Combinatorial Chemistry & High Throughput Screening - Volume 20, Issue 8, 2017

Aim and Objective: Interleukin-6 has become an attractive protein target. This is found in the progression of colon cancer. It performs various functions in the colon cancer cells such as inflammation, activates various cell types signaling and also promotes proliferation in colon cancer cells. It is a valid target to develop anticolon cancer drug. The purpose of our study is to develop the Three-dimensional Quantitative Structure-Activity Relationship (3D-QSAR) models, pharmacophore modeling and docking study as well as MD simulation to find out the novel potent inhibitors that bind with Interleukin-6 in colon cancer treatment. Material and Methods: In this study, common pharmacophore models and atom-based 3D-QSAR studies were carried out by using 1,4-benzothiazine derivatives with their experiential GI50values towards HT-29 human colon cancer cell line. Results: The common pharmacophore model (ADHR26) was developed and the survival score was found to be 3.828. The generated pharmacophore-based alignment was used to develop a predictive atom-based 3D-QSAR model by using Partial Least Square (PLS) method. Phase predictable activity and LogGI50 also exhibited the most significant atomic position in the backbone structure of ligands for anticolon cancer activity. Molecular dynamic and docking studies for the IL-6 target provide key framework of ligand for the anticolon cancer activity. Conclusion: Finally, results generated from the work data, that exhibited the pharmacophore models and 3D-QSAR hypothesis might be a path of milestone in the area of medicinal chemistry to researchers for further design of new and potent IL-6 inhibitors.

Aim and Objective: Caffeic acid (CA) is a cinnamic acid derivative, found in many vegetable products, with powerful antioxidant activity, the ability to increase collagen production and capacity to prevent premature aging of the skin. The classic emulsions of CA are widely used by the consumer to provide a pleasant, refreshing sensorial experience; however, preparations developed in the form of dry film are presented as a technological alternative due to its facile and safe transportation. The aim of this study was to evaluate the release, permeation, and retention of CA in a film and emulsion through in vitro experiments. Material and Methods: The release evaluation of CA from the emulsion and the film was performed using modified Franz diffusion cells, with an area of 1.77 cm², using Microette equipment (Hanson Research) with a cellulose membrane. The evaluation of the permeation of CA from the formulations was conducted using a similar technique of release, except that a biological membrane was used. Results: High release of active compound and reduced permeation was observed, indicating that CA was able to be retained in the epidermis/dermis, where it should have the desired action. The concentration of caffeic acid in the skin was higher for the film formulation than for the emulsion. This demonstrates a greater efficiency of this type of innovative release system, besides its facile and safe transportation. Conclusion: The formulations tested in this paper can release caffeic acid with a Higuchi kinetic profile, in which release of active ingredient occurs by a diffusion process. The film formulations exhibited a lower permeation rate and higher retention in the skin, which is essential for a cosmetic product. The concentration of CA in the skin was also higher for the film formulation when compared to the emulsion. This demonstrates a greater efficiency of this type of innovative release system, in addition to its easy and safe transportation. Therefore, it is possible to suggest CA as a promising substance for dermal use due to its antioxidant, anti-inflammatory, antimicrobial, and collagen production stimulating activity.

Aim and Objective: Vinca domain of tubulin protein is the potential target for different microtubule targeting drugs (MTD). However, its binding mechanism and structure-activityrelationship (SAR) is not well understood in terms of ligand-receptor interactions and structure functionality requirements. This limits the exploitation of vinca domain for developing novel clinical leads. Herein, as a progressive step towards the exploration of this target, we rendered the in-silico insight through the development of a robust pharmacophore model followed by the QSAR, Molecular Docking and Molecular Dynamics (MD) simulations. Furthermore, the study was undertaken to identify potent inhibitors that can inhibit vinca domain of tubulin. Materials and Methods: Utilizing the well-defined tubulin polymerization inhibition activities, common pharmacophore hypotheses were constructed and scored for their rankings. The hypotheses were validated by 3D-Atom based QSAR and tested for various statistically relevant metrices. Thereafter, virtual screening was performed with ZINC natural product database and the screened hits were evaluated for structure-based studies via molecular docking and molecular dynamics simulations. Results: The predictive 3D-QSAR based pharmacophore model consists of two hydrogen bond acceptors (A), two hydrogen bond donors (D) and one hydrophobic (H) group. Significance of the model was reflected from the statistical parameters viz. r2 = 0.98, q2 = 0.72, F = 562.9, RMSE = 0.11 and Pearson-R = 0.87. Further, the docking scores of the retrieved hits deciphered that the ligands were adequately bound in the pocket. Moreover, RMSD fluctuations of protein (1.0 to 1.75A) and ligand (0.3 to 2.3 ũ in molecular dynamics simulations insinuate towards the conformational and interactions stability of the complexes. Conclusion: The quantitative pharmacophore model was developed from range of natural product scaffolds in order to incorporate all the complimentary features accountable for inhibition. The obtained hits were found to occupy similar binding region and superimpose well over the reference ligand. Therefore, it can be concluded that hierarchical combination of methods exploited in this study can steer the identification of novel scaffolds. Moreover, the rendered hit molecules could serve as potential inhibitory leads for the development of improved inhibitors targeting Vinca domain.

