On-line ABTS Research Articles

Anti-cyclooxygenase, anti-glycation, and anti-skin aging effect of Dendrobium officinale flowers' aqueous extract and its phytochemical validation in aging.

Dendrobium officinale Kimura et Migo (D. officinale) , widely called as "life-saving immortal grass" by Chinese folk, is a scarce and endangered species. The edible stems of D. officinale have been extensively studied for active chemical components and various bioactivities. However, few studies have reported the well-being beneficial effects of D. officinale flowers (DOF). Therefore, the present study aimed to investigate the in vitro biological potency of its aqueous extract and screen its active components. Antioxidant tests, including 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), the ferric reducing ability of plasma (FRAP), and intracellular reactive oxygen species (ROS) level analyses in primary human epidermal keratinocytes, anti-cyclooxygenase2 (COX-2) assay, anti-glycation assay (both fluorescent AGEs formation in a BSA fructose/glucose system and glycation cell assay), and anti-aging assay (quantification of collagen types I and III, and SA-β-gal staining assay) were conducted to determine the potential biological effects of DOF extracts and its major compounds. Ultra-performance liquid chromatography-electrospray ionisation-quadrupole-time-of-flight-mass spectrometry (UPLC-ESI-QTOF-MS/MS) was performed to investigate the composition of DOF extracts. Online antioxidant post-column bioassay tests were applied to rapidly screen major antioxidants in DOF extracts. The aqueous extract of D. officinale flowers was found to have potential antioxidant capacity, anti-cyclooxygenase2 (COX-2) effect, anti-glycation potency, and anti-aging effects. A total of 34 compounds were identified using UPLC-ESI-QTOF-MS/MS. Online ABTS radical analysis demonstrated that 1-O-caffeoyl-β-D-glucoside, vicenin-2, luteolin-6-C-β-D-xyloside-8-C-β--D-glucoside, quercetin-3-O-sophoroside, rutin, isoquercitrin, and quercetin 3-O-(6″-O-malonyl)-β-D-glucoside are the major potential antioxidants. In addition, all selected 16 compounds exerted significant ABTS radical scavenging ability and effective AGE suppressive activities. However, only certain compounds, such as rutin and isoquercitrin, displayed selective and significant antioxidant abilities, as shown by DPPH and FRAP, as well as potent COX-2 inhibitory capacity, whereas the remaining compounds displayed relatively weak or no effects. This indicates that specific components contributed to different functionalities. Our findings justified that DOF and its active compound targeted related enzymes and highlighted their potential application in anti-aging.

The impact of simulated gastrointestinal digestion on the bioaccessibility and antioxidant activity of purple rice phenolic compounds

Polyphenol-rich purple rice has been shown to exhibit a wide range of health properties including antioxidant activity. This study aimed to determine the impact that gastrointestinal digestion of purple rice had on its phenolic bioaccessibility and antioxidant activity. Our results demonstrated a significant difference (p < 0.01) in bioaccessible phenolic content level and antioxidant activity between simulated gastric and intestinal digestion. However, mass spectrometry and ultra-high-performance liquid chromatography (UHPLC) coupled with online ABTS•+ scavenging activity demonstrated a significant loss in the number of polyphenols that were bioaccessible after digestion. Interestingly, substantial free radical scavenging activity was retained after digestion due to the bioaccessibility of bioactive compounds such as tryptophan and protocatechuic acid. Hence, purple rice may be considered as a source of bioaccessible phenolic and antioxidant compounds.

Characterization and antioxidant activity of avenanthramides from selected oat lines developed by mutagenesis technique

From a mutagenized oat population, produced by ethyl methanesulfonate mutagenesis, hulled grains from 17 lines with elevated avenanthramide (AVN) content were selected and their AVN structures, concentrations and antioxidant potentials were determined by HPLC-MS2 and HPLC equipped with an on-line ABTS+ antioxidant detection system. The data obtained showed qualitative and quantitative differences in the synthesis of AVNs in the different lines, with a total AVN concentration up to 227.5 µg/g oat seed flour in the highest line, compared with 78.2 µg/g seed in the commercial line, SW Belinda. In total, 25 different AVNs were identified with avenanthramide B structures being among the most abundant, and AVN C structures having the highest antioxidant activity. The findings indicate the potential of oat mutagenesis in combination with a high precision biochemical selection method for the generation of stable mutagenized lines with a high concentration of total and/or individual AVNs in the oat seed grain.

