Targeting inhibitory Siglec-3 to suppress IgE-mediated human basophil degranulation.

BACKGROUND: Sialic acid-binding immunoglobulin-like lectin-3 (Siglec-3 [CD33]) is a major Siglec expressed on human mast cells and basophils; engagement of CD33 leads to inhibition of cellular signaling via immunoreceptor tyrosine-based inhibitory motifs. OBJECTIVE: We sought to inhibit human basophil degranulation by simultaneously recruiting inhibitory CD33 to the IgE-FcεRI complex by using monoclonal anti-IgE directly conjugated to CD33 ligand (CD33L). METHODS: Direct and indirect basophil activation tests (BATs) were used to assess both antigen-specific (peanut) and antigen-nonspecific (polyclonal anti-IgE) stimulation. Whole blood from donors with allergy was used for direct BAT, whereas blood from donors with nonfood allergy was passively sensitized with plasma from donors with peanut allergy in the indirect BAT. Blood was incubated with anti-IgE-CD33L or controls for 1 hour or overnight and then stimulated with peanut, polyclonal anti-IgE, or N-formylmethionyl-leucyl-phenylalanine for 30 minutes. Degranulation was determined by measuring CD63 expression on the basophil surface by flow cytometry. RESULTS: Incubation for 1 hour with anti-IgE-CD33L significantly reduced basophil degranulation after both allergen-induced (peanut) and polyclonal anti-IgE stimulation, with further suppression after overnight incubation with anti-IgE-CD33L. As expected, anti-IgE-CD33L did not block basophil degranulation due to N-formylmethionyl-leucyl-phenylalanine, providing evidence that this inhibition is IgE pathway-specific. Finally, CD33L is necessary for this suppression, as monoclonal anti-IgE without CD33L was unable to reduce basophil degranulation. CONCLUSIONS: Pretreating human basophils with anti-IgE-CD33L significantly suppressed basophil degranulation through the IgE-FcεRI complex. The ability to abrogate IgE-mediated basophil degranulation is of particular interest, as treatment with anti-IgE-CD33L before antigen exposure could have broad implications for the treatment of food, drug, and environmental allergies.

Design and characterization of a binary CT complex of imidazole-oxyresveratrol: exploring its pharmacological and computational aspects.

A new binary charge transfer (CT) complex between imidazole (IMZ) and oxyresveratrol (OXA) was synthesized and characterized experimentally and theoretically. The experimental work was carried out in solution and solid state in selected solvents such as chloroform (CHL), methanol (Me-OH), ethanol (Et-OH), and acetonitrile (AN). The newly synthesized CT complex (D1) has been characterized by various techniques such as UV-visible spectroscopy, FTIR, 1H-NMR, and powder-XRD. The 1:1 composition of D1 is confirmed by Jobs' method of continuous variation and spectrophotometric (at λmax 554 nm) methods at 298 K. The infrared spectra of D1 confirmed the existence of proton transfer hydrogen bond beside charge transfer interaction. These findings indicate that the cation and anion are joined together by the weak hydrogen bonding as N+-H-O-. Reactivity parameters strongly recommended that IMZ behaves as a good electron donor and OXA an efficient electron acceptor. Density functional theory (DFT) computations with basis set B3LYP/6-31G (d,p) was applied to support the experimental results. TD-DFT calculations gives HOMO (-5.12 eV) → LUMO (-1.14 eV) electronic energy gap (ΔE) to be 3.80 eV. The bioorganic chemistry of D1 was well established after antioxidant, antimicrobial, and toxicity screening in Wistar rat. The type of interactions between HSA and D1 at the molecular level was studied through fluorescence spectroscopy. Binding constant along with the type of quenching mechanism, was investigated through the Stern-Volmer equation. Molecular docking demonstrated that D1 binds perfectly with human serum albumin and EGFR (1M17) and exposes free energy of binding (FEB) values of -295.2 and -283.3 kcal/mol, respectively. The D1 fits successfully into the minor groove of HAS and 1M17, the results of molecular docking show that the D1 binds perfectly with the HAS and 1M17, the higher value of binding energy shows stronger interaction between HAS and 1M17 with D1. Our synthesized complex shows good binding results with HAS compared to 1M17.Communicated by Ramaswamy H. Sarma.

