Synthesis, biological evaluation, and molecular docking study of some new rohitukine analogs as protein tyrosine phosphatase 1B inhibitors.

Rohitukine (RH) was extracted from the stem bark of Dysoxylum binectariferum Hook. It was derivatized to different arylsulphanmides by treating with the corresponding aryl sulphonyl chlorides. These derivatives were tested in-vitro on protein tyrosine phosphatase 1B (PTP1B) inhibition. Among these the active compounds K2, K3, K5, and K8 significantly inhibited the PTP1B by 51.3%, 65.6%, 71.9%, and 55.9% respectively at 10 µg/ml, the results were also supported by in-silico docking experiments. The most potent compound K5 was analyzed for antidiabetic and antidyslipidemic activity in vivo. It showed a marked reduction in blood glucose level (random and fasting) and serum insulin level in db/db mice. It improved glucose intolerance as ascertained by the oral glucose tolerance test (OGTT). These NCEs (New Chemical Entities) also lowered cholesterol and triglyceride profiles while improved high-density lipoprotein cholesterol in db/db mice. The K5 was further evaluated for antiadipogenic activity on MDI (Methylisobutylxanthine, dexamethasone, and insulin)-induced adipogenesis. where it significantly inhibited MDI-induced adipogenesis in 3 T3-L1 preadipocytes, at 10 µM and 20 µM concentration. These results were compared with the parent compound RH which inhibited 35% and 45% lipid accumulation while the RH analog K5 inhibited the lipid accumulation by 41% and 51% at 10 and 20 µM concentration, respectively. These results well corroborated with in-silico studies.

Assessment of Clinical Pharmacokinetic Drug-Drug Interaction of Antimalarial Drugs α/ß-Arteether and Sulfadoxine-Pyrimethamine.

Antimalarial drug combination therapy is now being widely used for the treatment of uncomplicated malaria. The objective of the present study was to investigate the effects of coadministration of intramuscular α/ß-arteether (α/ß-AE) and oral sulfadoxine-pyrimethamine (SP) on the pharmacokinetic properties of each drug as a drug-drug interaction study to support the development of a fixed-dose combination therapy. A single-dose, open-label, crossover clinical trial was conducted in healthy adult Indian male volunteers (18 to 45 years, n = 13) who received a single dose of AE or SP or a combination dose of AE and SP. Blood samples were collected up to 21 days postadministration, and concentrations of α-AE, ß-AE, sulfadoxine, and pyrimethamine were determined by using a validated liquid chromatography-tandem mass spectrometry method. Pharmacokinetic parameters were calculated and statistically analyzed to calculate the geometric mean ratio and confidence interval. Following single-dose coadministration of intramuscular AE and oral SP, the pharmacokinetic properties of α/ß-AE were not significantly affected, and α/ß-AE had no significant effect on the pharmacokinetic properties of SP in these selected groups of healthy volunteers. However, more investigations are needed to explore this further. (This study has been registered in the clinical trial registry of India under approval no. CTRI/2011/11/002155.).

Pharmacokinetics, Tissue Distribution and Plasma Protein Binding Studies of Rohitukine: A Potent Anti-hyperlipidemic Agent.

Rohitukine (RH) is a chromone alkaloid considered as one of the major active component of Dysoxylum binectariferum, exhibiting diverse pharmacological activities such as anti-hyperlipidemic, anti-cancer, anti-inflammatory, immuno-modulatory, anti-leishmanial, anti ulcer and anti-fertility. There's still a lack of information of RH, inclusive of pharmacokinetics, tissue distribution and excretion, in vivo studies in experimental animals, such as hamster and rats. In this study, a selective and sensitive bioanalytical method was developed and validated using HPLC-UV system. The assay was applied to estimate pharmacokinetics, tissue distribution and excretion of RH in hamster at 50 mg/kg oral dose. It rapidly reached systemic circulation and distributed to various tissues, and highest concentration was observed in liver. The pharmacokinetic parameters such as clearance (CL/F) was 3.95±0.9 L/h/kg, volume of distribution (Vd/F) was 17.34±11.34 L/kg and elimination half-life was 2.62±1.34 h. RH shows moderate protein binding ~ 60% and found stable in gastro-intestinal fluid, a property that favors oral administration.

Mucoadhesive nanoparticles for prolonged ocular delivery of natamycin: In vitro and pharmacokinetics studies.

The aim of this study was to prepare natamycin encapsulated lecithin/chitosan mucoadhesive nanoparticles (NPs) for prolonged ocular application. These NPs were characterized by their mean particle size 213nm, encapsulation efficiency 73.57%, with a theoretical drug loading 5.09% and zeta potential +43. In vitro release exhibited a biphasic drug release profile with initial burst followed by a very slow drug release. The MIC(90) and zone of inhibition of NPs showed similar antifungal activity as compared to marketed suspension and free natamycin against Candida albicans and Aspergillus fumigates. The ocular pharmacokinetics of NPs and marketed formulation were evaluated in NZ rabbits. The NPs exhibit significant mucin adhesion. The AUC((0-∞)) was increased up to 1.47 fold and clearance was decreased up to 7.4-fold as compared to marketed suspension. The PK-PD and pharmacokinetic simulation was carried out to estimate optimum dosing regimen for good efficacy. Thus, lecithin/chitosan NPs could be considered useful approach aiming to prolong ocular residence and reduce dosing frequency.

