A rapid, sensitive and specific ultra-high-performance liquid chromatography tandem mass spectrometry （UPLC-MS） method was developed for the analysis of tetracycline antibiotics, including tetracycline （TC）, oxyte...A rapid, sensitive and specific ultra-high-performance liquid chromatography tandem mass spectrometry （UPLC-MS） method was developed for the analysis of tetracycline antibiotics, including tetracycline （TC）, oxytetracycline （OTC）, chlortetracycline （CTC） and their 4-epimers （4-epiTCs） in agricultural soil fertilized with swine manure. Soil samples were extracted and cleaned-up with 10 mL EDTA-McIlvaine buffer solution （pH 4.0）, then cleaned-up and pre-concentrated using the Oasis MAX cartridge and then eluted with 1 mL solution by mixing formic acid, methanol and water at a ratio of 2：15：83 （v/v/v）. The purified samples were separated by an ACQUITY UPLC BEH C18 column using acetonitrile and water containing 0.1% formic acid mobile phase and detected by a single quadrupole MS. The limits of detection for the soil extraction method （LODsoil） ranged from 0.6-2.5 lag kg-~ with recoveries from 23.3-159.2%. Finally, the method was applied to an agricultural field in an area with intensive pig-fattening farming. Tetracyclines were detected in soil from 2.8 to 42.4 μg kg-1 soil. These results demonstrate that soil from swine farms can become severely contaminated with tetracycline antibiotics and their metabolites.展开更多
A pair of new tirucallane triterpenoid epimers,picraquassins M and N(1 and 2),were isolated from the stems of Picrasma quassioides(D.Don)Benn.Their structures were determined based on comprehensive spectroscopic and X...A pair of new tirucallane triterpenoid epimers,picraquassins M and N(1 and 2),were isolated from the stems of Picrasma quassioides(D.Don)Benn.Their structures were determined based on comprehensive spectroscopic and X-ray crystallographic analyses.In addition,their ACh E inhibitory activity,cytotoxicity against five human tumour cell lines(SW480,MCF-7,HepG2,Hela,and PANC-1),and antimicrobial activity against two bacteria(Staphylococcus.aureus 209 P and Escherichia coli ATCC0111)and two fungi(Candida albicans FIM709 and Aspergillus niger R330)were evaluated.展开更多
The singlet-singlet intramolecular energy transfer between naphthalene moiety and dansyl group held apart by a rigid steroid bridge was investigated for two molecules:3β-(1-naphthyl)acetoxy- 17α-dansyl-△~5androsten...The singlet-singlet intramolecular energy transfer between naphthalene moiety and dansyl group held apart by a rigid steroid bridge was investigated for two molecules:3β-(1-naphthyl)acetoxy- 17α-dansyl-△~5androstene(3a)and 3β-(1-naphthyl)acetoxy-17β-dansyl-△~5androstene(3b).The rates of energy transfer for 3a and 3b in cyclohexane are 6.9×10~6 and 1.1×10~8s^(-1) respectively.The difference in energy transfer rate between 3a and 3b is attributed to the different donor-acceptor separation and orientation.The ratio of the two epimers in the synthesized product mixture was obtained from the fluorescence decay measurements.展开更多
Baogongteng A is a tropane alkaloid with cholinergic activity. It has been used clinically for the treatment of glaucoma, and its pharmacological activity on heart function has also been reported.In the synthesis of b...Baogongteng A is a tropane alkaloid with cholinergic activity. It has been used clinically for the treatment of glaucoma, and its pharmacological activity on heart function has also been reported.In the synthesis of baogongteng A, the cycloadducts of Katritzky cycloaddition of 1-benzyl-3-oxidepyridinium with a-chloroacrylonitrile were ketalized with ethylene glycol in benzene by azeotropic distillation. After recrystallization from ethanol, two compounds（A, prisms, m.p.127—129℃; B, needles, m.p.75—77℃） were obtaines.Their MS, IR spectral data and elemental analysis were consistent with the proposed structures. They were assigned as C<sub>6</sub>-chloro nitrile epimers by <sup>1</sup>H-<sup>1</sup>H展开更多
The natural product, neoclausenamide was synthesized through the 'biomimetic' route and the stereoselective reduction of the ketone group wherein were described.
