EXAFS and IR structural study of platinum-based anticancer drugs' degradation by diethyl dithiocarbamate

Platinum compounds constitute a discrete class of DNA-damaging anticancer drug agents, including cisplatin, carboplatin, and oxaliplatin. The toxicity of such drugs raises the problem of waste detoxification. Diethyl dithiocarbamate (DDTC) is recommended by the World Heath Organization (WHO) for the destruction of cisplatin, but the degradation product has not been structurally characterized. This paper deals with the extended X-ray absorption fine structure (EXAFS) and IR structural study of the reaction products of DDTC with cisplatin, carboplatin, and oxaliplatin. Cisplatin and carboplatin give the same reaction product: Pt(DDTC)2. In the case of oxaliplatin, we observed the formation of [(diaminocyclohexane)(DDTC)Pt(II)]. In all cases, the replacement of labile ligands by strong ligands should lead to inactive compounds. Our results suggest that the WHO inactivation protocol might be extended to carboplatin and oxaliplatin. Nevertheless, this should be validated by toxicity tests of the degradation products.     

Protection against photoaging in the hairless mouse by the isoflavone equol

Topical application of the isoflavone equol immediately following solar-simulated UV (SSUV) radiation exposure has previously been demonstrated to have significant photoprotective effects. Equol reduced both the inflammatory edema and the systemic suppression of the contact hypersensitivity reaction in hairless mice. Furthermore, daily topical equol application immediately following irradiation during a 10-week chronic SSUV exposure regime also reduced photocarcinogenesis severity in the mouse. This study examines the potential for topical equol to prevent photoaging in response to chronic SSUV irradiation for up to 30 weeks. We did not find consistent expression of the characteristic markers of photoaging until 30 weeks, although moderate epidermal hyperplasia and a transient increase in dermal mast cell numbers were evident after 1 week. Daily application of 10 muM equol lotion significantly reduced these early changes. However after 30 weeks of SSUV exposure, photoaging was well developed, as shown histologically by markedly increased epidermal hyperplasia, increased dermal mast cell number, pronounced focal elastotic deposits, degraded dermal collagen and deposition of glycosaminoglycans in the lower dermis. Topical equol treatment protected significantly from each of these impairments, as demonstrated histologically and quantitatively. Additionally, equol was found to have strong antioxidant action against acute UVA (320-400 nm)-induced lipid peroxidation of mouse skin, this property accounting for its antiphotoaging mechanism. The evidence for equol's antiphotoaging activity, taken together with its anti-inflammatory, immunoprotective and anticarcinogenic efficacy against SSUV irradiation in the mouse, suggests that equol could be developed as a helpful topical photoprotective agent for daily use by humans.     

Formation of a reversible, intramolecular main-group metal-CO2 adduct

The P,P-chelated stannylene [(i-Pr(2)P)(2)N](2)Sn takes up 2 equiv of carbon dioxide (CO(2)) to form an unusual product in which CO(2) binds to the Sn and P atoms, thus forming a six-membered ring complex. Gentle heating of the solid product releases CO(2), indicating that CO(2) is bound as an adduct to the main-group complex. The groups bound to the CO(2) fragment are not particularly sterically crowded or highly acidic, thus indicating that "frustrated" Lewis acid-base pairs are not required in the binding of CO(2) to main-group elements.     

The effect of cooking and washing rice on the bio-accessibility of As,Cu, Fe,V and Zn using an on-line continuous leaching method

A previously developed method based on continuous on-line leaching with artificial gastro-intestinal fluids was used to determine the bio-accessible fraction of As, Cu, Fe, V and Zn in brown and white rice from California by inductively coupled mass spectrometry (ICP-MS). Saliva generally accounted for the largest percentage of total element leached in comparison to gastric and intestinal juices. Arsenic speciation analysis was performed on the saliva and gastric juice leachates using ion exchange chromatography coupled to ICP-MS. The four most toxic species of As (As(III), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and As(V)), as well as Cl⁻ in the gastric juice leachate, were successfully separated within 5.5 min using a simple nitric acid gradient. While cooking rice had relatively little effect on total bio-accessibility, a change in species from As(V) and DMA to As(III) was observed for both types of rice. On the other hand, washing the rice with doubly deionized water prior to cooking removed a large percentage of the total bio-accessible fraction of As, Cu, Fe, V and Zn.     

Trimethylsilyl-directed 1,3-dipolar cycloaddition reactions in the solid-phase synthesis of 1,2,3-triazoles

[reaction: see text] A regioselective method for the preparation of 1,5-trisubstituted 1H-1,2,3-triazoles via a 1,3-dipolar cycloaddition of 1-trimethylsilylacetylenes with organoazides is described. Immobilization of the azide on REM resin and subsequent cycloaddition afforded a 2 x 2 x 4 x 3 membered 1,5-disubstituted 1H-1,2,3-triazole library with an average purified yield of 68%.     

