Mohamed M. El-Kerdawy

Spectrophotometeric determination of someN-substituted phenothiazine derivatives usingN-bromophthalimide

A simple, rapid and sensitive spectrophotometric method is described for the quantitative determination ofN-substituted phenothiazines. The method depends on the formation of a stable phenothiazine free radical cation by the use ofN-bromophthalimide as oxidising agent in a strong acid medium (methanol/ sulphuric acid 1∶ 1 v/v). The produced red or violet color possesses absorption maximum range from 500 to 530 nm. A linear relationship exists between the absorbance at (λmax) and concentration in the range 5 to 40 μg ml−1 with apparent molar absorptivities range from 6 × 103 to 12 × 1031 mol−1 cm−1. The color is developed instantaneously for all the studied phenothiazines except for thioproperazine mesylate, trifluoperazine dihydrochloride and prochlorperazine mesylate that require 25, 15 and 25 min, respectively, for complete reaction. The developed colors are stable over 24 h. The average % recovery is 99.85±0.61 to 100.28±0.95. The method was applied successfully to the microdetermination of chlorpromazine HCl, promethazine HCl, pericyazine, thioproperazine mesylate, perphenazine, prochlorperazine mesylate, trimeprazine tartrate and trifluoperazine 2HCl either in pure form or incorporated in their pharmaceutical preparations. The results of analysis are in good agreement with those of the official B.P. 1988 and USP XXII.

Synthesis and pharmacological evaluation of novel fused thiophene derivatives as 5-HT2A receptor antagonists: Molecular modeling study

Novel derivatives of cyclopentathienopyrimidinediones 6, pyridothienopyrimidinediones 7, ethyl cycloheptathiophene-3-carboxylates 10, ethyl tetrahydrothienopyridine-3-carboxylates 11, tetrahydrocycloheptathienopyrimidin-4(3H)-ones 12, tetrahydrotriazolobenzothienopyrimidin-5(4H)-ones 17 and tetrahydro-5H-cycloheptathienopyrimidin-4(3H)-ones 21 have been synthesized and tested for their 5-HT2A antagonist activity. Preliminary pharmacological studies showed that compounds 3-[2-[4-phenylpiperazin-1-yl]ethyl]-6,7-dihydro-5H-cyclopenta[b]thieno[2,3-d]pyrimidine-2,4(1H,3H)-dione 6a and ethyl 2-[[4-(2-methoxyphenyl)piperazin-1-yl]acetylamino]-4,5,6,7-tetrahydro-6-methylthieno[2,3-c]pyridine-3-carboxylate 11d were found to be the most active molecules as 5-HT2A antagonists. Molecular modeling and pharmacophore prediction methodology are used to study the structural features required for 5-HT2A antagonist properties of the active compounds compared with nonactive species by means of the molecular mechanic method. The 2-methoxy substituent in the structure of 11d seems to be necessary for its full antagonistic properties. Optimal placement of basic nitrogen relative to the plane of thiophene core was found to have a profound effect on affinity and biological activity.

Synthesis, Docking Study and β-Adrenoceptor Activity of Some New Oxime Ether Derivatives

A new series of oxime ethers 4a–z was designed and synthesized to test the blocking activity against β1 and β2-adrenergic receptors. Docking of these ether derivatives into the active site of the identified 3D structures of β1 and β2-adrenergic receptors showed MolDock scores comparable to those of reference compounds. Biological results revealed that the inhibition effects on the heart rate and contractility are less than those of propranolol. Nevertheless, the two compounds 4p and 4q that displayed the highest negative MolDock score with β2-adrenergic receptors showed β2-antagonistic activity by decreasing salbutamol relaxation of precontracted tracheal strips, which indicates the importance of a chlorothiophene moiety in the hydrophobic region for best complementarity with β2 receptors. On other hand, the presence of a homoveratryl moiety increases the MolDock score of the tested compounds with the β1 receptor.

