QSAR Studies to Predict Activity of HSP90 Inhibitors

Heat shock protein 90 (HSP90) is a multichaperone complex that mediates the maturation and stability of a variety of oncogenic signaling proteins. HSP90 has emerged as a promising target for the development of anticancer agents. Heterocyclic chemical moieties with HSP90 inhibitory activity were studied continuously during the last decades, and resulting data were applied by medicinal chemists to design and develop new drugs. Their structure-activity relationship (SAR) studies and QSAR models have been derived to assist the current drug development process. The QSAR models are obtained via multiple linear regression (MLR) and non-linear approaches. Interpretation of the reported model highlights the core template required to design novel, potent HSP90 inhibitors to be used as anticancer agents.

Molecular Processes Exploited as Drug Targets for Cancer Chemotherapy

Cancer is an uncontrolled malignant tumor growth taking place in any tissue of the body and attains complex diversity which makes it difficult for oncologists to choose therapeutics. The changes leading to formation of cancerous cells occur due to a series of molecular events. Now scientists are trying to understand the various molecular processes that are involved in the growth of cancers. This article presents a brief account of epigenetics with reference to DNA methylation and histone modification as an important contributor to the formation of cancer cells. Drug targeting the epigenetic regulators has been considered for various types of cancer. The enzymes in DNA methylation and histone modification, FDA approved clinical drugs along with the challenges associated with the development of anti-cancer target based therapeutics are summarized.

An Overview of Ovarian Cancer: Molecular Processes Involved and Development of Target-based Chemotherapeutics

Ovarian cancer is one of the leading gynecologic diseases with a high mortality rate worldwide. Current statistical studies on cancer reveal that over the past two decades, the fifth most common cause of death related to cancer in females of the western world is ovarian cancer. In spite of significant strides made in genomics, proteomics and radiomics, there has been little progress in transitioning these research advances into effective clinical administration of ovarian cancer. Consequently, researchers have diverted their attention to finding various molecular processes involved in the development of this cancer and how these processes can be exploited to develop potential chemotherapeutics to treat this cancer. The present review gives an overview of these studies which may update the researchers on where we stand and where to go further. The unfortunate situation with ovarian cancer that still exists is that most patients with it do not show any symptoms until the disease has moved to an advanced stage. Undoubtedly, several targets-based drugs have been developed to treat it, but drug-resistance and the recurrence of this disease are still a problem. For the development of potential chemotherapeutics for ovarian cancer, however, some theoretical approaches have also been applied. A description of such methods and their success in this direction is also covered in this review.

Progress in Studies on Structural and Remedial Aspects of Newly Born Coronavirus, SARS-CoV-2

The article highlights an up-to-date progress in studies on structural and the remedial aspects of novel coronavirus 2019-nCoV, renamed as SARS-CoV-2, leading to the disease COVID-19, a pandemic. In general, all CoVs including SARS-CoV-2 are spherical positive single-stranded RNA viruses containing spike (S) protein, envelope (E) protein, nucleocapsid (N) protein, and membrane (M) protein, where S protein has a Receptor-binding Domain (RBD) that mediates the binding to host cell receptor, Angiotensin Converting Enzyme 2 (ACE2). The article details the repurposing of some drugs to be tried for COVID-19 and presents the status of vaccine development so far. Besides drugs and vaccines, the role of Convalescent Plasma (CP) therapy to treat COVID-19 is also discussed.

In-silico Studies and Biological Activity of Potential BACE-1 Inhibitors

BACKGROUND

Alzheimer's disease is a neurological condition causing cognitive inability and dementia. The pathological lesions and neuronal damage in the brain are caused by self-aggregated fragments of mutated Amyloidal precursor protein (APP).

OBJECTIVE

The controlled APP processing by inhibition of secretase is the strategy to reduce Aβ load to treat Alzheimer's disease.

METHODS

A QSAR study was performed on 55 Pyrrolidine based ligands as BACE-1 inhibitors with an activity magnitude greater than 4 of compounds.

RESULTS

In the advent of designing new BACE-1 inhibitors, the pharmacophore model with correlation (r = 0.90) and root mean square deviation (RMSD) of 0.87 was developed and validated. Further, the hits retrieved by the in-silico approach were evaluated by docking interactions.

