To study the antioxidant constituents from the stems of Dendrobium nobile, and to discuss theft structure-activity relationship. Compounds were isolated from a 60% ethanolic extract by various chromatographic techniqu...To study the antioxidant constituents from the stems of Dendrobium nobile, and to discuss theft structure-activity relationship. Compounds were isolated from a 60% ethanolic extract by various chromatographic techniques and were identified by spectral analysis. The antioxidant activities of compounds were evaluated by DPPH free radical scavenging assay. Five phenanthrenes and four lignans were obtained from the active fractions ofD. nobile. Their structures were identified as fimbriatone （1）, confusarin （2）, flavanthrinin （3）, 2,5-dihydroxy-4,9-dimethoxyphenanthrene （4）, 3,7-dihydroxy-2,4-dimethoxyphenanthrene （5）, syringaresinol （6）, pinoresinol （7）, medioresinol （8） and lirioresinol-A （9）, respectively. Compounds 2 and 6 exhibited more potent DPPH scavenging activities than vitamin C. All the above compounds were reported from this plant for the first time, and compounds 3, 4 and 9 were reported for the first time from the genus of Dendrobiurn. For all phenanthrenes and lignans, an electron-donating methoxyl group in the ortho position to the phenolic hydroxyl group exhibits enhanced antioxidant activities.展开更多
Seven kinds of Schiff base metal complexes(C1-C7)were synthesized by the reaction of substituted salicylaldehyde Schiff base with cobalt nitrate,nickel nitrate,and copper nitrate,respectively.The oxygen carrying perfo...Seven kinds of Schiff base metal complexes(C1-C7)were synthesized by the reaction of substituted salicylaldehyde Schiff base with cobalt nitrate,nickel nitrate,and copper nitrate,respectively.The oxygen carrying performance,and the catalytic property of complexes for the oxidation of model sulfides 1-hexanethiol,dibutyl sulfide,and 2-methylthiophene along with their influencing factors were explored,while the oxidized products of the model sulfides were also analyzed and characterized.The results show that the catalytic oxidation property of the complexes is determined by their oxygen carrying performance and solubility in n-octane.The oxygen carrying performance of the complexes is mainly affected by the central ion species,the electronic effects,and the spatial effects of the substituents as well as the degree of conjugation.More specifically,the oxygen carrying performance can be improved by enhancing the oxygenation capacity of the central metal ions,increasing the electron donating ability of the ligand substituent,and diminishing the steric hindrance as well as extending the conjugated chain.Complexes C7 were found to be with high oxygen carrying capacity and high solubility in n-octane,which shows the best catalytic oxidation property,and the oxidation conversion rates for 1-hexylthiol,dibutyl sulfide,and 2-methylthiophene are 74.2%,65.1%,and 22.7%,respectively.Upon using the oxidation catalyst of Schiff base metal complexes,three sulfides can be oxidized by oxygen to form sulfones and sulfoxides.1-Hexanethiol and dibutyl sulfide will continue to be oxidized to form sulfates and sulfites.展开更多
Adenine derivatives, in particular the scaffold bearing the acyclic nucleoside phosphonates (ANPS), possess significant antiviral and cytostatic now, several effective adenine derivatives have been marketed for the tr...Adenine derivatives, in particular the scaffold bearing the acyclic nucleoside phosphonates (ANPS), possess significant antiviral and cytostatic now, several effective adenine derivatives have been marketed for the treatment of HIV, HBV, CMV and other virus-infected diseases. These compounds are represented by tenofovir (PMPA) a medicine for both HIV and HBV, and adefovir as an anti-HBV agent. More than this, other analogs, such as GS9148, GS9131, and GS7340, are also wellknown anti-viral agents that have been progressed to the clinical studies for their excellent activity. in general, the structures of these compounds include an adenine nueleobase linked to a phosphonate side ehain. Considerable structural modifications on the scaffold itself and the peripheral sections were made. The structure-activity relationships (SARs) of this skeleton will provide valuable clues to identify more effective adenine derivatives as antiviral drugs. Here, we systematically summarized the SARs of the adenine derivatives, and gave important information for further optimizing this template. (c) 2015 Chinese Pharmaceutical Association and Institute of Materia Medial., Chinese Academy of Medical Sciences. Production and hosting by Elsevier B.V.展开更多
