Osama I. El-Sabbagh

Synthesis and antiviral activity of new pyrazole and thiazole derivatives

New N-acetyl (5-8) and N-thiocarbamoyl (9-12) derivatives of 4,5-dihydropyrazole were synthesized starting from alpha,beta-unsaturated ketones under the effect of hydrazine hydrate and thiosemicarbazide, respectively. N-Thiocarbamoylpyrazole derivatives (9-12) were cyclized using either ethyl bromoacetate or phenacyl bromides to afford the novel pyrazolothiazol-4(5H)-ones (13-16) or pyrazolothiazoles (17-24). The antiviral activity for such novel compounds against a broad panel of viruses in different cell cultures revealed that N-acetyl 4,5-dihydropyrazole 7 was the only active one at subtoxic concentrations against vaccinia virus (Lederle strain) in HEL cell cultures with a 50% effective concentration (EC(50)) value of 7 microg/ml.

Synthesis of new acridines and hydrazones derived from cyclic β-diketone for cytotoxic and antiviral evaluation

Cyclic beta-diketone namely, dimedone was utilized to prepare different chemical entities whether cyclic such as acridines, thiadiazole and triazole or acyclic systems as hydrazide, hydrazones, thiosemicarbazide and semicarbazide. The structures of the novel compounds were determined using elemental analyses and various spectroscopic methods. Most acyclic derivatives especially semicarbazide 19, hydrazide 9 and thiosemicarbazide 16 showed a higher in vitro cytotoxic activity against hepatoma cell line (HepG2) than the cyclized acridine derivatives. The antiviral activity of the new compounds against Hepatitis A Virus (HAV) using the plague infectivity reduction assay revealed that the acridine 4 and the hydrazone 12 were more active than the reference drug amantadine.

New octahydroquinazoline derivatives: Synthesis and hypotensive activity

Several novel 1-(4-chlorophenyl)-7,7-dimethyl-1,2,3,4,5,6,7,8-octahydro-5-oxo-3-(substitutedphenyl)quinazoline derivatives (2-21) structurally similar to prazosin, were prepared using Mannich reaction of 3-(4-chlorophenylamino)-5,5-dimethyl-2-cyclohexenone (1) with different aromatic amines in the presence of formaline. The structures of the quinazoline derivatives were established using elemental and spectral analyses. Compounds 18, 20 and 21 were found to possess a high hypotensive effect through their expected α(1)-blocking activity like the clinically used drug prazosin but with advantageous of being did not cause reflex tachycardia and having prolonged duration of action when tested in adrenaline-induced hypertension in anaesthetized rats.

Design, synthesis and in vitro anticancer evaluation of 4,6-diamino-1,3,5-triazine-2-carbohydrazides and -carboxamides

Series of substituted 4,6-diamino-1,3,5-triazine-2-carbohydrazides and -carboxamides have been synthesised, based on molecular modelling of candidate structures related to the previously reported Rad6B-inhibitory diamino-triazinylmethyl benzoate anticancer agents TZ8 and TZ9. Synthesis of the target compounds was readily accomplished in two steps from aryl biguanides via reaction of phenylhydrazine or benzylamines with key 4-amino-6-(arylamino)-1,3,5-triazine-2-carboxylate intermediates. These new triazine derivatives were tested for in vitro anticancer activity against the Rad6B expressing human breast cancer cell lines MDA-MB-231 and MCF-7. Active compounds, such as the triazinyl-carbohydrazides 3a-e, were found to exhibit low micromolar IC50 values particularly in the Rad6B-overexpressing MDA-MB-231 cell line.

Synthesis and Some Pharmacological Studies of New Benzenesulfonamide Derivatives

Summary. New benzenesulfonamide derivatives containing pyrazole and oxadiazole moieties were prepared starting from sodium saccharin. The structures of the novel compounds were characterized by elemental analyses and spectroscopic methods. The new compounds are structurally related to the COX-2 inhibitor celecoxib (Celebrex®). A pharmacological study of the pyrazoles revealed that several compounds possess higher analgesic and antiinflammatory activities than celecoxib, particularly 11 and 17. Most of the pyrazoles showed a significant increase in the sleeping time of thiopentone anaesthesized mice and also protected mice against the convulsive and lethal effects of pentylenetetrazole. Moreover, the ulcerogenic activity of those compounds showing a pronounced antiinflammatory effect was also studied.

