Rupesh Chikhale

Development of selective DprE1 inhibitors: Design, synthesis, crystal structure and antitubercular activity of benzothiazolylpyrimidine-5-carboxamides

Decaprenylphosphoryl-b-D-ribose 20-epimerase (DprE1) is a potential drug target for development of antitubercular agents. Structure based drug discovery approach yielded twenty novel derivatives of benzothiazolylpyrimidine-5-carboxamides (7a-t) which were synthesised by three component one pot reaction involving benzothiazolyl oxobutanamide, thiourea and substituted aromatic benzaldehydes. These derivatives were evaluated for antitubercular activity to determine MIC and compound 7a, 7e, 7f and 7o were found to be potentially active against Mycobacterium tuberculosis (H37Rv). Log P of these compounds was found to be between 2.0 and 3.0 making them suitable for oral dosing. DprE1 selectivity and pharmacokinetic studies were carried out for these compounds of which 7a and 7o were found to be highly selective and bioavailability was found to be above 52% by oral dose. Crystal structure of 7a was studied and molecular packing was determined, it exhibited a triclinic crystal lattice arrangement having hydrogen bonded dimeric arrangement. Drug receptor interactions were studied which exhibited docking in the active site of receptor with hydrogen bonding, hydrophobic interactions, vdW interactions with amino acid residues such as Cys387, Asn385, Lys418, Tyr314, Gln334 and Lys367 respectively. 3D QSAR analysis was carried out by kNN-MFA method to determine and develop theoretical model, best suitable model was found to be based on Simulated Annealing k-Neariest Neighbour Molecular Field Analysis (SA kNN-MFA). The model provided with hydrophobic descriptors in positive side indicating the need of bulky groups, steric and electronegative descriptors in negative coordinates hints with contribution by the electronegative substitutions as favourable and desirable moieties for enhancing the activity. The q(2), q(2)_se and Pred_r(2)se were found to be 0.5000, 0.6404 and 1.0094 respectively. A pharmacophore model was generated which suggested for necessity of aromatic, aliphatic carbon centre and hydrogen bond donor for development of newer DprE1 selective inhibitors.

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.

Determination and Pharmacokinetic Study of Pirfenidone in Rat Serum by High-Performance Thin-Layer Chromatography

A rapid, sensitive and selective high-performance thin-layer chromatography (HPTLC) method was developed and validated for the determination and pharmacokinetics of pirfenidone in rat serum. One-step protein precipitation by methanol is reported, and serum samples were separated by HPTLC using a simple mobile phase of toluene-methanol in the ratio of 8:2. The retardation factor of pirfenidone in the serum sample was 0.45 with the detection performed at 315 nm. The calibration curve was linear over the range of 100-1,200 ng/spot with a lower limit of quantitation of 40 ng/spot. The mean recovery of pirfenidone in serum was in the range of 70.6-75.8%, and intra-day and inter-day precision were both <14.1%. This method was successfully applied to the pharmacokinetic study of pirfenidone in rats on oral administration of the drug at a dose of 15.0 mg/kg.

A validated stability-indicating high-performance thin-layer chromatographic method for the analysis of methotrexate in bulk drug and marketed injection

Methotrexate (MTX) is a folic acid antagonist used for the treatment of cancer and autoimmune diseases such as psoriasis, rheumatoid arthritis (RA), lupus, and sarcoidosis. It belongs to the class of antimetabolite and antifolate drugs that can be taken orally as well as parenterally. Structurally, it is analogous to folic acid and thus acts as a competitive inhibitor (Figure 1) [1]. As an anticancer agent, it acts by inhibiting the dihydrofolate reductase (DHFR) necessary for the pathway leading to the synthesis of DNA, and, in the case of autoimmune disorders like RA, the drug acts by inhibition of the T-cell function and by down regulation of the B-cells [2, 3]. Chemically, it is 2-[(4-{[(2,4-diaminopteridin-6-yl)methyl](methyl)amino} benzoyl)amino]pentanedioic acid and it is available in various dosage forms for administration such as injectable and tablet formulations. MTX is known to persist for longer duration in the body and is secreted in urine, excreta, and saliva and found in tooth enamel as well [1, 4]. It is one of the old anticancer drugs still used in therapy for the treatment of cancer.

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.

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.

Smallest Organism; Highest Threat -

Ever since the discovery of virus in beginning of 20th century, infections caused by these organisms have captured attention of researchers. The evolution of viruses is still a controversy, even same for their categorization in either living or non-living. It is clear that besides many controversies virus remains challenging to treat as well as to control in some extent. Though vaccines are available as prophylactic tool and antiviral drugs for treatment, still virus exist in host cells if they successfully invade biological machinery. Now it remains as challenge to treat these smallest organisms with high degree of efficacy and safety. To answer the demand of the present world there is urgent need of more potent and novel drugs for treatment and vaccines to prevent infection. Answer to this problem will definitely reduce casualties occurring worldwide. This review presents few of the pandemics, their causative agents, current status of treatment and future prospective.