Response Surface Methodology in Spectrophotometric Estimation of Saxagliptin, Derivatization with MBTH and Ninhydrin

Objectives: Design of experiments assisted spectrophotometric methods have been established for the quantification of saxagliptin in pharmaceutical formulation via charge transfer complexation and Schiff's base formation. Materials and Methods: Box-Behnken design was exploited in method-1, involved the measurement of absorbance of green/blue-colored complex (at 600 nm), formed by the reaction of saxagliptin with 3-methyl-2-benzothiazolinone hydrazone in the presence of ferric chloride. The central composite design was employed in method-2, involved the determination of absorbance of Ruhemann's purple (at 585 nm), formed by the reaction of the primary amine group of saxagliptin with ninhydrin reagent in presence of sodium hydroxide. Optimization of reaction variables namely, reagent concentration (A), oxidizing agent/alkalinity (B) and reaction/heat time (C) was performed through response surface methodology for the response (Y) i.e. absorbance of colored compound. The reliability of both methods was investigated through validation as per International Council for Harmonisation guidelines. Results: Saxagliptin executed linearity in the concentration range of 0.01-0.25 µg/mL and 1-10 µg/mL by method-1 and 2. A high value of molar absorptivity, low values of Sandell's sensitivity and limit of detection/limit of quantification divulges the good sensitivity methods. The % assay of saxagliptin in the marketed formulation was found to be 100.27 and 99.86 by method-1 and method-2, respectively. Conclusion: The proposed eco-friendly and economical methods can be routinely employed in quality control for the analysis of saxagliptin in the pharmaceutical dosage forms.

Quality-by-Design Approach for Chromatographic Analysis of Metformin, Empagliflozin and Linagliptin.

New analytical quality by design-oriented HPLC method with multiple response optimization (Derringer's desirability function) was demonstrated for simultaneous analysis of three antidiabetic drugs (metformin hydrochloride/empagliflozin/linagliptin) in a fixed-dose combination. Central composite design was employed for systematic optimization of critical method parameters, namely, % organic phase (X1), aqueous phase pH (X2) and flow rate (X3) while resolution, capacity factor and theoretical plate number as critical analytical attributes. Effective chromatographic separation of title analytes was accomplished on Std. Discovery C18 column at 30°C with mobile phase comprising acetonitrile: phosphate buffer pH 5 (38:62% v/v), pumped at a flow rate of 1 mL/min by isocratic elution pattern and UV detection at 222 nm. The model is rectilinear in the range of 1.0-200, 0.2-40 and 0.1-20 µg/mL at retention times of 3.04, 3.93 and 5.99 min for metformin, empagliflozin and linagliptin, respectively. The method obeyed all validation parameters of ICH Q2(R1) guidelines. The proposed HPLC method was highly robust for method transfer, regulatory flexibility within design space and can be used for assay of pharmaceutical dosage forms comprising these analytes. The proposed method was applied for stability studies of drugs under various stress conditions.

Discovery of N-pyridoyl-Δ2 -pyrazolines as Hsp90 inhibitors.

Hsp90, as a key molecular chaperone, plays an important role in modulating the activity of many cell signaling proteins and is an attractive target for anticancer therapeutics. Herein, we report the discovery of N-pyridoyl-Δ2 -pyrazoline analogs as novel Hsp90 inhibitors by integrated approaches of drug design, organic synthesis, cell biology, and qualitative proteomic analysis. Novel chemical compounds were designed and optimized in the adenosine triphosphate-binding site of Hsp90; lead optimized compounds were found to have significant interactions with Asp93 and other amino acids crucial for Hsp90 inhibition. The designed compounds were synthesized by a two-step procedure; different aromatic aldehydes were reacted with various acetophenones to form substituted 1,3-diphenyl-prop-2-enones (Ic-Io), which upon reaction with isonicotinic acid hydrazide in the presence of glacial acetic acid form N-pyridoyl-Δ2 -pyrazoline compounds (PY1-PY13). Compounds PY3, PY2, and PY1 were identified as potential leads amongst the series, with promising anticancer activity against human breast cancer and melanoma cells, and the ability to inhibit Hsp90 similar to radicicol by drug-affinity responsive target stability proteomic analysis in a whole-cell assay.

Drug Design, Synthesis and In Vitro Evaluation of Substituted Benzofurans as Hsp90 Inhibitors.

BACKGROUND: Heat shock protein 90 is a molecular chaperone required for the stability and function of several client proteins that promote cancer cell growth and/or survival. Discovery of Hsp90 inhibitors has emerged as an attractive target of research in cancer therapeutics. Natural products like geldanamycin and radicicol are established Hsp90 inhibitors, but face limitations with toxicity and inactivity, by in vivo studies respectively. However, they lay the logical starting point for the design of novel synthetic or semi-synthetic congeners as Hsp90 inhibitors. OBJECTIVE: In this article, the structure based drug design of substituted 2-aryl/heteroarylidene-6- hydroxybenzofuran-3(2H)-one analogues to optimize and mimic the pharmacophoric interactions of the valid Hsp90 inhibitor radicicolis focused. METHOD: In silico docking study was performed by Surflex dock-Geom (SYBYL- X 1.2 drug discovery suite) and the designed ligands were chemically synthesized by conventional method using resorcinol and chlororesorcinol as starting materials. Two dimensional chemical similarity search was carried out to identify the chemical space of 'SY' series in comparison with reported Hsp90 inhibitors. The in vitro cell proliferation assay (resazurin reduction method) and proteomic investigation (DARTS) was carried out on whole cell lysate to evaluate anticancer activity. RESULTS: The chemical structures of all the synthesized compounds were confirmed by IR, 1H-NMR and Mass spectral analysis. The results of chemical similarity search show that SY series fit it in the chemical space defined by existing Hsp90 inhibitors. In vitro cell proliferation assay, against human melanoma and breast cancer cell lines, identified 'SY3' as the promising anticancer agent amongst the series. CONCLUSION: Docking studies, 2D chemical similarity search, resazurin reduction assay and qualitative proteomic analysis identify 'SY3'as a promising Hsp90 inhibitor amongst the series.

Role of mass media on knowledge generation and countering misconceptions about tuberculosis transmission in Nepal

Objective: To explore the role of mass media on knowledge generation and counter the misconceptions about tuberculosis (TB) transmission in Nepal. Methods: A cross-sectional study was performed in the largest referral hospital in Nepal. The quota sampling technique was used to recruit 283 subjects into the sample. Results: A total of 235 (83.0%) respondents correctly replied that TB transmits through air by coughing or sneezing. A total of 29 (10.2%) respondents had correct knowledge about TB transmission without having misconceptions. Similarly, regarding the misconceptions about TB transmission, 157 (55.5%) replied that TB transmits through utensils, 163 (57.6%) respondents replied that TB transmits through sharing clothes/bed sheets/towel, 62 (21.9%) respondents replied that TB transmits through touching a person with TB, 142 (50.2%) respondents replied that TB transmits through food, 88 (31.1%) respondents replied that TB transmits through sexual contact. Respondents who read newspaper (ajusted odd ratio=3.004, cofidence interval=1.208-7.471) and listen to the radio daily (ajusted odd ratio=4.610, cofidence interval=1.738-12.234) were more likely to have correct knowledge on transmission of TB. Conclusions: National TB Control Program in Nepal should give priority in disseminating TB related message through newspapers, magazines and radio programs.