Synthesis, spectrophotometric, pharmacology and theoretical investigation of a new electron transfer complex of 8-hydroxyquinoline with oxalic acid in different polar solvents.

Preparation, characterization, and investigation of a novel organic charge transfer (CT) complex were carried out, with a focus on exploring its antibacterial and antifungal characteristics. Theoretical analysis backs up the experimental findings. CT complex formed was synthesized between 8-hydroxyquinoline (8HQ) and oxalic acid (OA) at RT (room temperature). Different analyses were used to describe the CT complex, including 1H-NMR, FTIR, TGA/DTA, and UV-vis spectra (in different solvents). These indicate that the CT interaction is linked to proton transfer from OA to 8HQ and the subsequent development of 'N+__H…O-" type bonding. On the basis of wave number, the CT complex and reactants are distinguished in FTIR spectra. By using Thermo gravimetric Analysis/Differential Thermal Analysis (TGA/DTA) tests, the thermal stability of complicated and thorough corrosion was examined. Through UV-visible spectroscopy, physical characteristics like ECT (interaction energy), RN (resonance energy), ID (ionization potential), f (oscillator strength) and ΔG (free energy) were calculated. The εCT (molar extinction coefficient), the KCT (formation constant), and additional physical properties of this complex were calculated by the Benesi-Hildebrand equation in order to determine its 1:1 stoichiometry. The biological properties are also supported by theoretical study. The protein, Human Serum Albumin (HSA), is observed to bind with CT complex, as shown by molecular docking and the observed binding energy value is -167.04 kcal/mol. Molecular dynamics (MD) simulation 100 ns run was used to refine docking results and binding free energy was calculated using MM-PBSA. This study introduces a novel CT complex, offering fresh perspectives on molecular interactions.Communicated by Ramaswamy H. Sarma.

Biochemical and histopathological analysis after sub-chronic administration of oxyresveratrol in Wistar rats.

Oxyresveratrol (OXY) is a naturally occurring phenolic compound; however, there are no toxicity studies reported on its long term use. The aim of our work was to demonstrate the evaluation of acute and sub-chronic toxicity of oxyresveratrol in rats to assess its safety profile. To evaluate the LD50 value, 2000 mg/kg of oxyresveratrol was administered to Wistar rats by oral gavage. For sub-chronic toxicity assessment, 80 Wistar rats were randomly divided into four groups (10 animal/sex/group) and oxyresveratrol administered at a dose of 50, 100, 150 mg/kg/day by oral gavage. Bodyweight, food, and water consumption were monitored every week. At the end of the experiments, biochemical and hematological parameters were analyzed. Gross and microscopic organ analyses were also carried out. LD50 of oxyresveratrol was greater than 2000 mg/kg sub-chronic administration of oxyresveratrol did not influence any mortality. Doses of 50 and 100 mg/kg of oxyresveratrol did not produce any sign of toxicity. However, the 150 mg/kg oxyresveratrol group depicted changes in multiple biochemical and hematological parameters with changes in the pathology of cardiac, hepatic, and renal tissues when compared with control. Therefore, no observed adverse effect level (NOAEL) of oxyresveratrol was observed to be 100 mg/kg per day for both male and female rats.

Design, synthesis, characterizing and DFT calculations of a binary CT complex co-crystal of bioactive moieties in different polar solvents to investigate its pharmacological activity.

Imidazole (IM) and salicylic acid (SA) have a significant class among the medical compound. These are widely used as topical drugs like antifungal, antibacterial, anticancer, immunosuppressive agent, etc. These two bioactive organic moieties are combined by a weak hydrogen bond formed by hydrogen transfer. The charge transfer (CT) complex of acceptor (SA) and donor (IM), has been synthesized at room temperature in methanol and confirmed by signal-crystal XRD, conductance and UV-visible spectroscopy. The X-ray crystallography provides the original structural information of CT complex and displays the existence of N+-H--O- bond between IM and SA. The physical properties such as (ECT), (RN), (ID), (f), (D) and (Δ G0) along with molar extinction coefficient (εCT) and formation constant (KCT) were estimated through UV-visible spectroscopy. Job's method and Benesi-Hildebrand equation suggested 1:1 stoichiometry of ([IM]+[SA]-). The results indicate a complete transfer of hydrogen atom and CT complex formation with 1:1 molar ratio of IM and SA. Antimicrobial activity was veiled against different bacteria like Escherichia coli, Bacillus subtilis and Staphylococcus aureus; and different fungi as Fusarium oxysporum, Candida albicans and Aspergillus niger by disc diffusion method. CT complex was also tested for cytotoxic activity against lung cancer cell lines in comparison to breast cancer cell lines. Molecular docking provides the information of binding of [(IM)+(SA)-] with the cancer marker (1M17), which has substantial application for drug designing. The investigational studies were supplemented through time-dependent density functional theory (TD-DFT) using basis set B3LYP/6-311G**. Through DFT calculations, HOMO→LUMO electronic energy gap (ΔE) was obtained.

