Design, Synthesis, and Antitumor Activity Evaluation of 2-Arylmethoxy-4-(2,2'-dihalogen-substituted biphenyl-3-ylmethoxy) Benzylamine Derivatives as Potent PD-1/PD-L1 Inhibitors.

Novel 2-arylmethoxy-4-(2,2'-dihalogen-substituted biphenyl-3-ylmethoxy) benzylamine derivatives were designed, synthesized, and evaluated in vitro and in vivo against cancers as PD-1/PD-L1 inhibitors. Through the computer-aided structural optimization and the homogeneous time-resolved fluorescence (HTRF) assay, compound A56 was found to most strongly block the PD-1/PD-L1 interaction with an IC50 value of 2.4 ± 0.8 nM and showed the most potent activity. 1H NMR titration results indicated that A56 can tightly bind to the PD-L1 protein with KD < 1 µM. The X-ray diffraction data for the cocrystal structure of the A56/PD-L1 complex (3.5 Å) deciphered a novel binding mode in detail, which can account for its most potent inhibitory activity. Cell-based assays further demonstrated the strong ability of A56 as an hPD-1/hPD-L1 blocker. Especially in an hPD-L1 MC38 humanized mouse model, A56 significantly inhibited tumor growth without obvious toxicity, with a TGI rate of 55.20% (50 mg/kg, i.g.). In conclusion, A56 is a promising clinical candidate worthy of further development.

Heart Failure after Cardiac Surgery: The Role of Halogenated Agents, Myocardial Conditioning and Oxidative Stress.

Heart disease requires a surgical approach sometimes. Cardiac-surgery patients develop heart failure associated with ischemia induced during extracorporeal circulation. This complication could be decreased with anesthetic drugs. The cardioprotective effects of halogenated agents are based on pre- and postconditioning (sevoflurane, desflurane, or isoflurane) compared to intravenous hypnotics (propofol). We tried to put light on the shadows walking through the line of the halogenated anesthetic drugs' effects in several enzymatic routes and oxidative stress, waiting for the final results of the ACDHUVV-16 clinical trial regarding the genetic modulation of this kind of drugs.

Anti-Pathogenic Properties of the Combination of a T3SS Inhibitory Halogenated Pyrrolidone with C-30 Furanone.

Antimicrobial resistance is one of the current public health challenges to be solved. The World Health Organization (WHO) has urgently called for the development of strategies to expand the increasingly limited antimicrobial arsenal. The development of anti-virulence therapies is a viable option to counteract bacterial infections with the possibility of reducing the generation of resistance. Here we report on the chemical structures of pyrrolidones DEXT 1-4 (previously identified as furan derivatives) and their anti-virulence activity on Pseudomonas aeruginosa strains. DEXT 1-4 were shown to inhibit biofilm formation, swarming motility, and secretion of ExoU and ExoT effector proteins. Also, the anti-pathogenic property of DEXT-3 alone or in combination with furanone C-30 (quorum sensing inhibitor) or MBX-1641 (type III secretion system inhibitor) was analyzed in a model of necrosis induced by P. aeruginosa PA14. All treatments reduced necrosis; however, only the combination of C-30 50 µM with DEXT-3 100 µM showed significant inhibition of bacterial growth in the inoculation area and systemic dispersion. In conclusion, pyrrolidones DEXT 1-4 are chemical structures capable of reducing the pathogenicity of P. aeruginosa and with the potential for the development of anti-virulence combination therapies.

A Borondifluoride-Complex-Based Photothermal Agent with an 80 % Photothermal Conversion Efficiency for Photothermal Therapy in the NIR-II Window.

