Protein arginine methyltransferase 1, a major regulator of biological processes.

Protein arginine methyltransferase 1 (PRMT1) is a major type I arginine methyltransferase that catalyzes the formation of monomethyl and asymmetric dimethylarginine in protein substrates. It was first identified to asymmetrically methylate histone H4 at the third arginine residue forming the H4R3me2a active histone mark. However, several protein substrates are now identified as being methylated by PRMT1. As a result of its association with diverse classes of substrates, PRMT1 regulates several biological processes like chromatin dynamics, transcription, RNA processing, and signal transduction. The review provides an overview of PRMT1 structure, biochemical features, specificity, regulation, and role in cellular functions. We discuss the genomic distribution of PRMT1 and its association with tRNA genes. Further, we explore the different substrates of PRMT1 involved in splicing. In the end, we discuss the proteins that interact with PRMT1 and their downstream effects in diseased states.

Insights into Multifunctional Nanoparticle-Based Drug Delivery Systems for Glioblastoma Treatment.

Glioblastoma (GB) is an aggressive cancer with high microvascular proliferation, resulting in accelerated invasion and diffused infiltration into the surrounding brain tissues with very low survival rates. Treatment options are often multimodal, such as surgical resection with concurrent radiotherapy and chemotherapy. The development of resistance of tumor cells to radiation in the areas of hypoxia decreases the efficiency of such treatments. Additionally, the difficulty of ensuring drugs effectively cross the natural blood-brain barrier (BBB) substantially reduces treatment efficiency. These conditions concomitantly limit the efficacy of standard chemotherapeutic agents available for GB. Indeed, there is an urgent need of a multifunctional drug vehicle system that has potential to transport anticancer drugs efficiently to the target and can successfully cross the BBB. In this review, we summarize some nanoparticle (NP)-based therapeutics attached to GB cells with antigens and membrane receptors for site-directed drug targeting. Such multicore drug delivery systems are potentially biodegradable, site-directed, nontoxic to normal cells and offer long-lasting therapeutic effects against brain cancer. These models could have better therapeutic potential for GB as well as efficient drug delivery reaching the tumor milieu. The goal of this article is to provide key considerations and a better understanding of the development of nanotherapeutics with good targetability and better tolerability in the fight against GB.

Glycation and Oxidative Stress Increase Autoantibodies in the Elderly.

Aging causes gradual changes in free radicals, antioxidants, and immune-imbalance in the elderly. This study aims to understand links among aging, gluco-oxidative stress, and autoantibodies in asymptomatic individuals. In vitro glycation of human serum albumin (Gly-HSA) induces appreciable biochemical changes. Significant inhibition of advanced glycation end products (AGEs) formation was achieved using garlic extract (53.75%) and epigallocatechin-3-gallate from green tea (72.5%). Increased amounts of serum carbonyl content (2.42 ± 0.5) and pentosidine (0.0321 ± 0.0029) were detected in IV-S (S represent smokers) vs. IV group individuals. Direct binding ELISA results exhibited significantly high autoantibodies against Gly-HSA in group IV-S (0.55 ± 0.054; p < 0.001) and III-S (0.40 ± 0.044; p < 0.01) individuals as compared to the age matched subjects who were non-smokers (group IV and III). Moreover, high average percent inhibition (51.3 ± 4.1%) was obtained against Gly-HSA in IV-S group individuals. Apparent association constant was found to be high for serum immunoglobulin-G (IgG) from group IV-S (1.18 × 10-6 M) vs. serum IgG from IV group (3.32 × 10-7 M). Aging induced gluco-oxidative stress and AGEs formation may generate neo-epitopes on blood-proteins, contributing to production of autoantibodies in the elderly, especially smokers. Use of anti-glycation natural products may reduce age-related pathophysiological changes.

Synergistic fungicidal activity with low doses of eugenol and amphotericin B against Candida albicans.