CONCLUSION

Two structurally diverse compounds exhibited Asp32 and Thr232 binding with the BACE-1 receptor. The aryl-substituted carbamate compound exhibited the highest fit value and docking score. The biological activity evaluation by in-vitro assay was found to be >0.1μM.

Recent Studies on Design and Development of Drugs Against Alzheimer's Disease (AD) Based on Inhibition of BACE-1 and Other AD-causative Agents

BACKGROUND

Alzheimer's disease (AD) is one of the neurodegenerative diseases and has been hypothesized to be a protein misfolding disease. In the generation of AD, β-secretase, γ-secretase, and tau protein play an important role. A literature search reflects ever increasing interest in the design and development of anti-AD drugs targeting β-secretase, γ-secretase, and tau protein.

OBJECTIVE

The objective is to explore the structural aspects and role of β-secretase, γ-secretase, and tau protein in AD and the efforts made to exploit them for the design of effective anti-AD drugs.

METHODS

The manuscript covers the recent studies on design and development of anti-AD drugs exploiting amyloid and cholinergic hypotheses.

RESULTS

Based on amyloid and cholinergic hypotheses, effective anti-AD drugs have been searched out in which non-peptidic BACE1 inhibitors have been most prominent.

CONCLUSION

Further exploitation of the structural aspects and the inhibition mechanism for β-secretase, γ-secretase, and tau protein and the use of cholinergic hypothesis may lead still more potent anti-AD drugs.

Quantum Molecular Dynamics, Topological, Group Theoretical and Graph Theoretical Studies of Protein-Protein Interactions

BACKGROUND

Protein-protein interactions (PPIs) are becoming increasingly important as PPIs form the basis of multiple aggregation-related diseases such as cancer, Creutzfeldt-Jakob, and Alzheimer's diseases. This mini-review presents hybrid quantum molecular dynamics, quantum chemical, topological, group theoretical, graph theoretical, and docking studies of PPIs. We also show how these theoretical studies facilitate the discovery of some PPI inhibitors of therapeutic importance.

OBJECTIVE

The objective of this review is to present hybrid quantum molecular dynamics, quantum chemical, topological, group theoretical, graph theoretical, and docking studies of PPIs. We also show how these theoretical studies enable the discovery of some PPI inhibitors of therapeutic importance.

METHODS

This article presents a detailed survey of hybrid quantum dynamics that combines classical and quantum MD for PPIs. The article also surveys various developments pertinent to topological, graph theoretical, group theoretical and docking studies of PPIs and highlight how the methods facilitate the discovery of some PPI inhibitors of therapeutic importance.

RESULTS

It is shown that it is important to include higher-level quantum chemical computations for accurate computations of free energies and electrostatics of PPIs and Drugs with PPIs, and thus techniques that combine classical MD tools with quantum MD are preferred choices. Topological, graph theoretical and group theoretical techniques are shown to be important in studying large network of PPIs comprised of over 100,000 proteins where quantum chemical and other techniques are not feasible. Hence, multiple techniques are needed for PPIs.

CONCLUSION

Drug discovery and our understanding of complex PPIs require multifaceted techniques that involve several disciplines such as quantum chemistry, topology, graph theory, knot theory and group theory, thus demonstrating a compelling need for a multi-disciplinary approach to the problem.

QSAR and Molecular Docking Studies on a Series of 1-Amino-5H-pyrido [4, 3-b]indol-4-carboxamides Acting as Janus Kinase 2 (JAK2) Inhibitors

Background:

The Janus enzyme family is regulated by various cytokines together with interleukins, interferons, and hormones like glycoprotein, thromboprotein, and hormone. Metamorphosis and translocations in the Janus Kinase genes leading to constitutively active Janus Kinase proteins are associated with a variety of hematopoietic malignancies, comprising the myeloproliferative disorders, acute lymphoblastic leukemia, acute myeloid leukemia (JAK2, JAK1), acute megakaryoblastic leukemia (JAK2, JAK3). Hence the study of the inhibitors of Janus Kinase is desired.

Methods:

Research and online content related to 1-amino-5H-pyrido [4,3-b]indol-4-carboxamide analogues (I) that were synthesized and evaluated for their JAK2 inhibitory activity is reviewed, and in order to design and develop still better and more effective JAK inhibitors, we have made Quantitative Structure Activity Relationship (QSAR), docking and ADMET studies on these compounds

Results:

The best GA-MLR equation based on four descriptors along with statistical parameters is obtained using QSARINS software. Using the model expressed by this study we predicted some new compounds of high JAK2 inhibition potency. Each predicted compound has very high potency with which only a few compounds of existing series can match.

