A water-soluble Pd4 molecular tweezer for selective encapsulation of isomeric quinones and their recyclable extraction

Quinones (QN) are one of the main components of diesel exhaust particulates that have significant detrimental effects on human health. Their extraction and purification have been challenging tasks because these atmospheric particulates exist as complex matrices consisting of inorganic and organic compounds. In this report, we introduce a new water soluble Pd4L2 molecular architecture (MT) with an unusual tweezer-shaped structure obtained by self-assembly of a newly designed phenothiazine-based tetra-imidazole donor (L) with the acceptor cis-[(tmeda)Pd(NO3)2] (M) [ tmeda = N,N,N',N'-tetramethylethane-1,2-diamine]. The molecular tweezer encapsulates some quinones existing in diesel exhaust particulates (DEPs) leading to the formation of host-guest complexes in 1 : 1 molar ratio. Moreover, MT binds phenanthrenequinone (PQ) more strongly than its isomer anthraquinone (AQ), an aspect that enables extraction of PQ with a purity of 91% from an equimolar mixture of the two isomers. Therefore, MT represents an excellent example of supramolecular receptor capable of selective aqueous extraction of PQ from PQ/AQ with many cycles of reusability.

Possible mechanisms for induction of oxidative stress and suppression of systemic nitric oxide production caused by exposure to environmental chemicals

The cytotoxic effects evoked by exposure to environmental chemicals having electrophilic properties are often attributable to covalent attachment to intracellular macromolecules through sulfhydryl groups or enzyme-mediated redox cycling, leading to the generation of reactive oxygen species (ROS). When huge amounts of ROS form they overwhelm antioxidant defenses resulting in the induction of oxidative stress. Nitric oxide (NO) which plays a crucial role in vascular tone, is formed by endothelial NO synthase (eNOS). Since a decrease in systemic NO production is implicated in the pathophysiological actions of vascular diseases, dysfunction of eNOS by environmental chemicals is associated with cardiopulmonary-related diseases and mortality. In this review, we introduce the mechanism-based toxicities (covalent attachment and redox cycling) of electrophiles. Therefore, this review will focus on the possible mechanisms for the induction of oxidative stress and impairment of NO production caused by environmental chemicals.

[Development of selective determination methods for quinones with fluorescence and chemiluminescence detection and their application to environmental and biological samples]

Quinones are compounds that have various characteristics such as a biological electron transporter, an industrial product and a harmful environmental pollutant. Therefore, an effective determination method for quinones is required in many fields. This review describes the development of sensitive and selective determination methods for quinones based on some detection principles and their application to analyses in environmental, pharmaceutical and biological samples. Firstly, a fluorescence method was developed based on fluorogenic derivatization of quinones and applied to environmental analysis. Secondly, a luminol chemiluminescence method was developed based on generation of reactive oxygen species through the redox cycle of quinone and applied to pharmaceutical analysis. Thirdly, a photo-induced chemiluminescence method was developed based on formation of reactive oxygen species and fluorophore or chemiluminescence enhancer by the photoreaction of quinones and applied to biological and environmental analyses.

Determination of 9, 10-phenanthrenequinone in airborne particulates by High-Performance Liquid Chromatography with post-column fluorescence derivatization using 2-aminothiophenol

9, 10-Phenanthrenequinone (PQ) is regarded as a harmful environmental pollutant and its presence has been reported in atmospheric environment. The measurement of PQ in environment should be necessary to evaluate the influence of PQ on human health. We found that PQ reacted with 2-aminothiophenol under acidic condition to form fluorescent derivative which emits green fluorescence at 510nm. Based on this reaction, a simple and rapid determination method for PQ was developed by HPLC with post-column derivatization and fluorescence detection. By the proposed HPLC system, PQ was detected at 24min and the detection limit was 67fmol/injection (S/N=3). The proposed method was able to determine the atmospheric PQ concentrations by the direct injection of extract from airborne particulates.

Concentration and trend of 9,10-phenanthrenequinone in airborne particulates collected in Nagasaki city, Japan

9,10-Phenanthrenequinone (PQ), one of the components of atmospheric pollutants, has potent harmful effects on human health. PQ in airborne particulates collected in Nagasaki city was determined by HPLC with fluorescence derivatization. PQ extracted from airborne particulates using methanol was derivatized with benzaldehyde in the presence of ammonium acetate to give a fluorescent compound. The average concentration (mean+/-SD, n=52) of PQ found in airborne particulates collected from July 1997 to June 1998 was 0.287+/-0.128 ng m-3. Concentrations of PQ in winter were higher than those in summer. In a weekly variation study, PQ concentrations were higher during weekdays and lower at weekend. The levels of PQ were obviously correlated with those of phenanthrene (PH) that is considered as a parent compound of PQ. This observation suggested that PQ was emitted into the atmosphere from the same source as PH, or PQ was converted from PH in the atmosphere.

Highly sensitive and selective determination of 9,10-phenanthrenequinone in airborne particulates using high-performance liquid chromatography with pre-column derivatization and fluorescence detection

9,10-Phenanthrenequinone (PQ), is one of the components of diesel exhaust particulates, has potent harmful effects on human health. For the determination of PQ in airborne particulates, a highly sensitive and selective high-performance liquid chromatography (HPLC) method was developed with fluorescence detection following the pre-column fluorescent derivatization. PQ was derivatized with benzaldehyde as a derivatizing reagent in the presence of ammonium acetate to give fluorescent 2-phenyl-1H-phenanthro [9,10-d] imidazole. The maximum fluorescence intensity of the derivative was observed by the reaction with 0.2M benzaldehyde and 0.5 M ammonium acetate at 100 degrees C for 30 min. The HPLC separation of fluorescent derivative of PQ was performed within 20 min on an ODS column with a mixture of acetonitrile-water (55:45, v/v) as a mobile phase. Highly sensitive and selective determination of PQ was attained with the detection limit of 5 fmol (S/N = 3). By the proposed method, PQ in airborne particulates was successfully determined in the range 0.26-0.30 ng/m3 (n = 3).