Herb and Spices in Colorectal Cancer Prevention and Treatment: A Narrative Review.

Colorectal cancer (CRC) is the second most deadly cancer worldwide. CRC management is challenging due to late detection, high recurrence rate, and multi-drug resistance. Herbs and spices used in cooking, practised for generations, have been shown to contain CRC protective effect or even be useful as an anti-CRC adjuvant therapy when used in high doses. Herbs and spices contain many bioactive compounds and possess many beneficial health effects. The chemopreventive properties of these herbs and spices are mainly mediated by the BCL-2, K-ras, and MMP pathways, caspase activation, the extrinsic apoptotic pathway, and the regulation of ER-stress-induced apoptosis. As a safer natural alternative, these herbs and spices could be good candidates for chemopreventive or chemotherapeutic agents for CRC management because of their antiproliferative action on colorectal carcinoma cells and inhibitory activity on angiogenesis. Therefore, in this narrative review, six different spices and herbs: ginger (Zingiber officinale Roscoe), turmeric (Curcuma longa L.), garlic (Allium sativum L.), fenugreek (Trigonella foenum-graecum L.), sesame (Sesamum indicum L.), and flaxseed (Linum usitatissimum L.) used in daily cuisine were selected for this study and analyzed for their chemoprotective or chemotherapeutic roles in CRC management with underlying molecular mechanisms of actions. Initially, this study comprehensively discussed the molecular basis of CRC development, followed by culinary and traditional uses, current scientific research, and publications of selected herbs and spices on cancers. Lead compounds have been discussed comprehensively for each herb and spice, including anti-CRC phytoconstituents, antioxidant activities, anti-inflammatory properties, and finally, anti-CRC effects with treatment mechanisms. Future possible works have been suggested where applicable.

Suppressing Immune Responses Using Siglec Ligand-Decorated Anti-receptor Antibodies.

The sialic acid-binding immunoglobulin-type lectins (Siglecs) are expressed predominantly on white blood cells and participate in immune cell recognition of self. Most Siglecs contain cytoplasmic inhibitory immunoreceptor tyrosine-based inhibitory motifs characteristic of inhibitory checkpoint co-receptors that suppress cell signaling when they are recruited to the immunological synapse of an activating receptor. Antibodies to activatory receptors typically activate immune cells by ligating the receptors on the cell surface. Here, we report that the conjugation of high affinity ligands of Siglecs to antibodies targeting activatory immune receptors can suppress receptor-mediated activation of immune cells. Indeed, B-cell activation by antibodies to the B-cell receptor IgD is dramatically suppressed by conjugation of anti-IgD with high affinity ligands of a B-cell Siglec CD22/Siglec-2. Similarly, degranulation of mast cells induced by antibodies to IgE, which ligate the IgE/FcεR1 receptor complex, is suppressed by conjugation of anti-IgE to high affinity ligands of a mast cell Siglec, CD33/Siglec-3 (CD33L). Moreover, the anti-IgE-CD33L suppresses anti-IgE-mediated systemic anaphylaxis of sensitized humanized mice and prevents anaphylaxis upon subsequent challenge with anti-IgE. The results demonstrate that attachment of ligands of inhibitory Siglecs to anti-receptor antibodies can suppress the activation of immune cells and modulate unwanted immune responses.

Synthesis, spectroscopic characterization, antimicrobial activity, molecular docking and DFT studies of proton transfer (H-bonded) complex of 8-aminoquinoline (donor) with chloranilic acid (acceptor).

