Aisyah Saad Abdul Rahim

A virtual screening approach for identifying plants with anti H5N1 neuraminidase activity

Recent outbreaks of highly pathogenic and occasional drug-resistant influenza strains have highlighted the need to develop novel anti-influenza therapeutics. Here, we report computational and experimental efforts to identify influenza neuraminidase inhibitors from among the 3000 natural compounds in the Malaysian-Plants Natural-Product (NADI) database. These 3000 compounds were first docked into the neuraminidase active site. The five plants with the largest number of top predicted ligands were selected for experimental evaluation. Twelve specific compounds isolated from these five plants were shown to inhibit neuraminidase, including two compounds with IC50 values less than 92 μM. Furthermore, four of the 12 isolated compounds had also been identified in the top 100 compounds from the virtual screen. Together, these results suggest an effective new approach for identifying bioactive plant species that will further the identification of new pharmacologically active compounds from diverse natural-product resources.

Acid corrosion inhibition of copper by mangrove tannin

Purpose – The purpose of this paper is to evaluate the corrosion inhibition potential of mangrove (Rhizopora apiculata) tannin in hydrochloric acid medium on copper with the view of developing a natural corrosion inhibitor.Design/methodology/approach – The mangrove tannin was extracted from the mangrove bark and its anticorrosion potential was studied by weight loss, electrochemical and scanning electron microscopy (SEM) analysis.Findings – It has been found that the mangrove tannin effectively inhibits the corrosion on copper metal in hydrochloric acid solution. The results of the electrochemical and weight loss methods showed that the inhibition efficiency of mangrove tannin increases with increasing its concentration. Inhibition is achieved through the adsorption of tannin molecules onto the copper surface and the adsorption follows the Langmuir adsorption isotherm model. SEM study also supports the adsorption of the inhibitor molecules onto the copper surface.Originality/value – In this paper, mangrov...

Ethyl 1-sec-butyl-2-(4-chloro­phen­yl)-1H-benzimidazole-5-carboxyl­ate

In the title compound, C20H21ClN2O2, the ethyl 1H-benzimidazole-5-carboxylate ring system, excluding the methylene and methyl H atoms, is almost planar, with a maximum deviation of 0.055 (1) Å, and makes a dihedral angle of 40.63 (4)° with the benzene ring. The sec-butyl group is disordered over two positions, with refined site occupancies of 0.855 (4) and 0.145 (4). In the crystal, molecules are linked into chains along [010] via intermolecular C—H⋯O hydrogen bonds and are further interconnected by C—H⋯Cl interactions into two-dimensional networks parallel to (001). The crystal structure is further consolidated by C—H⋯π interactions.

3-(2-Methyl­amino-1,3-thia­zol-4-yl)-2H-chromen-2-one

In the title compound, C13H10N2O2S, the essentially planar 2H-chromene ring system [maximum deviation = 0.0297 (13) Å] and the thiazole ring [maximum deviation = 0.0062 (11) Å] form a dihedral angle of 3.47 (5)°. In the crystal, N—H⋯N and C—H⋯O hydrogen bonds link the molecules into two-dimensional networks parallel to the bc plane. C—H⋯π and π–π [centroid–centroid separation = 3.6796 (8) Å] interactions further stabilize the crystal structure.

Ethyl 1-tert-butyl-2-(4-methoxy-phen-yl)-1H-benzimidazole-5-carboxyl-ate.

In the title molecule, C21H24N2O3, the imidazole ring is essentially planar, with a maxium deviation of 0.015 (1) Å. The dihedral angle between the benzene and imidazole rings is 65.47 (6)°. The crystal packing is stabilized by weak intermolecular C—H⋯O and C—H⋯N hydrogen bonds, forming zigzag chains along the c axis. The crystal structure is further stabilized by C—H⋯π interactions.

Ethyl 1-sec-butyl-2-phenyl-1H-benzimidazole-5-carboxyl­ate

In the title molecule, C20H22N2O2, the benzimidazole ring system is essentially planar, with a maximum deviation of 0.024 (1) Å. The dihedral angle between the phenyl and benzimidazole ring system is 43.71 (5)°. The atoms of the butyl group are disordered over two sets of sites with occupancies of 0.900 (4) and 0.100 (4). In the crystal structure, molecules are connected by weak intermolecular C—H⋯O hydrogen bonds, forming chains along the b axis. The crystal structure is further stabilized by C—H⋯π interactions.

Ethyl 1-(2-hy-droxy-eth-yl)-2-[2-(methyl-sulfan-yl)eth-yl]-1H-benzimidazole-5-carboxyl-ate.

In the crystal structure of the title compound, C15H20N2O3S, the hydroxy group is involved in the formation of O—H⋯N hydrogen bonds, which link two molecules into a centrosymmetric dimer. Weak C—H⋯O hydrogen bonds further link these dimers into chains propagating along the a axis. The crystal packing exhibits π–π interactions between the five- and six-membered rings of neighbouring molecules [centroid–centroid distance = 3.819 (2) Å] and short intermolecular S⋯S contacts of 3.495 (1) Å.

Ethyl 1-(2-hy­droxy­eth­yl)-2-p-tolyl-1H-benzimidazole-5-carboxyl­ate

The asymmetric unit of the title compound, C19H20N2O3, contains two molecules (A and B) with slightly different orientations of the ethyl groups with respect to the attached carboxylate groups. Intramolecular C—H⋯O hydrogen bonds generate S(8) ring motifs in both molecules A and B. In each molecule, the benzimidazole ring system is essentially planar, with maximum deviations of 0.023 (1) and 0.020 (1) Å, respectively, for molecules A and B. The dihedral angle between the benzimidazole ring system and the phenyl ring is 37.34 (5)° for molecule A and 42.42 (5)° for molecule B. In the crystal, O—H⋯N and C—H⋯O hydrogen bonds link the molecules into [100] columns with a cross-section of two-molecule by two-molecule wide, and further stabilization is provided by weak C—H⋯π and π–π interactions [centroid separations = 3.5207 (7) and 3.6314 (8) Å].

Ethyl 1-sec-butyl-2-(4-methoxy­phen­yl)-1H-benzimidazole-5-carboxyl­ate

In the title molecule, C21H24N2O3, the dihedral angle between the benzene and imidazole rings is 66.33 (13)°. The imidazole ring is essentially planar, with a maximum deviation of 0.004 (2) Å. In the crystal structure, molecules are connected by weak C—H⋯O hydrogen bonds, forming chains along the b axis

Ethyl 4-(2-hydroxy-ethyl-amino)-3-nitro-benzoate.

In the title compound, C11H14N2O5, the molecular structure is stabilized by an intramolecular N—H⋯O hydrogen bond, which generates an S(6) ring motif. The nitro group is twisted slightly from the attached benzene ring, forming a dihedral angle of 5.2 (2)°. In the crystal packing, intermolecular O—H⋯O and C—H⋯O hydrogen bonds link the molecules into a three-dimensional network. The crystal studied was a non-merohedral twin, the refined ratio of the twin components being 0.264 (2):0.736 (2).