Conclusion:

The QSAR and molecular modelling studies suggested that still better compounds can be designed if the flexibility of the molecules can be increased for which attempts can be made to have more saturated atoms in the molecules. Such a compound predicted by us was found to have interactions with the enzyme JAK2 almost in the same manner as the FDA approved compound, Momelotinib.

Designing of Selective γ-Secretase Inhibitory Benzenesulfonamides through Comparative In Vitro and In Silico Analysis

BACKGROUND

In Alzheimer's disease (AD), the gene mutations have been identified in the amyloid precursor protein (APP), the presenilin-1 (PS1) and -2 (PS2) genes. APP is a transmembrane protein which gets cleaved by α- and β- secretase enzymes and releases Aβ peptides which forms senile plaques in brain tissue. It contributes for local inflammatory response, subsequent oxidative stress, biochemical changes and neuronal death. Targeting the development of Aβ aggregates in the senile plaques is an important strategy in the treatment of AD. To facilitate the normal processing of APP, some of the reported approaches are stimulation of α- secretase activity or the modulation/inhibition of the β- and γ-secretase complex.

METHODS

The mechanism of γ-secretase inhibition is targeted based on the QSAR and molecular docking methods. The series based on 3-chloro-2-hydroxymethylbenzenesulfonamide was selected for in silico ligand-based modeling. Significant correlations, between their γ-Secretase inhibitory profile and 2D-descriptors, were obtained through multiple linear regression (MLR) computational procedure.

RESULTS

During QSAR nalysis, calculated molar refractivity (CMR) and surface tension (ST) were found to be contributing parameters along with halogen substituent at a particular position. Applicability analysis revealed that the suggested models have acceptable predictability (rpred2 = 0.827).

CONCLUSION

The inferences drawn from MLR were utilized to prepare a data set of fourteen substituted benzenesulfonamides (N1-N14). The in silico studies provides strong impetus towards systematic application of such methods during lead identification and optimization.

Retrospective Analysis of Giant Cell Tumor Lower End Radius Treated with En bloc Excision and Translocation of Ulna

BACKGROUND

Distal end of radius is third most common site for GCT of long bones and 1% of these metastasize mostly to lungs. Reconstruction methods commonly used are fibula (vascularized and nonvascularized), centralization of ulna, translocation of ulna, and endoprosthetic replacement. We report the outcome of series of twenty cases where we did en bloc excision of tumor with translocation of ulna.

MATERIALS AND METHODS

Twenty cases of giant cell tumor (GCT) of lower end of radius were included in this retrospective study. The mean age of patients was 33.15 years (range 21-55 years). We had 14 of Campanacci Grade III and 6 of Grade II. Preoperative radiographs and magnetic resonance imaging of the involved wrist and forearm were done.

RESULTS

Of all twenty patients, 14 were males and 6 were females. Mean followup duration was 3.9 years (range 1.5-17 years). Mean grip strength of involved side as a percentage of normal side was 71% (range 42%-86%) and the actual mean value for operated side was 29 kg as compared to 40 kg for normal side. The average range of forearm movement was supination 80.25° (60°-90°) and pronation 77.5° (70°-90°). No patient was dissatisfied as far as cosmesis was concerned.

DISCUSSION

In our opinion considering the propensity to recur with more aggressiveness after recurrence, en bloc excision with translocation of ulna has become a standard treatment option for GCT of lower end of radius, with advantages of better functional outcomes, retained vascularity, and elimination of risk of donor site morbidity.

GENIUS In Silico Screening Technology for HCV Drug Discovery

The various reported in silico screening protocols such as molecular docking are associated with various drawbacks as well as benefits. In molecular docking, on interaction with ligand, the protein or receptor molecule gets activated by adopting conformational changes. These conformational changes cannot be utilized to predict the 3D structure of a protein-ligand complex from unbound protein conformations rigid docking, which necessitates the demand for understanding protein flexibility. Therefore, efficiency and accuracy of docking should be achieved and various available/developed protocols may be adopted. One such protocol is GENIUS induced-fit docking and it is used effectively for the development of anti-HCV NS3-4A serine protease inhibitors. The present review elaborates the GENIUS docking protocol along with its benefits and drawbacks.