Small organic photothermal agents (SOPTAs) that absorb in the second near-infrared (NIR-II, 1000-1700 nm) window are highly desirable in photothermal therapy for their good biocompatibility and deeper tissue penetration. However, the design of NIR-II absorbing SOPTAs remains a great challenge. Herein, we report that molecular engineering of BF2 complex via strengthening the donor-acceptor conjugation and increasing the intramolecular motions is an efficient strategy to achieve NIR-II absorbing SOPTAs with high photothermal performance. Based on this strategy, a BF2 complex, BAF4, was designed and synthesized. BAF4 exhibits an intense absorption maximum at 1000 nm and negligible fluorescence. Notably, the nanoparticles of BAF4 achieve a high photothermal conversion efficiency value of 80 % under 1064 nm laser irradiation (0.75 W cm-2 ). In vitro and in vivo studies reveal the great potential of BAF4 nanoparticles in photoacoustic imaging-guided photothermal therapy in the NIR-II window.

Synthesis of novel halogenated triarylpyrazoles as selective COX-2 inhibitors: Anti-inflammatory activity, histopatholgical profile and in-silico studies.

A novel series of halogenated triarylpyrazoles 12a-l was designed and synthesized. All target compounds showed good in vitro COX-2 inhibitory activity (IC50 = 0.043-0.17 µM) over COX-1 (IC50 = 7.8 - 15.4 µM) relative to celecoxib (COX-1/IC50 = 9.87, COX-2/IC50 = 0.055), with acceptable selectivity index values (SI = 50.6-253.1). Also, they displayed moderate to potent in vivo anti-inflammatory activity (% edema inhibition = 16.9-87.9) comparable to celecoxib (% edema inhibition = 46.6-72.1) as standard drug. Three fluorinated pyrazoles 12a, 12g and 12j, exhibited superior anti-inflammatory activity at all time intervals (% edema inhibition = 42.1-87.9) with better gastric profile (UI = 1.25-2.5) than the traditional NSAID; indomethacin (UI = 14) and were close to the selective COX-2 inhibitor; celecoxib (UI = 1.75). In-silico docking and ADME studies of 12a, 12g and 12j supported the obtained biological data and pointed out their potential use for the development of bio-available, safe and potent anti-inflammatory drugs.

Correction of microtubule defects within Aß plaque-associated dystrophic axons results in lowered Aß release and plaque deposition.

The hallmark pathologies of the Alzheimer's disease (AD) brain are amyloid beta (Aß)-containing senile plaques and neurofibrillary tangles formed from the microtubule (MT)-binding tau protein. Tau becomes hyperphosphorylated and disengages from MTs in AD, with evidence of resulting MT structure/function defects. Brain-penetrant MT-stabilizing compounds can normalize MTs and axonal transport in mouse models with tau pathology, thereby reducing neuron loss and decreasing tau pathology. MT dysfunction is also observed in dystrophic axons adjacent to Aß plaques, resulting in accumulation of amyloid precursor protein (APP) and BACE1 with the potential for enhanced localized Aß generation. We have examined whether the brain-penetrant MT-stabilizing compound CNDR-51657 might decrease plaque-associated axonal dystrophy and Aß release in 5XFAD mice that develop an abundance of Aß plaques. Administration of CNDR-51657 to 1.5-month-old male and female 5XFAD mice for 4 or 7 weeks led to decreased soluble brain Aß that coincided with reduced APP and BACE1 levels, resulting in decreased formation of insoluble Aß deposits. These data suggest a vicious cycle whereby initial Aß plaque formation causes MT disruption in nearby axons, resulting in the local accumulation of APP and BACE1 that facilitates additional Aß generation and plaque deposition. The ability of a MT-stabilizing compound to attenuate this cycle, and also reduce deficits resulting from reduced tau binding to MTs, suggests that molecules of this type hold promise as potential AD therapeutics.

Differential Cytotoxicity of Haloaromatic Disinfection Byproducts and Lead Co-exposures against Human Intestinal and Neuronal Cells.