The proton transfer complex has been synthesized by mixing 1:1 ratio of 8-aminoquinoline (donor) and chloranilic acid (acceptor) in methanol. FTIR, 13C NMR, 1H NMR, Powder XRD and UV-visible studies confirmed the formation of the newly synthesized compound. These methods ascertain that cations and anions combine to form weak hydrogen bonds as N+-H----O-. The physical properties such as energy of interaction (ECT), resonating energy (RN), Ionization potential (ID), and oscillator strength (f), transition dipole strength (D) and free energy (Δ G) were estimated through UV-visible spectroscopy. The thermal stability of this complex and extensive erosion was analyzed by TGA/DTA study. Benesi-Hildebrand equation was used to determine 1:1 stoichiometry of this complex and to calculate the molar extinction coefficient (εCT), the formation constant (KCT) and other physical parameters. The nature of transfer of charge relations plays a vital role in chemistry and in biological systems. The synthesized proton transfer complex has been screened for antibacterial activities against different bacteria and antifungal activities against different fungi. The proton transfer complex also displays outstanding interaction with the human protein (globulin) protein. The DFT calculations by B3LYP/6-311G** basis set gave theoretical establishment and HOMO (-5.468 eV) to LUMO (-3.328 eV) electronic energy gap (ΔE) as 2.140 eV. Theoretical analysis proves the biological characteristics as well. Molecular docking displays that CT complex is fully bound to the protein and determines the free binding energy value of -290.18 kcal/mol (FEB).A new organic charge transfer complex has been prepared, characterized and explored for antibacterial, antifungal and protein binding properties. The experimental results are supported by theoretical analysis.Communicated by Ramaswamy H. Sarma.

Link between Excessive Smartphone Use and Sleeping Disorders and Depression among South Korean University Students.

The purpose of this study was to explore the link between smartphone use and sleeping disorders and depression among university students in South Korea. South Korea has the highest mobile phone penetration rate as well as the highest rate of suicide of any of the Organization for Economic Cooperation and Development (OECD) nations, thus making this study of great importance. The core aim was to see whether the excessive use of smartphones has an association with sleeping disorders and depression. A cross-sectional analysis was performed to establish if there was any link between smartphone use and sleeping disorders and depression. Samples from 188 participants were used for this study. Data were collected using two well-established questionnaires, the Center for Epidemiologic Studies-Depression (CES-D) and the Athene Insomnia Scale (AIS), as well as a few questions on smartphone use. A few demographic questions were added to the questionnaire. The results of this study concluded that a significant relationship exists between smartphone use and depression. However, the finding of this research could not uncover a significant relationship between smartphone use and sleeping disorders among university students in South Korea. The excessive use of smartphones shows a relationship to an unhealthy lifestyle. There is a clear indication that the overuse of smartphones could be linked to depression. Furthermore, the study found that students with depression also tend to have sleeping disorders.

ppGpp signaling plays a critical role in virulence of Acinetobacter baumannii.

Acinetobacter baumannii, a major nosocomial pathogen, survives in diverse hospital environments, and its multidrug resistance is a major concern. The ppGpp-dependent stringent response mediates the reprogramming of genes with diverse functions in several bacteria. We investigated whether ppGpp is involved in A. baumannii's pathogenesis by examining biofilm formation, surface motility, adhesion, invasion, and mouse infection studies. Transcriptome analysis of early stationary phase cultures revealed 498 differentially-expressed genes (≥ 2-fold change) in a ppGpp-deficient A. baumannii strain; 220 and 278 genes were up and downregulated, respectively. Csu operon expression, important in pilus biosynthesis during early biofilm formation, was significantly reduced in the ppGpp-deficient strain. Our findings suggest that ppGpp signaling influences A. baumannii biofilm formation, surface motility, adherence, and virulence. We showed the association between ppGpp and pathogenicity in A. baumannii for the first time; ppGpp may be a novel antivirulence target in A. baumannii.

Development of a Lung Cancer Model in Wistar Rat and In Silico Screening of its Biomarkers.