Studies on Chloride Channels and their Modulators

The prime roles of mutations in the genes, encoding chloride ion channels, in various human diseases of muscle, kidney, bone and brain, such as congenital myotonia, myotonic dystrophy, cystic fibrosis, osteopetrosis, epilepsy, glioma, etc., have been well established. Chloride ion channels are also responsible for glioma progression in brain and malaria parasite in red blood cells. The present article thus emphasises on the various diseases associated with chloride channel regulation and their modulators. Studies on various chloride channels and their modulators have been discussed in detail.

Fundamentals of Viruses and Their Proteases

Viruses are major pathogenic agents that can cause a variety of diseases, such as AIDS, hepatitis, respiratory diseases, and many more, in humans, plants, and animals. The most prominent of them have been adenoviruses, alphaviruses, flaviviruses, hepatitis C virus, herpesviruses, human immunodeficiency virus of type 1, and picornaviruses. This chapter presents an introductory remark on such viruses, mechanisms of their invasion, and diseases related to them. The inhibition of these viruses is of great concern to human beings. Each of these viruses encodes one or more proteases that play crucial roles in their replication, and thus they are important targets for the design and development of potent antiviral agents. The chapter, therefore, also introduces the readers to such proteases and their structures and functions. This chapter is thus a prelude to the remaining chapters in the book, which present in detail about the different viruses and their proteases.

Heterocyclic Secretase Inhibitors for the Treatment of Alzheimer's Disease: An Overview

Alzheimer's disease (AD), the most common neurodegenerative disorder and demands to find a way for prevention and delayed onset. The development of therapeutics for AD is based on the amyloid cascade hypothesis (vaccines, β- and γ-Secretase inhibitors), or targeting tau and neurofibrillary tangle formation, neuroinflammation, etc. Cholinesterase, BACE-1, amyloid-β 1-42, γ and β-Secretase, Phosphodiesterase type IV (PDE4) inhibitors are the reported treatment strategies. Among these, the γ- and β-Secretase inhibitors can be clustered in several heterocyclic classes (imidazoles, thiazoles, indoles, benzaldehydes, pyrimidine, etc), with subsequent description of the structure-activity relationships, and extended to the pharmacological profile in order to evaluate their drug-likeness, with special attention to toxicity and bioavailability. This article discusses the approaches proposed by several research groups working on the synthesis of enzyme inhibitors, based on modelling studies and the way these findings were used to obtain new drugs for the treatment of AD.

A comparative 2D QSAR study on a series of hydroxamic acid-based histone deacetylase inhibitors vis-à-vis comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA)

A quantitative structure-activity relationship (QSAR) study was performed on a series of indole amide analogues reported by Dai et al. [Bioorg Med Chem Lett (2003), 13, 1897-1901] to act as histone deacetylase (HDAC) inhibitors. The multiple regression analysis (MRA) revealed a model showing the significant dependence of the activity on molar refractivity (MR) and global topological charge index (GTCI) of the compounds, suggesting that inhibition of the HDAC by this series of compounds might involve the dispersion interaction with the receptor, where charge transfer between pairs of atoms might greatly help to polarize the molecule. The MRA results were then compared with those obtained by Guo et al. [Bioorg Med Chem (2005), 13, 5424-5434] by comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). It was found that MRA gave as good results and had as good predictive ability as CoMFA and CoMSIA. Besides, MRA was also able to throw the light on the physicochemical properties of the molecules that were involved in drug-receptor interactions, while CoMFA and CoMSIA could not. The dispersion interaction between the molecule and the active site of the receptor is suggested to be the main interaction.

A quantitative structure-activity relationship (QSAR) study on a few series of potent, highly selective inhibitors of nitric oxide synthase

QSAR study was performed on a series of 1,2-dihydro-4-quinazolinamines, 4,5-dialkylsubstituted-2-imino-1,3-thiazolidine derivatives and 4,5-disubstituted-1,3-oxazolidin-2-imine derivatives studied by Tinker et al. [J Med Chem (2003), 46, 913-916], Ueda et al. [Bioorg Med Chem (2004) 12, 4101-4116] and Ueda et al. [Bioorg Med Chem Lett (2004) 14, 313-316], respectively, as potent, highly selective inhibitors of inducible nitric oxide synthase (iNOS). The iNOS inhibition activity of the whole series of compounds was analyzed in relation to the physicochemical and molecular properties of the compounds. The QSAR analysis revealed that the inhibition potency of the compounds was controlled by a topological parameter 1chi(v) (Kier's first order valence molecular connectivity index), density (D), surface tension (St) and length (steric parameter) of a substituent. This suggested that the drug-receptor interaction predominantly involved the dispersion interaction, but the bulky molecule would face steric problem because of which the molecule may not completely fit in active sites of the receptor and thus may not have the optimum interaction.

