ABSTRACT
In 0.01 mol x L(-1) Hepes, pH 7.4 and at room temperature the binding of HBED with Gd(III) or Yb(III) was monitored by UV difference spectrum. The results show that the molar ratio of the complexes is most likely 1 : 1. Gd-HBED or Yb-HBED complex produced peaks at 237 nm and 291 nm. The molar absorptivities of Gd-HBED and Yb-HBED at 237 nm are deltaepsilon(Gd) = (22.52 +/- 0.20) x 10(3) cm(-1) x mol(-1) x L, deltaepsilon(Yb) = (27.15 +/- 0.11) x 10(3) cm(-1) x mol(-1) x L, respectively. The conditional equilibrium constants for the complexes were measured to be lgK(Gd-HBED) = 13.56 +/- 0.28 and lgK(Yb-HBED) = 16.06 +/- 0.03. A linear free energy relationship for the complexes of Yb(III) and Gd(III) has been established by using equilibrium data on 18 complexes. The HBED binding constants for Yb(III) and Gd (III) are in agreement with the linear free energy relationship.
Subject(s)
Edetic Acid/analogs & derivatives , Gadolinium/chemistry , Spectrophotometry, Ultraviolet , Ytterbium/chemistry , Algorithms , Edetic Acid/chemistry , Hydrogen-Ion Concentration , Kinetics , Models, Chemical , Molecular Structure , Organometallic Compounds/chemistry , Temperature , ThermodynamicsABSTRACT
OBJECTIVE: To investigate the alkaloids from the stem of Artabotrys hainanensis. METHOD: Compounds in plant extracts were separated by silica gel and sephadex LH-20 column chromatography. Chemical structures were elucidated by chemical and spectral analyses including UV, 1H-NMR, 13C-NMR, ESIMS and ESI-MS-MS. RESULT: Eight alkaloids were isolated and identified as spinosine (1), 3-hydroxynornuciferine (2), juzirine (3), artabotrine (4), liridine (5), assimilobine (6), isococlaurine (7), N-demethylarmepavine (8). CONCLUSION: All alkaloids were isolated from this plant for the first time and compounds 1, 3, 7 and 8 were isolated from genus Artabotrys for the first time.