Moderation of Inulin and Polyphenolics Contents in Three Cultivars of Helianthus tuberosus L. by Potassium Fertilization

Jerusalem artichoke, a widely consumed edible, is an excellent source of inulin and selected phytochemicals. However, the improvement of its chemical composition by potassium fertilization has not yet been studied. Thus, the aim of the study was to evaluate the effect of different potassium (K) fertilization levels (K2O 150 kg ha−1, 250 kg ha−1, 350 kg ha−1) on the content of inulin; profile and changes in polyphenolic compounds; and the antioxidant capacity, including on-line ABTS antioxidant profiles of freeze-dried tubers originated from Violette de Rennes, Topstar, and Waldspindel cultivars. Inulin content was highest in the early maturing cv. Topstar. The application of 350 kg ha−1 of K fertilizer rates during the growth of cv. Topstar increased the inulin content of tubers by 13.2% relative to the lowest K fertilizer rate of 150 kg ha−1. In cv. Violette de Rennes, inulin accumulation increased in response to the fertilizer rate of 250 kg ha−1. A further increase in K fertilizer rates had no effect on inulin content. The inulin content of cv. Waldspindel was not modified by any of the tested K fertilizer rates. Thus, the accumulation of the inulin was cultivar-dependent. In the cultivars analyzed, 11 polyphenolic compounds were identified and polyphenolic compound content was affected by the applied rate of potassium fertilizer, which was dependent on the cultivar. Chlorogenic acid was the predominant phenolic acid in all cultivars, and it accounted for around 66.4% of the identified polyphenolic compounds in cv. Violette de Rennes and for around 77% of polyphenolic compounds in cv. Waldspindel and Topstar.

A powerful on line ABTS+\u2013CE-DAD method to screen and quantify major antioxidants for quality control of Shuxuening Injection

A novel method of on-line 2,2′-Azinobis-(3-ethylbenzthiazoline-6-sulphonate)-Capillary Electrophoresis-Diode Array Detector (on-line ABTS+-CE-DAD) was developed to screen the major antioxidants from complex herbal medicines. ABTS+, one of well-known oxygen free radicals was firstly integrated into the capillary. For simultaneously detecting and separating ABTS+ and chemical components of herb medicines, some conditions were optimized. The on-line ABTS+-CE-DAD method has successfully been used to screen the main antioxidants from Shuxuening injection (SI), an herbal medicines injection. Under the optimum conditions, nine ingredients of SI including clitorin, rutin, isoquercitrin, Quercetin-3-O-D-glucosyl]-(1-2)-L-rhamnoside, kaempferol-3-O-rutinoside, kaempferol-7-O-β-D-glucopyranoside, apigenin-7-O-Glucoside, quercetin-3-O-[2-O-(6-O-p-hydroxyl-E-coumaroyl)-D-glucosyl]-(1-2)-L-rhamnoside, 3-O-{2-O-[6-O-(p-hydroxyl-E-coumaroyl)-glucosyl]}-(1-2) rhamnosyl kaempfero were separated and identified as the major antioxidants. There is a linear relationship between the total amount of major antioxidants and total antioxidative activity of SI with a linear correlation coefficient of 0.9456. All the Relative standard deviations of recovery, precision and stability were below 7.5%. Based on these results, these nine ingredients could be selected as combinatorial markers to evaluate quality control of SI. It was concluded that on-line ABTS+-CE-DAD method was a simple, reliable and powerful tool to screen and quantify active ingredients for evaluating quality of herbal medicines.