Disinfecting drinking water with chlorine inadvertently generates disinfection byproducts (DBPs) which can cause potential adverse health effects to humans. Haloaromatic DBPs are a group of emerging DBPs recently identified, suspected to be substantially more toxic than haloaliphatic DBPs but have not been extensively studied. Simultaneously, service pipelines made of lead materials are widely used in water distribution systems and become a source of dissolved lead (Pb) in tap water. In this study, we investigated the cytotoxicity of nine haloaromatic DBPs and lead ion (Pb2+), both separately as well as in combination, to human epithelial colorectal adenocarcinoma (Caco-2) and neuroblastoma (SH-SY5Y) cells. Results show that the cytotoxicity of the DBPs against Caco-2 cells followed the descending rank order of 2,4,6-triiodophenol ≅ 2,5-dibromohydroquinone > 2,4,6-tribromophenol > 3,5-dibromo-4-hydroxybenzaldehyde ≅ 2,4,6-trichlorophenol > 4-chlorophenol ≅ 3,5-dibromo-4-hydroxybenzoic acid > 2,6-dichlorophenol >5-chlorosalicylic acid, and the cytotoxicity of the DBPs against SH-SY5Y cells followed a similar rank order, 2,4,6-triiodophenol ≅ 2,5-dibromohydroquinone > 2,4,6-tribromophenol > 3,5-dibromo-4-hydroxybenzaldehyde ≅ 2,4,6-trichlorophenol > 4-chlorophenol > 3,5-dibromo-4-hydroxybenzoic acid > 2,6-dichlorophenol ≅ 5-chlorosalicylic acid. Lead in water did not change the toxicity of 3,5-dibromo-4-hydroxybenzoic acid (to either cell-type) or the toxicity of 4-chlorophenol (to the neuronal cell-type); but Pb2+ exhibited different degrees of synergistic effects with other tested DBPs. The synergism resulted in different rank orders of cytotoxicity against both intestinal and neuronal cells. These data indicate that future prioritization and regulation of emerging haloaromatic DBPs in drinking water should be considered in terms of their own toxicity and combinatorial effects with lead in water.

Increased Lipophilicity of Halogenated Ruthenium(II) Polypyridyl Complexes Leads to Decreased Phototoxicity in†vitro when Used as Photosensitizers for Photodynamic Therapy.

In the fight against cancer, photodynamic therapy is generating great interest thanks to its ability to selectively kill cancer cells without harming healthy tissues. In this field, ruthenium(II) polypyridyl complexes, and more specifically, complexes with dipyrido[3,2-a:2',3'-c]phenazine (dppz) as a ligand are of particular interest due to their DNA-binding and photocleaving properties. However, ruthenium(II) polypyridyl complexes can sometimes suffer from low lipophilicity, which hampers cellular internalisation through passive diffusion. In this study, four new [Ru(dppz-X2 )3 ]2+ complexes (X=H, F, Cl, Br, I) were synthesized and their lipophilicity (logP), cytotoxicity and phototoxicity on cancerous and noncancerous cell lines were assessed. This study shows that, counterintuitively, the phototoxicity of these complexes decreases as their lipophilicity increases; this could be due solely to the atomic radius of the halogen substituents.

Efficient Biocatalytic Synthesis of Dihalogenated Purine Nucleoside Analogues Applying Thermodynamic Calculations.

The enzymatic synthesis of nucleoside analogues has been shown to be a sustainable and efficient alternative to chemical synthesis routes. In this study, dihalogenated nucleoside analogues were produced by thermostable nucleoside phosphorylases in transglycosylation reactions using uridine or thymidine as sugar donors. Prior to the enzymatic process, ideal maximum product yields were calculated after the determination of equilibrium constants through monitoring the equilibrium conversion in analytical-scale reactions. Equilibrium constants for dihalogenated nucleosides were comparable to known purine nucleosides, ranging between 0.071 and 0.081. To achieve 90% product yield in the enzymatic process, an approximately five-fold excess of sugar donor was needed. Nucleoside analogues were purified by semi-preparative HPLC, and yields of purified product were approximately 50% for all target compounds. To evaluate the impact of halogen atoms in positions 2 and 6 on the antiproliferative activity in leukemic cell lines, the cytotoxic potential of dihalogenated nucleoside analogues was studied in the leukemic cell line HL-60. Interestingly, the inhibition of HL-60 cells with dihalogenated nucleoside analogues was substantially lower than with monohalogenated cladribine, which is known to show high antiproliferative activity. Taken together, we demonstrate that thermodynamic calculations and small-scale experiments can be used to produce nucleoside analogues with high yields and purity on larger scales. The procedure can be used for the generation of new libraries of nucleoside analogues for screening experiments or to replace the chemical synthesis routes of marketed nucleoside drugs by enzymatic processes.

