Abstract
The stability and degradation pathways of barbaloin (BA) in aqueous solution were investigated over the pH range of 1.1-8.4. The experiments were performed at three different temperatures (5, 20 and 50°C) by the use of high performance liquid chromatography. The degradation of BA was observed as a pseudo first-order kinetics and shown to proceed via racemization (Keq) and degradation processes (K2), (Keq>K2). The racemization product, isobarbaloin (isoBA), further underwent the same degradation as did BA. 10-hydroxyaloins A (10-HA), 10-hydroxyaloins B (10-HB) and aloe-emodin (AE) were detected as the degradation products of BA and isoBA. On the basis of kinetic studies, it was found that the degradation rate of BA decreased with decreasing pH and temperature. The half-lives of BA at pH7.2 (20°C) and pH3.4 (20°C) were 1.15day and 5.00day, respectively. The present results are useful for the integrity of foods containing aloe.
