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Fulltext Synthesis of new 2,5-di-substituted 1,3,4-oxadiazoles bearing 2,6-di-tert-butylphenol moieties and evaluation of their antioxidant activity

Shakir RM, Ariffin A, Abdulla MA

Molecules, 2014;19(3):3436-49.

PMID: 24658568 DOI: 10.3390/molecules19033436

Eleven new 2,6-di-tert-butyl-4-(5-aryl-1,3,4-oxadiazol-2-yl)phenols 5a-k were synthesized by reacting aryl hydrazides with 3,5-di-tert butyl 4-hydroxybenzoic acid in the presence of phosphorus oxychloride. The resulting compounds were characterized based on their IR, ¹H-NMR, ¹³C-NMR, and HRMS data. 2,2-Diphenyl-1-picrylhydrazide (DPPH) and ferric reducing antioxidant power (FRAP) assays were used to test the antioxidant properties of the compounds. Compounds 5f and 5j exhibited significant free-radical scavenging ability in both assays.

Fulltext Ethyl 4-[(3,5-di-tert-butyl-2-hy-droxy-benz-yl)amino]-benzoate

Shakir RM, Ariffin A, Ng SW

Acta Crystallogr Sect E Struct Rep Online, 2010;66(Pt 11):o2916.

PMID: 21589090 DOI: 10.1107/S1600536810040742

The title amine, C(24)H(33)NO(3), has two substituted aromatic rings at either end of the -CH(2)NH- linkage [C(ar-yl)-CH(2)-NH-C(ar-yl) torsion angle = 77.4 (3)°]. The amino and hy-droxy groups are hydrogen-bond donors to the carbonyl O atom of an adjacent mol-ecule. These hydrogen bonds give rise to a chain that runs along the b axis. One of the tert-butyl groups is disordered over two positions with a site-occupation factor of 0.834 (6) for the major occupied site.

Fulltext Ethyl 4-[(3,5-di-tert-butyl-2-hy-droxy-benzyl-idene)-amino]-benzoate

Shakir RM, Ariffin A, Ng SW

Acta Crystallogr Sect E Struct Rep Online, 2010;66(Pt 11):o2915.

PMID: 21589089 DOI: 10.1107/S1600536810041383

The title compound, a Schiff base, C(24)H(31)NO(3), has a substituted aromatic ring at both ends of the azomethine linkage and these make a dihedral angle of 24.9 (1)°. There is an intra-molecular hydrogen bond between the hy-droxy group (donor) and the N atom of themazomethine linkage.

Fulltext Synthesis and antibacterial evaluation of some novel imidazole and benzimidazole sulfonamides

Al-Mohammed NN, Alias Y, Abdullah Z, Shakir RM, Taha EM, Hamid AA

Molecules, 2013 Sep 26;18(10):11978-95.

PMID: 24077176 DOI: 10.3390/molecules181011978

Several new substituted sulfonamide compounds were synthesized and their structures were confirmed by ¹H-NMR, ¹³C-NMR, FT-IR, and mass spectroscopy. The antibacterial activities of the synthesized compounds were screened against standard strains of six Gram positive and four Gram negative bacteria using the microbroth dilution assay. Most of the compounds studied showed promising activities against both types of bacteria.

Fulltext 2-Methyl-3-[(4-methyl-phen-yl)sulfon-yl-oxy]-2-{[(4-methyl-phen-yl)sulfon-yloxy]meth-yl}propyl 4-methyl-benzene-sulfonate

Al-Mohammed NN, Shakir RM, Alias Y, Abdullah Z, Abd Halim SN, Tiekink ER

Acta Crystallogr Sect E Struct Rep Online, 2011 Jul 1;67(Pt 7):o1838.

