A new phthalazinone derivative and a new isoflavonoid glycoside from lichen-associated Amycolatopsis sp.

A new phthalazinone derivative, named amycophthalazinone A (1), and a new isoflavonoid glycoside, 7-O-methyl-5-O-α-L-rhamnopyranosylgenestein (2), along with an isoflavonoid glycoside, 7-O-α-D-arabinofuranosyl daidzein (3) firstly found from natural sources, and eight known compounds (4-11), were isolated from the culture broth of the lichen-associated Amycolatopsis sp. YIM 130642. The structures of new compounds were elucidated on the basis of spectroscopic analysis. Compound 1 was the first example of naturally occurring phthalazinone derivative. The antimicrobial activities of all compounds towards five pathogenic strains were evaluated by a broth microdilution assay. Compound 1 exhibited the most potent inhibitory activity against Staphylococcus aureus, Salmonella typhi, and Candida albicans with MIC values of 32, 32, and 64 µg/mL, respectively.

A novel methylthio metabolite of s-triazolo[3,4-a]phthalazine, a lead compound for the development of antianxiety drugs, in rats.

When s-triazolo[3,4-a]phthalazine (Tri-P) was orally administered in rats, a more lipophilic metabolite M-1 than the parent compound was isolated from the urine. The metabolite M-1 was identified as 7-methylthio Tri-P by means of high resolution MS and two-dimensional NMR spectrometry. Furthermore, the 7-methylthio conjugate was generated from the parent compound Tri-P in isolated rat hepatocytes. Although the contribution of the intestinal microflora to the formation of methylthio metabolite has been pointed out so far, the limited data in this study lead us to conclude that the liver plays a role in all metabolic reactions of Tri-P to its 7-methylthio conjugate in rats.

Simultaneous enantioselective separation of azelastine and three of its metabolites for the investigation of the enantiomeric metabolism in rats. I. Liquid chromatography-ionspray tandem mass spectrometry and electrokinetic capillary chromatography.

Enantioselective separation methods and the enantioselective determination of the anti-allergic drug azelastine and of three of its main phase I metabolites in a biological matrix underwent chromatographic and electrophoretic investigations. An enantioselective assay of a coupling of HPLC using a beta-cyclodextrin chiral stationary phase to ionspray tandem mass spectrometry is presented. Additionally, this assay is compared to another enantioselective assay using electrokinetic capillary chromatography with beta-cyclodextrin and carboxymethyl-beta-cyclodextrin in polyacrylamide-coated capillaries. For capillary electrophoresis (CE) the importance of polyacrylamide coating for the validation of this separation method is highlighted. Extracted rat plasma samples of enantioselective metabolism studies were measured by both validated assays. Differences in the pharmacokinetics and pharmacodynamics were evaluated for the main substance azelastine and its main metabolite demethylazelastine. So, a first hint about the enantioselectivity of biotransformation of azelastine in rats was seen after oral application of either enantiomer or the racemate to rats.

An investigation of the properties of a "shielded" phase for the solid phase extraction of acidic and basic compounds.

The extraction properties of Hisep, a novel bonded phase for solid phase extraction, have been investigated using a number of acidic and basic analytes and compared with those of a conventional ODS bonded material. Marked differences in extraction properties for the test analytes propranolol, anisic acid and ICI 128436 from aqueous buffer were noted between the two materials. Thus, extraction onto the ODS material was by both ionic and reversed-phase mechanisms whilst retention on the Hisep phase appeared to be mediated predominantly by reversed-phase hydrophobic interactions. The presence of dog plasma had no effect on the extraction of propranolol but did reduce the extraction efficiencies observed for anisic acid and ICI 128436 in a pH dependent manner.

Conalbumin-conjugated silica gel, a new chiral stationary phase for high-performance liquid chromatography.

A new chiral stationary phase using conalbumin (from chicken egg white) was developed for high-performance liquid chromatography. Chiral resolution of racemic azelastine, an antiallergic drug, was achieved on a conalbumin-conjugated silica gel column. The effects of the pH, the concentration of organic solvents and salts in the mobile phase, and the temperature on the capacity factor and resolution of racemic azelastine were examined. This column shows good stability and can separate optical isomers with an aqueous mobile phase. It should be very useful in studies on pharmacokinetics and in clinical chemistry.