Candida albicans frequently causes variety of superficial and invasive disseminated infections in HIV infected patients. Further, the emergence of non albicans species causing candidiasis predominantly in patients with advanced immune-suppression and drug resistance brings great apprehension. Hence, in this study we evaluate the capability of eugenol (EUG), a natural compound in combination with less toxic concentrations of amphotericin B (AmpB) for enhanced antifungal effects and reduced toxicity. Antifungal activity and time-kill assay were employed according to Clinical Laboratory Standard Institute (CLSI) guidelines with minor modifications on clinical isolates of Candida albicans. To confirm the synergistic interaction of EUG and AmpB, checkerboard experiments were employed. Interestingly, EUG-Amp B combination shows many fold higher anti-candida activity compared to single component treatment. Furthermore, our results depicts reactive oxygen species (ROS) driven killing and mitochondrial hyperpolarisation on treatment. Our data also suggests inhibition of calcium channel by EUG and predicts longer retainment of AmpB. Pronounced cellular damage was observed with combination treatment than to EUG and AmpB alone. Our finding is helpful for the removal of toxic concentrations of antifungal agents.

Understanding the mode of binding mechanism of doripenem to human serum albumin: Spectroscopic and molecular docking approaches.

The infections caused by multidrug resistant bacteria are widely treated with carabapenem antibiotics as a drug of choice, and human serum albumin (HSA) plays a vital role in binding with drugs and affecting its rate of delivery and efficacy. So, we have initiated this study to characterize the mechanism of doripenem binding and to locate its site of binding on HSA by using spectroscopic and docking approaches. The binding of doripenem leads to alteration of the environment surrounding Trp-214 residue of HSA as observed by UV spectroscopic study. Fluorescence spectroscopic study revealed considerable interaction and complex formation of doripenem and HSA as indicated by Ksv and Kq values of the order of 104  M-1 and 1012  M-1  s-1 , respectively. Furthermore, doripenem quenches the fluorescence of HSA spontaneously on a single binding site with binding constant of the order of 103  M-1 , through an exothermic process. Van der Waals forces and hydrogen bonding are the major forces operating to stabilize HSA-doripenem complex. Circular dichroism spectroscopic study showed changes in the structure of HSA upon doripenem binding. Drug displacement and molecular docking studies revealed that the binding site of doripenem on HSA is located on subdomain IB and III A. This study concludes that, due to significant interaction of doripenem on either subdomain IB or IIIA of HSA, the availability of doripenem on the target site may be compromised. Hence, there is a possibility of unavailability of threshold amount of drug to be reached to the target; consequently, resistance may develop in the bacterial population.

Myeloma is characterized by stage-specific alterations in DNA methylation that occur early during myelomagenesis.

Epigenetic changes play important roles in carcinogenesis and influence initial steps in neoplastic transformation by altering genome stability and regulating gene expression. To characterize epigenomic changes during the transformation of normal plasma cells to myeloma, we modified the HpaII tiny fragment enrichment by ligation-mediated PCR assay to work with small numbers of purified primary marrow plasma cells. The nano-HpaII tiny fragment enrichment by ligation-mediated PCR assay was used to analyze the methylome of CD138(+) cells from 56 subjects representing premalignant (monoclonal gammopathy of uncertain significance), early, and advanced stages of myeloma, as well as healthy controls. Plasma cells from premalignant and early stages of myeloma were characterized by striking, widespread hypomethylation. Gene-specific hypermethylation was seen to occur in the advanced stages, and cell lines representative of relapsed cases were found to be sensitive to decitabine. Aberrant demethylation in monoclonal gammopathy of uncertain significance occurred primarily in CpG islands, whereas differentially methylated loci in cases of myeloma occurred predominantly outside of CpG islands and affected distinct sets of gene pathways, demonstrating qualitative epigenetic differences between premalignant and malignant stages. Examination of the methylation machinery revealed that the methyltransferase, DNMT3A, was aberrantly hypermethylated and underexpressed, but not mutated in myeloma. DNMT3A underexpression was also associated with adverse overall survival in a large cohort of patients, providing insights into genesis of hypomethylation in myeloma. These results demonstrate widespread, stage-specific epigenetic changes during myelomagenesis and suggest that early demethylation can be a potential contributor to genome instability seen in myeloma. We also identify DNMT3A expression as a novel prognostic biomarker and suggest that relapsed cases can be therapeutically targeted by hypomethylating agents.

Directional preference for glioblastoma cancer cell membrane encapsulated nanoparticle population: A probabilistic approach for cancer therapeutics.

