Differential scanning calorimetry and thin layer chromatography: Emerging tools for predicting stability of herbal products

Abstract

The stability of extracts made from plant material is essential to ensure the quality, safety and efficacy of the finished product. NIPRIMAL® is a mono herbal formulation of Nauclea latifolia used in the treatment of malaria. This study assessed the stability of the formulation under three different storage conditions; normal room temperature, infrared and under refrigeration. Differential Scanning Calorimetry (DSC) and Thin Layer Chromatography (TLC) were used to monitor the formulations. The DSC analysis was done from 0 to 350°C under the three storage conditions. Results obtained indicate that NIPRIMAL® was stable at all the storage conditions investigated. TLC after 24 months showed there was no significant difference between the retention factor (RF) values for the various storage conditions. The reference sample had four spots with RF values of 0.47, 0.68, 0.76, 0.82 respectively and these spots were retained in the test formulations with corresponding RF values after 24 months at room temperature and refrigerated temperature being 0.56, 0.73, 0.80, 0.92 and 0.47, 0.68, 0.76, 0.82 respectively. On the other hand, the RF values (0.55, 0.74, 0.77, 0.93) obtained under infrared after 24 months varied slightly from the reference. The sample exposed to infrared had a lower heat capacity compared to that stored under room temperature or refrigeration. A combination of TLC and DSC measurements has been applied for assessing the stability of NIPRIMAL®. Both methods were found to be rapid, sensitive and reliable in determining its stability. It is concluded that, NIPRIMAL® can be stored under any of the tested conditions without degradation. This study is a major contribution towards developing appropriate stability monitoring parameters for herbal products; a major challenge in the nutraceutical industry.