BACKGROUND: Cancer is usually caused by three factors: Nutrition, inflammation and cigarette smoke. This study on rat experimental models would enable us to understand the mechanism of lung cancer caused by NNK to which humans are continuously exposed, help us understand possible molecular targets, and assist in designing drugs for humans against lung cancer. AIM: A lung cancer model was developed by administering tobacco-specific carcinogen: NNK [4- methylnitrosamino)-1-(3-pyridyl)-1-butanone] to male Wistar rats for 24 weeks. Furthermore, in silico approach was followed to screen the molecular targets. METHODS: A method was established in which subcutaneous and intraperitoneal injections of NNK were administered to male Wistar rats simultaneously. For authentication of lung cancer in vivo, we performed molecular docking simulations with protein biomarkers: Cox-2, p53, p38 MAPKs and EGFR using Hex-Discovery Studio, Schrödinger-maestro software. RESULTS: Lung morphology and histopathology indicated the initiation of bronchiolar epithelial hyperplasia and squamous dysplasia in the cancer 1 group after 16 weeks of NNK exposure. 66.66% incidence of squamous cell carcinoma (SCC) and 33.3% incidence of adenocarcinoma were observed in cancer 2 group after being exposed to NNK. Results indicated that the incidence of SCC and adenocarcinoma gradually increased from 66.66% to 85.71% in cancer 2 group and from 33.33% to 42.58% in cancer 3 group, respectively. Docking results indicate the total binding energy and glide energy of Cox-2, p53, p38 MAPKs, EGFR : 38.14, -211.58, -181.58, -213.05 Kcal/mol and -39.25, -32.16,-36.49, -40.19 Kcal/mol, respectively. CONCLUSION: Pulmonary adenocarcinoma model was developed by administering tobacco-specific carcinogen: NNK [4-methylnitrosamino)-1-(3-pyridyl)-1-butanone] to male Wistar rats in 24 weeks. In silico experiments confirmed EGFR to be the most potential target for NNK induced lung Cancer.

CRISPR-Cas9: A Promising Genome Editing Therapeutic Tool for Alzheimer's Disease-A Narrative Review.

Alzheimer's disease (AD) is a chronic and irreversible neurodegenerative disorder characterized by cognitive deficiency and development of amyloid-ß (Aß) plaques and neurofibrillary tangles, comprising hyperphosphorylated tau. The number of patients with AD is alarmingly increasing worldwide; currently, at least 50 million people are thought to be living with AD. The mutations or alterations in amyloid-ß precursor protein (APP), presenilin-1 (PSEN1), or presenilin-2 (PSEN2) genes are known to be associated with the pathophysiology of AD. Effective medication for AD is still elusive and many gene-targeted clinical trials have failed to meet the expected efficiency standards. The genome editing tool clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 has been emerging as a powerful technology to correct anomalous genetic functions and is now widely applied to the study of AD. This simple yet powerful tool for editing genes showed the huge potential to correct the unwanted mutations in AD-associated genes such as APP, PSEN1, and PSEN2. So, it has opened a new door for the development of empirical AD models, diagnostic approaches, and therapeutic lines in studying the complexity of the nervous system ranging from different cell types (in vitro) to animals (in vivo). This review was undertaken to study the related mechanisms and likely applications of CRISPR-Cas9 as an effective therapeutic tool in treating AD.

Slow-light application using dielectrics in a metallic terahertz plasmonic waveguide.

In this paper, a metallic terahertz (THz) plasmonic waveguide comprising subwavelength scale pillars is proposed. The pillars are periodically arranged in one dimension and are assumed to be metallic; on the top of the pillars, dielectric material is deposited. The fundamental guided resonant mode properties of the waveguide are comprehensively examined with and without dielectric material. Furthermore, guided modes are examined while varying the refractive index value (n) of the dielectric material, and it is observed that resonant modes supported by the waveguide strongly depend on n value of dielectrics. The dispersion relations of the guided modes are analyzed to ensure the plasmonic response. To support the numerical results, a Drude model is employed to fit the real and imaginary parts of the complex dielectric function for the proposed waveguide design. The group velocity of the fundamental guided terahertz mode is calculated in order to investigate slow-light properties of the terahertz wave. Additionally, the phase of transmission output and electric field profiles are studied in support of slow-light phenomena. The slow-light phenomenon using a dielectric-metal-based plasmonic waveguide could be very useful in construction of terahertz buffers, storage devices, terahertz sensors, detectors, etc.

Exploring interaction dynamics of designed organic cocrystal charge transfer complex of 2-hydroxypyridine and oxalic acid with human serum albumin: Single crystal, spectrophotometric, theoretical and antimicrobial studies.

