Antioxidant properties of 2-O-beta-D-glucopyranosyl-L-ascorbic acid

A comprehensive review of goji berry processing and utilization

Goji berry (wolfberry, Lycium), is a genus of Solanaceae, in which the roots, stems, leaves, and fruits are for both food and medicinal uses. In recent years, the demand for health food and research purposes has led to increasing attention being paid to the application of goji berry nutrients and resources. There are three general strategies to process and utilize the goji berry plant. First, the primary processing of goji berry products, such as dried goji berry pulp, and fruit wine with its by-products. Second, deep processing of sugar-peptides, carotenoids, and the extraction of other efficacy components with their by-products. Third, the utilization of plant-based by-products (roots, stems, leaves, flowers, and fruit residuals). However, the comprehensive use of goji berry is hampered by the non-standardized production technology of resource utilization and the absence of a multi-level co-production and processing technology systems. On the basis of this, we review some novel techniques that are made to more effectively use the resources found in goji berry or its by-products in order to serve as a guide for the thorough use of these resources and the high-quality growth of the goji berry processing industry.

2-O-β-d-Glucopyranosyl l-Ascorbic Acid, a Stable Form of Vitamin C, Is Widespread in Crop Plants

2-O-β-d-Glucopyranosyl l-ascorbic acid (AA-2βG) is a stable, bioavailable vitamin C (AA) derivative. We report the distribution and seasonal variation of AA-2βG in apples and its occurrence in other domesticated crops and in wild harvested Ma̅ori foods. Liquid chromatography-mass spectrometry analyses showed high AA-2βG concentrations in crab apples (Malus sylvestris) but low concentrations in domesticated apples. Leaves of crab and domesticated apple cultivars contained similar intermediate AA-2βG concentrations. Fruits and leaves of other crops were analyzed: mainly Rosaceae but also Actinidiaceae and Ericaceae. AA-2βG was detected in all leaves (0.5-6.1 mg/100 g fr. wt.) but was at lower concentrations in most fruits (0.0-0.5 mg/100 g fr. wt.) except for crab apples (79.4 mg/100 g fr. wt.). Ma̅ori foods from Solanaceae, Piperaceae, Asteraceae, and a fern of Aspleniaceae also contained AA-2βG. This extensive occurrence suggests a general role in AA metabolism for AA-2βG.

Ascorbic Acid Derivative 2-O-β-d-Glucopyranosyl-l-Ascorbic Acid from the Fruit of Lycium barbarum Modulates Microbiota in the Small Intestine and Colon and Exerts an Immunomodulatory Effect on Cyclophosphamide-Treated BALB/c Mice

2-O-β-d-Glucopyranosyl-l-ascorbic acid (AA-2βG) is a natural and stable ascorbic acid derivative isolated from the fruits of Lycium barbarum. In our present study, cyclophosphamide (Cy) was used to make BALB/c mice immunosuppressive and AA-2βG was used to intervene immunosuppressive mice. It was found that Cy treatment resulted in a series of changes on basic immune indexes including a decrease of thymus and spleen indexes and levels of pro-inflammatory cytokines and destruction of leucocyte proportion balance, accompanied with weight loss, reduction in colon length, and changes of hepatic function markers. However, all these changes were reversed in varying degrees by AA-2βG intervention. Notably, AA-2βG could significantly change both mouse colonic and small-intestinal microbiota. The key responsive taxa found in a mouse colon were Muribaculaceae, Ruminococcaceae, Oscillibacter, Rikenella, Helicobacter, Negativibacillus, Alistipes, and Roseburia, and the key responsive taxa found in a mouse small intestine were Muribaculaceae, Anaerotruncus, and Paenibacillus. The results demonstrated that AA-2βG could modulate microbiota in the small intestine and colon and exert an immunomodulatory effect. Further studies should focus on the degradation pathways of AA-2βG and the interaction between AA-2βG and Muribaculaceae.

