Bannimath Gurupadayya

Design, synthesis and biological evaluation of 1,3,4-oxadiazoles as promising anti-inflammatory agents

A series of 1,3,4-oxadiazole derivatives were designed, synthesized and evaluated for radical scavenging and anti-inflammatory properties. Molecular docking simulation studies onto the proteins cyclooxygenase-1 (PDB: 1CQE) and cyclooxygenase-2 (PDB: 3LN1) to visualize the probable binding affinity towards anti-inflammatory importance and in silico studies, towards their appreciable ADME & probable toxicity property were screened. The best-ranked molecules; N-((5-substituted-1,3, 4-oxadiazol-2-yl)methyl) benzo[d]thiazol-2-amine (5a–5j) were synthesized from 2-(benzo[d]thiazol-2-ylamino)acetohydrazide (4) on reaction with aryl/heteroaryl/aliphatic carboxylic acid derivatives via acid catalyzed dehydrative cyclization. N-((5-mercapto-1,3,4-oxadiazol-2-yl)methyl) benzo[d]thiazol-2-amine (5k) was synthesized by base catalyzed condensation of hydrazide derivative 4 and with carbon disulfide. The newly synthesized compounds were characterized and established on the basis of elemental analysis, IR, 1H NMR, 13C NMR and mass studies. The 1,3,4-oxadiazoles were evaluated for in vitro antioxidant property by 2,2′-diphenyl-1-picryl hydrazyl radical scavenging assay method and in vivo anti-inflammatory activity by carrageenan induced paw edema method. The radical scavenging activity indicated that the 1,3,4-oxadiazoles at 25 µM test concentration exhibited significant radical scavenging property ranging from 32.0 to 87.3 % in comparison to 76.0 % radical scavenging activity obtained for the reference drug, ascorbic acid. The results of the in vivo anti-inflammatory activity highlighted that the 1,3,4-oxadiazoles at 25 mg Kg−1 test dose exhibited significant edema inhibition with a mean value ranging from 23.6 to 82.3 % in comparison to 48.3 % edema inhibition obtained for the reference drug, indomethacin. The compound 5h with mean edema inhibition value of 82.3 % and potent among the series was further evaluated for in vitro COX inhibition and was found to more selective towards COX-2. The acute ulcerogenic evaluation of compound 5h indicated it to be safe at the dose of 50 mg Kg−1.

Synthesis of 1,3,4-oxadiazoles as promising anticoagulant agents

In the present study, a series of 2,5-disubstituted-1,3,4-oxadiazole derivatives (4a–4k) were designed and subjected to molecular docking simulation studies onto the enzymes vitamin K epoxide reductase (PDB: 3KP9) and factor Xa (PDB: 1NFY) to visualize their binding affinity towards the said target proteins. In silico ADME studies highlighted that the designed compounds are safe enough and have the potential to be considered as drug like molecules, indicating the appreciable ADME property & probable toxicity of the designed compounds. The title compounds were synthesized from (benzo[d]oxazol-2-yl)methanamine and evaluated for in vitro radical scavenging properties and ex vivo anticoagulant activity. The results of the ex vivo anticoagulant evaluation highlighted that the compounds exhibited a significant increase in prothrombin time and clotting time, and a minimal increase in the activated partial thromboplastin time, indicating that the compounds can be considered for promising anticoagulant therapy. The results of the radical scavenging experiments indicated that the compounds have substantial antioxidant activity.

Recent Advances in Chiral Separation of Antihistamine Drugs: Analytical and Bioanalytical Methods

Chirality is now a key area in the field of research. Researchers are well versed with analytical separations but at the same time, they are unaware of the growth in the field of chiral separation. According to the United States Food and Drug Administration (US FDA) guidelines, it is mandatory to separate chiral drugs before they are marketed. Chiral separation has gained importance in the last 10 years due to the differential biological responses of the enantiomers in chiral environment. Identical physical and chemical properties of the enantiomers pose a major challenge for the separation of chiral compounds. Further, bioanalytical method development is also necessary to throw light on the fate of separated enantiomers in biological environment. High Performance Liquid Chromatography (HPLC) and Capillary Electrophoresis (CE) are the most widely used techniques for such separation. Antihistamines are a class of drugs that are represented by a wide number of chiral compounds. Hence this review focuses on enantioseparation of chiral antihistamine drugs. It begins with a brief discussion about antihistamine drugs, chiral separation and its need for study, followed by a brief overview of the analytical and bio-analytical work carried out on different chiral antihistamine drugs. The analytical and bio-analytical techniques that are used include HPLC, CE and some new techniques.