Background: Selective cancer cell recognition is the most challenging objective in the targeted delivery of anti-cancer agents. Extruded specific cancer cell membrane coated nanoparticles, exploiting the potential of homotypic binding along with certain protein-receptor interactions, have recently proven to be the method of choice for targeted delivery of anti-cancer drugs. Prediction of the selective targeting efficiency of the cancer cell membrane encapsulated nanoparticles (CCMEN) is the most critical aspect in selecting this strategy as a method of delivery. Materials and methods: A probabilistic model based on binding scores and differential expression levels of Glioblastoma cancer cells (GCC) membrane proteins (factors and receptors) was implemented on python 3.9.1. Conditional binding efficiency (CBE) was derived for each combination of protein involved in the interactions. Selective propensities and Odds ratios in favour of cancer cells interactions were determined for all the possible combination of surface proteins for 'k' degree of interaction. The model was experimentally validated by two types of Test cultures. Results: Several Glioblastoma cell surface antigens were identified from literature and databases. Those were screened based on the relevance, availability of expression levels and crystal structure in public databases. High priority eleven surface antigens were selected for probabilistic modelling. A new term, Break-even point (BEP) was defined as a characteristic of the typical cancer cell membrane encapsulated delivery agents. The model predictions lie within ±7% of the experimentally observed values for both experimental test culture types. Conclusion: The implemented probabilistic model efficiently predicted the directional preference of the exposed nanoparticle coated with cancer cell membrane (in this case GCC membrane). This model, however, is developed and validated for glioblastoma, can be easily tailored for any type of cancer involving CCMEN as delivery agents for potential cancer immunotherapy. This probabilistic model would help in the development of future cancer immunotherapeutic with greater specificity.

New Framework for the Discovery of PRC2 Inhibitors: Epigenetic Drugs.

Over the past several years, remarkable progress towards the recognition of new therapeutic targets in tumor cells has led to the discovery and development of newer scaffolds of anti-tumor drugs. The exploration and exploitation of epigenetic regulation in tumor cells are of immense importance to both the pharmaceutical and academic biomedical literatures. Epigenetic mechanisms are indispensable for the normal development and maintenance of tissue-specific gene expression. Disruption of epigenetic processes to eradicate tumor cells is among the most promising intervention for cancer control. Polycomb repressive complex 2 (PRC2), a complex that methylates lysine 27 of histone H3 to promote transcriptional silencing, is involved in orchestrating significant pathways in a cell. Overexpression of PRC2 has been found in a number of cancerous malignancies, making it a major target for anti-cancer therapy. Despite its well-understood molecular mechanism, hyperactivation and drug resistance mutations in its subunits have become a matter of discussion. This review outlines the current understanding of the components of PRC2 in active complex formation and assesses their potential as a promising therapeutic target for cancer therapy. We also review the effects of mutations in the PRC2 components, in the purview of human cancers. Finally, we discuss some of the current challenges for therapeutic drug designs targeting the PRC2 complex.

Biologically Active α-Amino Amide Analogs and γδ T Cells-A Unique Anticancer Approach for Leukemia.

Advanced stage cancers are aggressive and difficult to treat with mono-therapeutics, substantially decreasing patient survival rates. Hence, there is an urgent need to develop unique therapeutic approaches to treat cancer with superior potency and efficacy. This study investigates a new approach to develop a potent combinational therapy to treat advanced stage leukemia. Biologically active α-amino amide analogs (RS)-N-(2-(cyclohexylamino)-2-oxo-1-phenylethyl)-N-phenylpropiolamide (α-AAA-A) and (RS)-N-(2-(cyclohexylamino)-2-oxo-1-phenylethyl)-N-phenylbut2-enamide (α-AAA-B) were synthesized using linear Ugi multicomponent reaction. Cytotoxicities and IC50 values of α-AAA-A and α-AAA-B against leukemia cancer cell lines (HL-60 and K562) were analyzed though MTT assay. Cytotoxic assay analyzed percent killing of leukemia cell lines due to the effect of γδ T cells alone or in combination with α-AAA-A or α-AAA-B. Synthesized biologically active molecule α-AAA-A exhibited increased cytotoxicity of HL-60 (54%) and K562 (44%) compared with α-AAA-B (44% and 36% respectively). Similarly, α-AAA-A showed low IC50 values for HL-60 (1.61 ± 0.11 µM) and K562 (3.01 ± 0.14 µM) compared to α-AAA-B (3.12 ± 0.15 µM and 6.21 ± 0.17 µM respectively). Additive effect of amide analogs and γδ T cells showed significantly high leukemia cancer cell killing as compared to γδ T cells alone. A unique combinational therapy with γδ T cells and biologically active anti-cancer molecules (α-AAA-A/B), concomitantly may be a promising cancer therapy.

