A novel complex of lanthanum （ Ⅲ ） with demethylcantharidate group （DCA）, Na [ La （DCA） 2 （H2O） ], was synthesized in aqueous solution and characterized by elemental analysis, molar conductance, IR, UV, ^1H-N...A novel complex of lanthanum （ Ⅲ ） with demethylcantharidate group （DCA）, Na [ La （DCA） 2 （H2O） ], was synthesized in aqueous solution and characterized by elemental analysis, molar conductance, IR, UV, ^1H-NMR spectra and TG-DTA. The results suggest that lanthanum ion is seven-coordinated. Six oxygen atoms are from carboxyl groups and cyclic ethers of two DCA ligand, and on oxygen is from a H2O. The antitumor activities of the complex against HL-60 human leukemia, BGC-823 human gastric carcinoma, Bel-7402 human hepatic carcinoma, Hela human cervical carcinoma were investigated with MT＇F or SRB assays. Na[La（DCA）2（H2O）] exhibits stronger inhibition against certain kinds of cancer cells than Na2DCA in vitro.展开更多
A new lanthanum complex, （H3O）2[La（C7H3NO5）2（H2O）212.3（H2O） or （HaO）E[La（HChel）2（HEO）E]2.3（H2O） 1 （H3Chel = 4-hydroxypyridine-2,6-dicarboxylic（chelidamic） acid）, has been prepared by the hydrotherm...A new lanthanum complex, （H3O）2[La（C7H3NO5）2（H2O）212.3（H2O） or （HaO）E[La（HChel）2（HEO）E]2.3（H2O） 1 （H3Chel = 4-hydroxypyridine-2,6-dicarboxylic（chelidamic） acid）, has been prepared by the hydrothermal reaction, and its crystal structure was determined based on single-crystal diffraction data. Compound I crystallizes in triclinic, space group Pi with a = 9.6939（19）, b = 10.176（2）, c = 11.502（2）A, α = 111.52（3）, β = 93.74（3）, γ = 103.33（3）°, V = 1013.0（3）A3, Dc = 1.912 g/cm3, Z = 1, Mr = 1166.40, p = 2.188 mm-1, 2（MoKa） = 0.71073 A and F（000） = 574. The final R = 0.0342 and wR = 0.0737 for 4080 observed reflections with I 〉 2σ（I）, and R = 0.0429 and wR = 0.0772 for all data. Compound 1 contains two lanthanum ions, four chelidamic acid ligands, four coordinated water molecules, two hydroniums, and three discrete water molecules. The LaⅢ atom is ten-coordinated by four oxygen and two nitrogen atoms from two tridentate chelating chelidamic acid ligands, two carboxylic oxygen atoms from an adjacent chelidamic acid ligand and two coordinated water molecules, leading to a distorted dodecahedral geometry. A three-dimensional network is formed by H-bonds.展开更多
A novel lanthanum（III） complex, [LaL2（NO3）3].H2O （1） based on L （L = N-（na- phthalene-l-yl）-2-（quinolin-8-yloxy）acetamide）, was synthesized and characterized by X-ray diffraction. The crystal of I belongs ...A novel lanthanum（III） complex, [LaL2（NO3）3].H2O （1） based on L （L = N-（na- phthalene-l-yl）-2-（quinolin-8-yloxy）acetamide）, was synthesized and characterized by X-ray diffraction. The crystal of I belongs to the monoclinic system, space group C2c with Mr= 1017.69, a = 25.1438（17）, b = 13.5950（9）, c = 18.2349（12） A, β= 132.4980（10）° V= 4595.8（5） A3, Z= 4, Dc = 1.471 Mg/m3, F（000） = 2056,μ= 1.004 mm-1, R = 0,0588 and wR = 0.1402. The central La（lI1） ion is coordinated to four oxygen atoms, two nitrogen atoms from two independent acetarnide ligands and six oxygen atoms from three nitrate anions, possessing a distorted icosahedron coordination geometry. In the crystal of 1, intermolecular N-H……O hydrogen bonds linked the molecules into chains along the c axis. In solid state and CH3CN solution, complex 1 exhibits stronger fluorescent emission than the ligand L.展开更多