Determination of seven arsenic species in seafood by ion exchange chromatography coupled to inductively coupled plasma-mass spectrometry following microwave assisted extraction: method validation and occurrence data

The determination of seven arsenic species in seafood was performed using ion exchange chromatography on an IonPac AS7 column with inductively coupled plasma mass spectrometry detection after microwave assisted extraction. The effect of five parameters on arsenic extraction recoveries was evaluated in certified reference materials. The recoveries of total arsenic and of arsenic species with the two best extraction media (100% H₂O and 80% aqueous MeOH) were generally similar in the five seafood certified reference materials considered. However, because MeOH co-elutes with arsenite, which would result in a positively biased arsenite concentration, the 100% H₂O extraction conditions were selected for validation of the method. Figures of merit (linearity, LOQs (0.019-0.075 mg As kg⁻¹), specificity, trueness (with recoveries between 82% (As(III)) and 104% (As(V) based on spikes or certified concentrations), repeatability (3-14%), and intermediate precision reproducibility (9-16%) of the proposed method were satisfactory for the determination of arsenite, monomethylarsonic acid, dimethylarsinic acid, arsenate, arsenobetaine and arsenocholine in fish and shellfish. The performance criteria for trimethylarsine oxide, however, were less satisfactory. The method was then applied to 65 different seafood samples. Arsenobetaine was the main species in all samples. The percentage of inorganic arsenic varied between 0.4-15.8% in shellfish and 0.5-1.9% at the utmost in fish. The main advantage of this method that uses only H₂O as an extractant and nitric acid as gradient eluent is its great compatibility with the long-term stability of both IEC separation and ICP-MS detection.     

Parameterization of Org27569: An allosteric modulator of the cannabinoid CB1 G protein‐coupled receptor

The cannabinoid CB₁ receptor is a class A G protein‐coupled receptor (GPCR) that is the most widely expressed GPCR in the brain. Many GPCRs contain allosteric binding sites for endogenous and/or synthetic ligands, which are topographically distinct from the agonist‐binding site that is known as the orthosteric site. While both endogenous and synthetic ligands that act at the CB₁ orthosteric site have been known for some time, compounds that act at a CB₁ allosteric site have only recently been discovered. The most studied of these is 5‐chloro‐3‐ethyl‐1H‐indole‐2‐carboxylic acid [2‐(4‐piperidin‐1‐ylphenyl)ethyl]amide (Org27569). Because allosteric ligands are thought to act through conformational changes in the receptor that are transmitted from the allosteric to the orthosteric site, computational studies of the structural and dynamic interactions of Org27569 with the CB₁ receptor are crucial to achieve a molecular level understanding of the basis of action of this important new class of compounds. To date, such computational studies have not been possible due to the lack of a complete set of molecular mechanics force field parameters for Org27569. Here, we present the development of missing CHARMM force field parameters for Org27569 using previously published methods and the validation and application of these new parameters using normal mode analysis and molecular dynamics simulations combined with experimental infrared measurements. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011     

The simultaneous saccharification and fermentation of pretreated woody crops to ethanol

Four promising woody crops (Populusmaximowiczii x nigra (NE388), P.trichocarpa x deltoides (Nll), P.tremuloides, and SweetgumLiquidambar styraciflua) were pretreated by dilute sulfuric acid and evaluated in the simultaneous saccharification and fermentation (SSF) process for ethanol production. The yeastSaccharomyces cerevisiae was used in the fermentations alone, and in mixed cultures with β -glucosidase producingBrettanomyces dausenii. Commercial Genencor 150L cellulase enyme was either employed alone or supplemented with β- glucosidase. All SSFs were run at 37 …C for 8 d and compared to saccharifications at 45…C under the same enzyme loadings.S. cerevisiae alone achieved the highest ethanol yields and rates of hydrolysis at the higher enzyme loadings, whereas the mixed culture performed better at the lower enzyme loadings without β -glucosidase supplementation. The best overall rates of fermentation (3 d) and final theoretical ethanol yields (86–90%) were achieved with P.maximowiczii x nigra (NE388) and SweetgumLiquidambar styraciflua, followed by P.tremuloides and P.trichocarpa xdeltoides (N1l) with slightly slower rates and lower yields. Although there were some differences in SSF performance, all these pretreated woody crops show promise as substrates for ethanol production.     

An application of the mannich reaction using hydroxylamine and some of its derivatives. 6-Substituted-2,4-diamino-5,6,7,8-tetrahydropyrimido[4,5-dpyrimidines

Hydroxylamine and some of its O -substituted derivatives ( 2 ) have been used as the amine component in Mannich reactions with 2,4,6-triaminopyrimidine ( 1 ). The resulting 6-substituted tetrahydropyrimido[4,5-d]-pyrimidines ( 3 ) contain an N-0 bond linking the substituent to the ring. These results extend the utility of this modified Mannich reaction to otherwise inaccessible substituents. Reaction conditions, spectral data and certain limitations of the reaction are discussed.