Optimization of methods for peripheral blood mononuclear cells isolation and expansion of human gamma delta T cells.

Human Vg9/Vδ2 T cells (γδ T cells) are immune surveillance cells both in innate and adaptive immunity and are a possible target for anticancer therapies, which can induce immune responses in a variety of cancers. Small non-peptide antigens such as zoledronate can do activation and expansion of T cells in vitro. It is evident that for adoptive cancer therapies, large numbers of functional cells are needed into cancer patients. Hence, optimization of methods needs to be carried out for the efficient expansion of these T cells. Standardization of peripheral blood mononuclear cells (PBMCs) isolation was devised. Cytokines (interleukin 2 (IL-2) and interleukin 15 (IL-15)) and zoledronate were also standardized for different concentrations. It was found that an increased number of PBMCs were recovered when washing was done at 1100 revolution per minute (rpm). Significantly high expansion fold was (2524 ± 787 expansion fold) achieved when stimulation of PBMCs was done with 1 µM of zoledronate and both cytokines IL-2 and IL-15 supported the expansion and survival of cells at the concentrations of 100 IU/ml and 10 ng/ml respectively. 14-day cultures showed highly pure (91.6 ± 5.1%) and live (96.5 ± 2.5%) expanded γδ T cells. This study aimed to standardize an easy to manipulate technique for the expansion of γδ T cells, giving a higher yield.

Combinational therapeutics to combat cancer.

Mono-therapeutics is rarely effective as a treatment option, which limits the survival of patients in advanced grade aggressive cancers. Combinational therapeutics (multiple drugs for multiple targets) to combat cancer is gaining momentum in recent years. Hence, it is of interest to document known data for combinational therapeutics in cancer treatment. An amalgamation of therapeutic agents enhances the efficacy and potency of the therapy. Combinational therapy can potentially target multiple pathways that are necessary for the cancer cells to proliferate, and/or target molecules, which may help cancer to become more aggressive and metastasize. In this review, we discuss combinational therapeutics, which include human γδ T cells in combinations with biologically active anti-cancer molecules, which synergistically may produce promising combinational therapeutics.

DNA methylation inhibition in myeloma: Experience from a phase 1b study of low-dose continuous azacitidine in combination with lenalidomide and low-dose dexamethasone in relapsed or refractory multiple myeloma.

