Characterization and Estimation of Harpagoside in Dried Root Extract and Oral Powder Formulations of Harpagophytum Procumbens by Validated RP-HPLC-PDA Method

The present investigation was undertaken to perform structural, physicochemical characterization and to estimate the harpagoside in dried root extract and flavoured powder formulations of harpagophytum procumbens (devils claw). The extraction of harpagoside from the root extract was carried out using different solvents and the harpagoside content was estimated using an RP-HPLC-PDA method. The HPLC analysis was carried out using methanol: 0.02% formic acid (60:40 v/v) as the mobile phase, pumped at flow rate of 1mL/min through C18 column (Kinetex XB, 150x4.6mm, 5µ). The structural and physicochemical characterization of the root extract was performed using FT-IR, DSC and SEM analysis. Flavoured powder formulations (effervescent and non-effervescent) of the root extract were prepared and the harpagoside content was estimated by HPLC method. Higher percentage of harpagoside (1.6 %) was extracted with water as extraction solvent when compared to methanol and methanol: water (50:50 v/v). The developed RP-HPLC-PDA method resulted in shorter elution time (harpagoside was eluted at 5.3min) and the method was linear with good regression coefficient (R2>0.998) within the concentration range tested (0.2-4µg/mL). The FT-IR spectra of root extract showed the presence of characteristic peaks corresponding to the harpagoside and the results from photomicrographs and SEM analysis revealed spherical morphology of the particles in the extract. The prepared powdered formulations readily dispersed and dissolved in water and showed more than 98% of harpagoside content even after 6months time period indicating the stability of the formulations. Overall, the results from the present investigation can form basis to establish standardization parameters for formulations containing root extract of devil’s claw. Keywords: Harpagophytum procumbens, Structural and physicochemical characterization, RP-HPLC-PDA method, FT-IR, DSC, SEM