Thin-layer chromatographic method optimization of a Piper guineense extract: comparison with published methods

Piper guineense Schumach is a medicinal plant that contains piperine as its major bioactive compound. Piperine alkaloid has antidepressant like properties [1]. The analysis of piperine is usually performed by thin layer chromatography (TLC), a method widely used in the analysis of bioactive compounds for drug discovery. However, the TLC method used for the separation of P. guineense extracts lacks optimization of the mobile phase and the effects of the developing chamber on the separation. The aim of the study was to develop an optimal TLC method for the separation of P. guineense extracts.

In the present study, a TLC method was optimized for the analysis of P. guineense extracts using solvents of various solvent strength (ST) and solvent selectivity (PS) values according to Nyiredy [2]. The mobile phase composition was systematically tested using various proportions of solvents differing in ST and PS under the same experimental conditions. In addition, the effects of developing chamber were tested using three types of unsaturated chamber conditions: horizontal chamber in sandwich configuration, horizontal chamber in non-sandwich configuration and twin trough chamber and vertical development. During the study a TLC method was developed and the best mobile phase composition giving good resolution of bands was found to be ethyl acetate: toluene (PS 4 – 6 at ST 3.2; corresponding to 40:60% v/v). The tested developing chamber conditions did not affect the TLC separation efficacy.

The optimized TLC method resulted in improved separation when compared with the published method on the extracts of this species [3]. This present study provides the improved choice of mobile phase for the analysis of Piper guineense extracts.

References:

[1] Li S et al Life Sci., 2007; 80: 1373 – 1381

[2] Nyiredy Sz. J Chromatogr Sci 2002; 40: 1 – 11

[3] Ntonifor N et al J Agric Food Chem 2002; 50: 6295 – 6300