Objective:To evaluate inhibitoy potential of seven Korean thistles against the advanced glyeatinn endproducts(AGE) formation as well as to identify responsible compounds from the most active species.Methods:We used an...Objective:To evaluate inhibitoy potential of seven Korean thistles against the advanced glyeatinn endproducts(AGE) formation as well as to identify responsible compounds from the most active species.Methods:We used an in vitro AGE inhibition assay to evaluate the antidiabetic complication potential of the methanol extracts of the selected Korean thistles.Results:Among the seven Korean thistles,the leaves of Cirsium maackii(C.maackii) exhibited the most significant inhibitory activity against AGE formation.By means of bioassay-directed fractionation,a lignan.chlorogenic acid and 14 flavonoids were isolated from the active ethyl acetate soluble fraction of a methanol extract from C.maackii leaves.Luteolin and its 5-O-glueoside have been previously isolated:however,a lignan and 13 known compounds were isolated for the first lime from C maackii leaves in this study.Most of the isolated compounds exhibited inhibitory activities against potential AGE formation.Among them,cernuoside was shown to be the most potent AGE inhibitor with an IC_(50) value of 21.21 μ mol/L.Most importantly,two major flavonoids,luteolin and ils 5-O-glucoside,also significantly inhibited AGE formation,with IC_(50) values of36.33 and 37.47 μmol/L,respectively.Structure activity relationship revealed that the presence of free 3'and 4' dihydroxyl group in flavonoids skeleton played an important role in AGE inhibition.Conclusions:These results indicate that C.maackii and C maackii-derived flavonoids might be explored further to develop therapeutic agents for the prevention of diabetic eoniplicalions due to their significant inhibitory activity against AGE formation.展开更多
The microstructures of the brazed joints for commercially pure Ti and stainless steel were investigated by the applications of various filler alloys including Ag-, Ti-, Zr- and Ni-based alloys. Generally, the dissimil...The microstructures of the brazed joints for commercially pure Ti and stainless steel were investigated by the applications of various filler alloys including Ag-, Ti-, Zr- and Ni-based alloys. Generally, the dissimilar joints between Ti and stainless steel were dominated by the Ti-based intermetallic compounds （IMCs）, e.g. （Ti, Zr）2（Fe, Ni）, TiFe, TiCu, and Ti2（Fe, Ni）, due to a significant dissolution of Ti from the base metal. The （Fe-Cr） cr phase was also observed near the stainless steel due to a segregation of Cr into the interface region. This research demonstrates empirically that the brittleness of the Ti and stainless steel joint can not be avoided only by applying single braze alloy or single insert metal, and thus an introduction of additional suitable interlayer between the filler alloy and the base metal is necessary to prevent the brittleness of the joint.展开更多
基金supported by the Pukyoug National University Research Fund in 2011(C-D-2011-0766)
文摘Objective:To evaluate inhibitoy potential of seven Korean thistles against the advanced glyeatinn endproducts(AGE) formation as well as to identify responsible compounds from the most active species.Methods:We used an in vitro AGE inhibition assay to evaluate the antidiabetic complication potential of the methanol extracts of the selected Korean thistles.Results:Among the seven Korean thistles,the leaves of Cirsium maackii(C.maackii) exhibited the most significant inhibitory activity against AGE formation.By means of bioassay-directed fractionation,a lignan.chlorogenic acid and 14 flavonoids were isolated from the active ethyl acetate soluble fraction of a methanol extract from C.maackii leaves.Luteolin and its 5-O-glueoside have been previously isolated:however,a lignan and 13 known compounds were isolated for the first lime from C maackii leaves in this study.Most of the isolated compounds exhibited inhibitory activities against potential AGE formation.Among them,cernuoside was shown to be the most potent AGE inhibitor with an IC_(50) value of 21.21 μ mol/L.Most importantly,two major flavonoids,luteolin and ils 5-O-glucoside,also significantly inhibited AGE formation,with IC_(50) values of36.33 and 37.47 μmol/L,respectively.Structure activity relationship revealed that the presence of free 3'and 4' dihydroxyl group in flavonoids skeleton played an important role in AGE inhibition.Conclusions:These results indicate that C.maackii and C maackii-derived flavonoids might be explored further to develop therapeutic agents for the prevention of diabetic eoniplicalions due to their significant inhibitory activity against AGE formation.
基金supported by the Korea Atomic Energy Research Institute (KAERI) R&D Program
文摘The microstructures of the brazed joints for commercially pure Ti and stainless steel were investigated by the applications of various filler alloys including Ag-, Ti-, Zr- and Ni-based alloys. Generally, the dissimilar joints between Ti and stainless steel were dominated by the Ti-based intermetallic compounds （IMCs）, e.g. （Ti, Zr）2（Fe, Ni）, TiFe, TiCu, and Ti2（Fe, Ni）, due to a significant dissolution of Ti from the base metal. The （Fe-Cr） cr phase was also observed near the stainless steel due to a segregation of Cr into the interface region. This research demonstrates empirically that the brittleness of the Ti and stainless steel joint can not be avoided only by applying single braze alloy or single insert metal, and thus an introduction of additional suitable interlayer between the filler alloy and the base metal is necessary to prevent the brittleness of the joint.
