The catalytic aerial oxidation of As(III) in alkaline solution by Mn-loaded diatomite.

The oxidization of As(III) to As(V) is necessary for both the detoxification of arsenic and the removal of arsenic by solidification. In order to achieve high efficiency and low cost As(III) oxidation, a novel process of catalytic aerial oxidation of As(III) is proposed, using air as oxidant and Mn-loaded diatomite as a catalyst. Through systematic characterization of the reaction products, the catalytic oxidation reaction law of Mn-loaded diatomite for As(III) was found out, and its reaction mechanism was revealed. Results show that Mn-loaded diatomite achieved a good catalytic effect for aerial oxidation of As(III) and maintained high performance over multiple cycles of reuse, which was directly related to the structure of diatomite and the behavior of manganese. Under the conditions of a catalyst concentration of 20 g/L, an air flow rate of 0.3 m3/h, a reaction temperature of 50 °C and an initial pH of 12.6, 96.04% As(III) oxidation was achieved after 3 h. Furthermore, the efficiency of As(III) oxidation did not change significantly after ten cycles of reuse. XPS analysis of the reaction products confirmed that the surface of the catalyst was rich in Mn(III), Mn(IV) and adsorbed oxygen(O-H), which was the fundamental reason for the excellent performance of Mn-loaded diatomite in the catalytic oxidation of As(III).

Chemical Synthesis of the ODM-201's Diastereomers through an Efficient Intramolecular 1,3-Dipolar Cycloaddition.

An efficient synthesis of ODM-201's diastereomers has been developed from (R)-methyl 3-hydroxybutanoate or (S)-methyl 3-hydroxybutanoate, respectively, with high overall yield and excellent diastereomeric purity. The key step in this synthesis is the preparation of the key intermediate (R)-5-(1-((tert-butyldimethylsilyl)oxy)ethyl)-1H-pyrazole-3-carboxylic acid or (S)-5-(1-((tert-butyldimethylsilyl)oxy)ethyl)-1H-pyrazole-3-carboxylic acid through intramolecular 1,3-dipolar cycloaddition of the vinyl diazo carbonyl compounds.

Chemiluminescence screening assay for diethylstilbestrol in meat.

A simple, rapid, and sensitive flow injection method with chemiluminescence detection was developed for the screening of meat samples containing diethylstilbestrol, based on the enhancement by diethylstilbestrol of the cerium(IV)-rhodamine 6G chemiluminescence system in sulfuric acid medium. Under the optimal conditions, the chemiluminescence intensity was linear for the diethylstilbestrol concentration in four types of meat (chicken, beef, mutton, and pork) matrix, with the linear ranges of CL detection more than three orders of magnitude and the detection limits (3σ) in the range 0.75-1.12pg/mL. The relative standard deviations for intra-day and inter-day precision were less than 3.0%. The proposed method was found to be highly reliable for screening purpose and successfully applied to the screening of diethylstilbestrol residue in four types of meat samples, with the good quantitative recoveries for the different concentration levels varied from 93.1% to 104.5%. The mechanism of this chemiluminescence reaction has also been proposed.

A gradient HPLC method for the quality control of chlorogenic acid, linarin and luteolin in Flos Chrysanthemi Indici suppository.

The Flos Chrysanthemi Indici suppository, a famous traditional Chinese medicine, is marketed for the treatment of prostatitis and chronic pelvic inflammation. A simple, relatively rapid and accurate high-performance liquid chromatographic (HPLC) method was applied to the simultaneous determination of chlorogenic acid, linarin and luteolin in Flos Chrysanthemi Indici suppository. The good separation was achieved on a Hypersil ODS column by a gradient elution using the mixture of acetonitrile and aqueous 1.0% acetic acid as mobile phase within 23 min. The method was validated for three active phenolic compounds with the relative standard deviations (R.S.D.) of intra- and inter-day precision below 3.0%, and the detection limits (S/N=3) of chlorogenic acid, linarin and luteolin were 0.32, 0.08 and 0.05 microg ml(-1), respectively. This assay was successfully applied to the determination of three active phenolic compounds in Flos Chrysanthemi Indici suppository samples with the quantitative recoveries in the range of 94.7-101.8%. The results indicate that the developed HPLC method can be readily utilized as a quality control method for Flos Chrysanthemi Indici suppository and its related traditional Chinese medicinal preparations.

Three New C20-Diterpenoid Alkaloids from Aconitum tanguticum var. trichocarpum.

Continuous investigations on the whole herbs of Aconitum tanguticum var. trichocarpum led to the isolation of three new C20-diterpenoid alkaloids trichocarpisines A-C (1-3). Their structures were elucidated on the basis of extensive interpretation of the spectroscopic data.

Further Studies on Structure-Cardiac Activity Relationships of Diterpenoid Alkaloids.

The cardiac effect of thirty-eight diterpenoid alkaloids was evaluated on the isolated bullfrog heart model. Among them, twelve compounds exhibited appreciable cardiac activity, with compounds 3 and 35 being more active than the reference drug lanatoside. The structure-cardiac activity relationships of the diterpenoid alkaloids were summarized based on our present and previous studies [2]: i) 1α-OMe or 1α-OH, 8-OH, 14-OH, and NH (or NMe) are key structural features important for the cardiac effect of the aconitine-type C19-diterpenoid alkaloids without any esters. C18-diterpenoid alkaloids, lycoctonine-type C19-diterpenoid alkaloids, and the veatchine- and denudatine-type C20-diterpenoid alkaloids did not show any cardiac activity; ii) the presence of 3α-OH is beneficial to the cardiac activity; iii) the effect on the cardiac action of 6α-OMe, 13-OH, 15α-OH, and 16-demethoxy or a double bond between C-15 and C-16 depends on the substituent pattern on the nitrogen atom.

Sensitive determination of kaempferol in rat plasma by high-performance liquid chromatography with chemiluminescence detection and application to a pharmacokinetic study.

A simple and sensitive method based on high-performance liquid chromatography (HPLC) coupled with chemiluminescence detection was developed for the quantitation of kaempferol (KA) in rat plasma. Isorhamnetin (IS) was used as an internal standard. Plasma samples were prepared only by acidification with 20% phosphoric acid and protein precipitation using methanol. Good separations of kaempferol and internal standard were achieved with an isocratic elution using a mobile phase consisting of methanol and aqueous 0.4% phosphoric acid (47:53, v/v) within 25 min. The detection limit for kaempferol was 1.0x10(-9) g/ml. The mean accuracy was within 80.0-100.2%, and the intra- and inter-day precision had RSD (%) < 5.0. The sample preparation method was able to produce high recovery (> or = 80.0%). The proposed method with wide linear range has been successfully applied to a pharmacokinetic study in SD rats after oral administration at a dose of 2500 or 1250 mg/kg bodyweight (BW) kaempferol. Kaempferol concentration was detectable in plasma up to 24 h post-dosing, and the pharmacokinetic parameters of T(max), C(max), AUC(0-infinity), MRT(0-infinity), and T(1/2) of kaempferol were reported.