Wenkui Li

Cyclooxygenase-2 inhibitors in ginger (Zingiber officinale)

Ginger roots have been used to treat inflammation and have been reported to inhibit cyclooxygenase (COX). Ultrafiltration liquid chromatography mass spectrometry was used to screen a chloroform partition of a methanol extract of ginger roots for COX-2 ligands, and 10-gingerol, 12-gingerol, 8-shogaol, 10-shogaol, 6-gingerdione, 8-gingerdione, 10-gingerdione, 6-dehydro-10-gingerol, 6-paradol, and 8-paradol bound to the enzyme active site. Purified 10-gingerol, 8-shogaol and 10-shogaol inhibited COX-2 with IC(50) values of 32 μM, 17.5 μM and 7.5 μM, respectively. No inhibition of COX-1 was detected. Therefore, 10-gingerol, 8-shogaol and 10-shogaol inhibit COX-2 but not COX-1, which can explain, in part, the anti-inflammatory properties of ginger.

Determination of 24(R)-pseudoginsenoside F11 in North American ginseng using high performance liquid chromatography with evaporative light scattering detection

A gradient liquid chromatographic method with evaporative light scattering detection (ELSD) for the determination of 24(R)-pseudoginsenoside F(11) in North American ginseng is described. Samples are analyzed by means of a reverse-phase column (Waters Spherisorb ODS-2, C(18)) using acetonitrile and water under gradient conditions as the mobile phase over 20 min. The evaporative light scattering detector (ELSD) used, was set at an evaporating temperature of 35 degrees C and nitrogen gas pressure of 3.4 bar. The detection limit (S/N>5) of 24(R)-pseudoginsenoside F(11) is 53 ng on column.

Simultaneous determination of terpene lactones and flavonoid aglycones in Ginkgo biloba by high-performance liquid chromatography with evaporative light scattering detection.

A gradient high performance liquid chromatographic method with evaporative light scattering detection (ELSD) for the simultaneous determination of ginkgolide A, ginkgolide B, ginkgolide C, ginkgolide J, bilobalide, quercetin, kaempferol and isorhamnetin in Ginkgo biloba is described. Samples are analyzed by means of a reverse-phase column (Supelco Discovery C-18) using methanol (containing 0.05% TFA) and water (containing 5% methanol and 0.05% TFA) under gradient conditions as the mobile phase over 35 min. The evaporative light scattering detector (ELSD) used, is set at an evaporating temperature of 61 degrees C and compressed air pressure of 2.9 bar. The detection limits (S/N>3) of the compounds tested are 20-35 ng on the column. The exponential linear calibration curves are observed for all the compounds tested with r(2) more than 0.998. The reproducibility of the method was evaluated by analyzing three sets of controls on 3 consecutive days with RSD% and relative errors (RE%) less than 17.26 and 14.67%.

HPLC DETERMINATION OF GINSENOSIDES CONTENT IN GINSENG DIETARY SUPPLEMENTS USING ULTRAVIOLET DETECTION

ABSTRACT A total of 21 ginseng products, including Asian ginseng (Panax ginseng) and North American ginseng (Panax quinquefolius) in the form of powdered roots, capsules, liquid extracts, caplets, tablets, and softgels, etc., were analyzed for ginsenoside content by using high performance liquid chromatography (HPLC) with ultraviolet detection at 203 nm. The present method was validated for linearity, sensitivity, reproducibility, and recovery. Two methods of extraction for powdered ginseng root samples were compared by employing (1) sonication with methanol (3 × 30 min) and (2) extraction with 30% methanol (50°C, 30 min), with the former yielding a higher efficiency for the extraction of ginsenosides from powdered ginseng roots. Analysis of 21 ginseng products revealed that the ginsenoside content in Asian ginseng (P. ginseng) is generally lower than that in North American ginseng (P. quinquefolius). The comparability of ginsenosides profiles might help to identify the origin of the ginseng.

A validated method for quantitative determination of saponins in notoginseng (Panax notoginseng) using high-performance liquid chromatography with evaporative light-scattering detection.

A gradient high‐performance liquid chromatographic (HPLC) method with evaporative light‐scattering detection (ELSD) for the determination of major saponins in a Chinese traditional herbal medicine, Panax notoginseng, is described. Samples were analysed by means of a reverse‐phase column (Waters Spherisorb ODS‐2, C‐18) using acetonitrile and water under gradient conditions as the mobile phase over 60 min. The ELSD used was set at an evaporating temperature of 35°C and pressurized air pressure of 3.4 bars. The detection limit (signal/noise > 3) of the saponins was 50 ng. The method was validated by inter‐ and intra‐day assays and recovery tests.

