Estimation of individual sennosides in plant materials and marketed formulations by an HPTLC method

Senna is a well-known drug, used in the Ayurvedic and Allopathic systems of medicine, and is a treatment for constipation. The purgative action of sen na and its formulations is due to the presence of sennosides A and B. An HP TLC method has been developed for the determination of individual sennoside s (A, B, C, D) without any derivatization in marketed formulations (three t ablet formulations, two granule formulations and one liquid formulation) an d plant materials (senna leaf and pod). The methanolic solution of a sample was applied on a pre-coated silica gel G60 F-254 TLC plate (E. Merck.) and was developed using n-propanol:ethyl ac etate:water: glacial acetic acid (3 : 3 : 2 : 0.1 v/v) as the mobile phase. The relative band speeds (R-f values) obtained were 0.35, 0.25, 0.61, 0.46 for sennosides A, B, C and D, respectively. The densitometric response was monitored at 366 nm. Calibration curves were found to be linear in the con centration ranges 193-1356, 402-2817, 71-497 and 132-927 ng per spot for se nnosides A, B, C, and D, respectively. The correlation coefficients were fo und to be 0.9978, 0.9987, 0.9939 and 0.9983 respectively for sennosides A, B, C and D. The result obtained with the HPTLC method for total sennoside c ontent was compared with the results using the pharmacopoeial methods (spec trophotometric (British Pharmacopoeia) and spectrofluorimetric (United Stat es Pharmacopeia) using the 'F' test). The results revealed no significant d ifference in the three different methods for estimation of total sennoside. The proposed HPTLC method was found to be simple, specific, precise, accura te and rapid. It can be used for routine quality control of sennosides or s enna-containing formulations for individual sennosides.