Nagarajan Sulochana

An anti-inflammatory and anti-microbial flavone glycoside from flowers of Cleome viscosa.

Background Natural products isolated from plant sources have been demonstrated as potential candidates against several ailments. The scientific investigations on the underlying principles of phytotherapy can pave way for the convergence of traditional medicines and modern science and technologies. Results Quercetin 3-O-(2′′-acetyl)-glucoside obtained from ethyl acetate fraction of Cleome viscosa is studied against inflammatory of carrageenan-induced rat paw edema ( in vivo) and microbial activity on ( in vitro). The structure of the glycoside is confirmed by means of hydrogen-1 nuclear magnetic resonance spectroscopy, carbon nuclear magnetic resonance spectroscopy, attached proton test, and mass spectrum. The flavonoid glycoside showed significant anti-inflammatory activity of on carrageenan-induced rat paw edema ( in vivo) and anti-microbial activity ( in vitro) on Staphylococcus aureus (gram positive) and Escherichia coli (gram negative). The anti-inflammatory effect of the flavonoid glycoside may be due to the inhibition of prostaglandin synthesis. Selective toxicity with flavonoid glycoside towards the gram-positive bacteria was found on S. aureus. Conclusions The present study reveals the anti-inflammatory and antimicrobial activities of an isolated quercetin 3-O-(2′′-acetyl)-glucoside from a natural source ( C. viscosa).

Studies On The Inhibitive Effect Of 3-Hydroxyflavone On The Acid Corrosion Of Mild Steel

The corrosion inhibition effect of 3-hydroxyflavone was studied on mild steel in 1 M hydrochloric acid (HCl). The anticorrosive effect was evaluated by weight loss and electrochemical methods which include Tafel polarization and AC impedance studies at 300 K. In weight loss method, the inhibition efficiency increased with increase in inhibitor concentration, and decreased with increase in temperature and immersion time, and acid concentration. The inhibitor showed maximum efficiency of 91% at 4 × 10-4 M concentration in 1 M hydrochloric acid. The Tafel polarization study showed that the inhibitor behaves likely as cathodic type. The corrosion inhibition effect measured by weight loss method and electrochemical studies was in good agreement with each other. The surface analysis was done by using scanning electron microscope (SEM). Several adsorption isotherms are assessed to study the adsorption behavior of the inhibitor on the mild steel surface. The negative value of ΔGads indicates the spontaneous adsorption of the inhibitor on mild steel surface.

A new biflavone glycoside from flowers of Asystasia gangetica

The yellow parts of the flowers of Asystasia gangetica were extracted with 85% methanol under reflux. The alcoholic extract was concentrated in vacuo and the aqueous extract was fractionated with solvents of increasing polarity. The ethyl acetate fraction yielded a yellow solid, which was characterized as apigenin 7-O-glucosyl(3′ → 6″)luteolin 7″-O-glucoside using UV, 1H, 1H–1H COSY, 13C NMR, and mass spectral studies.

2,6,6-Trimethyl-cyclo-hex-2-ene-carb-oxy-lic acid.

In the title crystal structure, C10H16O2, inversion-related molecules are linked by pairs of O—H⋯O hydrogen bonds involving carboxyl groups to form R 2 2(8) dimers. The cyclohexene ring displays a half-chair conformation.

2,6,6-Trimethyl­cyclo­hexene-1-carbaldehyde oxime

In the crystal of the title compound C10H17NO, synthesized by the reaction of β-cyclocitral with hydroxylamine hydrochloride, inversion-related molecules are linked by a pair of O—H⋯N hydrogen-bonding interactions between the oxime functionalities, forming R 2 2(6) loops. The molecular conformation is stabilized by intramolecular methyl C—H⋯N interactions. The cyclohexene ring has the typical half-chair conformation.

Dimethyl 2,2'-[(4-oxo-2-phenyl-4H-chromene-5,7-di-yl)di-oxy]diacetate: a less densely packed polymorph.

The title molecule, C21H18O8, crystallizes in two crystal polymorphs, see also Nallasivam, Nethaji, Vembu & Jaswant [Acta Cryst. (2009), E65, o312–o313]. The main difference between the two polymorphs is in the conformation of the oxomethylacetate groups with regard to the almost planar [total puckering amplitude 0.047 (2) Å] chromene ring. In the title compound, the best planes of the oxomethylacetate groups through the non-H atoms are almost perpendicular to the chromene ring [making dihedral angles of 89.61 (6) and 80.59 (5)°], while in the second polymorph the molecules are close to planar. Both crystal structures are stabilized by C—H⋯O.

5,7-Dimeth­oxy-2-phenyl-4H-chromen-4-one

The asymmetric unit of the title compound, C17H14O4, contains two independent molecules which differ in the relative orientations of the phenyl rings with repect to the essentially planar [maximum deviations of 0.029 (2) and 0.050 (2) Å in the two molecules] chromene fused-ring system, forming dihedral angles of 10.3 (5) and 30.86 (5)° in the two molecules. The crystal structure is stabilized by weak C—H⋯O and C—-H⋯π interactions, and π–π stacking interactions.

2-Phenyl-5,7-bis-(prop-2-en-1-yl-oxy)-4H-chromen-4-one.

In the title compound, C21H18O4, tthe dihedral angle between the chromene ring system and the pendant phenyl ring is 6.1 (1)°. The crystal structure is stabilized by an intermolecular C—H⋯O and C—H⋯π interactions.

6,8-Dibromo-5-hydr-oxy-4-oxo-2-phenyl-4H-chromen-7-yl acetate.

In the title compound, C17H10Br2O5, the chromene ring is almost planar with minimal puckering [total puckering amplitude = 0.067 (4) Å]. The dihedral angle between chromeme ring system and phenyl ring is 3.7 (2)°. The crystal structure is stabilized by intermolecular C—H⋯O interactions and an intramolecular O—H⋯O hydrogen bond also occurs.

4-Meth­oxy-5-[4-(4-meth­oxy-1,3-benzodioxol-5-yl)perhydro-1H,3H-furo[3,4-c]furan-1-yl]-1,3-benzodioxole

The 1,3-benzodioxole ring systems in the title compound, C22H22O8, are almost planar. The perhydrofurofuranyl system linking them adopts a distorted double-envelope conformation. Supramolecular aggregation is effected by C—H⋯O, C—H⋯π and π–π [centroid–centroid distance of 3.755 Å, interplanar distance of 3.633 Å and dihedral angle of 14.6°] interactions.