Optimized and Validated RP-UPLC Method for the Determination of Losartan Potassium and Chlorthalidone in Pharmaceutical Formulations.

PURPOSE A validated ultra performance liquid chromatography (UPLC) method has been developed and validated for the simultaneous determination of losartan potassium and chlorthalidone in pharmaceutical preparations. METHODS Waters-Acquity UPLC system equipped with Auto Sampler, PDA detector and operated with Empower-2 software was used for the present study. Detection was done at wavelength of 230 nm, HSS C18, 100 mm x 2.1x 1.8 μm column with a reverse phase elution and mobile phase composed of A and B mixed in the ratio 56:44 v/v (Where mobile phase A consists of potassium dihydrogen phosphate buffer of pH 3.0 and Mobile phase B consists of acetonitrile and methanol mixed in the ratio of 90:10 v/v) used at a flow rate of 0.4ml per minute. RESULTS The retention times for losartan potassium and chlorthalidone were observed at 0.72 and 1.89 minutes. The developed method was validated as per ICH guidelines. Linearity ranges were found to be 12.5-125 μg/ml and 3.125-31.25 μg/ml for losartan potassium and chlorthalidone, respectively. CONCLUSION This method is fast, accurate, precise and sensitive hence it can be employed for routine quality control of tablets containing both drugs in industries.

Bioanalytical method development and validation for simultaneous estimation of clopidogrel and pantoprazole

