Characterization of novel radicals from COX-catalyzed arachidonic acid peroxidation.

The peroxidation of arachidonic acid (AA) catalyzed by cyclooxygenase (COX) is a well-known free radical-mediated process that forms many bioactive products. Because of a lack of appropriate methodologies, however, no comprehensive structural evidence has been found previously for the formation of COX-mediated and AA-derived free radicals. Here we have used a combination of LC/ESR and LC/MS with a spin trap, alpha-[4-pyridyl-1-oxide]-N-tert-butylnitrone (POBN), to characterize the carbon-centered radicals formed from COX-catalyzed AA peroxidation in vitro, including cellular peroxidation in human prostate cancer cells (PC-3). Three types of radicals with numerous isomers were trapped by POBN as ESR-active peaks and MS-active ions of m/z 296, 448, and 548, all stemming from PGF(2)-type alkoxyl radicals. One of these was a novel radical centered on the carbon-carbon double bond nearest the PGF ring, caused by an unusual beta-scission of PGF(2)-type alkoxyl radicals. The complementary nonradical product was 1-hexanol, another novel beta-scission product, instead of the more common aldehyde. The characterization of these novel products formed from in vitro peroxidation provides a new mechanistic insight into COX-catalyzed AA peroxidation in cancer biology.

[Simultaneous analysis of six effective components in the anti-Alzheimer's disease effective component group of Xiao-Xu-Ming Decoction].

A method based on high performance liquid chromatography (HPLC) was developed for the quantitative determination of six components in an anti-Alzheimer medicine, Xiao-Xu-Ming Decoction, which is an effective prescription in treating stroke and the sequela of stroke by herbalist doctors for thousands years. The effective component group (ECG) was made according to the results of high-throughput screening, and the curative effect of ECG was validated on aging rats. In this method an ODS column was used. The mobile phase consisted of water-formic acid-ethylenediamine (A; 100: 0.1: 0.1, v/v) and methanol-formic acid (B; 100 : 0.05, v/v), eluted with gradient (0 - 5 min, 20% B; 5 - 100 min, 20% B - 40% B; 100 - 140 min, 40% B - 70% B). The flow rate was 1 mL/min. The detection wavelength was set at 240 nm. Under the above separation conditions, six components belonged to two different categories, indicans and alkaloids, were determined simultaneously. The relationships between the concentrations and the peak areas of these six components were all linear. The recoveries of the six components were 99.1% for paeoniflorin, 99.6% for prim-O-glucosylcimifugin, 98.4% for baicalin, 99.9% for 4'-O-beta-D-glucosyl-5-O-methylvisamminol, 99.6% for fangchinoline, and 102.0% for tetrandrine. The relative standard deviations (RSD) were 1.3%, 1.4%, 0.4%, 0.8%, 0.2%, and 1.4%, respectively. This method is simple and reproducible and it can be used for the quality control of the effective component group of Xiao-Xu-Ming Decoction.