Thermal Degradation Kinetics and pH-Rate Profile of Verbascoside and Stability Improvement by Solid Lipid Nanoparticles.

Thermal degradation of verbascoside (VB) in Acanthus ebracteatus Vahl (AE) always affects its health benefit. Here the temperature effect on VB in both AE extract and solid lipid nanoparticles (SLNs)-encapsulated AE extract was demonstrated using the Arrhenius plot. The reaction rate constants were calculated for shelf life and plotted to obtain pH-rate profiles. VB degradation was a first-order reaction. The reaction rate in a neutral to alkaline solution was faster than in an acidic solution. VB in AE extract-loaded SLNs was more stable than in uncapped AE extract. The shelf life of VB in SLNs was 153 days with activation energy (E a) of 76.16 kJ mol-1, whereas those of VB in AE extract and in AE extract solution were 75 days with E a = 78.03 kJ mol-1 and 12 days with E a = 49.24 kJ mol-1, respectively. Therefore, we anticipate that the AE extract-loaded SLNs will be beneficial for product development.