H metal ion pollution is a serious environment problem that has attracted more and more attentions in recent years. Mercury ion (Hg2+) and lead ion (Pb2+) are two of the most toxic metallic pollutants even at an extremely low concentration. Copper ion (Cu2+), an essential micronutrient element for human life, can cause adverse health effects when present in high concentrations. Considerable efforts have been devoted to the detection of heavy metal ions due to their high toxicity towards the ecosystem and human health. Unlike the traditional detection technologies, we have developed some simple and sensitive biosensors without the requirement of sophisticated instrumentation and skilled personnel. With the combination of DNAzyme, DNA machine and lateral flow biosensor, the visual instrument-free method offers a point-of-use solution for heavy metal ion analysis and provides a basis for the future work aiming at the development of household devices for sensitive detection of various analytes.Purpose: The aim of our present work was to develop and validate a reverse phase high-performance liquid chromatography (RP-HPLC) method for the determination of Decitabine (DCB). The developed method was further applied to observe the degradation of DCB under various stress conditions. Methods: Chromatographic separation was achieved on C18, 250 × 4.6 mm, particle size 5 μm, Agilent column, using ammonium acetate (0.01M) as mobile phase with flow rate of 1mL/min and injection volume was 20 μL. Quantification was carried out with UV detector at 230 nm with a linear calibration curve in the concentration range of 10–100 μg/mL based on peak area. Thus, developed method was validated for linearity, accuracy, precision, and robustness. Results: Linearity was found to be in the range between 10–100 μg/mL with a significantly higher value of correlation coefficient r = 0.9994. The limits of detection (LOD) and the limits of quantification (LOQ) were found to be 1.92μg/mL and 5.82 μg/mL respectively. Moreover, validated method was applied to study the degradation profile of DCB under various stress degradation conditions. Examination of different stress conditions on degradation of DCB showed that its degradation was highly susceptible to oxidative condition as 31.24% of drug was degraded. In acidic and alkaline conditions, the drug was degraded by 21.03% and 12.16% respectively, while thermal and photolytic condition causes least degradation, i.e. 0.21% and 0.3% respectively. Conclusion: The proposed method was found to be sensitive, specific and was successfully applied for the estimation of DCB in bulk drug, and lipid based nanoparticles.Abstract: A validated stability-indicating HPLC method has been reported for the determination of Ilaprazole in bulk drug and tablet. The drug was subjected to the various stress conditions as per the ICH guidelines. The degradation behavior of Ilaprazole was studied under hydrolytic, oxidative, photolytic and thermal conditions and was found to be unstable in almost all conditions except under alkaline and photolytic conditions. The separation of drug and its degraded products was carried out on Kinetex C-18 100A (5µ, 250×4.6 mm) column. The initial mobile phase composition used was Acetonitrile and water in the ratio 50:70v/v for 1 min then changed to 70:30v/v in next 6 min and finally equilibrated back to initial composition in 14min. The method was applied for the determination of Ilaprazole in marketed tablet formulation. The detection was carried at 305 nm using PDA detector with a flow rate of 1.0ml/min and injection volume 20µl. The validation of developed method was performed for linearity, accuracy, precision, selectivity and specificity and robustness.In the present work orodispersible tablets of Ondansetron hydrochloride were formulated by effervescent and sublimation method using factorial design. In the effervescent method, crospovidone (1.31%-4.68%) was used as superdisintegrant whereas citric acid (7.95%-18.04%) and sodium bicarbonate (5.22%-28.77%) were used as effervescent agent. In the sublimation method, crospovidone (1.58%-4.41%) was used as superdisintegrant whereas camphor (6.34%-17.35%) was used as subliming agent. The prepared batches of tablets were evaluated for hardness, friability, drug content uniformity, wetting time, disintegration time and In Vitro drug release pattern. Total 15 batches were formulated by effervescent method and 9 batches were formulated by sublimation method. Disintegration time of the formulations prepared by effervescent method was found between 13-36 secs whereas formulations prepared by sublimation method showed disintegration time between 7-39 secs. Among all the formulations, the formulation (S6) prepared by sublimation method using crospovidone 4% and camphor 8% was found to have the minimum disintegration time (7 seconds). Finally, it was concluded that Orodispersible tablet of Ondansetron Hydrochloride can be successfully formulated using effervescent and sublimation method and can be used as a novel drug dosage form for pediatric and geriatric with improved patient compliance and enhanced bioavailability.I this presentation, the interaction between cilostazol and two different cyclodextrins (β-CD and DM-β-CD) is studied by using LC. The capacity factors (k) of cilostazol were monitored in the presence of increasing concentrations of β-CD or DM-β-CD from the reduction of the retention time (tR). It was observed that cilostazol forms a 1:1 inclusion complex with β-cyclodextrin (β-CD) and dimethyl-β-cyclodextrin (DM-β-CD) at 250C, 370C and 450C. The interaction of cilostazol with DM-β-CD was more efficient and the highest the formation constant (K) was found for DM-β-CD (23.82M-1) at 250C. Moreover, the values of K decreased as the system temperature increased. To obtain the information on the mechanism of cilostazol affinity for β-CD and DM-β-CD, the thermodynamic parameters of the complexation (ΔG, ΔH, and ΔS) were studied. Finally, a comparison of the K values obtained for the two different cyclodextrins revealed that the K values of the complexation are dependent upon the structure of the host molecule. The change in the thermodynamic parameters suggested that the complexation could proceed spontaneously (ΔG<0) along with the releasing of heat (ΔH<0) and the decrease of entropy (ΔS<0).T light scattering of single nanoparticle, such as gold and silver nanoparticles, is stable and efficient, hence the applications of single nanoparticle-based dark-field microscopic imaging have attracted extensive attention. Both the changes of single nanoparticle scattering imaging color and scattering intensity can be used as effective detection signal in analytical chemistry. In the author’s group, to study the localized surface plasmon resonance (LSPR) light scattering of single nanoparticle, first the shape effect of single silver nanoparticle on the scattering light color and refractive index sensitivities was investigated. It was found that particles with a large radial ratio or a tip structure always had a higher sensitivity which could be due to the LSPR maxima at long wavelengths and the strong electric field intensity distribution. Then single nanoparticle-based RGB analytical method was established by coding the colors of the scattering light of individual nanoparticles with the RGB system, and the imaging date was manipulated with the IPP software. In addition, the scattering light intensity of single gold nanoparticle was digitized and expressed as digital information through the aforementioned software. Based on the RGB system and digitized method, it was established new scattering analytical method which had been certified in our other energy transfer experiment. Furthermore, the single nanoparticle-based dark-field microscopic imaging was also used to monitoring some chemical reactions. Real-time monitoring of the etching process of gold nanoparticles by iodine, in situ growth of single Ag@Hg nanoalloys and photochemical reaction were successfully achieved by dark-field microscopic imaging. In addition to the chemical reactions, the single nanoparticle-based dark-field microscopic imaging has a potential to real-time monitoring the intracellular biochemical reactions and infection process of bacteria and virus which may provide a new method for the diagnosis of the disease.