Synthesis of New 2,3‐Dihydroquinazolin‐4(1H)‐one Derivatives for Analgesic and Anti‐inflammatory Evaluation

Starting from isatoic anhydrides, several new 2,3‐dihydroquinazolin‐4(1H)‐one derivatives bearing chalcone or pyrazole or thiazole moieties at the third position were synthesized. The analgesic and anti‐inflammatory activities for most compounds were studied at a dose level of 50 mg/kg via the acetic‐acid‐induced writhing‐response method and carrageenan‐induced edema method, respectively. The study showed that the chalcones bearing a 4‐chlorophenyl group 4c or 4‐nitrophenyl group 4b were the most active ones as analgesics. Both chalcone 4c and N‐phenyl pyrazole bearing 4‐methoxy phenyl group 5b showed a higher anti‐inflammatory activity than celecoxib but still lower than that of diclofenac sodium. Moreover, the chalcone 4c has nearly the same ulcerogenic index as the selective cyclooxygenase‐2 inhibitor celecoxib.

Design, synthesis and preliminary antiviral screening of new N-phenylpyrazole and dihydroisoxazole derivatives

A new series of N-phenylpyrazoles and dihydroisoxazles was synthesized starting from α,β-unsaturated ketones in basic media using phenyl hydrazine and hydroxylamine HCl, respectively. Antiviral evaluation of the target compounds revealed that the dihydroisoxazole derivatives have promising antiviral activity against hepatitis A virus and herpes simplex virus type 1.

Synthesis of Some New Benzisothiazolone and Benzenesulfonamide Derivatives of Biological Interest Starting from Saccharin Sodium

Two new series of benzenesulfonamide (4a–f, 5a–b, 6, 7) and 1,2‐benzisothiazol‐3(2H)‐one‐1,1‐dioxide (9a–c, 10, 12a–d) derivatives were prepared starting from saccharin sodium. The novel compounds were characterized using elemental analyses and different spectroscopic methods. Assessment of the antiviral activities of these novel compounds against a broad panel of viruses in different cell cultures revealed that only the thiazole derivatives belonging to the benzisothiazol‐3(2H)‐one‐1,1‐dioxide series are the active ones. All thiazole derivatives 12a–d showed activity against both varicella‐zoster virus, especially TK− VZV strain 07‐1, and the cytomegalovirus strains AD‐169 and Davis in human embryonic lung (HEL) cell culture.

Synthesis and biological evaluation of some N-arylpyrazoles and pyrazolo[3,4-d]pyridazines as anti-inflammatory agents.

A series of 3,4‐bis‐chalcone‐N‐arylpyrazoles 3a–k was prepared from diacetyl pyrazoles 2a–e. The reaction of 2d and 2e with hydrazine hydrate gave pyrazolo[3,4‐d]pyridazine derivatives 4a–b. Furthermore, the reaction of 2a–e with thiosemicarbazide afforded pyrazolo[3,4‐d]pyridazine thiocyanate salts 5a–e. The synthesized compounds were subjected to in vivo anti‐inflammatory and ulcerogenic activity measurements, in addition to determination of their in vitro COX selectivity, to give a full profile about their anti‐inflammatory activities. Compounds 3c, 3f, 3i, and 3e showed significant anti‐inflammatory activity among the synthesized compounds. Moreover, docking studies were performed to give an explanation for their anti‐inflammatory activity through COX selectivity.

Design, synthesis and cytotoxic activity of novel 1-aroyl-4-(2-chloroethyl)semicarbazides

A series of aroyl derivatives of 4-(2-chloroethyl)semicarbazide were designed and synthesized to explore their antiproliferative activity against human brain carcinoma (U251) and human liver carcinoma (Hepg2) cell lines. The synthesized compounds were characterized by elemental analyses and spectroscopic data. It was established that compounds in which semicarbazide fragments are substituted with a (2-indolyl)carbonyl moiety showed a higher cytotoxic activity than the corresponding benzoyl derivatives. 1-[(5-Benzyloxy-1H-indol-2-yl)carbonyl]-4-(2-chloroethyl)semicarbazide (24) showed the highest cytotoxic activity against Hepg2 (IC50= 21 µg/ml), while 4-(2-chloroethyl)-1-[(5-methoxy-1H-indol-2-yl)carbonyl]semicarbazide (23) was the most active compound against U251 (IC50 = 8 µg/ml).