The new lanthanum (Ⅲ) and praseodymium (Ⅲ) complexes of the general formula [Ln(L)3] (Ln=La(Ⅲ) or Pr(Ⅲ); LK=potassium salt of dithiocarbazinates) were prepared by both, conventional thermal and by the use of micro...The new lanthanum (Ⅲ) and praseodymium (Ⅲ) complexes of the general formula [Ln(L)3] (Ln=La(Ⅲ) or Pr(Ⅲ); LK=potassium salt of dithiocarbazinates) were prepared by both, conventional thermal and by the use of microwave technology. Elemental analyses, electrical conductance, magnetic moment and electronic, infrared, far-infrared, 1H and 13C NMR spectral studies were used to characterize the complexes. The molecular weights of few complexes were determined by FAB-mass spectra. Nephelauxetic ratio, covalency parameter and bonding parameter for these complexes were also calculated. The probable structures of the complexes were proposed. The antifungal and antibacterial activities of the complexes were evaluated. The activities were correlated with the structures of the compounds.展开更多
A new dimeric lanthanum (Ⅲ) complex [La_2(phen)_2(C_7H_3N_2O_6)_6] (phen=1, 10-phenanthroline) was synthesized by the hydrothermal method and determined by single crystal X-ray diffraction analysis. The La(Ⅲ) ion is...A new dimeric lanthanum (Ⅲ) complex [La_2(phen)_2(C_7H_3N_2O_6)_6] (phen=1, 10-phenanthroline) was synthesized by the hydrothermal method and determined by single crystal X-ray diffraction analysis. The La(Ⅲ) ion is coordinated to seven oxygen atoms from five carboxylate groups and two nitrogen atoms from a phen ligand, forming a monocapped square antiprismatic geometry. Six carboxylate groups coordinate to two La(Ⅲ) ions in three modes which are chelating bidentate, bridging bidentate and bridging tridentate. The crystal is triclinic with space group P-1, a=1.2030(4) nm, b=1.2962(5) nm, c=1.3330(5) nm, α=104.410(5)°, β=114.048(4)°, γ=100.054 (4)°, V=1.7467 (10) nm^3, M_r=952.46, Z=2, D_c=1.811 g·cm^(-3), F(000)=944, S=1.017, μ=1.320 mm^(-1), with R1=0.0298 and wR2=0.0625.展开更多
ABSTRACT A new lanthanumm-ironm complex [La（DMSO）5（H2O）]（μ-CN）2[Fe（CN）4]·H2O 1 （DMSO = dimethylsulfoxide） has been prepared by a facile approach, ball-milling method, and characterized by X-ray diffrac...ABSTRACT A new lanthanumm-ironm complex [La（DMSO）5（H2O）]（μ-CN）2[Fe（CN）4]·H2O 1 （DMSO = dimethylsulfoxide） has been prepared by a facile approach, ball-milling method, and characterized by X-ray diffraction. The crystal belongs to monoclinic, space group P21/n with a = 9.7125（3）, b = 21.5336（7）, c = 14.3804（5）A, β = 93.242（3）°, C16H34FeLaN60O7S5, Mr= 777.55, V = 3002.8（2）A^3, Z = 4, Dc = 1.720 g/cm^3, S = 1.053, μ（MoKα） = 2.278 mm^-1, F（000） = 1564, R = 0.0490 and ωR = 0.1270. The crystal structure analysis of 1 reveals a slightly distorted squareantiprism eighffold-coordinated La（Ⅲ） ion and a 1-D zigzag chain structure extending through the Fe-CN-La-NC-Fe linkages. The [La（DMSO）5（H2O）]（μ-CN）2[Fe（CN）4] species are held together via hydrogen bonds to form a three-dimensional framework.展开更多
A novel metal-organic complex [La（o-NCP）3]n （o-HNCP = 2-（2-carboxyphen- yl）imidazo（4,5- f）（1,10）-phenanthroline） has been hydrothermally synthesized and characterized by elemental analysis, infrared analysis...A novel metal-organic complex [La（o-NCP）3]n （o-HNCP = 2-（2-carboxyphen- yl）imidazo（4,5- f）（1,10）-phenanthroline） has been hydrothermally synthesized and characterized by elemental analysis, infrared analysis and X-ray single-crystal diffraction. The complex crystallizes in triclinic, space group P1 with a = 9.898（2）, b = 16.193（3）, c = 16.909（3） A, a = 67.68（3）, β = 80.85（3）, y = 78.78（3）°, V= 2448.2（8） A3, Z = 2, Mr = 1156.9, Dc = 1.569 g/cm3,μ = 0.71073 A, F（000） = 1164, GOOF = 1.065, the final R = 0.051 and wR = 0.123 for 8539 observed reflections with I 〉 2o（I）. The complex exhibits a one-dimensional double chain structure. The adjacent chains are further connected by N-H...N hydrogen bonds which help to form a two-dimensional suprarnolecular architecture. Furthermore, the complex exhibits excellent thermal stability and luminescent property.展开更多
