Pramod B. Khedekar

Derivative and Q-analysis spectrophotometric methods for estimation of hydrochlorothiazide and olmesartan medoxomil in tablets

Two methods for simultaneous estimation of hydrochlorothiazide and olmesartan medoxomil in combined tablet dosage form have been developed. The first method is the application of Q–analysis method (absorbance ratio), which involves the formation of Q–absorbance equation at 264 nm (isobestic point) and at 271 nm, the maximum absorption of hydrochlorothiazide. The linearity ranges for hydrochlorothiazide and olmesartan medoxomil were 2.5-22.5 μg/ml and 4-36 μg/ml, respectively. The second method is based on the derivative spectrophotometric method at zero crossing wavelengths. The linearity ranges for hydrochlorothiazide and olmesartan medoxomil were 2.5-20 μg/ml and 4-32 μg/ml, respectively. The accuracy of the methods were assessed by recovery studies and was found to be 100.45% ±0.4215 and 100.24% ±0.3783 for absorbance ratio method and 99.39% ±0.221 and 99.72% ±0.11 for first derivative method, for hydrochlorothiazide and olmesartan medoxomil, respectively. These methods are simple, accurate and rapid, those require no preliminary separation and can therefore be used for routine analysis of both drugs in quality control laboratories.

Chandipura Virus: an emerging tropical pathogen.

Chandipura Virus (CHPV), a member of Rhabdoviridae, is responsible for an explosive outbreak in rural areas of India. It affects mostly children and is characterized by influenza-like illness and neurologic dysfunctions. It is transmitted by vectors such as mosquitoes, ticks and sand flies. An effective real-time one step reverse-transcriptase PCR assay method is adopted for diagnosis of this virus. CHPV has a negative sense RNA genome encoding five different proteins (N, P, M, G, and L). P protein plays a vital role in the viruss life cycle, while M protein is lethal in nature. There is no specific treatment available to date, symptomatic treatment involves use of mannitol to reduce brain edema. A Vero cell based vaccine candidate against CHPV was evaluated efficiently as a preventive agent against it. Prevention is the best method to suppress CHPV infection. Containment of disease transmitting vectors, maintaining good nutrition, health, hygiene and awareness in rural areas will help in curbing the menace of CHPV. Thus, to control virus transmission some immense preventive measures need to be attempted until a good anti-CHPV agent is developed.

Design, synthesis and pharmacological evaluation of pyrimidobenzothiazole-3-carboxylate derivatives as selective L-type calcium channel blockers.

L-type voltage gated calcium channels play essential role in contraction of various skeletal and vascular smooth muscles, thereby plays important role in regulating blood pressure. Dihydropyridine receptors have been targeted for development of newer antihypertensive agents, one of the structurally analogs nucleus dihydropyrimidines have been reported earlier by us as a potential agent toward development of calcium channel modulator. A pre-synthetic QSAR was run and on the basis of structure activity relationship a series of twenty three molecules was synthesized and studied by myosin light chain kinase assay (MLCK), Angiotensin Converting Enzyme (ACE) colorimetric assay, non-invasive blood pressure (NIBP) and invasive blood pressure (IBP) methods. Molecules with significant efficacy were studied for their single crystal X-ray diffraction, molecular docking, molecular dynamics and post-synthetic QSAR. The NIBP and IBP methods screened molecules with better percentage inhibition versus time compared to standard drug Nifedipine. The lead compound ethyl 2-methyl-4-(3-nitrophenyl)-4H-pyrimido [2,1-b] [1,3] benzothiazole-3-carboxylate (26) presented a triclinic structure with polymeric chain packing in lattice. 26 exhibited IC50 on MLCK assay of 2.1±1.7 μM with selectivity of L-type calcium channels and comparative to Nifedipine. It offered satisfactory physicochemical properties with partition coefficient of (ClogP) 4.64. Its pharmacokinetic profile is also good with Cmax at 0.40 μg/ml by oral route with Tmax reaching in 0.5 h which means in 30 min. 26 also exhibits superior t1/2 of 5.4 h and oral bioavailability of (F) 56.75% with an AUC0-∞ of 0.84 μg h/ml. Molecular docking studies indicates toward the interaction of lead compound via hydrogen bonds with Lys144, Glu181 and Asp183, it forms the Van der Walls interactions with Ser18, Asp20, Asn187, Pro185, Glu180, Glu181 and Arg10 with Glide score and Glide energy to be -3.602 and -47.098, respectively. Post-synthetic QSAR of newly synthesized molecules indicates toward improvement with respect to steric descriptor which contributed negatively in former series.

