Stability evaluation
Effect of light on the stability of the extract
The extracts were kept in the well-closed containers and stored either under fluorescent light or protected from light, at room 30±2 °C for a period of 4 months. The results demonstrated that under both conditions, the physical appearances of the extracts were not changed from those at the initial time. The total rhinacanthin content of the RRn extract that kept in the light protection container was not decreased through the period of four months. In contrast, the total content of rhinacanthin in the extract that exposed to light was markedly decreased from 75.05 to 48.61 %w/w (Table 3). This finding suggests that the RRn extract should be kept in a well-closed container, protected from light, to avoid instability of rhinacanthins.