporation of LA and especially DHLA in polymer side chains are scarce. Herein, the first examples of the anti-amyloidogenic effect of LA and DHLA incorporated into the side-chain of a block copolymer with a water-soluble poly(polyethylene glycol methyl ether methacrylate) (PPEGMA) segment are presented. The resultant polymers show improved ROS scavenging activity and improved ability to reduce insulin fibrillation compared to free LA and DHLA. Furthermore, the resultant polymers are also capable of disintegrating preformed insulin firbrils. Interestingly, polymers with dihydro-lipoate moieties showed 93% free radical scavenging activity with 91% anti-fibrillating efficacies for insulin protein confirmed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and Thioflavin T (ThT) dye binding study, respectively. Further, the antioxidant polymers increase the cell viability against fibrillar insulin aggregates that may be involved in the etiology of several diseases. Overall, this work reveals that antioxidant polymer-based therapeutic agents can serve as a powerful modulation strategy for developing novel drugs in future against amyloid-related disorders.

Cytotoxic Imidazolyl-Mesalazine Ester-Based Ru(II) Complexes Reduce Expression of Stemness Genes and Induce Differentiation of Oral Squamous Cell Carcinoma.

The aggressiveness and recurrence of cancer is linked to cancer stem cells (CSCs), but drugs targeting CSCs may not succeed in the clinic due to the lack of a distinct CSC subpopulation. Clinical Pt(II) drugs can increase stemness. We screened 15 RuII or IrIII complexes with mesalazine or 3-aminobenzoate Schiff bases of the general formulas [Ru(p-cym)L]+, [Ru(p-cym)L], and [Ir(Cp*)L]+ (L = L1-L9) and found three complexes (2, 12, and 13) that are active against oral squamous cell carcinoma (OSCC) CSCs. There is a putative oncogenic role of transcription factors (viz. NOTCH1, SOX2, c-MYC) to enhance the stemness. Our work shows that imidazolyl-mesalazine ester-based RuII complexes inhibit growth of CSC-enriched OSCC 3D spheroids at low micromolar doses (2 µM). Complexes 2, 12, and 13 reduce stemness gene expression and induce differentiation markers (Involucrin, CK10) in OSCC 3D cultures. The imidazolyl-mesalazine ester-based RuII complex 13 shows the strongest effect. Downregulating c-MYC suggests that RuII complexes may target c-MYC-driven cancers.

Ferric ion (hydr)oxo clusters in the "Venus flytrap" cleft of FbpA: Mössbauer, calorimetric and mass spectrometric studies.

Isothermal calorimetric studies of the binding of iron(III) citrate to ferric ion binding protein from Neisseria gonorrhoeae suggested the complexation of a tetranuclear iron(III) cluster as a single step binding event (apparent binding constant K(app) (ITC) = 6.0(5) × 10(5) M(-1)). High-resolution Fourier transform ion cyclotron resonance mass spectrometric data supported the binding of a tetranuclear oxo(hydroxo) iron(III) cluster of formula [Fe(4)O(2)(OH)(4)(H(2)O)(cit)](+) in the interdomain binding cleft of FbpA. The mutant H9Y-nFbpA showed a twofold increase in the apparent binding constant [K(app) (ITC) = 1.1(7) × 10(6) M(-1)] for the tetranuclear iron(III) cluster compared to the wild-type protein. Mössbauer spectra of Escherichia coli cells overexpressing FbpA and cultured in the presence of added (57)Fe citrate were indicative of the presence of dinuclear and polynuclear clusters. FbpA therefore appears to have a strong affinity for iron clusters in iron-rich environments, a property which might endow the protein with new biological functions.