Identification and Anti‐oxidant Capacity Determination of Phenolics and their Glycosides in Elderflower by On‐line HPLC–CUPRAC Method

Development and application of an on-line cupric reducing anti-oxidant capacity (CUPRAC) assay coupled with HPLC for separation and on-line determination of phenolic anti-oxidants in elderflower (Sambucus nigra L.) extracts for their anti-oxidant capacity are significant for evaluating health-beneficial effects. Moreover, this work aimed to assay certain flavonoid glycosides of elderflower that could not be identified/quantified by other similar on-line HPLC methods (i.e. 2,2-diphenyl-1-picrylhdrazyl and 2, 2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid). To identify anti-oxidant constituents in elderflower by HPLC and to evaluate their individual anti-oxidant capacities by on-line HPLC-CUPRAC assay with a post-column derivatisation system. The separation and UV detection of polyphenols were performed on a C18 -column using gradient elution with two different mobile phase solutions, that is acetonitrile and 1% glacial acetic acid, with detection at 340 nm. The HPLC-separated anti-oxidant polyphenols in column effluent react with copper(II)-neocuproine in a reaction-coil to reduce the latter to copper(I)-neocuproine (Cu(I)-Nc) chelate having maximum absorption at 450 nm. The detection limits of tested compounds at 450 nm after post-column derivatisation were compared with those of at 340 nm UV-detection without derivatisation. LOD values (µg/mL) of quercetin and its glycosides at 450 nm were lower than those of UV detection at 340 nm. This method was applied successfully to elderflower extract. The flavonol glycosides of quercetin and kaempferol bound to several sugar components (glucose, rhamnose, galactose and rutinose) were identified in the sample. The on-line HPLC-CUPRAC method was advantageous over on-line ABTS and DPPH methods for measuring the flavonoid glycosides of elderflower.

Rapid Detection of Antioxidant Flavonoids in Azalea (Rhododendron mucronulatum) Flowers using On-line HPLC-ABTS+ System and Preparative Isolation of Three Flavonoids by Centrifugal Partition Chromatography

High-performance liquid chromatography coupled to an on-line ABTS+-based assay (on-line HPLC-ABTS+) system was used to determine the principle antioxidants in azalea flowers. Three flavonoids, myricetin, quercetin, and kaempferol, recovered in ethyl acetate extracts of azalea flowers were determined to have antioxidant activities. These three flavonoids were isolated and purified by successive centrifugal partition chromatography (CPC) using two different biphasic solvent systems, consisting of n-hexane-ethyl acetate-methanol-water (3:5:3:5 or 4:5:4:5, v/v). A total of 46.2 mg of myricetin, 28.9 mg of quercetin, and 10.6 mg of kaempferol with purities of 97.0%, 95.4%, and 93.9%, respectively, were purified from 500 mg of ethyl acetate soluble material from azalea flowers. The structures were identified by their retention time, UV spectra, and ESI-MS in the positive ion mode and were confirmed by NMR experiments.

Tea prepared from Anastatica hirerochuntica seeds contains a diversity of antioxidant flavonoids, chlorogenic acids and phenolic compounds

HPLC–PDA–MS 2 was used to identify phenolic and polyphenolic compounds in an herbal tea made from seeds of Anastatica hirerochuntica, a plant found in the Sahara–Arabian deserts and used to treat a variety of ailments. Twenty compounds comprising a series of flavone C- and O-linked glycosides, phenolic acids, chlorogenic acids and flavonols were identified or partially identified on the basis of co-chromatography with reference compounds and MS 2 and MS 3 fragmentation patterns. The flavones were the principal components, occurring as luteolin, apigenin and diosmetin conjugates. The antioxidant potential of individual compounds in Anastatica was assessed using HPLC with an on-line ABTS + detection system. This revealed that 14 compounds exhibited antioxidant activity. The highest contribution to the antioxidant capacity of the tea, 56%, came from 3,4-dihydroxybenzoic acid and caffeoyl- and dicaffeoylquinic acids while 6- C-glucosides of luteolin and apigenin contributed 41%.

The rapid identification of radical scavenging constituents from the root of Belamcanda chinensis by the HPLC coupled to an on-line ABTS+ based assay and LC-NMR/MS

The rapid identification of radical scavenging constituents from the root of Belamcanda chinensis by the HPLC coupled to an on-line ABTS+ based assay and LC-NMR/MS