A QSAR study on a series of thiourea derivatives acting as anti-hepatitis C virus agents

A quantitative structure-activity relationship (QSAR) study was performed on a large series of thiourea derivatives reported by Kang et al. [Bioorg Med Chem Lett (2009), 19, 1950-55 & 6063-68], acting as anti-hepatitis C virus (anti-HCV) agents. The activity of the compounds was found to be significantly correlated with their hydrophobic property and three indicator variables I1, I2 and I3, the first two specifying a negative effect of an alkyl and an aromatic group, respectively on their R-moiety and the third one specifying a negative effect of their Ar-moiety having a nitrogen-containing heterocyclic ring. The whole set containing 85 compounds was divided into two subsets: the training set and the test set containing 61 and 24 compounds, respectively. For the training set, the correlation coefficient (r) and the square of cross-validated correlation coefficient (r2cv) were found to be 0.926 and 0.83, respectively. The correlation obtained suggested that anti-HCV activity of the compounds would depend on their hydrophobic property, conformational flexibility and the steric effects of an alkyl or an aromatic group on the R-moiety. This suggested that the molecules might have significant hydrophobic interactions with the receptor which might be aided by their conformational flexibility, but hindered sterically by an alkyl or an aromatic group on their R-moiety. Using the correlation obtained, some new compounds having activity higher (> 8.0) than the most active compound in the existing series were predicted.

Evaluation of Serum HDL and LDL levels in Type II Diabetes Mellitus

  Introduction: Diabetes mellitus is a type of metabolic disorder characterized by hyperglycemia resulting from defect in insulin secretion, insulin action or both. This study intended to compare High Density Lipoprotein Cholesterol (HDL) and Low Density Lipoprotein Cholesterol (LDL) profile between type II diabetic and non-diabetic subjects and also find the correlation between HDL and LDL cholesterol in type II diabetic.   Methods: The study was conducted on 100 total subjects out of which experimental group with 50 subjects of known Type II Diabetes mellitus and control group with 50 subjects.   Results: The result of the present study suggests that fasting blood sugar and LDL cholesterol levels were increased but HDL cholesterol level was reduced in type II diabetic subjects when compared to controls.   Conclusion: The estimation of HDL cholesterol and LDL cholesterol in type II diabetes mellitus is very useful as it may serve as a useful parameter to monitor the prognosis of the patient.

A QSAR and molecular modeling study on a series of 3, 4-dihydro-1-isoquinolinamines and thienopyridines acting as nitric oxide synthase inhibitors

A quantitative structure-activity relationship (QSAR) and molecular modeling study were performed on a series of 3,4-dihyro-1-isoquinolinamines and thienopyridines reported by Beaton et al. [Beaton et al. (2001) Bioorg Med Chem Lett 11, 1023-1026, 1027-1030] as potent, highly selective inhibitors of two isoforms of nitric oxide synthase (NOS)--neuronal NOS (nNOS) and endothelial NOS (eNOS), in order to find the physicochemical properties that governed their activity and the mode of interaction with the receptors, so that still more potent compounds in the series could be suggested. A multiple regression analysis revealed that nNOS and eNOS inhibition potency of these compounds could be controlled by their hydrophobic property and molar refractivity, respectively. Thus, nNOS and eNOS inhibition was indicated to involve the hydrophobic interaction and steric effects, respectively, suggesting some structural differences of the two isoforms of NOS. Based on the correlations obtained, some new, more potent compounds belonging to the series were predicted. These compounds were then docked into the receptors to see their interactions and find out the docking scores. The docked structures of two representative compounds, whose interaction energies with nNOS and eNOS, respectively were found to be the lowest, were given as an example to exhibit the possible orientation of the compounds to interact with the receptors.

Sjogren-Larsson syndrome: A case report of a rare disease

We report a case of Sjogren-Larsson syndrome with clinical profile (spastic diplegia, icthyosis, mental retardation) and imaging findings on magnetic resonance imaging.