PMID: 21837205 DOI: 10.1107/S1600536811024664

The title mol-ecule, C(26)H(30)O(9)S(3), adopts an extended conformation whereby two approximately parallel benzene rings [dihedral angle = 8.32 (10)°] are orientated in opposite directions along the pseudo-threefold axis through the central quaternary C atom, while a third ring occupies a position mid-way and face-on to these rings [dihedral angles = 82.28 (10) and 78.81 (7)°]. The crystal packing is dominated by C-H⋯O contacts and π-π inter-actions [ring centroid distance = 3.6902 (12) Å].

Fulltext (E,E)-1,2-Bis[3-meth-oxy-4-(prop-2-yn-1-yl-oxy)benzyl-idene]hydrazine

Al-Mehana WN, Shakir RM, Yahya R, Abd Halim SN, Tiekink ER

Acta Crystallogr Sect E Struct Rep Online, 2011 Jul 1;67(Pt 7):o1659.

PMID: 21837059 DOI: 10.1107/S1600536811022410

The complete mol-ecule in the title compound, C(22)H(20)N(2)O(4), is generated by the application of an inversion centre. With the exception of the terminal acetyl-ene groups [C-O-C-C = -78.02 (17)°], the remaining atoms constituting the mol-ecule are essentially coplanar. The configuration around the C=N bond [1.282 (2) Å] is E. The formation of supra-molecular chains mediated by C-H⋯O inter-actions, occurring between methyl-ene H and meth-oxy O atoms, is the most notable feature of the crystal packing.

Fulltext Gastroprotective activity of ethyl-4-[(3,5-di-tert-butyl-2-hydroxybenzylidene) amino]benzoate against ethanol-induced gastric mucosal ulcer in rats

Halabi MF, Shakir RM, Bardi DA, Al-Wajeeh NS, Ablat A, Hassandarvish P, et al.

PLoS One, 2014;9(5):e95908.

PMID: 24800807 DOI: 10.1371/journal.pone.0095908

BACKGROUND: The study was carried out to determine the cytotoxic, antioxidant and gastro-protective effect of ethyl-4-[(3,5-di-tert-butyl-2-hydroxybenzylid ene)amino] benzoate (ETHAB) in rats.

METHODOLOGY/PRINCIPAL FINDINGS: The cytotoxic effect of ETHAB was assessed using a MTT cleavage assay on a WRL68 cell line, while its antioxidant activity was evaluated in vitro. In the anti-ulcer study, rats were divided into six groups. Group 1 and group 2 received 10% Tween 20 (vehicle). Group 3 received 20 mg/kg Omeprazole. Groups 4, 5 and 6 received ETHAB at doses of 5, 10, and 20 mg/kg, respectively. After an hour, group 1 received the vehicle. Groups 2-6 received absolute ethanol to induce gastric mucosal lesions. In the WRL68 cell line, an IC50 of more than 100 µg/mL was observed. ETHAB results showed antioxidant activity in the DPPH, FRAP, nitric oxide and metal chelating assays. There was no acute toxicity even at the highest dosage (1000 mg/kg). Microscopy showed that rats pretreated with ETHAB revealed protection of gastric mucosa as ascertained by significant increases in superoxide dismutase (SOD), pH level, mucus secretion, reduced gastric lesions, malondialdehyde (MDA) level and remarkable flattened gastric mucosa. Histologically, pretreatment with ETHAB resulted in comparatively better gastric protection, due to reduction of submucosal edema with leucocyte infiltration. PAS staining showed increased intensity in uptake of Alcian blue. In terms of immunohistochemistry, ETHAB showed down-expression of Bax proteins and over-expression of Hsp70 proteins.

CONCLUSION/SIGNIFICANCE: The gastroprotective effect of ETHAB may be attributed to antioxidant activity, increased gastric wall mucus, pH level of gastric contents, SOD activity, decrease in MDA level, ulcer area, flattening of gastric mucosa, reduction of edema and leucocyte infiltration of the submucosal layer, increased PAS staining, up-regulation of Hsp70 protein and suppressed expression of Bax.

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