Aim and Objective: According to our interest in developing new methods for the construction of intricate molecules, a reliable polymer-supported (-)-8-phenylmenthyl chiral auxiliary for the addition of different nucleophiles to chiral-supported N-acyliminium precursors were developed. Materials and Methods: Merrifield resin was employed to anchor (-)-8-phenylmenthol, which was prepared by nitration of (-)-8-phenylmenthyl chloroacetate followed by reduction of nitro group and subsequent Merrifield resin coupling. Treatment of a suspension of polymer-supported chloroformate and piperidinone in the presence of Et3N resulted in attachment of the substrate onto the solid-support. Treatment of the resulting resin with LiEt3BH/MeOH afforded methoxypiperidine in 87% yield. Then, the addition of allyltrimethylsilane, TMSCN, 2-(trimethylsiloxy)propene and triisopropylsilyloxyfuran and others to the N-acyliminium ion derived from chiral 2- methoxypiperidine carbamate was studied. Results: The stereochemical outcome of the addition of nucleophiles to the supported N-acyliminium ion derived from 2-methoxypiperidine carbamate was proposed through the Si-face, affording after resin cleavage 2-substituted piperidines in 70%-84% yields and selectivities ranging from 4:1-11.1. Moreover, the key intermediates of chiral piperidines have been employed for the synthesis of simple chiral alkaloids such as (R)-pipecolic acid, (R)-pelletierine, (S)-coniine and (R,R)-myrtine. Conclusion: The proposed supported-chiral auxiliary for asymmetric approach may be expected to result not only in efficient solid-phase syntheses of a wide range of alkaloids but also in the development of useful new solid-phase methodologies, particularly for the asymmetric additions to iminium precursors. This work describes the first example of solid-phase synthesis by using supported (-)-8-phenylmenthyl as an effective chiral inductor and would be useful for the synthesis of chiral building block libraries.

Aim and Objective: Inspired by the impressive biological properties of pyrrolo[2,3- d]pyrimidine units, the objective of this study was to synthesize some new derivatives of heterocyclic compounds with different substituent’s using solvent-free microwave irradiation conditions from readily available starting material. The synthesized compounds were screened for their in vitro anti-microbial, anti-oxidant, anti-cancer activities and theoretical molecular docking studies. Material and Methods: Structural elucidation of the synthesized compounds was determined on the basis of various spectroscopic methods. Synthesized compounds have been evaluated for their in vitro antimicrobial activity (MIC) against various microbial strains. After the primary screening, synthesised compounds are further studied for anti-oxidant activity using DPPH assay method, anticancer activity against MCF-7 cell line using MTT assay and molecular docking studies. Moreover, molecular dynamics and simulation was done for best compound using GROMACS. Results: A series of 2-chloro-7-cyclopentyl-7H-pyrrolo[2,3-d]pyrimidine derivatives 6(a-f), 7(a-c) and 8(a-c) were synthesised using solvent-free microwave irradiation technique. Among all the synthesized compounds, compounds 6e (51.35 μg/mL) and 6f (60.14 μg/mL) showed better activity profile against MCF-7 cell line for breast cancer activity. Compounds 6f and 6d have shown potent antibacterial activity against most of the employed strains, especially against S. pneumoniae, B. cerus and S. aureus. Compound 7a (52.21 μg/mL) showed high potential activity for antioxidant using DPPH assay. Molecular docking study showed good binding of these compounds to the active site of ER- alpha with binding energy ranging from -7.12 kcal/mol to -1.21 kcal/mol. Furthermore, molecular dynamics and simulation was conducted for best pose interacted compound 6e with active site of protein to study its stability and behaviour in nanoscale. Conclusion: The present research work is intended for facile and efficient green synthesis of various biologically useful potent bio-active molecules from inexpensive and readily available starting substrates under mild reaction condition. These classes of synthesized various heterocyclic compounds holds a great importance to discover newer anti-microbial, anti-oxidant and anti-cancer drugs in future prospects. Further structural modification in these structures will be of interest and may result in compounds having a better therapeutic and biological activity. Hence, this efficient green synthetic protocol and biological results of newly synthesized heterocyclic derivatives are found to be interesting lead molecules for bioactivity in the near future. It could be considered for investigation of their mode of action and for further development.

