Quality evaluation of salt-fired Eucommiae Cortex based on HPLC fingerprint, multi-component content determination, and chemometrics

Abstract

This study established an HPLC fingerprint and multi-component content determination method for salt-fired Eucommiae Cortex, and evaluated the quality of salt-fired Eucommiae Cortex from different sources using fingerprint similarity evaluation, cluster analysis(CA), principal component analysis(PCA), and orthogonal partial least square discriminate analysis(OPLS-DA). HPLC was launched on a Cosmosil 5C_(18)-MS-Ⅱ column(4.6 mm×250 mm, 5 μm) by gradient elution with a mobile phase of methanol-0.2% phosphoric acid aqueous solution at a flow rate of 1.0 mL·min~(-1), detection wavelength of 238 nm, column temperature of 30 ℃, and an injection volume of 10 μL. The results of fingerprint similarity evaluation for 20 batches of salt-fired Eucommiae Cortex indicated that, except for batch S3 with a similarity of 0.893, the similarity of the other 19 batches was of ≥ 0.919, suggesting good similarity. Fourteen common peaks were calibrated and seven common peaks were identified including geniposidic acid. The mass fractions of geniposidic acid, chlorogenic acid, geniposide, genipin, pinoresinol diglucoside, liriodendrin, and pinoresinol-4-O-β-D-glucopyranoside were 0.062 0%-0.426 9%, 0.024 9%-0.116 5%, 0.009 5%-0.052 9%, 0.005 5%-0.034 8%, 0.115 9%-0.317 8%, 0.016 4%-0.108 8%, and 0.026 4%-0.039 8%, respectively. Using CA, PCA, and OPLS-DA, the 20 batches of salt-fired Eucommiae Cortex were classified into three categories. Additionally, through the analysis of variable importance in projection(VIP) under OPLS-DA, two differential quality markers, geniposidic acid and chlorogenic acid, were identified. The established HPLC fingerprint and multi-component content determination method is stable and reliable, providing a reference for quality control of salt-fired Eucommiae Cortex.