Hypepontine,a new quaternary alkaloid with antimicrobial properties

Abstract

New isoquinoline alkaloid hypepontine (1) together with a five known compounds, were identified in Hypecoum ponticum Velen, the partial synonym of Hypecoum procumbens L. The structure of the new substance was elucidated based on spectroscopic evidence. The tertiary and quaternary alkaloid mixtures as well as the isolated alkaloids were evaluated for their antibacterial and antifungal activity. The result revealed that the crude alkaloid mixture containing quaternary isoquinoline alkaloids showed potent antifungal and antibacterial activity.     

Leptopyrine,new alkaloid from Leptopyrum fumarioides L. (Ranunculaceae)

A new type of isoquinoline alkaloid leptopyrine was isolated from the aerial parts of Leptopyrum fumarioides L. (Ranunculaceae) of Mongolian origin. The known alkaloids protopine and thalifoline were isolated for the first time from this the species. All structures were established by physical and spectral analyses.     

Spectrometric studies about some dyes - anionic surfactant interactions in aqueous solutions

This work presents some alternative analytical methods for anionic surfactant quantitative determination in aqueous solutions. Interactions of aqueous solutions of three dyes (Rhodamin B, Methyl violet and Fuchsin basic), concentrations 0.3x10(-6) M, with two anionic surfactants in the concentration range of 10(-5) M (sodium salt of naphthalene sulphonate formaldehyde condensates and melamine sulphonate formaldehyde condensates) have been investigated. Spectrometric measurements were performed on an UV-Vis spectrometer Hewlett Packard 8452A with diode array detection. From the UV-Vis spectra of individual and mixed dye-anionic surfactant aqueous solutions in various concentration ranges, specific changes in the chromophore microenvironment and in the intensity of absorbance is observed. These changes can be attributed to the chemical and structural characteristics of dyes and anionic surfactants, and could be exploited for analytical purposes.     

Special regime of liquid-assisted laser ablation of ceramics

Results of experimental study the peculiarities of liquid-assisted laser ablation of alumina–silicate ceramics are reported giving attention particularly to effect of thin-wall glass macrosphere appearance at the end of irradiation onto a formed hole in bulk material. Typical times of formation, size and temperature dynamics, and chemical composition were determined; kinetics and mechanism of formation are discussed in presented paper.     

Hydrogen tunneling steps in cyclooxygenase-2 catalysis

Cyclooxygenases-1 and -2 are tyrosyl radical (Y·)-utilizing hemoproteins responsible for the biosynthesis of lipid-derived autocoids. COX-2, in particular, is a primary mediator of inflammation and believed to be up-regulated in many forms of cancer. Described here are first-of-a-kind studies of COX-2-catalyzed oxidation of the substrate analogue linoleic acid. Very large (≥20) temperature-independent deuterium kinetic isotope effects (KIEs) on the rate constant for enzyme turnover were observed, due to hydrogen atom abstraction from the bisallylic C-H(D) of the fatty acid. The magnitude of the KIE depends on the O(2) concentration, consistent with reversible H/D tunneling mediated by the catalytic Y·. At physiological levels of O(2), retention of the hydrogen initially abstracted by the catalytic tyrosine results in strongly temperature-dependent KIEs on O-H(D) homolysis, also characteristic of nuclear tunneling.     

Application of Validated TLC—Densitometric Method for Simultaneous Identification and Determination of Losartan Potassium,Telmisartan, and Valsartan in Tablets

JPC – Journal of Planar Chromatography – Modern TLC - The antihypertensive effect of sartans is a result of inhibition of the binding of angiotensin (AT) II to the AT1 receptor in...