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Target-guided isolation and purification of antioxidants from Elsholtzia densa benth. var. densa by DPPH antioxidant assay and dual-mode HSCCC

Zhou W. N., Ouyang J., Wang Z. H., Wang X. Y., Suo Y. R., Zhang Z., Wang H. L.

Acta Chromatographica

2018

Vol. 30, no. 3

180--185

Elsholtzia densa Benth. var. densa (Lamiaceae) is a famous medicinal herb which has been widely used for treatment of colds, headaches, pharyngitis, fever, diarrhea, digestion disorder, rheumatic arthritis, nephritises, and nyctalopia in China. In this study, fraction of the ethyl alcohol extract of E. densa (aerial part) by different polarity solvents indicated that the ethyl acetate soluble fraction exhibited a potent 1,1-diphenyl-2-picryhydrazyl (DPPH) radical scavenging activity with the IC50 value of 148.2 μg/mL. Under the target guidance of DPPH experiment, isoquercitrin, trachelogenin, ethyl caffeate, and arctigenin were separated with purities 95.98%, 92.98%, 96.07%, and 88.83%, respectively, by a dual-mode high-speed counter-current chromatography (HSCCC) method using n-hexane–ethyl acetate–methanol–water (4.5:5:3:4, v/v/v/v) as the solvent system. In order to evaluate the scientific basis, antioxidant activity of four isolated compounds was assessed by the radical scavenging effect on DPPH radical; isoquercitrin and ethyl caffeate showed stronger antioxidant activities with IC50 values of 9.4 μg/mL and 9.2 μg/mL, respectively, while trachelogenin and arctigenin showed weak antioxidant activities with IC50 values of >500 μg/mL and 72.8 μg/mL, respectively. Results of the present study indicated that the combinative method using DPPH antioxidant assay and dual-mode HSCCC could be widely applied for rapid screening and isolating of antioxidants from complex traditional Chinese medicine extract.

Synthesis and Magnetic Studies of [Cu3IILnIII] Heterotetranuclear Complexes with N,N’- Bis(3-amino-2,2-dimethylpropyl)oxamidocopper (II)

Li Y. T., Yan C. W., Wang H. L.

Polish Journal of Chemistry

2001

Vol. 75, nr 12

1817-1824

Eleven newoxamido-bridged Cu"Ln"'-type (Ln = La, Ce, Pr.Nd, Sm, Eu, Gd, Tb, Ho, Er, Yb) heterotetranuclear complexes, namely Cu3(Me2Oxpn)3Ln(NOj)3, where Me2oxpn denotesN,N'-bis(3-amino-2,2-dimethylpropyl)oxamido dianion, have been synthesized and characterized by elemental analyses, molar conducti vity measurements, and spectro-scopic (IR, UV, ESR) studies. Cryomagnetic measurements (4.2~300 K) and studies of Cu3(Me2oxpn)jGd(NO3)3 complex have revealed that the gadolinium(Ill) and copper(II) ions arę ferromagnetically coupled with the exchang_e integraj J = +3.88 cm'1, on the basis of the spin Hamiltonian operator [H = -2J(S, o S" + S: o S" + Sj o S,>)].