Mohammed Saleh Shekhani

Development of the Predictor hERG Fluorescence Polarization Assay Using a Membrane Protein Enrichment Approach

The life-threatening consequences of acquired, or drug-induced, long QT syndrome due to block of the human ether-a-go-go-related gene (hERG) channel are well appreciated and have been the cause of several drugs being removed from the market in recent years because of patient death. In the last decade, the propensity for block of the hERG channel by a diverse and expanding set of compounds has led to the requirement that all new drugs be tested for hERG channel block in a functional patch-clamp assay. Because of the need to identify potential hERG blockers early in the discovery process, radiometric hERG binding assays are preferred over patch-clamp assays for compound triage, because of relative advantages in speed and cost. Even so, these radiometric binding assays are laborious and require dedicated instrumentation and infrastructure to cope with the regulatory and safety issues associated with the use of radiation. To overcome these limitations, we developed a homogeneous, fluorescence polarization-based assay to identify and characterize the affinity of small molecules for the hERG channel and have demonstrated tight correlation with data obtained from either radioligand binding or patch-clamp assays. Key to the development of this assay was a cell line that expressed highly elevated levels of hERG protein, which was generated by coupling expression of the hERG channel to that of a selectable cell surface marker. A high-expressing clone was isolated by flow cytometry and used to generate membrane preparations that contained >50-fold the typical density of hERG channels measured by [(3)H]astemizole binding. This strategy enabled the Predictor (Invitrogen, Carlsbad, CA) hERG fluorescence polarization assay and should be useful in the development of other fluorescence polarization-based assays that use membrane proteins.

Syntheses and Evaluation of the Analgesic Activity of Some 4-Acetyl- 4-phenylpiperidine and 4-Hydroxy-4-phenylpiperidine Derivatives

Synthesis and analgesic activity of 4-phenylpiperidine derivatives is a topic of high actuality. A s part of a programme towards obtaining new potential analgesics, ten derivatives of 4- acetyl-4-phenylpiperidine and ten derivatives of 4-hydroxy-4-phenylpiperidine were synthesised and characterized through spectroscopic techniques. All derivatives along with the parent compounds were evaluated for analgesic activity in the acetic acid-induced writhing assay and tail-flick test in mice. All derivatives of 4-acetyl-4-phenylpiperidine except one com pound exhibited more or less protection against mice writhing, whereas all the compounds proved to be inactive in the tail-flick test at doses of 50 and 100 mg/kg body weight.

Anhydro sugars, valuable intermediates in carbohydrate syntheses

The versility of the epoxyhydroxy functionlity in pyranoses is demonstrated giving access to sugar amino acids and peptides, aminodeoxy, halodeoxy , branched-chain, cyclopropanated and aziridino sugars.

Sodium hydride/hexamethylphosphoric triamide: a new and efficient reagent towards the synthesis of protected 1,2- and 5,6-enopyranosides

A new method for the elimination of hydrogen halides and p-toluenesulfonic acid from sugar moieties using sodium hydride (NaH) in hexamethylphosphoric triamide (HMPA) at room temperature is reported. NaH/HMPA has several advantages compared to NaH/DMF: elimination products are produced in high yields even from sterically hindered starting materials, and not only from halides, but also tosylates.

Convenient synthesis of mono and cyclic sulphates of carbohydrates via triflate displacement

The 2,3-anhydropyranoside-4-triflates (1), (3), and (6) react with tetrabutylammonium hydrogen sulphate to afford the sulphate esters (2), (4), and (7) respectively. In the case of triflates (3) and (6) the cyclic sulphates (5) and (8) were obtained as major products. The benzyl pyranoside (8) was successfully deblocked to yield the free sugar cyclic sulphate (9). The 1H NMR spectra of the newly synthesized sulphates have been discussed in detail. The 13C NMR spectral data are also described.

An Expeditious Approach to Trisubstituted Chiral Tetrahydrofurans

Abstract Ozonolysis of 3,6-anhydro-4-0-(p-toluenesulphonyl)-D-glucal (9), obtained in four steps from D-glucose, provided the target compound 11. The structure and configurations of 9 and 11 have been determined by spectral studies and X-ray crystallography. Similar strategy with D-galactose provided the corresponding derivatives 10 and 12, respectively

Synthesis of 3,4-dideoxy-3,4-C-cyanomethylene pyranosides: a new class of cyclopropanated sugars

A new class of 3,4-cyclopropanated sugars (5) and (6) has been synthesized by reacting the sugar triflates (1) and (2) with the nitrile-stabilized carbanion of acetonitrile.