Ultra trace determination of lantanum（Ⅲ） has been studied by adsorptive stripping voltammetry methods using an alizarin S as complexing agent and carbon paste electrode as working electrode. The electrode was made ...Ultra trace determination of lantanum（Ⅲ） has been studied by adsorptive stripping voltammetry methods using an alizarin S as complexing agent and carbon paste electrode as working electrode. The electrode was made from mixed of carbon powder and paraffin in micropipette tip with diameter of 4 ram. This method consists of two steps. The first step is the formation and adsorptive accumulation of metal ion with chelator at the electrode surface. The second step is stripping the complex from the electrode surface into the solution. The stripping step generates current which is recorded as voltammogram. The optimum conditions of instrumental parameter obtained were accumulation potential of 600 mV, accumulation time of 120 seconds, and pH of solution of 5.5. In this research, the limit detection obtained was 2.3348 × 10^-12 M （3.24× 10^-11μg/L） with sensitivity of 16.52 （nA/10u M） and the precision of standard solution of La3＋ with concentration of 2 × 10^-12 M, 4× 10^-12 M, 6 × 10^-12 M, 8 × 10^-12 M, and 10 × 10^-12M were 3.50%, 9.88%, 7.19%, 7.48% and 1.85% respectively. The linierity of this method is very good with correlation coefficient is 0.9780. Recovery percentage from La3＋ with concentration of 6× 10^-12 M and 10 × 10^-12 M are 108.84% and 91.51%, respectively.展开更多
The hydroponic culture experiments of soybean bean seedlings were conducted to investigate the effect of lanthanum （La） on nitrogen metabolism under two different levels of elevated UV-B radiation （UV-B, 280-320 nm...The hydroponic culture experiments of soybean bean seedlings were conducted to investigate the effect of lanthanum （La） on nitrogen metabolism under two different levels of elevated UV-B radiation （UV-B, 280-320 nm）. The whole process of nitrogen metabolism involves uptake and transport of nitrate, nitrate assimilation, ammonium assimilation, amino acid biosynthesis, and protein synthesis. Compared with the control, UV-B radiation with the intensity of low level 0.15 W/m^2 and high level 0.45 W/m^2 significantly affected the whole nitrogen metabolism in soybean seedlings （p 〈 0.05）. It restricted uptake and transport of NO3^-, inhibited activity of some key nitrogen-metabolism-related enzymes, such as： nitrate reductase （NR） to the nitrate reduction, glutamine systhetase （GS） and glutamine synthase （GOGAT） to the ammonia assimilation, while it increased the content of free amino acids and decreased that of soluble protein as well. The damage effect of high level of UV-B radiation on nitrogen metabolism was greater than that of low level. And UV-B radiation promoted the activity of the anti-adversity enzyme glutamate dehydrogenase （GDH）, which reduced the toxicity of excess ammonia in plant. After pretreatment with the optimum concentration of La （20 mg/L）, La could increase the activity of NR, GS, GOGAT, and GDH, and ammonia assimilation, but decrease nitrate and ammonia accumulation. In conclusion, La could relieve the damage effect of UV-B radiation on plant by regulating nitrogen metabolism process, and its alleviating effect under low level was better than that under the high one.展开更多
The effect of lanthanum （Ⅲ） on reactive oxygen metabolism of soybean seedlings under elevated ultraviolet-B radiation（UV-B：280~320 nm）at 0.15 and 0.45 W·cm-2 levels respectively was studied through hydropon...The effect of lanthanum （Ⅲ） on reactive oxygen metabolism of soybean seedlings under elevated ultraviolet-B radiation（UV-B：280~320 nm）at 0.15 and 0.45 W·cm-2 levels respectively was studied through hydroponics in the laboratory.Plasmolemma permeability and contents of malonadialdehyde（MDA）,hydrogen peroxide（H2O2）,and proline gradually increased during the imposition of UV-B radiation and subsequently decreased during recovery from UV-B stress.The dynamic tendency of catalase（CAT）activity was similar to that of the above four indices.The activity of peroxidase（POD）initially increased,then remained at a high level,and finally