Validated TLC method for simultaneous quantitation of kutkoside and picroside-I from Kutki extract

The two iridoid glycosides kutkoside and picroside-I are the active hepatoprotective principles of Picrorhiza kurroa Royle ex Benth (Scrophulariaceae), commonly known as Kutki. Quantitation of these phytoconstituents is important for the routine quality control of Kutki extract.

To develop and validate a simple, precise and rapid thin-layer chromatography (TLC) method for the simultaneous quantitation of kutkoside and picroside-I in Kutki extract.

The analysis was performed on a TLC precoated silica gel 60 F(254) plate with ethyl acetate:methanol:glacial acetic acid:formic acid (25:5:1:1, v/v/v/v) as mobile phase. Densitometric evaluation of kutkoside and picroside-I was carried out at 265  nm and the mobile phase showed good resolution with R(f) values 0.42 ± 0.03 and 0.61 ± 0.03 for kutkoside and picroside-I, respectively. The method was validated in terms of specificity, linearity, accuracy and precision.

The content of kutkoside and picroside-I was found to be 2.18 and 1.90%, respectively, and was comparable with those obtained by HPLC. The linearity was found to be in the range of 80-480  ng/spot for both kutkoside and picroside-I. The average recovery values were found to be 96.5 and 96.0% for kutkoside and picroside-I, respectively.

The developed method was found to be relatively simple, precise and reproducible for the simultaneous quantitation of kutkoside and picroside-I. The method does not employ any derivatisation procedure and can be used as a quality control tool for the routine analysis of commercial Kutki extracts.