The DNA methyltransferase inhibitor azacytidine (aza) may reactivate pathways associated with plasma cell differentiation, cell cycle control, apoptosis, and immune recognition and thereby restore sensitivity to lenalidomide (len) and dexamethasone (dex) in relapsed and/or refractory multiple myeloma (RRMM). We aimed to develop an aza regimen that reaches epigenetically active levels 8 times in 28 days with less bone marrow toxicity than the myeloid malignancy standard of 7 consecutive doses to enable safe combination with len. Aza was escalated from 30 mg/m2 once a week up to a predefined maximum of 50 mg/m2 twice a week in combination with GFR-adjusted len (≥ 60 mL/min: 25 mg, 3059 mL/min: 10 mg) day 1 to 21 every 28 days and dex 40 mg once a week followed by a limited expansion study to a total N of 23 at the highest tolerated dose. Fifty-one patients (pts) with RRMM were screened, 42 were treated and 41 were evaluable for response based on at least 1 response assessment or progression after treatment start. The median number of prior lines of therapy was 5 (1-11) and 81% (34) were refractory to len and/or pomalidomide (pom). Two DLTs occurred in different cohorts, 1 neutropenic fever in 1/6 pts on the aza 40 mg/m2 twice a week GFR ≥ 60 mL/min cohort and 1 GGT elevation in 1/6 pts on the aza 50 mg/m2 GFR 30-59 mL/min cohort. An MTD was not reached and aza 50 mg/m2 SC twice a week was chosen for the expansion study. At least possibly related Grade 3/4 AEs occurred in 28 pts (67%) with the following in > 1 pt: neutropenia (N = 16, 38%), anemia (N = 6, 14%), lymphopenia (N = 5, 12%), thrombocytopenia (N = 4, 10%), leukopenia (N = 4, 10%), febrile neutropenia (N = 4, 10%), fatigue (N = 3, 7%), fever (N = 2, 5%), and infection (N = 2, 5%). At a median follow up time for alive pts of 60.2 months (range: 36.1-82.5 months), the overall response rate (≥ partial response) and clinical benefit response rate (≥ minor response) was 22 and 32%, respectively, with 4 very good partial responses (10%), 5 partial responses (12%), and 4 minor responses (10%). The median PFS was 3.1 months (95% confidence interval [CI]: 2.1-5.1 months), median TTP 2.7 months (95% CI: 2.1-7.5 months), and median OS 18.6 months (95% CI: 12.9-33.0 months). Achieving at least minor response and reaching TTP > 6 months was associated with approximately 35% lower median plasma levels of the enzyme that inactivates aza, plasma cytidine deaminase (CDA, P< .0001). Two of the len refractory pts achieved longer disease control than with any prior regimen and 1 responded immediately after progression on len, bortezomib, and prednisone. Analyses of the methylation state of over 480,000 CpG sites in purified myeloma cells at screening were possible in 11 pts and on day 28 in 8 of them. As in other studies, the majority of differentially methylated CpGs compared to normal plasma cells were hypomethylated in myeloma. Treatment decreased the number of CpGs that were differentially methylated in normal plasma cells by > 0.5% in 6 and by > 5% in 3 of the 8 pts, most pronounced in 2 pts with clinically convincing aza contribution who achieved a reduction in overall differentially methylated CpGs by 23 and 68%, respectively, associated with increased expression of immunoglobulin genes. The study demonstrated tolerability of twice a week SC aza at 50 mg/m2 with len and dex in RRMM and suggested aza may help overcome the len/pom refractory state, possibly by activating differentiation pathways. Relatively low response rates and association of clinical benefit with low plasma levels of the aza inactivating enzyme CDA suggest the aza regimen will need to be optimized further and pt selection may be required to maximize benefit.

Inhibition of multi-drug resistant Klebsiella pneumoniae: Nanoparticles induced photoinactivation in presence of efflux pump inhibitor.

In the current scenario, frontline antibiotics are losing effectiveness against multidrug-resistant (MDR) bacteria because of the single mode of action. The accumulation of mutations and spread of antibiotic resistance markers among the bacteria results into the severe threat to community health. Now, there is an urgent requirement for the development of an alternate and as well as multiple-targeted action of drugs to stop the spread of resistance in bacteria. Here, we showed an alternative nanoparticle based photodynamic therapy (PDT) targeting the bacterial efflux pumps and its cell wall. The dextran capped gold nanoparticles (GNPDEX) were localized to the bacterial surface by nanoparticle attached Concanavalin-A (ConA), where GNPDEX attached methylene blue (MB) photosensitizer as an MB@GNPDEX-ConA formulation induced the killing of MDR Klebsiella pneumoniae clinical isolates in no time. The intervention of efflux pump inhibitor (EPI) further improved the MB@GNPDEX-ConA treatment modality and displayed the maximum bactericidal cytoplasmic phototoxicity. The CCCP EPI (carbonyl cyanide m-chlorophenylhydrazone) with the PDT increased the bacterial killing by>3 log10 as compared with or without EPI intervention. Further, the fractionated (two light treatment after long dark phase) PDT treatment modality decreased the bacterial biofilm growth up to ~90%. The microscopic as well as ROS fluorescent probes showed the singlet oxygen mediated cytotoxicity. The mode of interactions and genomic DNA photo-toxicity confirmed that EPI enhanced the killing mediated by singlet oxygen generation. The multi-targeted (Cell wall, DNA and efflux pump) modality of MB@GNPDEX-ConA in presence of EPI is an effective and alternative therapeutic approach against most potent Klebsiella MDR infections.

