Isolation and Purification of Unstable Iridoid Glucosides from Traditional Chinese Medicine by Preparative High Performance Liquid Chromatography Coupled with Solid-phase Extraction

An efficient preparative method was successfully developed for isolation and purification of unstable components from medicinal plant extracts, using a combined method of preparative high performance liquid chro-matography(HPLC) and solid-phase extraction(SPE). The aim of this study was to obtain an effective method with high preparative efficiency and importantly to avoid the transformation of unstable compounds. The preparative HPLC system was based on an LC/MS controlled four-channel autopurification system. The SPE method was performed with a C18 packing material to trap the target compounds and to remove the acidic additive derived from the mobile phase. Using this method, the unstable iridoid glucosides(IGs) as model compounds were successfully isolated and purified from the extract of Hedyotis diffusa Willd. Six IGs(including one new minor IG) and one nucleotide compound were simultaneously obtained, each with a purity of 91% as determined by HPLC. The structures of the isolated compounds were identified by UPLC/Q-TOF MS, UV, 1D and/or 2D NMR. It was demonstrated that the combination of preparative HPLC with SPE is a versatile tool for preparative purification of unstable compounds from complex natural products.

HPLC fingerprint-oriented preparative separation of major flavonoids from safflower extract by preparative pressurized liquid chromatography

The aim of this study was to rapidly isolate the major effective flavanoids from the extract of safflower（Carthamus tinctorius） using ODS medium pressure liquid chromatography（MPLC） and semi-preparative HPLC, guided by a developed fingerprint. Twelve compounds were isolated and their structures were elucidated as kaempferol 3-O-β-D-rutinoside（1）, kaempferol 3-O-β-D-glucoside（2）, rutin（3）, quercetin 3-O-β-D-glucoside（4）, 6-hydroxykaempferol 3,6,7-tri-O-β-D-glucoside（5）, 6-hydroxykaempferol 3-O-β-D-glucoside（6）, 6-hydroxykaempferol 6,7-di-O-β-D-glucoside（7）, 6-hydroxykaempferol 3-O-β-Drutinoside（8）, 6-hydroxykaempferol 3,6-di-O-β-D-glucosyl 7-O-β-D-glucuronide（9）, isosafflomin C（10）, safflomin C（11） and hydroxysafflor yellow A（12） by spectroscopic analysis and comparing with the literature. Our results demonstrated that preparative pressurized liquid chromatography combined with HPLC fingerprint guide is an efficient tool to isolate the target compounds quickly.

Study of the anti-MRSA activity of Rhizoma coptidis by chemical fingerprinting and broth microdilution methods

AIM： Methicillin-resistant Staphylococcus aureus （MRSA） is a pathogenic bacterium that causes both hospital- and community-acquired infections, and for which single-drug treatments are becoming less efficient. Rhizoma coptidis has been used for more than two thousand years in China to treat diarrhea, fever, and jaundice. In this study, the anti-MRSA activity of Rhizoma coptidis is examined and its effective components sought. METHODS： The mecA and norA genes were determined by PCR amplification and sequencing. Drug susceptibility of Staphylococcus aureus ATCC43300 was performed using the VITEK2 compact system. The chemical fingerprint of Rhizoma coptidis was investigated using HPLC and preparative liquid chromatography, and the anti-MRSA activity was determined using an improved broth microdilution method. RESULTS： The drug susceptibility test revealed that the penicillin-binding protein phenotype of the strain changed in comparison to penicillin-sensitive Staphylococcus aureus. Ten batches of Rhizoma coptidis showed anti-MRSA activity on the norA-negative Staphylococcus aureus strain, as well as the strain that contained a norA gene. The spectrum-effect relationship revealed that the berberine alkaloids were the effective components, within which berberine, coptisine, palmatine, epiberberine,, and jatrorrhizine were the major components. CONCLUSION： This study lays a foundation for in vivo studies of Rhizoma eoptidis and for the development of multi-component drugs.

A New Secoiridoid Glycoside from Swertia cincta

Objective To study the chemical constituents of Swertia cincta. Methods Preparative liquid chromatography was employed. The structures of the compounds were elucidated by spectroscopic analysis. isolated from S. cincta and identified as Results Three secoiridoid glycosides were 8-methoxyl-eustomorusside （1）, secoiridoids eustomorusside （2）, and eustomoside （3）. Conclusion Compound 1 is a new secoiridoid glycoside. Compounds 2 and 3 are isolated from this plant for the first time.