Alkaline earth metal ion coordination increases the radical scavenging efficiency of kaempferol
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Alkaline earth metal ion coordination increases the radical scavenging efficiency of kaempferol. / Qian, Ling-Ling; Lu, Yao; Xu, Yi; Yang, Zhi-Yin; Yang, Jing; Zhou, Yi-Ming; Han, Rui-Min; Zhang, Jian-Ping; Skibsted, Leif H.
In: RSC Advances, Vol. 10, No. 50, 2020, p. 30035-30047.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Alkaline earth metal ion coordination increases the radical scavenging efficiency of kaempferol
AU - Qian, Ling-Ling
AU - Lu, Yao
AU - Xu, Yi
AU - Yang, Zhi-Yin
AU - Yang, Jing
AU - Zhou, Yi-Ming
AU - Han, Rui-Min
AU - Zhang, Jian-Ping
AU - Skibsted, Leif H.
PY - 2020
Y1 - 2020
N2 - Flavonoids are used as natural additives and antioxidants in foods, and after coordination to metal ions, as drug candidates, depending on the flavonoid structure. The rate of radical scavenging of the ubiquitous plant flavonoid kaempferol (3,5,7,4'-tetrahydroxyflavone, Kaem) was found to be significantly enhanced by coordination of Mg(II), Ca(II), Sr(II), and Ba(II) ions, whereas the radical scavenging rate of apigenin (5,7,4'-trihydroxyflavone, Api) was almost unaffected by alkaline earth metal (AEM) ions, as studied for short-lived b-carotene radical cations (beta-Car(center dot+)) formed by laser flash photolysis in chloroform/ethanol (7 : 3) and for the semi-stable 2,2-diphenyl-1-picrylhydrazyl radical, DPPH center dot, in ethanol at 25 degrees C. A 1 : 1 Mg(II)-Kaem complex was found to be in equilibrium with a 1 : 2 Mg(II)-Kaem(2) complex, while for Ca(II), Sr(II) and Ba(II), only 1 : 2 AEM(II)-Kaem complexes were detected, where all complexes showed 3hydroxyl and 4-carbonyl coordination and stability constants of higher than 10(9) L-2 mol(-2). The 1 : 2 Ca(II)-Kaem(2) complex had the highest second order rate constant for both beta-Car(center dot+) (5 x 10(8) L mol(-1) s(-1)) and DPPH center dot radical (3 x 10(5) L mol(-1) s(-1)) scavenging, which can be attributed to the optimal combination of the stronger electron withdrawing capability of the (n - 1)d orbital in the heavier AEM ions and their spatially asymmetrical structures in 1 : 2 AEM-Kaem complexes with metal ion coordination of the least steric hindrance of two perpendicular flavone backbones as ligands in the Ca(II) complex, as shown by density functional theory calculations.
AB - Flavonoids are used as natural additives and antioxidants in foods, and after coordination to metal ions, as drug candidates, depending on the flavonoid structure. The rate of radical scavenging of the ubiquitous plant flavonoid kaempferol (3,5,7,4'-tetrahydroxyflavone, Kaem) was found to be significantly enhanced by coordination of Mg(II), Ca(II), Sr(II), and Ba(II) ions, whereas the radical scavenging rate of apigenin (5,7,4'-trihydroxyflavone, Api) was almost unaffected by alkaline earth metal (AEM) ions, as studied for short-lived b-carotene radical cations (beta-Car(center dot+)) formed by laser flash photolysis in chloroform/ethanol (7 : 3) and for the semi-stable 2,2-diphenyl-1-picrylhydrazyl radical, DPPH center dot, in ethanol at 25 degrees C. A 1 : 1 Mg(II)-Kaem complex was found to be in equilibrium with a 1 : 2 Mg(II)-Kaem(2) complex, while for Ca(II), Sr(II) and Ba(II), only 1 : 2 AEM(II)-Kaem complexes were detected, where all complexes showed 3hydroxyl and 4-carbonyl coordination and stability constants of higher than 10(9) L-2 mol(-2). The 1 : 2 Ca(II)-Kaem(2) complex had the highest second order rate constant for both beta-Car(center dot+) (5 x 10(8) L mol(-1) s(-1)) and DPPH center dot radical (3 x 10(5) L mol(-1) s(-1)) scavenging, which can be attributed to the optimal combination of the stronger electron withdrawing capability of the (n - 1)d orbital in the heavier AEM ions and their spatially asymmetrical structures in 1 : 2 AEM-Kaem complexes with metal ion coordination of the least steric hindrance of two perpendicular flavone backbones as ligands in the Ca(II) complex, as shown by density functional theory calculations.
KW - ANTIOXIDANT ACTIVITY
KW - COMPLEX SYNTHESIS
KW - MOLECULAR-STRUCTURE
KW - DNA CLEAVAGE
KW - FLAVONOIDS
KW - MECHANISM
KW - ELECTRON
KW - CAROTENOIDS
KW - BINDING
U2 - 10.1039/d0ra03249b
DO - 10.1039/d0ra03249b
M3 - Journal article
VL - 10
SP - 30035
EP - 30047
JO - RSC Advances
JF - RSC Advances
SN - 2046-2069
IS - 50
ER -
ID: 248499812