Template synthesis and physico-chemical characterization of 14-membered tetraimine macrocyclic complexes, [MLX(2)] [M=Co(II), Ni(II), Cu(II) and Zn(II)]. DNA binding study on [CoLCl(2)] complex.

The template condensation reaction between glyoxal and 1,8-diaminonaphthalene resulted a few novel mononuclear 14-membered tetraimine macrocyclic complexes of the type, [MLX(2)] [M=Co(II), Ni(II), Cu(II) and Zn(II), for X=Cl or NO(3)]. The stoichiometry and the nature of the complexes have been deduced from the results of elemental analyses and conductance data. The formation of macrocyclic framework has been inferred from the appearance of imine upsilon(CN) and upsilon(MN) band in IR spectra and the resonance signals observed in (1)H and (13)C-NMR spectra. However, the overall geometry of the complexes has been assigned on the positions of bands in electronic spectra and magnetic moment data. The distortion in Cu(II) complexes has been deduced on EPR data. The thermal behavior of these complexes has been studied by TGA analysis. Absorption and circular dichroism studies on the complex proved a significant binding to calf thymus DNA.

Polycomb repressive complex 2 inhibitors: emerging epigenetic modulators.

Polycomb repressive complex 2 (PRC2) plays a significant part in histone methylation - trimethylating K27 at H3, an epigenetic hallmark of gene silencing. Inhibition of PRC2 has been reported as a promising strategy for the treatment of various cancers. Significant efforts have been made toward the development of PRC2 inhibitors and some of them have progressed to clinical trials. The binding mode of these inhibitors is well understood. Here, we summarize the advances in drug discovery and development for PRC2 component inhibitors by focusing on their chemotypes, activity, selectivity and binding modes. We believe that such analysis will provide new avenues for the design and development of next-generation PRC2 inhibitors through establishment of a structure-based drug design platform.

Novel anti-adherence activity of mulberry leaves: inhibition of Streptococcus mutans biofilm by 1-deoxynojirimycin isolated from Morus alba.

OBJECTIVES: The present study focused on isolation, characterization and evaluation of purified compounds from Morus alba against Streptococcus mutans biofilm formation. METHODS: The effect of crude extract from M. alba leaves was evaluated against oral pathogens, chiefly S. mutans. MICs were determined by the microdilution method. The compound was purified by employing silica gel chromatography and critically analysed with GC-MS, NMR and IR spectroscopy. The S. mutans traits of adherence and biofilm formation were assessed at sub-MIC concentrations of the crude extract and purified compound. Both water-soluble and alkali-soluble polysaccharide were estimated to determine the effect of the purified compound on the extracellular polysaccharide secretion of S. mutans. Its effect on biofilm architecture was also investigated with the help of confocal microscopy. RESULTS: The purified compound of M. alba showed an 8-fold greater reduction of MIC against S. mutans than the crude extract (MICs, 15.6 and 125 mg/L, respectively). The extract strongly inhibited biofilm formation of S. mutans at its active accumulation and plateau phases. The purified compound led to a 22% greater reduction in alkali-soluble polysaccharide than in water-soluble polysaccharide. The purified compound was found to be 1-deoxynojirimycin (DNJ). Confocal microscopy revealed that DNJ distorts the biofilm architecture of S. mutans. CONCLUSIONS The whole study reflects a prospective role of DNJ as a therapeutic agent by controlling the overgrowth and biofilm formation of S. mutans.

Interaction of anesthetic supplement thiopental with human serum albumin.

Thiopental (TPL) is a commonly used barbiturate anesthetic. Its binding with human serum albumin (HSA) was studied to explore the anesthetic-induced protein dysfunction. The basic binding interaction was studied by UV-absorption and fluorescence spectroscopy. An increase in the binding affinity (K) and in the number of binding sites (n) with the increasing albumin concentration was observed. The interaction was conformation-dependent and the highest for the F isomer of HSA, which implicates its slow elimination. The mode of binding was characterized using various thermodynamic parameters. Domain II of HSA was found to possess a high affinity binding site for TPL. The effect of micro-metal ions on the binding affinity was also investigated. The molecular distance, r, between donor (HSA) and acceptor (TPL) was estimated by fluorescence resonance energy transfer (FRET). Correlation between the stability of the TPL-N and TPL-F complexes and drug distribution is discussed. The structural changes in the protein investigated by circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy reflect perturbation of the albumin molecule and provide an explanation for the heterogeneity of action of this anesthetic.

