Application of Combination High-Throughput Phenotypic Screening and Target Identification Methods for the Discovery of Natural Product-Based Combination Drugs.

Modern drug discovery efforts have had mediocre success rates with increasing developmental costs, and this has encouraged pharmaceutical scientists to seek innovative approaches. Recently with the rise of the fields of systems biology and metabolomics, network pharmacology (NP) has begun to emerge as a new paradigm in drug discovery, with a focus on multiple targets and drug combinations for treating disease. Studies on the benefits of drug combinations lay the groundwork for a renewed focus on natural products in drug discovery. Natural products consist of a multitude of constituents that can act on a variety of targets in the body to induce pharmacodynamic responses that may together culminate in an additive or synergistic therapeutic effect. Although natural products cannot be patented, they can be used as starting points in the discovery of potent combination therapeutics. The optimal mix of bioactive ingredients in natural products can be determined via phenotypic screening. The targets and molecular mechanisms of action of these active ingredients can then be determined using chemical proteomics, and by implementing a reverse pharmacokinetics approach. This review article provides evidence supporting the potential benefits of natural product-based combination drugs, and summarizes drug discovery methods that can be applied to this class of drugs.

Preclinical Development of a Nontoxic Oral Formulation of Monoethanolamine, a Lipid Precursor, for Prostate Cancer Treatment.

Purpose: Most currently available chemotherapeutic agents target rampant cell division in cancer cells, thereby affecting rapidly dividing normal cells resulting in toxic side-effects. This nonspecificity necessitates identification of novel cellular pathways that are reprogrammed selectively in cancer cells and can be exploited to develop pharmacologically superior and less toxic therapeutics. Despite growing awareness on dysregulation of lipid metabolism in cancer cells, targeting lipid biosynthesis is still largely uncharted territory. Herein, we report development of a novel nontoxic orally deliverable anticancer formulation of monoethanolamine (Etn) for prostate cancer by targeting the Kennedy pathway of phosphatidylethanolamine (PE) lipid biosynthesis.Experimental Design: We first evaluated gastrointestinal tract stability, drug-drug interaction liability, pharmacokinetic, and toxicokinetic properties of Etn to evaluate its suitability as a nontoxic orally deliverable agent. We next performed in vitro and in vivo experiments to investigate efficacy and mechanism of action.Results: Our data demonstrate that Etn exhibits excellent bioavailability, gastrointestinal tract stability, and no drug-drug interaction liability. Remarkably, orally fed Etn inhibited tumor growth in four weeks by approximately 67% in mice bearing human prostate cancer PC-3 xenografts without any apparent toxicity. Mechanistically, Etn exploits selective overexpression of choline kinase in cancer cells, resulting in accumulation of phosphoethanolamine (PhosE), accompanied by downregulation of HIF-1α that induces metabolic stress culminating into cell death.Conclusions: Our study provides first evidence for the superior anticancer activity of Etn, a simple lipid precursor formulation, whose nontoxicity conforms to FDA-approved standards, compelling its clinical development for prostate cancer management. Clin Cancer Res; 23(14); 3781-93. ©2017 AACR.

Applied Pharmaceutical Analysis India 2014 conference report.

Applied Pharmaceutical Analysis (APA) India 23-26 February 2014, Ahmedabad, India The fifth Applied Pharmaceutical Analysis (APA) India meeting was held in February 2014 at Hyatt Ahmedabad, India. With the theme of 'The Science of Measurement: Current status and Future trends in Bioanalysis, Biotransformation and Drug Discovery Platforms', the conference was attended by over 160 delegates. The agenda comprised advanced and relevant research topics in the key areas of bioanalysis and drug metabolism. APA India 2014 provided a unique platform for networking and professional linking to participants, innovators and policy-makers. As part of the global research community, APA India continues to grow and receive considerable attention from the drug discovery and development community of India.

Design, synthesis, ADME characterization and antileishmanial evaluation of novel substituted quinoline analogs.

In vitro ADME characterization of the lead compound 1 identified for visceral leishmaniasis was undertaken and further structural analogs were synthesized for antileishmanial screening. Compound 1 was highly permeable in intestinal PAMPA model (31 × 10(-6)cm/s) and was moderately bound to mouse and human plasma proteins (% bound 85-95%), its blood to plasma concentration ratio was less than 1, but the compound was unstable in blood. Compound 1 was found to have no CYP450 liability with CYP2C9, 2C19, 2D6 and 3A4. It showed inhibition with CYP1A2 with an IC50 value of 0.50 µM. Analogs of 1 were synthesized and subsequently characterized for in vitro activity against the intracellular form of Leishmania donovani. Resulting quinolines were found to have similar efficacy as 1 against the parasite. Compounds 8b and 8f were found to be the most active with IC50 values of 0.84 µM and 0.17 µM, respectively compared to 0.22 µM for compound 1. Of all the analogs tested, 8d was stable in hamster, mouse and human liver microsomes but lost the efficacy with an IC50 of 6.42 µM. Based on the in vitro efficacy and DMPK profile, compounds 8b and 8f seem the best candidates to be screened in further assays.

Validation of 96-well equilibrium dialysis with non-radiolabeled drug for definitive measurement of protein binding and application to clinical development of highly-bound drugs.

Definitive plasma protein binding (PB) studies in drug development are routinely conducted with radiolabeled material, where the radiochemical purity limits quantitative PB measurement. Recent and emerging regulatory guidances increasingly expect quantitative determination of the fraction unbound (Fu) for key decision making. In the present study, PB of 11 structurally- and therapeutically-diverse drugs spanning the full range of plasma binding was determined by equilibrium dialysis of non-radiolabeled compound and was validated against the respective definitive values obtained by accepted radiolabeled protocols. The extent of plasma binding was in agreement with the radiolabeled studies; however, the methodology reported herein enables reliable quantification of Fu values for highly-bound drugs and is not limited by the radiochemical purity. In order to meet the rigor of a development study, equilibrium dialysis of unlabeled drug must be supported by an appropriately validated bioanalytical method along with studies to determine compound solubility and stability in matrix and dialysis buffer, nonspecific binding to the dialysis device, and ability to achieve equilibrium in the absence of protein. The presented methodology establishes an experimental protocol for definitive PB measurement, which enables quantitative determination of low Fu values, necessary for navigation of new regulatory guidances in clinical drug development.

Purification of lysozyme from other hen's-egg-white proteins using metal-affinity precipitation.

It was found that the presence of 5 mM Cu(2+) caused precipitation of protein present in hen's egg white to a large extent. About 85% of lysozyme activity remained in the supernatant and the enzyme was purified by approx. 13-fold. A further gel-filtration step on Sephadex G-75 resulted in an overall yield of 80% for the enzyme with 655-fold purification, and showed a single band on SDS/PAGE.