Current Drug Discovery Technologies (v.12, #4)

Meet Our Editorial Board Member: by Gennady Poda (191-192).

Using NMR to Develop New Allosteric and Allo-Network Drugs by Robert E. Smith, Kevin Tran, Kristy M. Richards, Rensheng Luo (193-204).
NMR is becoming an important tool for developing new allosteric and allo-network drugs that bind to allosteric sites on enzymes, partially inhibiting them and causing fewer side effects than drugs already developed that target active sites. This is based on systems thinking, in which active enzymes and other proteins are known to be flexible and interact with each other. In other words, proteins can exist in an ensemble of different conformations whose populations are tunable. NMR is being used to find the pathways through which the effects of binding of an allosteric ligand propagate. There are NMR screening assays for studying ligand binding. This includes determining the changes in the spin lattice relaxation due to changes in the mobility of atoms involved in the binding, measuring magnetization transfer from the protein to the ligand by saturation difference transfer NMR (STD-NMR) and the transfer of bulk magnetization to the ligand by water-Ligand Observed via Gradient Spectroscopy, or waterLOGSY. The chemical shifts of 1H and 15N of some of the atoms in amino acids change when an allosteric ligand binds to a protein. So, 1H15N heteronuclear single quantum coherence (HSQC) spectra can be used to identify key amino acids and ligand binding sites. The NMR chemical shifts of amino acids affected by ligand binding form a network that can be characterized. Allosteric networks can be identified by chemical shift covariance analysis (CHESCA). This approach has been used recently to study the binding of new molecular entities (NMEs) to potentially therapeutic drug targets.

Sortase A Mediated Protein Modifications and Peptide Conjugations by Natalya Voloshchuk, Danni Liang, Jun F. Liang (205-213).
Bioactive peptides regulate many physiological processes, acting at some sites as endocrine or paracrine signals and at others as neurotransmitters or growth factors, and show useful properties for human health, including antimicrobial, antifungal, antiviral, and antitumor activities. Although most peptides can be produced using the molecular biology approach, they are produced in limited quantities at high costs and associated with some difficulties in purification and isolation. In addition, some peptides with special structures, such as cyclic peptides, can hardly be produced by the biological method. This is especially true for the biomedical applications in which long peptides with many repeated functional sequences are usually needed. Prokaryotic transpeptidase Sortase A mediates sequence specific peptide ligation and represents a new method for peptide modifications. Besides peptide and protein modifications to improve stability and specificity of therapeutic peptides, Sortase A mediated peptide ligation has been extended to wider applications such as molecular sensing, surface modification, and biomaterials. In this review, we will focus the pharmacological applications of Sortase A for the production of nucleic acid-peptide conjugates, glycosylated peptides, modified proteins/antibodies, and cyclic peptides.

NGA- A Novel Hypothetical Drug Model: Combinatorial Approach to Multifactorial Alzheimer's Disease by C. Subathra Devi, V. Mohanasrinivasan, C. George Priyadoss, Nikhil Arora, Bharti Singh, Neetu Mittal, Shubham Agarwal, Shwetank Saxena (214-217).
Alzheimer's disease (AD) is supposed to stanch from inappropriate waving in the brain sections related to memory and perception. The incidence of AD in distressed person associated with an upsurge in the accumulation of amyloid plaque-rich senile plaques and neurofibrillary tangles in the brain. We hypothesize that a combination therapy provides a new treatment for AD. We propose that an anti-AD drug, NGA, a combination of NSAIDS, Galanthamine and ACS-40 may be useful in preventing the formation of amyloid plaques from β-amyloid. Being a widespread incurable disease, the treatment for Alzheimer's has been at the forefront of the medical research work. We propose a novel drug-like NGA will allow for the effective control and treatment of the progression of AD by preventing acetylcholinesterase activity and reducing plaque formation that forms the distinctive symptom for the identification of the onset of AD. A combinatory use of NSAID with a natural neurotransmitter will allow for an efficient control of amyloid beta toxicity and will open doors for the treatment of a myriad of other neurodegenerative diseases.