Aim and Objective: Cancer has become one of the leading causes of morbidity and mortality worldwide. Limitations associated with existing agents increase the need to develop more effective anticancer drugs to improve the therapeutic arsenal available. The aim of this study was to synthesize and evaluate the antiproliferative effects of three new thiazacridine derivatives. Material and Methods: Using a three steps synthesis reaction, three novel thiazacridine derivatives were obtained and characterized: (Z)-5-acridin-9-ylmethylene-3-(4-methyl-benzyl)-4-thioxo-thiazolidin- 2-one (LPSF/AC-99), (Z)-5-acridin-9-ylmethylene-3-(4-chloro-benzyl)-4-thioxo-thiazolidin-2- one (LPSF/AC-119) and (Z)-5-acridin-9-ylmethylene-3-(3-chloro-benzyl)-4-thioxo-thiazolidin-2- one (LPSF/AC-129). Toxicity and selectivity assays were performed by colorimetric assay. Then, changes in cell cycle and cell death induction mechanisms were assessed by flow cytometry. Results: All compounds exhibited cytotoxicity to Raji (Burkitt's lymphoma) and Jurkat (acute T cell leukemia) cells, where LPSF/AC-119 showed best IC50 values (0.6 and 1.53 μ M, respectively). LPSF/AC-129 was the only cytotoxic compound in glioblastoma cell line NG97 (IC50 = 55.77 μ M). None of the compounds were toxic to normal human cells and induced neoplastic cell death primarily by apoptosis. Conclusion: All derivatives were more cytotoxic to hematopoietic neoplastic cells when compared to solid tumor derived cells. All three compounds are promising for in vivo and combination therapy studies against cancer.

Aim and Objective: MMP-13 belongs to a large family of proteases called matrix metalloproteinases (MMPs) that degrades type II collagen, the main structural protein of articular cartilage. The main pathologic role of MMP-13 over expression is to contribute to the development of osteoarthritis. Methods: To find new inhibitors with possible selectivity for MMP-13 a structure based virtual screening was employed. The inhibitory activities of 11 inhibitors among 19 purchased compounds were approved by enzyme inhibition assay. Results: Our results demonstrated that the CADD (computer aided drug design) could be successfully applied to find new MMP-13 inhibitors using a receptor structure (PDB code: 3O2X) which had been demonstrated a good performance in a cross-docking study. Conclusion: We discovered inhibitors with new scaffolds for inhibition of MMP-13 and some selectivity features such as proper S1′ occupancy and interactions with S1′ pocket that could be subjected to a future lead optimization study.

Aim and objective: This study describes the design and evaluation of an expression vector for Pichia pastoris (pPICZαBHF), which is based on the commercial vector construct pPICZαB. Material and Methods: The performance of pPICZαBHF was evaluated with red fluorescent protein as a reporter. Additional His- and Flag-tags on the N-terminal ensured a simplified protein purification procedure. Transformation efficiency, expression level and plasmid maintenance were studied in order to test the functionality and usefulness of the constructed vector. Results: We found that high transformation efficiencies were achieved using pPICZαBHF plasmid for yeast cell transformation in comparison with the commercial vector pPICZαB, which has to be integrated into the Pichia genome. However, expression levels of the recombinant protein were generally lower compared to the commercial construct. Recombinant plasmids were shown to be maintained in cells for approximately five days. Conclusion: Although pPICZαBHF may not be suitable for the production of high levels of recombinant protein, the simplicity of this P. pastoris expression system may still be of interest for the expression of proteins involved in cofactor regeneration or the expression of reporter genes. In addition, high transformation efficiency of pPICZαBHF may be beneficial for the applications such as high-throughput screening of mutant gene libraries.

Background: HIV integrase (IN) and reverse transcriptase (RT) are key enzymes for the replication of HIV-1. DNA polymerase and ribonuclease H (RNase H) are the two catalytic domains of HIV-1 RT which are validated as drug targets because of their essence for replication. IN and RNase H domain of RT shares striking structural similarity; it contains conserved DDE triad (two aspartates and one glutamate) and a pair of divalent Mg2+/Mn2+ ions at their catalytic core domain. Objective: To search for novel compounds with dual inhibition of IN and RNase H for the drug development against both wild and drug-resistant strains of HIV. Methods: In the present work, attempts have been made to search compounds against both IN and the RNase H domain of RT. Using structure-based virtual screening approach; Asinex database of small molecules was screened against the viral IN. Top thirty ranked hits obtained, were further evaluated against RNase H domain of RT using Extra Precision (XP) mode of Glide docking. Furthermore, eleven common potential hits were observed which were subjected to the in-silico prediction of drug-likeness properties. Later on, molecular dynamics simulation was performed for the best common active hit (AS6), in the complex with selected enzymes. Result: In silico screening of Asinex database compounds against IN and RNase H resulted in total seven compounds namely AS3, AS5, AS6, AS15, AS17, AS18, and AS20 having dual inhibition activity. Conclusion: This study warrants the dual inhibition activity of AS6 against IN and RNase H confirms its anti-HIV activity.