Comparison of UV spectrophotometry and high performance liquid chromatography methods for the determination of repaglinide in tablets

Background: Repaglinide is a miglitinide class of antidiabetic drug used for the treatment of type 2 diabetes mellitus. A fast and reliable method for the determination of repaglinide was highly desirable to support formulation screening and quality control. Objective: UV spectrophotometric and reversed-phase high performance liquid chromatography (RP-HPLC) methods were developed for determination of repaglinide in the tablet dosage form. Materials and Methods: The UV spectrum recorded between 200 400 nm using methanol as solvent and the wavelength 241 nm was selected for the determination of repaglinide. RP-HPLC analysis was carried out using Agilent TC-C18 (2) column and mobile phase composed of methanol and water (80:20 v/v, pH adjusted to 3.5 with orthophosphoric acid) at a flow rate of 1.0 ml/min. Parameters such as linearity, precision, accuracy, recovery, specificity and ruggedness are studied as reported in the International Conference on Harmonization (ICH) guidelines. Results: The developed methods illustrated excellent linearity (r2 > 0.999) in the concentration range of 5-30 μg/ml and 5-50 μg/ml for UV spectrophotometric and HPLC methods, respectively. Precision (%R.S.D < 1.50) and mean recoveries were found in the range of 99.63-100.45% for UV spectrophotometric method and 99.71-100.25% for HPLC method which shows accuracy of the methods. Conclusion: The developed methods were found to be reliable, simple, fast, accurate and successfully used for the quality control of repaglinide as a bulk drug and in pharmaceutical formulations.

Design, synthesis and anticancer studies of novel aminobenzazolyl pyrimidines as tyrosine kinase inhibitors

Abnormal signalling from the Protein tyrosine kinases (PTKs) like receptor tyrosine kinases and intracellular tyrosine kinases can lead to diseases such as cancer especially non-small cell lung cancer, chronic myeloid leukaemia and gastrointestinal stromal tumours. Various Protein tyrosine kinase inhibitors are available but face poor bioavailability, severe toxicities and recent cases of drug-resistant cancers prompts for development of better drug molecules. In this study we report the design and development of a novel Protein Tyrosine Kinase (PTK) inhibitor on the basis of pharmacophore modelling. Compound 2-(benzo[d]oxazol-2-ylamino)-N-(2-chloro-4-fluorophenyl)-4-methyl-6-(3-nitrophenyl) pyrimidine-5-carboxamide 31 was obtained containing essential pharmacophore structural features. This compound exhibited highest activity against leukaemia cell line (RPMI-8226) at 0.7244 µM, renal cancer cell line (A498) at 0.8511 µM and prostate cancer cell line (PC-3) at 0.7932 µM on the NCI five dose assay test. The PTK assay provides promising activity at IC50 of 0.07 µM in the human breast cancer cell line MDA-MB-468. Compound 31 had good intermolecular interaction with PTK in the molecular docking studies, this ligand-enzyme complex was found to stable in the MM-PBSA study over 100 ns. It had 54.22% oral bioavailability with Tmax of 0.60 h which is higher compared to the dasatinib with bioavailability and Tmax of 14-34% and 1-1.42 h respectively. Anticancer action of 31 was found to be impressive in pharmacokinetic studies making it a potential lead molecule.