2-O-β-d-Glucopyranosyl-l-ascorbic Acid, an Ascorbic Acid Derivative Isolated from the Fruits of Lycium Barbarum L., Modulates Gut Microbiota and Palliates Colitis in Dextran Sodium Sulfate-Induced Colitis in Mice

In this study, the effects of 2-O-β-d-glucopyranosyl-l-ascorbic acid (AA-2βG), a natural ascorbic acid derivative from the fruits of Lycium barbarum, on treating the dextran sulfate sodium (DSS)-induced colitis in mice were investigated. The results revealed that AA-2βG had palliating effects on DSS-induced inflammatory bowel disease (IBD) in terms of slowing down the trends of body weight and solid fecal mass loss, reducing colitis disease activity index, improving serum physiological and biochemical indicators, increasing colon length, blocking proinflammatory cytokines, and increasing tight junction proteins. Additionally, AA-2βG treatment could promote the production of short-chain fatty acids and modulate the composition of the gut microbiota. The key bacteria related to IBD were found to be Porphyromonadaceae, Prevotellaceae, Rikenellaceae, Parasutterella, Parabacteroides, and Clostridium. The results indicated that AA-2βG might treat IBD through the regulation of gut microbiota, suggesting that AA-2βG has the potential to be used as a dietary supplement in the treatment of IBD.

Therapeutic Perspective of Vitamin C and Its Derivatives

l-Ascorbic acid (ASA), vitamin C, is a ubiquitous carbohydrate-like compound that has an essential role in a number of cellular processes, such as collagen synthesis, cellular oxidation, and various hydroxylation reactions. ASA is a biomolecule of critical importance for protection of cellular components against oxidative damage caused by toxic free radicals and other reactive oxygen species (ROS) that are involved in the development of various types of chronic diseases. Vitamin C has a switchover role from being an antioxidant in physiological conditions to a prooxidant under pathologic conditions. Moreover, some l-ascorbic acid derivatives exhibit strong and selective antitumor and antiviral activity. This review emphasizes the advances on diverse and potent biological profiles of l-ascorbic acid and its derivatives, and their perspective in the development of new bioactive chemical entities in the future. The work is primarily addressed at antioxidant, anticancer, and antiviral potencies of l-ascorbic acid and compounds containing its butenolide structural motif.

2-O-β-d-glucopyranosyl-l-ascorbic acid, a novel vitamin C derivative from Lycium barbarum, prevents oxidative stress

Reducing agents are crucial for the management of maladaptive inflammation-induced macrophage death and hematopoietic toxicity of chemotherapy. 2-O-β-d-glucopyranosyl-_l-ascorbic acid (AA-2βG), a unique AA (or vitamin C) derivative identified in Lycium barbarum, exhibited enhanced free radical scavenging activity compared with AA and its synthetic derivative AA-2αG. AA-2βG protected hydrogen peroxide-induced cell death in murine macrophage RAW264.7 cells. Treatment with AA-2βG eliminated oxidative stress and the ratio of cellular glutathione to glutathione disulfide more effectively than AA and AA-2αG. AA-2βG also significantly reduced the fluorescent intensity of DCFH-DA triggered by chemotherapeutic agent camptotehcin-11 but not fluorouracil. AA, AA-2αG, and AA-2βG significantly decreased Keap-1expression, and increased the expression levels of nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1. All compounds triggered the nuclear translocation of Nrf2, while the ability of AA-2βG to enhance the Nrf2-DNA binding affinity was approximately two fold as those of AA and AA-2αG. Sodium ascorbate cotransporters (SVCT) inhibitors, sulfinpyrazone, phloretin, and 3-O-methyglucose, potently abrogated the free radical scavenging activities of AA, AA-2αG, and AA-2βG. The cellular uptake efficacy of AA-2αG and AA-2βG was less than 10% of AA, while the inhibition of SVCT with sulfinpyrazone considerably diminished the uptake efficacy of these compounds. AA-2αG and AA-2βG are more stable in the Fenton reagents than AA. In summary, AA-2βG from L. barbarum with excellent free radical scavenging activity is a promising natural AA derivative for further pharmacological evaluation.

Intracellular antioxidant effect of vanillin, 4-methylguaiacol and 4-ethylguaiacol: three components in Chinese Baijiu

Vanillin, 4-methylguaiacol, and 4-ethylguaiacol can improve AAPH-induced alterations in oxidative stress biomarkers and antioxidant enzymes in HepG2 cells.