As human serum albumin (HSA) being the most abundant blood protein involved in the role of transport of molecules (drugs), we have designed HSA binding organic charge transfer complex between 2-hydroxypyridine (donor) and oxalic acid (acceptor) showing antimicrobial activities. The type of interactions between HSA and synthesized complex at the molecular level was studied through fluorescence spectroscopy. Binding constant along with the type of quenching mechanism was shown through the Stern Volmer equation. Molecular docking tool also justifies the binding results obtained from fluorescence by providing different interactions, FEB, hydrogen bonding and H-bonding surfaces. Antimicrobial activity was screened against three bacteria - Escheichia coli, Bacteria subtilis and Staphylococus aureus strain and three fungi - Aspergillus Niger, Candida Albicans and Fusarium Oxysporun using disc diffusion method. The characterization of the complex was done through different techniques (FTIR, UV-vis spectroscopy, TGA-DTA). Job's method along with single crystal XRD provides 2:1 stoichiometry and O⋯H-O type of H-bonding between acceptor and donor molecule. Physical parameters (KCT, εCT, ID, ΔG°, µEN, f and RN) were also calculated for the synthesized complex. Theoretical computational data (DFT and Hirshfeld surface) have also been calculated for the complex.

Are Students Really Cautious about Food Waste? Korean Students' Perception and Understanding of Food Waste.

The amount of food wasted by Korean households is significant and to some extent could be preventable. It is not well illustrated how Korean students perceive food waste and how much they know about the consequences of food waste. This study aimed to examine Korean students' perception of food waste. Overall, results show that students' perception of food waste varies in different clusters. Considerate food wasters (cluster 1) are knowledgeable and have much information regarding food waste. This paper suggests that additional information about how to preserve food and about issues related to food wastes, which cause a bigger environmental problem over the long term, could influence the behavior of this cluster, reducing perhaps further food waste. On the other hand, unwitting and ruthless food wasters, who are in clusters 2 and 3, need extra attention. Marketers should initiate educational campaigns to raise awareness of food waste for students and youth. Students who fall under these two clusters may need to pay extra attention to their shopping behavior. They should be more connected to their food, and to their purchase behavior, which may reduce food waste.

Synthesis, characterization, antimicrobial and DNA binding properties of an organic charge transfer complex obtained from pyrazole and chloranilic acid.

The chemistry of an organic charge transfer complex (CT complex) between pyrazole (donor) and chloranilic acid (acceptor) has been explored in ethanol at room temperature. The synthesized complex has been characterized by various techniques such as FTIR, NMR, Single crystal X-ray diffraction and UV-visible spectroscopy. These techniques indicate that the cation and anion are joined together by the weak hydrogen bonding. This molecular framework is a result of inter N+-H⋯O- bonding between donor and acceptor moieties. The elemental analysis and FTIR spectrum of semi-crystal complex along with Job's plot indicate the formation of 2: 1 HBCT-complex. The bioorganic chemistry of the present CT complex is established well toward antimicrobial screening and DNA binding capabilities. Antimicrobial activity was screened for gram positive and gram negative bacteria and various fungi. Molecular docking shows that the CT complex binds perfectly with the B-DNA and reveals free energy of binding (FEB) value of -198.4 kcal mol-1. TD-DFT calculations using basis set B3LYP/6-311G** give theoretical confirmation along with HOMO (-3.9421 eV) â†’ LUMO (-2.4903 eV) electronic energy gap (ΔE) to be 1.4521 eV. Theoretical analysis corroborates well the biological properties.

Elucidating the interaction of Spathodea campanulata leaf extracts mediated potential bactericidal gold nanoparticles with human serum albumin: spectroscopic analysis.