Simultaneous estimation of 16α-hydroxycleroda-3,13(14) Z-dien-15,16-olide from Polyalthia longifolia and its metabolite in hamster plasma: application to pharmacokinetic study.

A selective and sensitive LC-MS-MS method was developed and validated for simultaneous estimation and pharmacokinetic studies of 16α-hydroxycleroda-3,13(14) Z-dien-15,16-olide (K-09) obtained from Polyalthia longifolia and its metabolite (K-9T), a novel antidyslipidemic agent. Sample clean-up involved liquid-liquid extraction of both the analytes and internal standard (rosuvastatin) from 200 µL of hamster plasma. The analytes were chromatographically separated on a Symmetry-Shield C18 (5 µm, 4.6 × 150 mm) column, using acetonitrile-0.1% aqueous formic acid (92:08, v/v) as the mobile phase. Detection was performed using negative ion electrospray ionization in multiple reaction monitoring mode. The MS/MS response was linear over the concentration range 1.56-200 ng/mL, with a correlation coefficient (r²) of 0.998 or better. The within- and between-batch precisions (relative standard deviation, %RSD) and the accuracy (percentage bias) were within acceptable limits as per FDA guidelines. The validated method was successfully applied to reveal the pharmacokinetic parameters of K-09 and metabolite after oral administration. This method will therefore be highly useful for future studies of K-09 and metabolite K-9T pharmacokinetics in preclinical and clinical studies.

Simultaneous estimation of E- and Z-isomers of guggulsterone in rabbit plasma using liquid chromatography tandem mass spectrometry and its application to pharmacokinetic study.

A sensitive and selective liquid chromatography/tandem mass spectrometric method was developed for simultaneous determination of E- and Z-guggulsterone isomers (antihyperlipidemic drug) in rabbit plasma. Both the isomers were resolved on a Symmetry-Shield C(18) (5 µm, 4.6 × 150 mm) column, using gradient elution comprising a mobile phase of methanol, 0.5% v/v formic acid and acetonitrile. With dexamethasone as internal standard, plasma samples were extracted by an automated solid-phase extraction method using C(18) cartridges. Detection was performed by electrospray ionization in multiple reaction monitoring (MRM) in positive mode. The calibration curve was linear over the concentration range of 1.56-200 ng/mL (r(2) ≥ 0.998) for both analytes. The intra-day and inter-day accuracy and precision were within -0.96 to 4.12 (%bias) and 2.73 to 8.00 (%RSD) respectively. The analytes were stable after three freeze-thaw cycles. The method was successfully applied to study steriospecific pharmacokinetics of E- and Z-guggulsterone in NZ rabbit.

Bioanalytical method development and validation of natamycin in rabbit tears and its application to ocular pharmacokinetic studies.

A new selective and sensitive high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method was developed for the quantification of natamycin in rabbit tears using amphotericin B as internal standard (IS). Chromatographic separation was achieved on a Luna Cyano column (100 mm × 2 mm, 3 µm) using ammonium acetate buffer (pH 4; 3.5mM): methanol (10:90, v/v) as the mobile phase. The run time was 5 min. Detection was performed by negative ion electrospray ionization in multiple reaction monitoring (MRM) mode. The calibration curve was linear over the concentration range from 25 to 800 ng/ml, and lower limit of detection of 12.5 ng/ml. The accuracy and precision of the method were within the acceptable limit of ± 20% at the lower limit of quantitation and ± 15% at other concentrations. Natamycin was stable during the battery of stability studies viz., bench-top, auto-sampler, freeze/thaw cycles and 30 days storage in a freezer at -70 ± 10 °C. The method was successfully applied to the ocular pharmacokinetic studies of natamycin eye drops in New Zealand rabbit tears.

Bioanalytical method development and validation of novel antithrombotic agent S002-333 by LC-MS/MS and its application to pharmacokinetic studies.

A rapid, sensitive and simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) method using an electrospray ionization (ECI) source for the quantification of novel anti-thrombotic agent S002-333 [2-(4-methoxy-benzenesulfonyl)-2,3,4,9-tetrahydro-1H-ß-carboxylic acid amide] in rabbit plasma was developed and validated. The extraction from plasma was carried out by simple protein precipitation extraction method. The chromatographic separation was performed on an Ultramex Cyno, (150 x 4.6 mm, 5 µm) with a guard column, using acetonitrile-water (75:25,v/v) with flow rate of 0.6 mL/min as the mobile phase. The tandem mass spectrometer was tuned in the multiple reaction monitoring mode to monitor the m/z transitions 386.4/215.4 for S002-333 and m/z 393.4/171 for the internal standard dexamethasone, using positive ion mode. The MS/MS response was linear over the concentration range from 1.56 to 200 ng/mL, with a lower limit of detection of 0.78 ng/mL. The accuracy and precision of the method were within the acceptable limit of ±20% at the lower limit of quantitation and ±15% at other concentrations and showed no significant matrix effect. The validated method can be used in most or all stages of the screening and optimizing process for future method validation of pharmacokinetic studies.