High performance liquid chromatographic analysis of St. John’s Wort with photodiode array detection

An RP-HPLC method with photodiode array detection was established for the determination of major constituents (rutin, hyperoside, isoquercitrin, quercitrin, quercetin, pseudohypericin, hyperforin and hypericin) in St. Johns Wort dietary supplements. The samples were extracted with methanol by means of sonication in low temperature. The extraction was rapid, with two steps of sonication (30 min each) recovering more than 99% of the major constituents in St. Johns Wort samples. The major components were separated by RP-18 chromatography column using a 60-min water-acetonitrile-methanol-trifluoroacetic acid gradient. The quantification was performed by using external standards. Sample preparation and stability of methanolic extract of St. Johns Wort were extensively explored. It is worth noting that the major constituents in the methanolic extract of St Johns Wort, especially hypericin and pseudohypericin, might be retained by some filter cartridges during the filtration. The current method may serve as a valuable tool for the QA/QC of St. Johns Wort dietary supplements.

Identification and Quantification of Gingerols and Related Compounds in Ginger Dietary Supplements Using High Performance Liquid Chromatography-Tandem Mass Spectrometry

Dietary supplements containing preparations of ginger roots/rhizomes (Zingiber officinale Roscoe) are being used by consumers, and clinical trials using ginger dietary supplements have been carried out to evaluate their anti-inflammatory or antiemetic properties with inconsistent results. Chemical standardization of these products is needed for quality control and to facilitate the design of clinical trials and the evaluation of data from these studies. To address this issue, methods based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) were developed for the detection, characterization, and quantitative analysis of gingerol-related compounds in botanical dietary supplements containing ginger roots/rhizomes. During negative ion electrospray with collision-induced dissociation, the cleavage of the C4-C5 bond with a neutral loss of 194 u and benzylic cleavage leading to the neutral loss of 136 u were found to be class-characteristic fragmentation patterns of the pharmacologically active gingerols or shogaols, respectively. On the basis of these results, an assay using LC-MS/MS with neutral loss scanning (loss of 194 or 136 u) was developed that is suitable for the fingerprinting of ginger dietary supplements based on the selective detection of gingerols, shogaols, paradols, and gingerdiones. In addition, a quantitative assay based on LC-MS/MS with selected reaction monitoring was developed for the quantitative analysis of 6-gingerol, 8-gingerol, 10-gingerol, 6-shogaol, 8-shogaol, and 10-shogaol in ginger dietary supplements. After method validation, the quantities of these compounds in three commercially available ginger dietary supplements were determined. This assay showed excellent sensitivity, accuracy, and precision and may be used to address the need for quality control and standardization of ginger dietary supplements.

HPLC WITH EVAPORATIVE LIGHT SCATTERING DETECTION AS A TOOL TO DISTINGUISH ASIAN GINSENG (PANAX GINSENG) AND NORTH AMERICAN GINSENG (PANAX QUINQUEFOLIUS)

A high performance liquid chromatography-evaporative light scattering detection (HPLC-ELSD) method was developed to identify Asian ginseng (Panax ginseng C. A. Meyer) and North American ginseng (P. quinquefolius L.), and their products. The method is based on the baseline chromatographic separation of ginsenoside Rf and 24(R)-pseudoginsenoside F11, two potential chemical markers present in the methanolic extracts of ginseng roots and their products, and their on-line detection using an evaporative light scattering detector. As a result, ginsenoside Rf could be detected only in Asian ginseng and 24(R)-pseudoginsenoside F11 could only be detected in North American ginseng in the current study. The method developed is very simple and highly sensitive down to the nanogram level.

HPLC DETERMINATION OF FLAVONOIDS AND TERPENE LACTONES IN COMMERCIAL GINKGO BILOBA PRODUCTS

ABSTRACT Ginkgo biloba products are one of the top ten botanical dietary supplements in the USA. The active constituents include flavonoids and terpene lactones (ginkgolides and bilobalide). Ginkgo flavonoids have been associated with reduced lipid peroxidation in vascular walls and nerve cells. Ginkgolides are well known to be antagonists of platelet-activating factor (PAF). Usually, enriched ginkgo extracts used for the preparation of ginkgo products are standardized to contain 24% flavonoids and 6% terpene lactones. In the present work, we examined nine commercial ginkgo products for the content of total flavonoids and terpene lactones by using high performance liquid chromatography (HPLC) with ultraviolet (UV) and evaporative light scattering detection (ELSD), respectively. The methods are reliable and sensitive with detection limits of 2 ng for flavonoids on column with HPLC-UV and 20–35 ng for terpene lactones on column with HPLC-ELSD. The results show that most of the commercial ginkgo products tested contain flavonoids and terpene lactones as claimed on the label.

HPLC–PDA Determination of Bioactive Diterpenoids from Plant Materials and Commercial Products of Andrographis paniculata

Abstract The present paper describes the development of an HPLC–PDA method for the simultaneous determination of bioactive diterpenoids, andrographolide, isoandrographolide, neoandrographolide, and 14‐deoxy‐11,12‐didehydroandrographolide in plant materials and commercial products of Andrographis paniculata. Separations were achieved using a conventional C18 column with PDA detection at 200–400 nm for UV spectrum and 225 nm for quantification. The mobile phase consists of water and acetonitrile with acetonitrile varying from 20% to 50% over 40 min. The quantification was performed using external standards. The method was validated for linearity, limit of detection (LOD), limit of quantification (LOQ), inter‐day and intra‐day reproducibility, and recovery.