Validated TLC densitometric method for stress degradation study of Asiaticoside from Centella asiatica

Stress degradation studies were carried out on Asiaticoside (triterpenoid component extracted form Centella asiatica) following the conditions prescribed in the parent drug stability testing guideline (Q1AR2) issued by International Conference on Harmonization (ICH). The present study describes degradation of Asiaticoside under different ICH prescribed stress conditions (acid and base hydrolysis, oxidation, and photodegradation) and establishment of a stability indicating TLC densitometric assay. The method employed TLC aluminium plates precoated with silica gel 60F₂₅₄ as the stationary phase. The optimized solvent system consisted of toluene:ethyl acetate:methanol:glacial acetic acid 2:7:3:1 (v/v/v/v). The derivatization was carried out with 10% methanolic sulphuric acid reagent. This system was found to give compact spots for asiaticoside (R _f value of 0.43). Densitometric analysis of Asiaticoside was carried out in the absorbance mode at 595 nm. The drug undergoes degradation under acidic and basic conditions, oxidation, and photodegradation. All the peaks of degraded products were resolved from the standard Asiaticoside with significantly different R_f values. As the method could effectively separate the drug from its degradation products, it can be employed as a stability indicating one.