dropped steeply when soybean seedlings were exposed to a low dosage of UV-B radiation.However,POD activity rose throughout and declined slightly on the eleventh day when soybean seedlings were stressed by a high dosage.With the addition of La （Ⅲ） of 20 mg·L-1,the rising tendency of plasmolemma permeability and contents of MDA,H2O2,and proline were slowed down during the stress period,whereas the declining speed was accelerated during the recovery period.The activities of CAT and POD were higher than those without La （Ⅲ） in all experiments.It suggested that the regulative effect of La （Ⅲ） on antioxidant enzymes such as CAT and POD could strengthen their capacities to scavenge reactive oxygen species（ROS）,decrease contents of MDA and proline,and maintain normal plasmolemma permeability.Further more,the protective potential of La （Ⅲ） was better under low UV-B radiation than under a high one.展开更多
文摘A novel complex of lanthanum （ Ⅲ ） with demethylcantharidate group （DCA）, Na [ La （DCA） 2 （H2O） ], was synthesized in aqueous solution and characterized by elemental analysis, molar conductance, IR, UV, ^1H-NMR spectra and TG-DTA. The results suggest that lanthanum ion is seven-coordinated. Six oxygen atoms are from carboxyl groups and cyclic ethers of two DCA ligand, and on oxygen is from a H2O. The antitumor activities of the complex against HL-60 human leukemia, BGC-823 human gastric carcinoma, Bel-7402 human hepatic carcinoma, Hela human cervical carcinoma were investigated with MT＇F or SRB assays. Na[La（DCA）2（H2O）] exhibits stronger inhibition against certain kinds of cancer cells than Na2DCA in vitro.
基金Supported by the Nanchang Hangkong University Doctoral Foundation (EA200702136)
文摘A new lanthanum complex, （H3O）2[La（C7H3NO5）2（H2O）212.3（H2O） or （HaO）E[La（HChel）2（HEO）E]2.3（H2O） 1 （H3Chel = 4-hydroxypyridine-2,6-dicarboxylic（chelidamic） acid）, has been prepared by the hydrothermal reaction, and its crystal structure was determined based on single-crystal diffraction data. Compound I crystallizes in triclinic, space group Pi with a = 9.6939（19）, b = 10.176（2）, c = 11.502（2）A, α = 111.52（3）, β = 93.74（3）, γ = 103.33（3）°, V = 1013.0（3）A3, Dc = 1.912 g/cm3, Z = 1, Mr = 1166.40, p = 2.188 mm-1, 2（MoKa） = 0.71073 A and F（000） = 574. The final R = 0.0342 and wR = 0.0737 for 4080 observed reflections with I 〉 2σ（I）, and R = 0.0429 and wR = 0.0772 for all data. Compound 1 contains two lanthanum ions, four chelidamic acid ligands, four coordinated water molecules, two hydroniums, and three discrete water molecules. The LaⅢ atom is ten-coordinated by four oxygen and two nitrogen atoms from two tridentate chelating chelidamic acid ligands, two carboxylic oxygen atoms from an adjacent chelidamic acid ligand and two coordinated water molecules, leading to a distorted dodecahedral geometry. A three-dimensional network is formed by H-bonds.
基金supported by the National Natural Science Foundation of China(21001040)Education Department of Henan Province(No.12B150011 and 14B150029)
文摘A novel lanthanum（III） complex, [LaL2（NO3）3].H2O （1） based on L （L = N-（na- phthalene-l-yl）-2-（quinolin-8-yloxy）acetamide）, was synthesized and characterized by X-ray diffraction. The crystal of I belongs to the monoclinic system, space group C2c with Mr= 1017.69, a = 25.1438（17）, b = 13.5950（9）, c = 18.2349（12） A, β= 132.4980（10）° V= 4595.8（5） A3, Z= 4, Dc = 1.471 Mg/m3, F（000） = 2056,μ= 1.004 mm-1, R = 0,0588 and wR = 0.1402. The central La（lI1） ion is coordinated to four oxygen atoms, two nitrogen atoms from two independent acetarnide ligands and six oxygen atoms from three nitrate anions, possessing a distorted icosahedron coordination geometry. In the crystal of 1, intermolecular N-H……O hydrogen bonds linked the molecules into chains along the c axis. In solid state and CH3CN solution, complex 1 exhibits stronger fluorescent emission than the ligand L.