Development of dual inhibitors targeting DprE1 and AHAS for treatment of Mycobacterium tuberculosis infection

Background The emerging multidrug resistant (MDR) and extensively drug resistant (XDR) Mycobacterium tuberculosis (MTB) infection is increasing with greater complexity, estimated 220000-400000 tuberculosis cases emerged in 2011 globally. A number of lead compounds have been developed for treatment of MDR and XDR TB, but no new chemical entity has emerged for clinical use. Recently DprE1 and AHAS have been identified as promising drug targets.

Design and Development of Novel 2-(Morpholinyl)-N-substituted Phenylquinazolin-4-amines as Selective COX-II inhibitor

Background: A novel series of 2-(Morpholin-4-yl)-N-phenylquinazolin-4-amine derivatives were synthesized and confirmed with spectral and elemental techniques. Methods: The compounds were tested for analgesic and anti-inflammatory activity by various pain models in rodents whereas the selectivity towards COX-2 receptor is determined by in vitro assay. Results: Screening results of compounds exhibited comparable biological activity with that of standard compound Indomethacin used for study. Compound 5d was found to be significantly potent with respect to its anti-inflammatory and analgesic activity with substantial COX-II selectivity. Conclusion: In silico analysis by molecular docking and 3D-QSAR studies justifies activity profile of compound 5d, suggesting that it may have potential for further evaluation and development as lead molecule for therapy in pain management.

Progress in Synthesis of Monoglycerides for Use in Food and Pharmaceuticals

Glycerides are lipid esters of the glycerol molecule and fatty acids. Their primary function is the storage of energy. Due to its structure and properties, glycerol participates in the formulation or synthesis of many compounds such as food products, cosmetics, pharmaceuticals, liquid detergents. Monoglycerides (MGs) can be formed by both industrial chemical glycerolysis and biological or enzymatic processes. Chemical glycerolysis bring issues of low MGs yield, high operating temperature, formation of undesirable by-products and high energy consumption. On the other hand enzymatic processes have advantages of mild reaction conditions and high purity of MGs. But, several purification steps are required to obtain food or pharmaceutical grade MG, such as neutralization of the reaction media and discoloration followed by expensive molecular distillation. The purpose of this article is to review the main challenges in the synthesis of MGs from triglycerides (TGs) contained in the various fixed oils and application thereof in the food and pharmaceuticals.

Investigation of Effect of Extensively Used Polymers on Thermoreversible Properties of Pluronic ® Tri-Block Polymer

An UV spectrophotometric area under curve method was developed for the estimation of Levofloxacin Hemihydrate in its mono component tablets. The spectrophotometric method for estimation employed Area under curve method for analysis using 0.1M Sodium Hydroxide as solvent for the drug Levofloxacin Hemihydrate at the wavelength range of 285-295nm. Levofloxacin Hemihydrate obeys Beer’s law in concentration range 10-50µg/ml. The recovery studies ascertained accuracy of the proposed method and the result validated according to ICH guideline. Results of analysis have been valid statistically by recovery studies. The method was successfully for evaluation of Levofloxacin Hemihydrate in tablet dosage form without the interference of common excipients.

LEDGF/p75 IN interaction inhibitors: in silico studies of an old target with novel approach

Background Despite development in Anti Retroviral Therapy (ART), reports of HIV infection remains in continuous momentum and a cure seems to be imaginary. Raltegravir, an Integrase (IN) inhibitor, provides some life expectancy to patients on salvage therapy. Nowadays, IN inhibitors reported with resistance and shows cross resistance to other drugs in this class. Human Lens Epithelium Derived Growth Factor (LEDGF)/p75 plays a vital role in the HIV life cycle and its importance has been shown in numerous studies. In the LEDGF/p75 IN complex, LEDGF binds to IN at a region other than the catalytic active site. Thus, we tried computationally to approach these IN-LEDGF interaction sites as a novel target in therapy.