Isolation and Characterization of the 2,2'-Azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) Radical Cation-Scavenging Reaction Products of Arbutin

Arbutin, a glucoside of hydroquinone, has shown strong 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation-scavenging activity, especially in reaction stoichiometry. This study investigated the reaction mechanism of arbutin against ABTS radical cation that caused high stoichiometry of arbutin in an ABTS radical cation-scavenging assay. HPLC analysis of the reaction mixture of arbutin and ABTS radical cation indicated the existence of two reaction products. The two reaction products were purified and identified to be a covalent adduct of arbutin with an ABTS degradation fragment and 3-ethyl-6-sulfonate benzothiazolone. A time-course study of the radical-scavenging reactions of arbutin and the two reaction products suggested that one molecule of arbutin scavenges three ABTS radical cation molecules to generate an arbutin-ABTS fragment adduct as a final reaction product. The results suggest that one molecule of arbutin reduced two ABTS radical cation molecules to ABTS and then cleaved the third ABTS radical cation molecule to generate two products, an arbutin-ABTS fragment adduct and 3-ethyl-6-sulfonate benzothiazolone.

Antioxidative properties of ascorbigen in using multiple antioxidant assays

The antioxidative properties of ascorbigen, one of the major indole-derived compounds of Brassica vegetables, were systematically evaluated using multiple assay systems with comparison to the well-known antioxidants ascorbic acid and Trolox. We first performed assays using model radicals, DPPH radical, galvinoxyl radical, and ABTS radical cation (ABTS(•+)). Ascorbigen showed stronger activity than that of ascorbic acid in the ABTS(•+)-scavenging assay but showed no activity in the DPPH radical- and galvinoxyl radical-scavenging assays. In the ABTS(•+)-scavenging assay, the indole moiety of ascorbigen contributed to scavenging of the radicals to produce indole-3-aldehyde as one of the final reaction products. The activity of ascorbigen was then evaluated by an oxygen radical absorbance capacity assay and an oxidative hemolysis inhibition assay using physiologically relevant peroxyl radicals, AAPH-derived radicals. Ascorbigen showed much stronger antioxidant activity than did ascorbic acid and Trolox. Therefore, antioxidant activity of ascorbigen might be more beneficial than has been thought for daily health care.

A derivative of ascorbic acid modulates cAMP production

We reported, in previous experiments, that AA is a global regulator of cAMP pools. In this study, we demonstrate that K873, an analog of AA we synthesized and presenting antiproliferative properties, has also an impact on cAMP production. However, K873 has no antioxidant activity, at the contrary of AA. It definitively demonstrates that action of AA on the cAMP production is not linked to antioxidant activity. These data suggest that AA, and derivatives of this molecule, could be promising drug acting on biological processes that are under the control of cAMP dependent pathway.

Comparative evaluation of the antioxidant effects of the natural vitamin C analog 2-O-β-D-glucopyranosyl-L-ascorbic acid isolated from Goji berry fruit

2-O-β-D-Glucopyranosyl-L-ascorbic acid (AA-2βG) is a natural derivative of vitamin C (Lascorbic acid, AA) isolated from Goji berry (Lycium barbarum L.) fruit. We evaluated the antioxidant activities of AA-2βG and AA using in vitro and in vivo model systems. In vitro radical scavenging assays demonstrated that AA-βG was capable of scavenging 1,1-diphenyl-2-picryl-hydrazyl and hydroxyl peroxide and inhibiting H(2)O(2)-induced hemolysis better than AA. AA-2βG and AA had similar hydroxyl radical scavenging capabilities, but AA-2βG was incapable of scavenging superoxide anion radicals, and its capacity to scavenge nitrite (NO(2) (-)) was lower than that of AA. The overall in vitro reduction capability of AA-2βG was also significantly lower than that of AA. Moreover, in vivo studies demonstrated that AA-2βG was capable of protecting the liver against carbon tetrachloride-induced acute liver injury in mice. These results suggest that AA-2βG is an important antioxidant component of Goji berry fruit, which may share similar but distinct antioxidant mechanistic properties with AA. This study furthers our understanding of the mechanisms of Goji berry fruit pharmacological activities on antiaging and antitumor properties as a traditional medicine and dietary supplement.