A pair of epimers of highly-oxygenated monoterpenes were isolated from the traditional Chinese medicine Eupatorium fortunei. Their structures were elucidated on the basis of the spectral analysis as （1R＊, 2S＊, 3R＊...A pair of epimers of highly-oxygenated monoterpenes were isolated from the traditional Chinese medicine Eupatorium fortunei. Their structures were elucidated on the basis of the spectral analysis as （1R＊, 2S＊, 3R＊, 4R＊, 6S＊）-1, 2, 3, 6-tetrehydroxy-p-menthane （1） and （1S＊, 2S＊, 3S＊, 4R＊, 6R＊）-1, 2, 3, 6-tetrehydroxy-p-menthane （2）.展开更多
Because many therapeutic agents are contaminated by epimeric impurities or form epimers as a result of metabolism, analytical tools capable of determining epimers are increasingly in demand. This article is a proof-of...Because many therapeutic agents are contaminated by epimeric impurities or form epimers as a result of metabolism, analytical tools capable of determining epimers are increasingly in demand. This article is a proof-of-principle report of a novel DMS–MS/MS method to separate and simultaneously quantify epimers, taking PGF2α and its 8-epimer, 8-iso-PGF2α, as an example. Good accuracy and precision were achieved in the range of 10–500 ng/m L with a run time of only 1.5 min. Isopropanol as organic modifier facilitated a good combination of sensitivity and separation. The method is the first example of the quantitation of epimers without chromatographic separation.展开更多
文摘A rapid, sensitive and specific ultra-high-performance liquid chromatography tandem mass spectrometry （UPLC-MS） method was developed for the analysis of tetracycline antibiotics, including tetracycline （TC）, oxytetracycline （OTC）, chlortetracycline （CTC） and their 4-epimers （4-epiTCs） in agricultural soil fertilized with swine manure. Soil samples were extracted and cleaned-up with 10 mL EDTA-McIlvaine buffer solution （pH 4.0）, then cleaned-up and pre-concentrated using the Oasis MAX cartridge and then eluted with 1 mL solution by mixing formic acid, methanol and water at a ratio of 2：15：83 （v/v/v）. The purified samples were separated by an ACQUITY UPLC BEH C18 column using acetonitrile and water containing 0.1% formic acid mobile phase and detected by a single quadrupole MS. The limits of detection for the soil extraction method （LODsoil） ranged from 0.6-2.5 lag kg-~ with recoveries from 23.3-159.2%. Finally, the method was applied to an agricultural field in an area with intensive pig-fattening farming. Tetracyclines were detected in soil from 2.8 to 42.4 μg kg-1 soil. These results demonstrate that soil from swine farms can become severely contaminated with tetracycline antibiotics and their metabolites.
基金supported by grants from the National Key Research and Development Program of China(Nos.2018YFA0903200 and 2018YFA0903201)the National Natural Science Foundation of China(No.31761143016)+6 种基金Chang Jiang Scholars Program(GAO Hao,2017)from the Ministry of Education of ChinaNational High-level Personnel of Special Support Program(No.2017RA2259)Guangdong Special Support Program(No.2016TX03R280)Young Elite Scientists Sponsorship Program by China Association of Chinese Medicine(No.QNRC2-B06)Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(GAO Hao,2014)Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(No.2017BT01Y036)K.C.Wong Education Foundation(GAO Hao,2016)
文摘A pair of new tirucallane triterpenoid epimers,picraquassins M and N(1 and 2),were isolated from the stems of Picrasma quassioides(D.Don)Benn.Their structures were determined based on comprehensive spectroscopic and X-ray crystallographic analyses.In addition,their ACh E inhibitory activity,cytotoxicity against five human tumour cell lines(SW480,MCF-7,HepG2,Hela,and PANC-1),and antimicrobial activity against two bacteria(Staphylococcus.aureus 209 P and Escherichia coli ATCC0111)and two fungi(Candida albicans FIM709 and Aspergillus niger R330)were evaluated.
文摘The singlet-singlet intramolecular energy transfer between naphthalene moiety and dansyl group held apart by a rigid steroid bridge was investigated for two molecules:3β-(1-naphthyl)acetoxy- 17α-dansyl-△~5androstene(3a)and 3β-(1-naphthyl)acetoxy-17β-dansyl-△~5androstene(3b).The rates of energy transfer for 3a and 3b in cyclohexane are 6.9×10~6 and 1.1×10~8s^(-1) respectively.The difference in energy transfer rate between 3a and 3b is attributed to the different donor-acceptor separation and orientation.The ratio of the two epimers in the synthesized product mixture was obtained from the fluorescence decay measurements.
文摘Baogongteng A is a tropane alkaloid with cholinergic activity. It has been used clinically for the treatment of glaucoma, and its pharmacological activity on heart function has also been reported.In the synthesis of baogongteng A, the cycloadducts of Katritzky cycloaddition of 1-benzyl-3-oxidepyridinium with a-chloroacrylonitrile were ketalized with ethylene glycol in benzene by azeotropic distillation. After recrystallization from ethanol, two compounds（A, prisms, m.p.127—129℃; B, needles, m.p.75—77℃） were obtaines.Their MS, IR spectral data and elemental analysis were consistent with the proposed structures. They were assigned as C<sub>6</sub>-chloro nitrile epimers by <sup>1</sup>H-<sup>1</sup>H
文摘The natural product, neoclausenamide was synthesized through the 'biomimetic' route and the stereoselective reduction of the ketone group wherein were described.
基金This work was supported by the NNSFC(No.20372029 and No.20021001-QT Program)by the Key Project of Chinese Ministry of Education(No.104178).
文摘A pair of epimers of highly-oxygenated monoterpenes were isolated from the traditional Chinese medicine Eupatorium fortunei. Their structures were elucidated on the basis of the spectral analysis as （1R＊, 2S＊, 3R＊, 4R＊, 6S＊）-1, 2, 3, 6-tetrehydroxy-p-menthane （1） and （1S＊, 2S＊, 3S＊, 4R＊, 6R＊）-1, 2, 3, 6-tetrehydroxy-p-menthane （2）.
基金supported by the National Natural Science Foundation of China(Grant Nos.81430087 and 81673396)
文摘Because many therapeutic agents are contaminated by epimeric impurities or form epimers as a result of metabolism, analytical tools capable of determining epimers are increasingly in demand. This article is a proof-of-principle report of a novel DMS–MS/MS method to separate and simultaneously quantify epimers, taking PGF2α and its 8-epimer, 8-iso-PGF2α, as an example. Good accuracy and precision were achieved in the range of 10–500 ng/m L with a run time of only 1.5 min. Isopropanol as organic modifier facilitated a good combination of sensitivity and separation. The method is the first example of the quantitation of epimers without chromatographic separation.