文摘The new lanthanum (Ⅲ) and praseodymium (Ⅲ) complexes of the general formula [Ln(L)3] (Ln=La(Ⅲ) or Pr(Ⅲ); LK=potassium salt of dithiocarbazinates) were prepared by both, conventional thermal and by the use of microwave technology. Elemental analyses, electrical conductance, magnetic moment and electronic, infrared, far-infrared, 1H and 13C NMR spectral studies were used to characterize the complexes. The molecular weights of few complexes were determined by FAB-mass spectra. Nephelauxetic ratio, covalency parameter and bonding parameter for these complexes were also calculated. The probable structures of the complexes were proposed. The antifungal and antibacterial activities of the complexes were evaluated. The activities were correlated with the structures of the compounds.
文摘A new dimeric lanthanum (Ⅲ) complex [La_2(phen)_2(C_7H_3N_2O_6)_6] (phen=1, 10-phenanthroline) was synthesized by the hydrothermal method and determined by single crystal X-ray diffraction analysis. The La(Ⅲ) ion is coordinated to seven oxygen atoms from five carboxylate groups and two nitrogen atoms from a phen ligand, forming a monocapped square antiprismatic geometry. Six carboxylate groups coordinate to two La(Ⅲ) ions in three modes which are chelating bidentate, bridging bidentate and bridging tridentate. The crystal is triclinic with space group P-1, a=1.2030(4) nm, b=1.2962(5) nm, c=1.3330(5) nm, α=104.410(5)°, β=114.048(4)°, γ=100.054 (4)°, V=1.7467 (10) nm^3, M_r=952.46, Z=2, D_c=1.811 g·cm^(-3), F(000)=944, S=1.017, μ=1.320 mm^(-1), with R1=0.0298 and wR2=0.0625.
基金the NNSFC (20571075, 20521101)the NSF for Distinguished Young Scientist of China (20425104)the NSF of Fujian Province (E0510028)
文摘ABSTRACT A new lanthanumm-ironm complex [La（DMSO）5（H2O）]（μ-CN）2[Fe（CN）4]·H2O 1 （DMSO = dimethylsulfoxide） has been prepared by a facile approach, ball-milling method, and characterized by X-ray diffraction. The crystal belongs to monoclinic, space group P21/n with a = 9.7125（3）, b = 21.5336（7）, c = 14.3804（5）A, β = 93.242（3）°, C16H34FeLaN60O7S5, Mr= 777.55, V = 3002.8（2）A^3, Z = 4, Dc = 1.720 g/cm^3, S = 1.053, μ（MoKα） = 2.278 mm^-1, F（000） = 1564, R = 0.0490 and ωR = 0.1270. The crystal structure analysis of 1 reveals a slightly distorted squareantiprism eighffold-coordinated La（Ⅲ） ion and a 1-D zigzag chain structure extending through the Fe-CN-La-NC-Fe linkages. The [La（DMSO）5（H2O）]（μ-CN）2[Fe（CN）4] species are held together via hydrogen bonds to form a three-dimensional framework.
基金Supported by the Program for New Century Excellent Talents in University(NCET-10-0176)
文摘A novel metal-organic complex [La（o-NCP）3]n （o-HNCP = 2-（2-carboxyphen- yl）imidazo（4,5- f）（1,10）-phenanthroline） has been hydrothermally synthesized and characterized by elemental analysis, infrared analysis and X-ray single-crystal diffraction. The complex crystallizes in triclinic, space group P1 with a = 9.898（2）, b = 16.193（3）, c = 16.909（3） A, a = 67.68（3）, β = 80.85（3）, y = 78.78（3）°, V= 2448.2（8） A3, Z = 2, Mr = 1156.9, Dc = 1.569 g/cm3,μ = 0.71073 A, F（000） = 1164, GOOF = 1.065, the final R = 0.051 and wR = 0.123 for 8539 observed reflections with I 〉 2o（I）. The complex exhibits a one-dimensional double chain structure. The adjacent chains are further connected by N-H...N hydrogen bonds which help to form a two-dimensional suprarnolecular architecture. Furthermore, the complex exhibits excellent thermal stability and luminescent property.