文摘To study the antioxidant constituents from the stems of Dendrobium nobile, and to discuss theft structure-activity relationship. Compounds were isolated from a 60% ethanolic extract by various chromatographic techniques and were identified by spectral analysis. The antioxidant activities of compounds were evaluated by DPPH free radical scavenging assay. Five phenanthrenes and four lignans were obtained from the active fractions ofD. nobile. Their structures were identified as fimbriatone （1）, confusarin （2）, flavanthrinin （3）, 2,5-dihydroxy-4,9-dimethoxyphenanthrene （4）, 3,7-dihydroxy-2,4-dimethoxyphenanthrene （5）, syringaresinol （6）, pinoresinol （7）, medioresinol （8） and lirioresinol-A （9）, respectively. Compounds 2 and 6 exhibited more potent DPPH scavenging activities than vitamin C. All the above compounds were reported from this plant for the first time, and compounds 3, 4 and 9 were reported for the first time from the genus of Dendrobiurn. For all phenanthrenes and lignans, an electron-donating methoxyl group in the ortho position to the phenolic hydroxyl group exhibits enhanced antioxidant activities.
基金This work was supported by the National Natural Science Foundation of China(No.21576292).
文摘Seven kinds of Schiff base metal complexes(C1-C7)were synthesized by the reaction of substituted salicylaldehyde Schiff base with cobalt nitrate,nickel nitrate,and copper nitrate,respectively.The oxygen carrying performance,and the catalytic property of complexes for the oxidation of model sulfides 1-hexanethiol,dibutyl sulfide,and 2-methylthiophene along with their influencing factors were explored,while the oxidized products of the model sulfides were also analyzed and characterized.The results show that the catalytic oxidation property of the complexes is determined by their oxygen carrying performance and solubility in n-octane.The oxygen carrying performance of the complexes is mainly affected by the central ion species,the electronic effects,and the spatial effects of the substituents as well as the degree of conjugation.More specifically,the oxygen carrying performance can be improved by enhancing the oxygenation capacity of the central metal ions,increasing the electron donating ability of the ligand substituent,and diminishing the steric hindrance as well as extending the conjugated chain.Complexes C7 were found to be with high oxygen carrying capacity and high solubility in n-octane,which shows the best catalytic oxidation property,and the oxidation conversion rates for 1-hexylthiol,dibutyl sulfide,and 2-methylthiophene are 74.2%,65.1%,and 22.7%,respectively.Upon using the oxidation catalyst of Schiff base metal complexes,three sulfides can be oxidized by oxygen to form sulfones and sulfoxides.1-Hexanethiol and dibutyl sulfide will continue to be oxidized to form sulfates and sulfites.
基金supported in part by grants from the National Natural Science Foundation of China (No. 81402788)the Ph.D. Start-up Fund of Natural Science Foundation of Liaoning Province (No. 20141115)
文摘Adenine derivatives, in particular the scaffold bearing the acyclic nucleoside phosphonates (ANPS), possess significant antiviral and cytostatic now, several effective adenine derivatives have been marketed for the treatment of HIV, HBV, CMV and other virus-infected diseases. These compounds are represented by tenofovir (PMPA) a medicine for both HIV and HBV, and adefovir as an anti-HBV agent. More than this, other analogs, such as GS9148, GS9131, and GS7340, are also wellknown anti-viral agents that have been progressed to the clinical studies for their excellent activity. in general, the structures of these compounds include an adenine nueleobase linked to a phosphonate side ehain. Considerable structural modifications on the scaffold itself and the peripheral sections were made. The structure-activity relationships (SARs) of this skeleton will provide valuable clues to identify more effective adenine derivatives as antiviral drugs. Here, we systematically summarized the SARs of the adenine derivatives, and gave important information for further optimizing this template. (c) 2015 Chinese Pharmaceutical Association and Institute of Materia Medial., Chinese Academy of Medical Sciences. Production and hosting by Elsevier B.V.