A QSAR study on a series of pyrrole derivatives acting as lymphocyte-specific kinase (Lck) inhibitors

A quantitative structure-activity relationship (QSAR) study has been made on a novel series of pyrrole derivatives acting as lymphocyte-specific kinase (Lck) inhibitors. The Lck inhibition activity of compounds is found to be significantly correlated with their molar volume (MV) and surface tension (ST) and the hydrophobic constant of one of their substituents. Both the molar properties MV and ST of the compounds are found to have the negative effect but the hydrophobic property of R(2)-substituen is found to have the positive effect. This leads to suggest that the bulky molecules and the those with high surface tension will not be advantageous to the Lck inhibition, rather their R(2)-substituent with hydrophobic property will be conducive to the activity.

A quantitative structure-activity relationship study on a few series of anti-hepatitis C virus agents

A 2-Dimensional Quantitative Structure-Activity Relationship study has been performed on 2 series of hepatitis C virus (HCV) inhibitors, i.e., Isothiazoles and Thiazolones. In each case significant correlations are found between the anti-HCV potencies and some physicochemical, electronic and steric properties of the compounds, indicating that for the first series the activity is controlled by density and two indicator parameters (one for halogen and other for methyl), while for the second series density, Hammett constant and Kier's first order valence molecular connectivity index are important for anti-HCV activity. The validity of the correlation has been judged by leave-one-out jackknife procedure and predicting the activity of some test compounds. Using the correlations obtained, some new compounds of high potency have been predicted in each series.

Quantitative structure-activity relationship studies on sulfonamide-based MMP inhibitors

Matrix metalloproteinases (MMPs) regulate a wide range of biological functions, but their overactivation leads to a wide array of disease processes such as rheumatoid arthritis, ostereoarthritis, tumor metastatis, multiple sclerosis, congestive heart failure, and a host of others. Therefore, the study of MMP inhibitors has evoked a great interest among scientists. As a result, different groups of compounds have been synthesized and studied for MMP inhibitions. Among them, a large number of structurally novel sulfonamide derivatives have been reported to be potential MMP inhibitors, but only a few have reached to the final stage of clinical trial. Many authors have made quantitative structure-activity relationship (QSAR) studies on them to provide the guidelines to design more potent MMP inhibitors. This article presents a comprehensive review on all such QSARs reported with critical assessment in order to provide a deeper insight into the structure-activity relationship of sulfonamides which can be used to synthesize highly potential drugs of pharmaceutical importance.

Specificity of binding with matrix metalloproteinases

Matrix metalloproteinases (MMPs) regulate a wide range of biological functions; hence, they have invited great attention for the studies on their structures and functions, and since their overactivation leads to several diseases, the design and discovery of their potent inhibitors have become the need of the day. Since there have been so far discovered 28 different types of human MMPs, the specificity of binding of inhibitors with each different MMP needs special attention. The chapter presents the X-ray crystallographic and NMR studies on three-dimensional structures of a number of MMPs to reveal their catalytic site, subsites, specificity of binding with substrate and inhibitors, and catalytic mechanism. In addition to catalytic site, MMPs possess some subsites designated by unprimed and primed S, e.g., S1, S2, S3 and S1', S2', S3'. Among these, the S1' pocket varies the most among the different MMPs varying in both the amino acid makeup and depth of the pocket (shallow, intermediate, and deep pocket MMPs). This, along with the flexibility in the structures of MMPs, could be of great help in the design and the development of selective MMP inhibitors (MMPIs). The determination of affinity of inhibitors and the cleavage position of peptide substrates is mainly based on P1'-S1' interaction (P1', the group in inhibitor or substrate binding to S1' pocket of the enzyme), and it is the main determinant for the affinity of inhibitors and the cleavage position of peptide substrates.

A QSAR study on a series of N-methyl pyrimidones acting as HIV integrase inhibitors

A quantitative structure-activity relationship (QSAR) study has been performed on integrase (IN) inhibition activity of a large series of N-methyl pyrimidones [Gardelli et al. (2007) J Med Chem 50, 4953-4975)] having varying heterocyclic ring substitution at 2-position of pyrimidone ring. The activity is found to be significantly correlated with surface tension and molar volume of the molecules. The whole series of compounds is divided into two subsets: a training set and a test set. A significant correlation is obtained for the training set, which is then used to predict the activity of compounds in the test set. The predicted activities of compounds in the test set are found to be very close to their observed activities. The predicting ability of the correlation obtained is judged by leave-one-out jackknife procedure. The correlation shows the effective role of the surface tension and molar volume of the molecules. From the correlation obtained, the integrase inhibition activities are predicted for some new prospective compounds.