Spectrophotometric Determination of Pyrithioxin in Pharmaceutical Preparations

Abstract Rapid direct and induced difference spectrophotometric methods for determination of pyrithioxin in single dosage forms (tablets and syrups) are reported. The direct methods depend upon measurement of the absorbance of pyrithioxin in different media at λmax i-e at 296 nm in 0.1 M hydrochloric acid, at 328 nm in citric acid-phosphate buffer of pH 7 and at 314 nm in 0.1 M sodium hydroxide. The mean percentage recovery of the authentic samples were 100.55±0.43, 101.21±0.58 and 100.29±0.64 respectively (P=0.05). The absorbance difference methods are based upon either measurement of the difference between the acid and the alkaline solutions i-e. Δ A (Alk-Acid) at 318 nm with an accuracy of 100.72±0.88 or the absorbance difference between the acid and neutral solutions i-e Δ A (pH 7-acid) at 328 nm with an accuracy of 100.31±0.68.

Structure-based drug design and biological evaluation of 2-acetamidobenzothiazole derivative as EGFR kinase inhibitor

Abstract EGFR tyrosine kinase has been reported mainly in 40–80% of non-small lung cancers, in addition to colon and breast cancers. In this study, we illustrate the synthesis of a highly potent antitumor agent. The synthesized compound 4 was screened at NCI, USA, for antitumor activity against non-small lung cancer, colon cancer and breast cancer cell lines. Results indicated that this compound is more potent antitumor agent compared to erlotinib against all tested cell lines except breast cancer (MDA-MB-468) cell line. In addition, it was tested initially at a single dose concentration of 100 µM over 11 different kinases. At this concentration, 94.45% inhibition of the enzymatic activity of EGFR kinase was observed, while the inhibition in activity was below 55% in all other kinases. Compound 4 was further tested in a 10-dose IC50 mode and showed IC50 value of 0.239 µM for EGFR kinase. In vivo acute toxicity of this compound was also tested.

Synthesis and in vitro antitumor evaluation of some new thiophenes and thieno[2,3-d]pyrimidine derivatives

New thiophene (2-13) and thienopyrimidine (15-27) derivatives have been synthesized. Twenty three compounds were screened against five cell lines namely; hepatocellular carcinoma (liver) HepG-2, epidermoid carcinoma (larynx) Hep-2, mammary gland (breast) MCF-7, human prostate cancer PC-3 and epithelioid cervix carcinoma HeLa. The results revealed that compounds 15,16,17,24 and 25 showed the highest antitumor activity against all tested cell lines compared to Doxorubicin. In order to explain the expected mode of action of the observed anticancer activity, compounds 15,16,17,24 and 25 were selected to screen their DNA binding affinity and enzyme inhibitory activity against DNA polymerase, thymidylate synthase and tyrosine kinase. The results revealed that the tested compounds showed good DNA binding affinity as well as good inhibitory activity against the three enzymes which might explain the observed anticancer activity of the target compounds.

New Benzimidazothiazole Derivatives as Anti-inflammatory, Antitumor active agents: Synthesis, In-vitro and In-vivo Screening and Molecular Modeling Studies

A new series of benzimidazothiazole derivatives has been synthesized. The structure of the products was confirmed by spectroscopic techniques such as IR, NMR and mass spectroscopy. The tested compounds were evaluated for their anti-inflammatory activity either in vitro through the COX enzyme inhibition assay, or in vivo through carrageenan paw edema technique. Results revealed that compound 25 and 29 represented the most active ones among the entire series with % inhibition 72.19, 72.07 for COX-1, and 87.46, 87.38 for COX-2, respectively. Interestingly, all synthesized compounds exhibited IC50 values less than both reference drugs celecoxib and naproxen, indicating their superior potency. For compound 25, it showed about 340 and 198 times more potent than celecoxib and naproxen respectively as COX-1 inhibitor (IC50 value 0.044 vs. 15.000 and 8.700 µM), and 10 and 115 times more potent than the same drugs as COX-2 inhibitor (IC50 value 4.52 vs. 40.00 and 520.00 nM). The antitumor activity of the products was also evaluated and the results obtained are consistent with those obtained by the anti-inflammatory screening where compounds 25 and 29 proved to be the most active ones among the other compounds with %GI ranging from 31.5 to 62.5% and they exhibited the lowest IC50 values as well. The ADMET analysis of the tested compounds was also performed in addition to the molecular modeling studies that included flexible alignment, surface and electrostatic maps in addition to the Lipinisks rule of five.