Current Drug Discovery Technologies - Volume 11, Issue 4, 2014

P. falciparum is highly virulent in nature because of its ability to modify the infected host red blood cells, adherence to the vascular endothelium and changes in antigenicity at different stages. Also slow migration time in the dermal and endothelial cells leads to decreased immune response. To overcome the problems, there is a need to design a vaccine which increases the migration time of the parasite, enhances the immune response, enables recognition of surface antigens and causes minimal clinical infection as a side-effect. An ITI-based (Infection-Treatment Immunization) vaccine development strategy is to be adopted to develop this novel vaccine. This will include administration of a liquid solution of purified, non-attenuated sporozoites from an infected female Anopheles mosquito, AS02A adjuvant and chlorate (a metabolic inhibitor of sulfation that decreases the extent of GAG sulfation). To control infection, a drug-cover of artemisinin will be administered as a part of the vaccination strategy along with a specific protease inhibitor MRT12113 which prevents RBC rupture and reinvasion by the parasite. This vaccine will intend to increase the overall migration time of the parasite in blood which is otherwise approximately 30 minutes, resulting in an overall enhanced immune response. It also intends to reduce parasite invasion in cells and their consequent rupture thus preventing the clinical condition-malaria.

Amyloid-β (Aβ) is widely believed to cause Alzheimer’s disease (AD), as it is the major constituent of the amyloid plaques observed in the brains of people with AD (the so-called amyloid hypothesis). Based on this hypothesis, therapies utilizing immune responses against Aβ have been performed and have succeeded in effectively removing amyloid plaques, but have shown no evidence of improvements in survival and/or cognitive function. Thus, it may be necessary to think about this problem from a different viewpoint. γ-Secretase was initially identified as an enzyme that cleaves amyloid precursor protein (APP) and produces Aβ. Although the primary function of γ-secretase has not been fully clarified, this enzyme is well known to play a central regulatory role in Notch signaling. After the shedding of the Notch ectodomain by metalloproteases, γ-secretase releases the intracellular domain (ICD) of Notch, which immediately translocates to the nucleus to modify the expression of certain genes. Recently, many type 1 transmembrane proteins have also been reported as substrates for γ-secretase. Interestingly, several of these substrates may share a γ-secretase-regulated signaling mechanism similar to that of Notch. Indeed, we have demonstrated that the ICD of APP (AICD) induces dynamic changes in gene expression and neuron-specific apoptosis, suggesting that APP also has a signaling mechanism that is closely linked with AD. In this review, we first summarize the evidence that γ-secretase–regulated mechanisms similar to Notch signaling may play wide-ranging roles in signaling events involving type 1 transmembrane proteins, including APP. We also focus on the possibility that APP signaling is involved in the onset and progression of AD. Based on these ideas, we hypothesize that APP signaling, especially AICD, may be an attractive therapeutic target in AD.

This paper describes a new RP-HPLC method for simultaneous quantification of these compounds in the bulk sample drug as well as in tablet dosage forms. The chromatographic separation was performed on an XTerra C8 (4.6 x 250 mm; 5 µm), with phosphate buffer [pH 3.5] and acetonitrile in the ratio of 40:60 (v/v) as mobile phase. The detection was carried out at 240 nm. The accuracy was found to be 99.59 % and 98.98 % for atorvastatin and ezetimibe respectively. The linearity was 5-25 µg/ml for both the drugs. The intra-day RSD was 0.57% and inter-day RSD was 0.13% for atorvastatin calcium and intra-day RSD was 0.56% and inter-day RSD was 0.09% for ezetimibe. The validation of method was carried out utilizing ICH-guidelines.

In the present investigation, an attempt has been made to improve aqueous solubility of a BCS class II drug by making an inclusion complex with Hydroxypropyl-β-cyclodextrin (HP-β-CD). Paliperidone (PALI) was selected as a model drug for the study. It is practically insoluble in water with low oral bioavailability. It is a major active metabolite of risperidone approved for the treatment of schizophrenia in adults. The inclusion complexes were prepared in 1:1 (PALI: HP-β-CD) molar ratio. Phase solubility studies were performed according to Higuchi Connors method to determine the optimum conditions for the complexation. The prepared solid inclusion complexes were characterized by Differential Scanning Calorimetry (DSC), Fourier- Transform Infrared Spectroscopy (FT-IR), Powder X-ray Diffractometry (PXRD), Scanning Electron Microscopy (SEM) and Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR). Dissolution study was performed using USP apparatus II in phosphate buffer, pH 6.8 (37 ± 0.5°C). The solid state characterization studies confirmed the formation of inclusion complex between PALI and HP-β-CD. The aqueous solubility and in-vitro dissolution study showed that the solubility and dissolution rate of drug were considerably improved by complexation with HP-β-CD with respect to the drug alone. The enhanced solubility and dissolution may help to improve in-vivo performance of PALI. Thus, the binary complexation of PALI with HP-β-CD can be used as an approach for its solubility enhancement.

Pseudomonas aeruginosa and Streptococcus pneumoniae are causative agents in a wide range of infections. Genes encoding proteins corresponding to phenylalanyl-tRNA synthetase (PheRS) were cloned from both bacteria. The two forms of PheRS were kinetically evaluated and the Km’s for P. aeruginosa PheRS with its three substrates, phenylalanine, ATP and tRNAPhe were determined to be 48, 200, and 1.2µM, respectively, while the Km’s for S. pneumoniae PheRS with respect to phenylalanine, ATP and tRNAPhe were 21, 225 and 0.94µM, respectively. P. aeruginosa and S. pneumoniae PheRS were used to screen a natural compound library and a single compound was identified that inhibited the function of both enzymes. The compound inhibited P. aeruginosa and S. pneumoniae PheRS with IC50’s of 2.3 and 4.9µM, respectively. The compound had a Ki of 0.83 and 0.98µM against P. aeruginosa and S. pneumoniae PheRS, respectively. The minimum inhibitory concentration (MIC) of the compound was determined against a panel of Gram positive and negative bacteria including efflux pump mutants and hyper-sensitive strains. MICs against wild-type P. aeruginosa and S. pneumoniae cells in culture were determined to be 16 and 32µg/ml, respectively. The mechanism of action of the compound was determined to be competitive with the amino acid, phenylalanine, and uncompetitive with ATP. There was no inhibition of cytoplasmic protein synthesis, however, partial inhibition of the human mitochondrial PheRS was observed.

Several different classes of compounds enhance the potency of aminergic receptor ligands three-fold or more and increase their duration of activity up to ten-fold. These enhancers include the vitamins ascorbic acid and folic acid, chelators such as ethylenediaminetetraacetic acid, corticosteroids, and opioids, opiates and opiate antagonists. We have previously demonstrated that all of these classes of enhancers share a common molecular motif consisting of a linear array of two hydroxyls and a carbonyl. We demonstrate here that because of this common molecular motif, all compounds known to enhance aminergic receptor ligands bind to highly conserved regions of the first or second extracellular loops of aminergic receptors at physiologically or pharmacologically relevant concentrations. These compounds also bind directly to aminergic ligands with significant specificity and affinity. These results suggest three very simple, complementary methods for screening for novel extracellular aminergic receptor enhancers: 1) in silico screening for the presence of the common aminergic receptor enhancer motif; 2) screening for binding to the aminergic ligand of choice; and 3) screening for binding to receptor peptides representing the enhancer binding site on the receptor. Using these three complementary methods, we predict a new class of enhancers (tartaric acids) and demonstrate the predicted enhancement in an in vitro smooth muscle assay.