A QSAR study on a series of simplified digitalis-like compounds acting on Na+,K(+)-ATPase

Among the cardiotonics (agents against congestive heart failure), the most important group is of the digitalis cardiac glycosides, but since these compounds suffer from a low therapeutic index, attention has been paid to investigating safer cardiotonic agents through the inhibition of Na+,K(+)-ATPase, the mechanism by which the digitalis cardiac glycosides elicit their action. Recently, a series of perhydroindenes were studied for their Na+,K(+)-ATPase inhibition activity. We report here a QSAR study on them to investigate the physicochemical and structural properties of the molecules that govern their activity in order to rationalize the structural modification to have more potent drugs. A multiple regression analysis reveals a significant correlation between the Na+,K(+)-ATPase inhibition activity of the compounds and Kier's first order valence molecular connectivity index of their R5-substituents and some indicator parameters, suggesting that the R5-substituents of the compounds containing atoms with low valence and high saturation and the R1-substituents having =N-O- moiety will be conducive to the activity.

A 3D-QSAR study on a series of benzimidazole derivatives acting as hepatitis C virus inhibitors: application of kNN-molecular field analysis

A k nearest neighbor-molecular field analysis (kNN-MFA) of benzimidazole derivatives, a series of hepatitis C virus (HCV) inhibitors, has been performed to determine the factors contributing the corresponding activities. The energy minimized conformations were obtained by molecular mechanics using VLife QSAR 1.0 package. The developed model was verified by performing leave-one out (LOO) cross-validation, which showed q2 value of 0.900 and pred_r2 value of 0.783. The model indicates the dominance of the steric field and also points out the regions around the benzamidazole ring where the bulky or less bulky groups can be substituted to increase the activity of the compounds.

Outcome of early active mobilization after flexor tendons repair in zones II-V in hand

BACKGROUND

The functional outcome of a flexor tendon injury after repair depends on multiple factors. The postoperative management of tendon injuries has paved a sea through many mobilization protocols. The improved understanding of splinting techniques has promoted the understanding and implication of these mobilization protocols. We conducted a study to observe and record the results of early active mobilization of repaired flexor tendons in zones II-V.

MATERIALS AND METHODS

25 cases with 75 digits involving 129 flexor tendons including 8 flexor pollicis longus (FPL) tendons in zones II-V of thumb were subjected to the early active mobilization protocol. Eighteen (72%) patients were below 30 years of age. Twenty-four cases (96%) sustained injury by sharp instrument either accidentally or by assault. Ring and little finger were involved in 50% instances. In all digits, either a primary repair (n=26) or a delayed primary repair (n=49) was done. The repair was done with the modified Kessler core suture technique with locking epitendinous sutures with a knot inside the repair site, using polypropylene 3-0/4-0 sutures. An end-to-end repair of the cut nerves was done under loupe magnification using a 6-0/8-0 polyamide suture. The rehabilitation program adopted was a modification of Kleinert's regimen, and Silfverskiold regimen. The final assessment was done at 14 weeks post repair using the Louisville system of Lister et al.

RESULTS

Eighteen of excellent results were attributed to ring and little fingers where there was a flexion lag of < 1 cm and an extension lag of < 15 degrees . FPL showed 75% (n=6) excellent flexion. 63% (n=47) digits showed excellent results whereas good results were seen in 19% (n=14) digits. Nine percent (n=7) digits showed fair and the same number showed poor results. The cases where the median (n=4) or ulnar nerve (n=6) or both (n=3) were involved led to some deformity (clawing/ape thumb) at 6 months postoperatively. The cases with digital or common digital nerve involvement (n=7 with 17 digits) showed five excellent, two good, four fair, and six poor results. Complications included tendon ruptures in 2 (3%) cases (one thumb and one ring finger) and contracture in 2 (3%) cases whereas superficial infection and flap necrosis was seen in 1 case each.

CONCLUSION

The early active mobilization of cut flexor tendons in zones II-V using the modified mobilization protocol has given good results, with minimal complications.