文摘Ultra trace determination of lantanum（Ⅲ） has been studied by adsorptive stripping voltammetry methods using an alizarin S as complexing agent and carbon paste electrode as working electrode. The electrode was made from mixed of carbon powder and paraffin in micropipette tip with diameter of 4 ram. This method consists of two steps. The first step is the formation and adsorptive accumulation of metal ion with chelator at the electrode surface. The second step is stripping the complex from the electrode surface into the solution. The stripping step generates current which is recorded as voltammogram. The optimum conditions of instrumental parameter obtained were accumulation potential of 600 mV, accumulation time of 120 seconds, and pH of solution of 5.5. In this research, the limit detection obtained was 2.3348 × 10^-12 M （3.24× 10^-11μg/L） with sensitivity of 16.52 （nA/10u M） and the precision of standard solution of La3＋ with concentration of 2 × 10^-12 M, 4× 10^-12 M, 6 × 10^-12 M, 8 × 10^-12 M, and 10 × 10^-12M were 3.50%, 9.88%, 7.19%, 7.48% and 1.85% respectively. The linierity of this method is very good with correlation coefficient is 0.9780. Recovery percentage from La3＋ with concentration of 6× 10^-12 M and 10 × 10^-12 M are 108.84% and 91.51%, respectively.
基金Project supported by the National Natural Science Foundation of China(No.30570323)Foundation of State Developing and Reforming Committee(No.IFZ20051210)
文摘The hydroponic culture experiments of soybean bean seedlings were conducted to investigate the effect of lanthanum （La） on nitrogen metabolism under two different levels of elevated UV-B radiation （UV-B, 280-320 nm）. The whole process of nitrogen metabolism involves uptake and transport of nitrate, nitrate assimilation, ammonium assimilation, amino acid biosynthesis, and protein synthesis. Compared with the control, UV-B radiation with the intensity of low level 0.15 W/m^2 and high level 0.45 W/m^2 significantly affected the whole nitrogen metabolism in soybean seedlings （p 〈 0.05）. It restricted uptake and transport of NO3^-, inhibited activity of some key nitrogen-metabolism-related enzymes, such as： nitrate reductase （NR） to the nitrate reduction, glutamine systhetase （GS） and glutamine synthase （GOGAT） to the ammonia assimilation, while it increased the content of free amino acids and decreased that of soluble protein as well. The damage effect of high level of UV-B radiation on nitrogen metabolism was greater than that of low level. And UV-B radiation promoted the activity of the anti-adversity enzyme glutamate dehydrogenase （GDH）, which reduced the toxicity of excess ammonia in plant. After pretreatment with the optimum concentration of La （20 mg/L）, La could increase the activity of NR, GS, GOGAT, and GDH, and ammonia assimilation, but decrease nitrate and ammonia accumulation. In conclusion, La could relieve the damage effect of UV-B radiation on plant by regulating nitrogen metabolism process, and its alleviating effect under low level was better than that under the high one.
基金Project supported by the National Natural Science Foundation of China(30570323)the Foundation of State Developingand Reforming Committee(IFZ20051210)
文摘The effect of lanthanum （Ⅲ） on reactive oxygen metabolism of soybean seedlings under elevated ultraviolet-B radiation（UV-B：280~320 nm）at 0.15 and 0.45 W·cm-2 levels respectively was studied through hydroponics in the laboratory.Plasmolemma permeability and contents of malonadialdehyde（MDA）,hydrogen peroxide（H2O2）,and proline gradually increased during the imposition of UV-B radiation and subsequently decreased during recovery from UV-B stress.The dynamic tendency of catalase（CAT）activity was similar to that of the above four indices.The activity of peroxidase（POD）initially increased,then remained at a high level,and finally dropped steeply when soybean seedlings were exposed to a low dosage of UV-B radiation.However,POD activity rose throughout and declined slightly on the eleventh day when soybean seedlings were stressed by a high dosage.With the addition of La （Ⅲ） of 20 mg·L-1,the rising tendency of plasmolemma permeability and contents of MDA,H2O2,and proline were slowed down during the stress period,whereas the declining speed was accelerated during the recovery period.The activities of CAT and POD were higher than those without La （Ⅲ） in all experiments.It suggested that the regulative effect of La （Ⅲ） on antioxidant enzymes such as CAT and POD could strengthen their capacities to scavenge reactive oxygen species（ROS）,decrease contents of MDA and proline,and maintain normal plasmolemma permeability.Further more,the protective potential of La （Ⅲ） was better under low UV-B radiation than under a high one.
