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KMID : 0369819950250030239
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Jorunal of Korean Pharmaceutical Sciences
1995 Volume.25 No. 3 p.239 ~ p.248
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Influence of pH, Temperature, Ionic Strength and Metal Ions of the Degradation of an Iridoid Glucoside, Aucubin, in Buffered Aqueous Solutions
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Abstract
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The physico-chemical stability of aucubin, a hepatoprotective iridoid glucoside, in buffered aqueous solutions was studied using a stability-indicating reversed-phase high performance liquid chromatography. The degradation of aucubin followed the
pseudo-first-order kinetics. In strong acidic regions, aucubin was rapidly degraded by the specific acid catalysis, forming dark brown precipitates. From the temperature dependence of degradation activation energies for aucubin at pH 2.1 and 4.9
were
calculated to be 22.0 and 24.3kcal/mole, respectively. The shelf-life (t90%) for aucubin at pH 9.07 and 20℃was predicted to be about 603days. A higher ionic strength accelerated the degradation of aucubin at pH 4.01. The effect of metal ions on
the
degradation rate of aucubin at pH 7.16 was in the rank order of Cu2+>Fe3+>Co2+>Mg2+. On the other hand, Mn2+ and Ba2+ slowed the degradation rate.
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