A QSAR study on some series of anti-hepatitis B virus (HBV) agents

A quantitative structure­activity relationship (QSAR) study has been made on some series of anti­hepatitis B virus (HBV) agents, namely, a series of novel bis(L­amino acid) ester prodrugs of 9­[2­­(phosphonomethoxy)ethyl]adenine, a similar series of compounds comprising of 2­ amino­6­arylthio­9­[2­(phosphonoethoxy)ethyl] purine bis(2,2,2­ trifluoroethyl) esters, and a series of 1­isopropylsulfonyl­2­amine benzimidazoles. In each case significant correlations are found between the anti­HBV potencies and some physicochemical and steric properties of the compounds, indicating that for the first two series the activity is controlled by the hydrophobic and the bulk properties of the molecules and, for the third series, the steric and hydrogen bonding properties of compounds are crucial for their anti­HBV potency.

A practical approach to designing operating instructions for medical products in late or post-design phases

User instructions, and especially operating instructions, are an essential part of the FDA's "medical device labeling" requirements and are intended to help ensure that the device is used safely and effectively. Their design should go hand-in-hand with the design of the product that they are going to accompany. However, for one reason or another, they are usually treated as something that can be tacked on at the end of the device development process. At this stage, it is often realized that, had the device been designed differently, it would have been easier to instruct the potential users. However, it is generally too late and the instructions have to be formulated around the fixed design of the product. Also, in the clinical engineering environment of healthcare organizations, sometimes there is a requirement to produce tailored operating instructions for certain groups of users (especially patients and carers) in certain circumstances, e.g. when the manufacturer's instructions are inadequate or a device has been configured for a particular type of user group. This paper attempts to demonstrate a practical approach to producing effective operating instructions for a product that is already at the far end of its development process or even marketed.

Management of radial clubhand with gradual distraction followed by centralization

BACKGROUND

Treatment of radial clubhand has progressed over the years from no treatment to aggressive surgical correction. Various surgical methods of correction have been described; Centralization of the carpus over the distal end of the ulna has become the method of choice. Corrective casting prior to centralization is an easy and effective method of obtaining soft tissue stretching before any definitive procedure is undertaken. Moreover, it helps put the limb in a correct position. The outcome of deformity correction by serial casting / JESS distractor followed by centralization is discussed.

MATERIALS AND METHODS

In a prospective study, of 17 cases with 18 radial clubhands of Heikel's Grade III and IV (with average age 11 months (range 20 days - 24 months) with M:F of 2.6:1, were treated by gradual soft tissue stretching using corrective cast (14 cases) and JESS distraction (4 cases), followed by centralization (16 cases) or radialization (2 cases) and tendon transfers.

RESULTS

The average correction attained during the study was 71 degrees of radial deviation and 31 degrees of volar flexion. The average third metacarpal to distal ulna angle in anteroposterior and lateral view at final follow-up was 7 degrees in both views. Angle of movement at elbow showed a small increase from 99 degrees to 101 degrees during the follow-up period. However, the range of movement at fingers showed increase in stiffness during the follow-up. No injury occurred to the distal ulnar epiphysis during the operative intervention. The results at the final follow-up, at the end of 2 years were graded on the basis of the criteria of F.W. Bora, and of Bayne and Klug. Considering the criteria of F.W. Bora, satisfactory result was shown by nine of the 18 hands (50%) while 16 out of 18 hands (89%) showed good or satisfactory result based on deformity criteria of Bayne and Klug.

CONCLUSION

The management of radial clubhand by gradual corrective cast or JESS distractor followed by centralization and tendon transfers in children is an acceptable method of treatment with consistently satisfactory results, both functional and cosmetic.

Development of Matrix-Membrane Transdermal Drug Delivery System for Atenolol

A polymer matrix system for transdermal delivery of Atenolol was developed for its prolonged and controlled release systemic availability. To achieve the desired and controlled release rate, different combinations of Eudragit RL with polyvinyl pyrrolidone and polyethylene glycol 4000 were used in the preparations of polymeric matrix system. These preparations were evaluated for in vitro release and permeation of the drug across pig skin. The desired systems exhibited linear relationship between drug release (Q) versus ne0.8(hr0.8). The product exhibiting required skin permeation 64 mcg/h/cm2 to achieve an effective plasma concentration was selected for the in vivo performance evaluation. The drug plasma profile was compared with the plasma profile obtained following the administration of a conventional oral dose of Atenolol. The study revealed that the designed polymeric matrix transdermal drug delivery system of Atenolol could be successful with improved performance.