Role of Voltage-Gated Sodium Channels in the Mechanism of Ether-Induced Unconsciousness.

Despite continuous clinical use for more than 170 years, the mechanism of general anesthetics has not been completely characterized. In this review, we focus on the role of voltage-gated sodium channels in the sedative-hypnotic actions of halogenated ethers, describing the history of anesthetic mechanisms research, the basic neurobiology and pharmacology of voltage-gated sodium channels, and the evidence for a mechanistic interaction between halogenated ethers and sodium channels in the induction of unconsciousness. We conclude with a more integrative perspective of how voltage-gated sodium channels might provide a critical link between molecular actions of the halogenated ethers and the more distributed network-level effects associated with the anesthetized state across species.

Costatone C-A New Halogenated Monoterpene from the New Zealand Red Alga Plocamium angustum.

Red algae of the genus Plocamium have been a rich source of halogenated monoterpenes. Herein, a new cyclic monoterpene, costatone C (7), was isolated from the extract of P. angustum collected in New Zealand, along with the previously reported (1E,5Z)-1,6-dichloro-2-methylhepta-1,5-dien-3-ol (8). Elucidation of the planar structure of 7 was achieved through conventional NMR and (-)-HR-APCI-MS techniques, and the absolute configuration by comparison of experimental and DFT-calculated ECD spectra. The absolute configuration of 8 was determined using Mosher's method. Compound 7 showed mild antibacterial activity against Staphylococcus aureus and S. epidermidis. The state of Plocamium taxonomy and its implications upon natural product distributions, especially across samples from specimens collected in different countries, is also discussed.

Stabilization of microtubules by cevipabulin.

We report the utility of cevipabulin as a stabilizing agent for microtubules. Cevipabulin-stabilized microtubules were more flexible compared to the microtubules stabilized by paclitaxel, the most commonly used microtubule stabilizing agent. Similar to the paclitaxel-stabilized microtubules, cevipabulin-stabilized microtubules were driven by kinesins in an in vitro gliding assay. The velocity of cevipabulin-stabilized microtubules was significantly higher than that of paclitaxel-stabilized microtubules. These findings will enrich the variety of microtubules with difference in mechanical and dynamic properties and widen their applications in nanotechnology.

Anverenes B⁻E, New Polyhalogenated Monoterpenes from the Antarctic Red Alga Plocamium cartilagineum.

The subtidal red alga Plocamium cartilagineum was collected from the Western Antarctic Peninsula during the 2011 and 2017 austral summers. Bulk collections from specific sites corresponded to chemogroups identified by Young et al. in 2013. One of the chemogroups yielded several known acyclic halogenated monoterpenes (2-5) as well as undescribed compounds of the same class, anverenes B-D (6-8). Examination of another chemogroup yielded an undescribed cyclic halogenated monoterpene anverene E (9) as its major secondary metabolite. Elucidation of structures was achieved through one-dimensional (1D) and 2D nuclear magnetic resonance (NMR) spectroscopy and negative chemical ionization mass spectrometry. Compounds 1-9 show moderate cytotoxicity against cervical cancer (HeLa) cells.

Isolation and Potential Biological Applications of Haloaryl Secondary Metabolites from Macroalgae.