From in vitro Experiments to in vivo and Clinical Studies; Pros and Cons by Soodabeh Saeidnia, Azadeh Manayi, Mohammad Abdollahi (218-224).
Biomedical investigators use different methods including experimental animals, tissue, and cell cultures as well as computational simulations and clinical studies finding the ways to treat human diseases and disorders. All the mentioned procedures have their own advantages and disadvantages. For instance although animal models provide some drawbacks like difference in biokinetics parameters or extrapolation of results to human, they are more reliable than in vitro tests. The disadvantage of the in vitro procedures is that they are mostly performed on cancerous cell lines that have a substantially abnormal function. Furthermore, although in vitro models are fruitfully used in biological fields, finding an end point, the initial aim of chemical attack, and extrapolation of the effects to the human are some real weaknesses. Absence of biokinetics in in vitro methods may lead to a misinterpretation of the data. The present review has criticized the pros and cons of both methods, especially in the fields of pharmacology, toxicology, and medical sciences.

Antimalarial Drug: From its Development to Deface by Tapan Kumar Barik (225-228).
Wiping out malaria is now the global concern as about three billion people are at risk of malaria infection globally. Despite of extensive research in the field of vaccine development for malaria, till now, no effective vaccine is available for use and hence only antimalarial drugs remain our best hope for both treatment and prevention of malaria. However, emergence and spread of drug resistance has been a major obstacle for the success of malaria elimination globally. This review will summarize the information related to antimalarial drugs, drug development strategies, drug delivery through nanoparticles, few current issues like adverse side effects of most antimalarial drugs, non availability of drugs in the market and use of fake/poor quality drugs that are hurdles to malaria control. As we don't have any other option in the present scenario, we have to take care of the existing tools and make them available to almost all malaria affected area.

Green Propolis: Thirteen Constituents of Polar Extract and Total Flavonoids Evaluated During Six Years through RP-HPLC by Sonia Maria de Figueiredo, Nancy Scardua Binda, Bruno de Moura Almeida, Sheila Rago Lemos Abreu, José Alexandre Silva de Abreu, Gláucia Maria Pastore, Hélia Harumi Sato, Viviane Cristina Toreti, Eulália Vargas Tapia, Yong Kun Park, Sidney Augusto Vieira Filho, Rachel Basques Caligiorne (229-239).
In order to verify the chemical qualities of polar extract of Green Propolis produced in the State of Minas Gerais, Brazil, was analyzed by means of RP-HPLC, the concentration of eleven flavonoids, Artepillin C and p-coumaric acid were analyzed by means of RP-HPLC. Samples were collected in the months of February, March, May, July, September, and October, during a period of six years (2008 to 2013) and the results compared with purchased standards. Artepillin C was the main constituent (80-90%) found in all samples. Lower concentrations of p-coumaric acid, chrysin and kaempferide were observed in March, and of ricin and galangin in September. Respectively, these months correspond to the end of Summer and Spring period in Brazil. The variation in concentration of the analyzed constituents always occurred in the same month, during the entire six years of evaluation period. All thirteen constituents of Green Propolis were detected throughout the study period, and the average concentration of each one was similar in relation to the respective monthly collection period of each year. Due to similarities among chemical constituents of Green Propolis with those present in B. dracuncufolia, this plant was identified as being the principal source of Green Propolis.

Background: Neurotransmitters had progressive effects on various cancers via their different type of receptors. Objective: This study was conducted to determine the pattern of serotonin receptors, respectively, 5HTR2A and 5HTR3A gene expression in MCF-7 cells and evaluate their selective antagonist effects on them. Method: RT-PCR was performed to determine the pattern of serotonin receptor gene expression in human breast cancer cell line (MCF-7). MCF-7 cells were cultured and treated via different doses of tropisetron (5HTR3A antagonist) and ketanserin (5HTR2A antagonist) for 48 hours. Oxidative and reductive enzyme activity was carried out by MTT assay. Subsequently, nuclear morphology of cells was observed by mixed dye florescent staining. To validate cell proliferation inhibition, Real time PCR was carried out for determining the descending rate of proliferating cell nuclear antigen (PCNA) gene expression in treating MCF-7 cells. Assessment of quantification of apoptosis and its discrimination with necrosis at single cell level using Flowcytometry technique was performed. Results: Results showed that 5HTR2A and 5HTR3A have expression in MCF-7 cells. Based on our finding, tropisetron and ketanserin had suppression effects on MCF-7 cells proliferation. (93.35% in tropisetron 50 µmoll-1 and 72.36% in Ketanserin 25µmoll-1 concentration). Conclusion: Therefore, the use of tropisetron and ketanserin as an antagonist of serotonin receptor may be as new approaches are recommended for the treatment of breast cancer cells.