Nanomaterials in different form have been thoroughly used in the area of pharmaceutics and medicine for drug delivery. The large scale of nanoparticles (NPs) synthesis from plant extract is much safe, cheap and eco-friendly. Here, we demonstrated a new, one-step, ultra-fast biosynthesis of gold nanoparticles (sc-AuNPs, 19.54 nm) by using aqueous Spathodea campanulata leaf extracts as a reducing and capping agent. And also, we presented the synthesis of citrate capped gold nanoparticles (cit-AuNPs) of approximately same size (19.66 nm). These two NPs were characterized by UV-Visible, dynamic light scattering, transmission electron microscope and energy dispersive X-ray spectroscopy. Fourier transform infrared spectroscopy confirmed that the functional groups like OH, NH, OH of COOH and CO were contributed in the sc-AuNPs formation. The negative zeta potential (-20.5, -22.8 mV) established the stability and dispersion of the sc- and cit-AuNPs. The anti-bacterial activity of the sc- and cit-AuNPs were checked against Escherichia coli (DH5-Alpha). Minimum inhibitory concentration was 2.4 and 3.0 nM, respectively for sc- and cit-AuNPs. The interaction study of the sc-AuNPs/cit-AuNPs-human serum albumin (HSA) system was done by UV-Visible absorbance, fluorescence, circular dichroism, time resolved fluorescence spectroscopy and the measurement of zeta potential. Absorbance, three dimensional fluorescence, synchronous fluorescence and circular dichroism spectroscopy showed a minor conformational change of HSA upon interaction with the sc-AuNPs compared to cit-AuNPs. The present comparative study will advance our knowledge about the binding mode, mechanism and conformational change of the protein upon interaction with green synthesized sc-AuNPs and cit-AuNPs. Communicated by Ramaswamy H. Sarma.

Role of Resonance Modes on Terahertz Metamaterials based Thin Film Sensors.

We investigate thin film sensing capabilities of a terahertz (THz) metamaterial, which comprises of an array of single split gap ring resonators (SRRs). The top surface of the proposed metamaterial is covered with a thin layer of analyte in order to examine various sensing parameters. The sensitivity and corresponding figure of merit (FoM) of the odd and even resonant modes are analyzed with respect to different thicknesses of the coated analyte film. The sensing parameters of different resonance modes are elaborated and explained with appropriate physical explanations. We have also employed a semi-analytical transmission line model in order to validate our numerically simulated observations. Such study should be very useful for the development of metamaterials based sensing devices, bio-sensors etc in near future.

Expedient synthesis of the heneicosasaccharyl mannose capped arabinomannan of the Mycobacterium tuberculosis cellular envelope by glycosyl carbonate donors.

The global incidence of tuberculosis is increasing at an alarming rate, and Mycobacterium tuberculosis (Mtb) is the causative agent for tuberculosis, a disease with high mortality. Lipoarabinomannan (LAM) is one of the major components of the Mtb cellular envelope and is an attractive scaffold for developing anti-tubercular drugs, vaccines and diagnostics. Herein, a highly convergent strategy is developed to synthesize heneicosasaccharyl arabinomannan for the first time. The arabinomannan synthesized in this endeavour has several 1,2-trans or α-Araf linkages and three 1,2-cis or ß-Araf linkages end capped with 1,2-trans or α-Manp linkages. All the key glycosidations were performed with alkynyl carbonate glycosyl donors under [Au]/[Ag] catalysis conditions, which gave excellent yields and stereoselectivity even for the reactions between complex and branched oligosaccharides. The resultant allyl oligosaccharide was globally deprotected to obtain the heneicosasaccharyl arabinomannan as a propyl glycoside. In summary, heneicosasaccharyl mannose capped arabinomannan synthesis was achieved in 56 steps with 0.016% overall yield.

[Au]/[Ag]-catalysed expedient synthesis of branched heneicosafuranosyl arabinogalactan motif of Mycobacterium tuberculosis cell wall.

Emergence of multidrug-resistant and extreme-drug-resistant strains of Mycobacterium tuberculosis (MTb) can cause serious socioeconomic burdens. Arabinogalactan present on the cellular envelope of MTb is unique and is required for its survival; access to arabinogalactan is essential for understanding the biosynthetic machinery that assembles it. Isolation from Nature is a herculean task and, as a result, chemical synthesis is the most sought after technique. Here we report a convergent synthesis of branched heneicosafuranosyl arabinogalactan (HAG) of MTb. Key furanosylations are performed using [Au]/[Ag] catalysts. The synthesis of HAG is achieved by the repetitive use of three reactions namely 1,2-trans furanoside synthesis by propargyl 1,2-orthoester donors, unmasking of silyl ether, and conversion of n-pentenyl furanosides into 1,2-orthoesters. Synthesis of HAG is achieved in 47 steps (with an overall yield of 0.09%) of which 21 are installation of furanosidic linkages in a stereoselective manner.