Macroalgae have been reported as an important source of halogenated aromatic secondary metabolites, being the majority of these derivatives isolated from red algae. Halophenols and haloindoles are the most common haloaryl secondary metabolites isolated from these marine organisms. Nevertheless, some halogenated aromatic sesquiterpenes and naphthalene derivatives have also been isolated. Most of these secondary metabolites showed interesting biological activities, such as antitumor, antimicrobial, antidiabetic, and antioxidant. This review describes in a systematic way the distribution and natural occurrence of halogenated aromatic secondary metabolites from extracts of red, brown, and green algae, as well as biological activities reported for these compounds.

Halogen Substituents in the Isoquinoline Scaffold Switches the Selectivity of Inhibition between USP2 and USP7.

Deubiquitinases are important components of the protein regulatory network and, hence, constitute a tempting drug target. We report herein structure-activity relationship studies to develop halogen-substituted isoquionoline-1,3-dione-based inhibitors of the deubiquitinase USP2. In contrast to our previous reports, the best compound discovered was found to act through a reactive oxygen species independent, uncompetitive mechanism with an IC50 of 250 nm. We show the crucial role of halogens in the common scaffold to provide potency and selectivity of our compound, where the introduction of the fluorine atom completely switches the selectivity of the inhibitor between USP2 and USP7. Our cellular studies highlight the potential applicability of the reported compound for in vivo experiments. The discovery of the isoquinoline-1,3-dione core and the knowledge obtained with regard to halogen substituents provide a platform towards understanding USP2 inhibition and the development of highly selective next-generation deubiquitinase inhibitors.

Small Molecule Modifiers of In Vitro Manganese Transport Alter Toxicity In Vivo.

Manganese (Mn) is essential for several species and daily requirements are commonly met by an adequate diet. Mn overload may cause motor and psychiatric disturbances and may arise from an impaired or not fully developed excretion system, transporter malfunction and/or exposure to excessive levels of Mn. Therefore, deciphering processes regulating neuronal Mn homeostasis is essential to understand the mechanisms of Mn neurotoxicity. In the present study, we selected two small molecules (with opposing effects on Mn transport) from a previous high throughput screen of 40,167 to test their effects on Mn toxicity parameters in vivo using Caenorhabditis elegans. We pre-exposed worms to VU0063088 and VU0026921 for 30 min followed by co-exposure for 1 h with Mn and evaluated Mn accumulation, dopaminergic (DAergic) degeneration and worm survival. Control worms were exposed to vehicle (DMSO) and saline only. In pdat-1::GFP worms, with GFP labeled DAergic neurons, we observed a decrease of Mn-induced DAergic degeneration in the presence of both small molecules. This effect was also observed in an smf-2 knockout strain. SMF-2 is a regulator of Mn transport in the worms and this strain accumulates higher Mn levels. We did not observe improved survival in the presence of small molecules. Our results suggest that both VU0063088 and VU0026921 may modulate Mn levels in the worms through a mechanism that does not require SMF-2 and induce protection against Mn neurotoxicity.

Halogenated Compounds from Corals: Chemical Diversity and Biological Activities.

As important marine biological resources, corals produce a large amount of active organic compounds in their secondary metabolic processes, including numerous brominated, chlorinated, and iodinated compounds. These compounds, with novel structures and unique activities, guide the discovery and research of important lead compounds and novel biological mechanisms. Through a large number of literature surveys, this paper summarized a total of 145 halogenated secondary metabolites which were roughly divided into four major classes of terpenes, prostaglandins, steroids and alkaloids, and they were mainly isolated from ten coral families, Ellisellidae, Gorgoniidae, Briareidae, Plexauridae, Anthothelidae, Alcyoniidae, Clavularidae, Tubiporidae, Nephtheidae and Dendrophyllidae to the best of our knowledge. In addition, their organism species, structure composition and biological activity were also discussed in the form of a chart in this essay.

