A Se—containing polysaccharide(Se-GPS),with average molecular weight of 1.5×10~4 was isolated from Hubei Enshi garlic(Allium sativum L.)and purified by means of Sephadex G25 to G200 chromatographies.Its chemical...A Se—containing polysaccharide(Se-GPS),with average molecular weight of 1.5×10~4 was isolated from Hubei Enshi garlic(Allium sativum L.)and purified by means of Sephadex G25 to G200 chromatographies.Its chemical homogeneity and composition were studied by optical rotation,HPLC and paper chromatographical methods.The abilities of scavenging active oxygen free radicals and inhibiting the damage of erythrocyte membrane by SiO_2 were established by spin trapping ESR studies.Se-GPS was shown to inhibit human cytomegalovirus by plague reduction assays and cytopathogenic effect tests.展开更多
The strained cyclopropane and/or cyclobutane subunits occurred in many complex natural products including terpenoids, steroids and alkaloids. Natural products with cyclopropane and/or cyclobutane motifs not only furni...The strained cyclopropane and/or cyclobutane subunits occurred in many complex natural products including terpenoids, steroids and alkaloids. Natural products with cyclopropane and/or cyclobutane motifs not only furnished fascinating structures, but also exhibited versatile biological activities, such as cytotoxic, anti-HIM antimicrobial, antiviral, and immunosuppressive effects. This review covered a large array of structurally unique natural products with strained cyclopropane and/or cyclobutane motifs and summarized their structural features, distributions, biological activities, as well as biogenetic considerations.展开更多
G-quadruplexes comprise a class of secondary structures that are formed in guanine-rich sequences in eukaryotic genomes and play a crucial role in the regulation of many biological events.G-quadruplexes have become ta...G-quadruplexes comprise a class of secondary structures that are formed in guanine-rich sequences in eukaryotic genomes and play a crucial role in the regulation of many biological events.G-quadruplexes have become targets for anticancer drugs with high selectivity vs.duplex DNA and low cytotoxicity against normal cells.Natural products and their derivatives display polymorphism,structural complexity,and potent activity.It is,therefore,reasonable to seek ligands targeting G-quadruplexes from natural products.Recently,many successful examples have been reported,showing ligands with excellent anticancer activities.In this review,we summarized the development of research on natural products and derivatives that target G-quadruplex structures in an effort to guide future studies.展开更多
The Diels–Alder(D–A)reaction is one of the most powerful reactions in organic synthesis.The intermolecular D–A reaction attracts much less attentions than its intramolecular counterpart in natural product synthesis...The Diels–Alder(D–A)reaction is one of the most powerful reactions in organic synthesis.The intermolecular D–A reaction attracts much less attentions than its intramolecular counterpart in natural product synthesis,possibly due to the issues of reactivity and selectivity.In the past decade,the intermolecular D–A reaction has been increasingly utilized in the total synthesis of structurally complex natural products.In this article,we present a few examples for the elegant applications of the intermolecular D–A reaction that are inspired by biosynthetic hypotheses of the target natural products.These examples demonstrate that D–A reaction is not only useful for preparing building blocks but also powerful for coupling structurally complicated and sterically demanding segments in a highly chemo-and stereo-controlled fashion,which may inspire further developments of intermolecular D–A reaction from both strategy and methodology perspectives.展开更多
文摘A Se—containing polysaccharide(Se-GPS),with average molecular weight of 1.5×10~4 was isolated from Hubei Enshi garlic(Allium sativum L.)and purified by means of Sephadex G25 to G200 chromatographies.Its chemical homogeneity and composition were studied by optical rotation,HPLC and paper chromatographical methods.The abilities of scavenging active oxygen free radicals and inhibiting the damage of erythrocyte membrane by SiO_2 were established by spin trapping ESR studies.Se-GPS was shown to inhibit human cytomegalovirus by plague reduction assays and cytopathogenic effect tests.
基金supported by the National Natural Science Foundation of China (21532007)
文摘The strained cyclopropane and/or cyclobutane subunits occurred in many complex natural products including terpenoids, steroids and alkaloids. Natural products with cyclopropane and/or cyclobutane motifs not only furnished fascinating structures, but also exhibited versatile biological activities, such as cytotoxic, anti-HIM antimicrobial, antiviral, and immunosuppressive effects. This review covered a large array of structurally unique natural products with strained cyclopropane and/or cyclobutane motifs and summarized their structural features, distributions, biological activities, as well as biogenetic considerations.
基金supported by the National Natural Science Foundation of China(21172272,21272291)
文摘G-quadruplexes comprise a class of secondary structures that are formed in guanine-rich sequences in eukaryotic genomes and play a crucial role in the regulation of many biological events.G-quadruplexes have become targets for anticancer drugs with high selectivity vs.duplex DNA and low cytotoxicity against normal cells.Natural products and their derivatives display polymorphism,structural complexity,and potent activity.It is,therefore,reasonable to seek ligands targeting G-quadruplexes from natural products.Recently,many successful examples have been reported,showing ligands with excellent anticancer activities.In this review,we summarized the development of research on natural products and derivatives that target G-quadruplex structures in an effort to guide future studies.
基金financially supported by the Ministry of Science&Technology(2013CB836900)the National Natural Science Foundation of China(21290180,21172235,and 21222202)the Chinese Academy of Sciences
文摘The Diels–Alder(D–A)reaction is one of the most powerful reactions in organic synthesis.The intermolecular D–A reaction attracts much less attentions than its intramolecular counterpart in natural product synthesis,possibly due to the issues of reactivity and selectivity.In the past decade,the intermolecular D–A reaction has been increasingly utilized in the total synthesis of structurally complex natural products.In this article,we present a few examples for the elegant applications of the intermolecular D–A reaction that are inspired by biosynthetic hypotheses of the target natural products.These examples demonstrate that D–A reaction is not only useful for preparing building blocks but also powerful for coupling structurally complicated and sterically demanding segments in a highly chemo-and stereo-controlled fashion,which may inspire further developments of intermolecular D–A reaction from both strategy and methodology perspectives.