Interaction of mitoxantrone with human serum albumin: spectroscopic and molecular modeling studies.

Mitoxantrone (MTX) is a clinically used antitumor anthracycline, which is made available to the target tissues by transport protein human serum albumin (HSA). Being less toxic unlike other member of this family, its binding characteristics are therefore of immense interest. The circular dichroism (CD), fluorescence and Fourier transform infrared (FTIR) spectroscopies were employed to elucidate the mode and the mechanism for this interaction. MTX binding is characterized by one high affinity binding site with the association constants of the order of 10(5). Correlation between stability of N-MTX (drug bound N form of HSA) and B-MTX (drug bound B form of HSA) complexes with drug distribution has been discussed. The molecular distance, r, between donor (HSA) and acceptor (MTX) was estimated according to Forster's theory of non-radiation energy transfer. The features of MTX induced structural perturbation of human serum albumin (HSA) has been studied in detail by CD and FTIR analysis. Domain I was assigned to possess high affinity binding site for MTX. Molecular docking showed that the MTX binds HSA to a non-classical drug binding site. The binding dynamics was expounded by synchronous fluorescence, thermodynamic parameters and molecular modeling, which entails that hydrophobic interactions, hydrogen bonding and electrostatic forces, stabilizes the interaction.

Characterization of doxorubicin binding site and drug induced alteration in the functionally important structural state of oxyhemoglobin.

Doxorubicin (DOX) binding to hemoglobin (Hb) was studied to investigate the drug induced protein dysfunction. The features of anti-tumor drug doxorubicin infused structural perturbation of human Hb were studied by circular dichroism (CD). The mechanism of DOX-Hb binding was elucidated by steady-state and synchronous fluorescence spectroscopy. The Stern-Volmer analysis indicated that the binding of Hb to DOX is characterized by more than one high affinity binding site with the association constants of the order of 10(5). Hydrophobic probe ANS was employed to elucidate the drug binding site. Binding mode expounded by thermodynamic parameters implied the role of hydrogen bonding, electrostatic and hydrophobic interaction in stabilizing the complex. The molecular distance between donor (Hb) and acceptor (DOX) was calculated according to Förster's theory of energy transfer. Fourier transform infrared (FT-IR) spectroscopy provides an insight to the changes occurring in protein on DOX binding. Treatment of Hb with DOX resulted in a dose dependent fragmentation of protein. The quantitative analysis revealed the release of acid soluble amino groups from the photoexcited Hb-DOX mixture. The free radical mediated degradation was suggested by its rescue on mannitol and superoxide dismutase (SOD) appliance. The loss of protein band further corroborates the concentration dependent Hb fragmentation. The molecular modeling complies with the thermodynamic data of forces involved in DOX binding and depicts its interaction in the proximity of oxygen binding pocket of Hb. Thus, this study enriches our understanding of the interaction dynamics of anticancer drugs to the physiologically important protein Hb.

Sulfaguanidine cocrystals: Synthesis, structural characterization and their antibacterial and hemolytic analysis.

Sulfaguanidine (SG), belongs to the class of sulfonamide drug used as an effective antibiotic. In the present work, using crystal engineering approach two novel cocrystals of SG were synthesized (SG-TBA and SG-PT) with thiobarbutaric acid (TBA) and 1,10-phenanthroline (PT), characterized by solid state techniques viz., powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and the crystal structures were determined by single crystal X-ray diffraction studies. A comparative antibacterial activity and hemolytic potential was done on SG drug, coformers and their cocrystals. The tested cocrystals formulations showed almost two fold higher antibacterial activity against the tested strains of bacteria Gram-positive bacteria (S. mutans and E. faecalis) and Gram-negative bacteria (E. coli, K. pneumonia and E. clocae) over SG alone and their coformers. Cocrystal SG-TBA showed better antibacterial activity and reduced hemolysis, thereby, reduced cytotoxicity than SG-PT.