Small-molecule compounds targeting the STAT3 DNA-binding domain suppress survival of cisplatin-resistant human ovarian cancer cells by inducing apoptosis.

Constitutive activation of signal transducer and activator of transcription 3 (STAT3) plays important roles in oncogenic occurrence and transformation by regulating the expression of diverse downstream target genes important for tumor growth, metastasis, angiogenesis and immune evasion. Feasibility of targeting the DNA-binding domain (DBD) of STAT3 has been proven previously. With the aid of 3D shape- and electrostatic-based drug design, we identified a new STAT3 inhibitor, LC28, and its five analogs, based on the pharmacophore of a known STAT3 DBD inhibitor. Microscale thermophoresis assay shows that these compounds inhibits STAT3 binding to DNA with a Ki value of 0.74-8.87 µM. Furthermore, LC28 and its analogs suppress survival of cisplatin-resistant ovarian cancer cells by inhibiting STAT3 signaling and inducing apoptosis. Therefore, these compounds may serve as candidate compounds for further modification and development as anticancer therapeutics targeting the DBD of human STAT3 for treatment of cisplatin-resistant ovarian cancer.

A Guinea pig cytomegalovirus resistant to the DNA maturation inhibitor BDCRB.

Herpesvirus DNA packaging is an essential step in virion morphogenesis and an important target for antiviral development. The halogenated benzimidazole 2-bromo-5,6-dichloro-1-ß-d-ribofuranosyl-1H-benzimidazole (BDCRB) was the first compound found to selectively disrupt DNA packaging. It has activity against human cytomegalovirus as well as guinea pig cytomegalovirus. The latter provides a useful small animal model for congenital cytomegalovirus infection. To better understand the mechanism by which BDCRB acts, a guinea pig cytomegalovirus resistant to BDCRB was derived and characterized. An L406P substitution occurred within GP89, a subunit of the complex that cleaves and packages DNA, but transfer of this mutation to an otherwise wild type genetic background did not confer significant BDCRB resistance. The resistant virus also had a 13.4-kb deletion that also appeared to be unrelated to BDCRB-resistance as a virus with a similar spontaneous deletion was sensitive to BDCRB. Lastly, the BDCRB-resistant virus exhibited a dramatic increase in the number of reiterated terminal repeats at both genomic termini. The mechanism that underlies this change in genome structure is not known but may relate to the duplication of terminal repeats that is associated with DNA cleavage and packaging. A model is presented in which BDCRB impairs the ability of terminase to recognize cleavage site sequences, but repeat arrays overcome this impairment by presenting terminase with multiple opportunities to recognize the correct cleavage site sequences that lie within the repeats. Further elucidation of this phenomenon should prove valuable for understanding the molecular basis of herpesvirus DNA maturation and the mechanism of action of this class of drugs.

Effects on tubulin polymerization and down-regulation of c-Myc, hTERT and VEGF genes by colchicine haloacetyl and haloaroyl derivatives.

Several colchicine analogues in which the N-acetyl residue has been replaced by haloacetyl, cyclohexylacetyl, phenylacetyl and various aroyl moieties have been synthesized. The cytotoxic activities of the synthesized compounds have been measured on three tumor cell lines (HT-29, MCF-7 and A549) and on one non-tumor cell line (HEK-293). These compounds exhibit high antiproliferative activities at the nanomolar level, in many cases with a higher potency than colchicine itself. Some of the compounds, particularly the haloacetyl derivatives, inhibit the polymerization of tubulin in a similar manner as colchicine. As regards the cell cycle, the most active compounds are the chlorobenzoyl and bromobenzoyl derivatives, which cause cell cycle arrest at the G2/M phase when tested at 20 nM, and the bromoacetyl derivative, which arrests the cell cycle at 15 nM. In addition, these colchicine derivatives have shown fairly active downregulating the expression of the c-Myc, hTERT and VEGF genes, as well as VEGF protein secretion, at very low concentrations.