Selective suppression of cervical cancer Hela cells by 2-O-β-D-glucopyranosyl-L-ascorbic acid isolated from the fruit of Lycium barbarum L

Lycium barbarum fruit has been used as a Chinese traditional medicine and dietary supplement for centuries. 2-O-β-D-Glucopyranosyl-L-ascorbic acid (AA-2βG), a novel stable vitamin C analog, is one of the main biologically active components of the fruit. In this report, we investigated the cytotoxic and antiproliferative effect of AA-2βG against cancer cells in vitro and identified the proteins with significantly differential expression in the cervical cancer cells (Hela) cultured in the presence of AA-2βG proteomic analysis. Our results demonstrated that the cytotoxic and antiproliferative activity of AA-2βG on cancer cell lines were in a cell type-, time-, and dose-dependent manner. Similar to vitamin C, the AA-2βG selectively induced cell death repressed the proliferation of Hela cells by the mechanism of cell apoptosis and cell cycle arrest induced by AA-2βG through a mechanism of stabilizing p53 protein. However, the biological activity of inhibition of cell proliferation in other malignant cancer cell lines or primary cells were varied, as demonstrated by either moderate inhibition or slight promotion following treatment with AA-2βG. Comparative analysis of the proteomic profiles and immunoblot analysis identified 15 proteins associated with repressing cell apoptosis and/or stimulating cell proliferation in Hela cells that were downregulated in the presence of AA-2βG or vitamin C. These data indicate that a mechanism of the AA-2βG and vitamin C mediated antitumor activity by downregulating the expression of proteins involved in cell apoptosis and proliferation and consequently inducing Hela cell apoptosis and cell cycle arrest, suggesting that AA-2βG and vitamin C may share a similar mechanism of inducing Hela cell apoptosis. These results also suggest that the L. barbarum fruit may be a potential dietary supplement and anticancer agent aimed at the prevention and treatment of cervical cancer.

Reassessment of antioxidant activity of arbutin: multifaceted evaluation using five antioxidant assay systems

Arbutin, a practically used skin-lightening agent, has been reported to possess a weak antioxidant activity compared to that of its precursor, hydroquinone. However, its antioxidant activity has not been systematically evaluated. Hence, this study reassessed its activity using five assay systems. Assays were first performed using model radicals, DPPH radical and ABTS(*+). Arbutin showed weak DPPH radical-scavenging activity compared to that of hydroquinone, but showed strong ABTS(*+)-scavenging activity. Its activity by ORAC assay was then evaluated using a physiologically relevant peroxyl radical. Arbutin exerted weak but long-lasting radical-scavenging activity and showed totally the same antioxidant activity as that of hydroquinone. Finally, it was shown that, in two cell-based antioxidant assays using erythrocytes and skin fibroblasts, arbutin exerted strong antioxidant activity comparable or even superior to that of hydroquinone. These findings indicate that the antioxidant activity of arbutin may have been under-estimated and suggest that it acts as a potent antioxidant in the skin.

Novel semiautomated method for assessing in vitro cellular antioxidant activity using the light-scattering properties of human erythrocytes

The novel method developed for screening cellular antioxidant activity relies on differences in light-scattering properties (turbidity) between intact and lysed human erythrocytes. AAPH, a peroxyl radical generator, was used to enhance lipid peroxidation. The consequent hemolysis triggered a loss of the light-scattering ability in the lysed erythrocytes. When an antioxidant was added, the area under the absorbance decay curve (AUC) was linearly proportional to the concentration of antioxidant compound. This erythrocyte cellular antioxidant activity (ERYCA) method was found to be relatively fast, sensitive, accurate, and repeatable, even when using erythrocytes from different donors and for different storage times. The method was used to assess the antioxidant capacity of pure phenolic compounds, fruit juices, stimulant beverages, and blood plasma and compared with ORAC values. The values resulting from the two methods did not correlate as the mechanisms involved were different.