Identification of antioxidants in essential oil of radix Angelicae sinensis using HPLC coupled with DAD-MS and ABTS-based assay

Angelica sinensis and its alkylphthalides induce the detoxification enzyme NAD(P)H: quinone oxidoreductase 1 by alkylating Keap1

The roots of Angelica sinensis (Oliv.) Diels (Dang Gui; Apiaceae) have a long history in traditional Chinese medicine as a remedy for women's disorders and are often called "lady's ginseng". Currently, extracts of A. sinensis are commonly included in numerous dietary supplements used for women's health and as antiaging products. In the present study, we examined the potential chemopreventive activity of A. sinensis extracts by measuring the relative ability to induce the detoxification enzyme, NAD(P)H:quinone oxidoreductase 1 (NQO1). The lipophilic partitions showed strong NQO1 induction with concentrations to double the enzyme activity (CD) of 5.5 +/- 0.7 (petroleum ether) and 3.9 +/- 0.5 microg/mL (chloroform). Fractionation led to the isolation of phenolic esters and alkylphthalides, especially Z-ligustilide, the main lipophilic compound, which showed strong NQO1 inducing properties (CD = 6.9 +/- 1.9 microM). Transcription of many detoxifying enzymes is regulated through the antioxidant response element (ARE) and its transcription factor Nrf2, which is repressed under basal conditions by Keap1. However, exposure to electrophilic inducers that alkylate Keap1 results in higher concentrations of free Nrf2 and ARE activation. The ARE reporter activity was therefore analyzed in HepG2-ARE-C8 cells after incubation with lipophilic extracts of A. sinensis or ligustilide for 24 h. Under these conditions, both the extract and the ligustilide increased ARE-luciferase reporter activity in a dose-dependent manner. Incubation of ligustilide with GSH and subsequent LC-MS-MS analysis revealed that ligustilide as well as oxidized ligustilide species covalently modified GSH. In addition, using MALDI-TOF mass spectrometry and LC-MS-MS, it was demonstrated that the lipophilic extracts, ligustilide, and monooxygenated ligustilide alkylated important cysteine residues in human Keap1 protein, thus activating Nrf2 and transcription of ARE regulated genes. These observations suggest that A. sinensis dietary supplements standardized to ligustilide have potential as chemopreventive agents through induction of detoxification enzymes.

Protective effects of Angelica sinensis extract on amyloid beta-peptide-induced neurotoxicity

The protective effects of alcohol extract from the root of Angelica sinensis (AS) on beta-amyloid peptide (Abeta)-induced toxicity and the mechanism of these effects were investigated. Abeta is a pathological hallmark of Alzheimer's disease; it decreased viability of Neuro 2A cells in a concentration-dependent manner with IC(50) of 14.9 microM. AS extract resulted in dose-dependent anti-Abeta toxicity according to MTT assay. Reactive oxygen species (ROS) analysis revealed a significant production of hydrogen peroxide, decreased glutathione (GSH) levels and increased lipid peroxidation (TBARS value) in the Abeta-treated Neuro 2A cells. The Abeta-treated cells also showed a significant decline in the mitochondrial transmembrane potential (DeltaPsim) and increase in the mitochondrial volume, and portions of the cytoplasm were sequestered by a membrane-bound vacuole. The malfunctions of Neuro 2A cells caused by Abeta were attenuated using AS extract. The AS extract protected cell viability against Abeta-induced oxidative damage (ROS, TBARS, and GSH contents) and rescued the DeltaPsim levels in a dose-dependent manner: the dosages of 25, 50, 100, and 200 microg/ml recovered 77%, 87%, 102%, and 105% of DeltaPsim, respectively. AS extract also recovered the enlarged mitochondria mass with dosages from 25 to 200 microg/ml. The results of this study demonstrated that AS extract possessed the activity to prevent the neurotoxicity induced by Abeta-associated oxidative stress, implying that AS has a potential role in the prevention of Alzheimer's diseases.

The analysis of Radix Angelicae Sinensis (Danggui)

Radix Angelicae Sinensis, known as Danggui in China, is one of the most popular traditional Chinese medicines (TCMs), which is contained by more than 80 composite formulae. Modern researches indicate that phthalides, organic acids and their esters, polysaccharides are main chemical components related to the bioactivities and pharmacological properties of Danggui. Some of them, such as Z-ligustilide and ferulic acid, are selected as marker compounds to evaluate the quality of Danggui frequently. Because of the diversity of chemical structures and characters of these components, analytical methods of Danggui are various, including GC-MS, HPLC-DAD-MS, TLC, CE-DAD, and so on. Besides that, the development of analytical technology makes the quality control of Danggui more effective and reliable. Quality evaluation is from single or several components' analysis to fingerprinting, or in combination. Furthermore, bioactive components screening of Danggui has also attracted much attention, which will help us evaluate the selected marker components to some extent. In this paper, the literatures about the major phytoconstituents of Danggui, quality control and bioactive components screening methods have been reviewed. Main attention is given to the different methodologies developed to perform chemical analysis, including separation, detection and identification.