1-1-diphenyl-2-picrylhydrazyl and vitexin

Roots of Rumex hastatus (Polygonaceae) are traditionally used for the treatment of various ailments including liver and lung diseases. In this study, various solvent extracts of R. hastatus roots, like methanolic, n-hexane, ethyl acetate, chloroform, butanol and aqueous fractions were assessed through their antioxidant properties in vitro and determination of phenolic contents.. Several parameters like DPPH˙, ABTS˙(+), ˙OH, H2O2, superoxide free radical scavenging, iron chelating power, reducing power, β-carotene bleaching power, antioxidant capacity and total phenolics and flavonoids were evaluated. High Performance liquid Chromatography (HPLC) was also considered.. Though all the fractions exhibited dose dependant activity. The samples with the highest activity were the butanol and methanol fractions in all the assays except hydrogen peroxide radical scavenging assay where chloroform fraction showed the highest scavenging aptitude. On the other hand, aquous fraction showed significant beta carotene linoleic acid, while n-hexane and ethyl acetate fractions exhibited a lesser antioxidant activity in all the assays. HPLC revealed the presence of rutin, luteolin-7-glucoside, vitexin and luteolin.. These results have to some extent substantiated the use of R. hastatus roots against different diseases, as an excellent basis of potential antioxidant due to the presence of sufficient amount of phenolics such as rutin and luteolin.

Topics: Antioxidants; Apigenin; Benzothiazoles; beta Carotene; Biphenyl Compounds; Flavonoids; Glucosides; Hydrogen Peroxide; Luteolin; Phenols; Picrates; Plant Extracts; Plant Roots; Rumex; Rutin; Sulfonic Acids

Indocalamus latifolius (Keng) McClure leaf is a popular food material in East Asia due to its antioxidant and anticorrosive activities. To utilize it more effectively, we investigated the discrepancy of antioxidant activities and active compound content in Indocalamus latifolius leaf along with the altitude change. Total flavonoids, phenolics, titerpenoids and eight characteristic active constituents, i.e, orientin, isoorientin, vitexin, homovitexin, p-coumaric acid, chlorogenic acid, caffeic acid, and ferulic acid, were determined by UV-spectrophotometer and synchronous RP-HPLC, respectively. Antioxidant activity was measured using DPPH and FRAP methods. Our data showed that the content of TP and TF, DPPH radical scavenging ability and ferric reduction power of Indocalamus latifolius leaf changed as altitude altered, with the trends of decreasing gradually when lower than 700 m and then increasing to 1,000 m. Chlorogenic acid and orientin were the main characteristic compounds in Indocalamus latifolius leaf and were also affected by altitude. Our result indicated that higher altitude with an adverse environment is conducive to secondary metabolite accumulation for Indocalamus latifolius. It would provide a theoretical basis to regulate the leaf collection conditions in the industrial use of Indocalamus latifolius leaf.

Topics: Antioxidants; Apigenin; Asia; Biphenyl Compounds; Caffeic Acids; Chlorogenic Acid; Coumaric Acids; Diet; Ecosystem; Ferric Compounds; Flavonoids; Glucosides; Picrates; Plant Extracts; Plant Leaves; Poaceae; Polyphenols; Secondary Metabolism; Triterpenes

Rhynchosia capitata (=Glycine capitata) Heyne ex roth, was found to possess polyphenolics including flavonoids, which acts as potential antioxidant. The study of ethanolic extract of roots and leaves reveals that the leaves possess high polyphenolics including flavonoids than roots. This was also confirmed by DPPH radical scavenging activity. Leaf powder of the plant was extracted with different solvents by soxhlet apparatus in the order of increasing polarity. The DPPH scavenging activity of methanol fraction was found to be high compared to the crude extract and other fractions. Nitric oxide scavenging activity was dominant in chloroform fraction compared to methanol fraction. Presence of flavonoids especially vitexin, a C-glycoside in methanol and chloroform fractions were confirmed by high pressure thin layer chromatography (HPTLC) analysis. The structural and molecular characteristics of naturally occurring flavonoid, vitexin was investigated in gas phase using density functional theory (DFT) approach with B3LYP/6-311G(d,p) level of theory. Analysis of bond dissociation enthalpy (BDE) reveals that the OH site that requires minimum energy for dissociation is 4'-OH from B-ring. To explore the radical scavenging activity of vitexin, the adiabatic ionization potential, electron affinity, hardness, softness, electronegativity and electrophilic index properties were computed and interpreted. The nonvalidity of Koopman's theorem has been verified by the computation of Eo and Ev energy magnitudes. Interestingly, from BDE calculations it was observed that BDE for 4'-OH, 5-OH and 7-OH are comparatively low for vitexin than its aglycone apigenin and this may be due to the presence of C-8 glucoside in vitexin. To substantiate this, plot of frontier molecular orbital and spin density distribution analysis for neutral and the corresponding radical species for the compound vitexin have been presented.

Topics: Apigenin; Biphenyl Compounds; Fabaceae; Free Radical Scavengers; Models, Molecular; Nitric Oxide; Picrates; Plant Extracts; Plant Leaves; Plant Roots

Natural flavonoids are secondary phenolic plant metabolites known for their bioactivity as antioxidants. The evaluation of this property is generally done by the estimation of their direct free radical-scavenging activity as hydrogen or electron donating compounds. This paper reviews experimental results available in the literature for a selection of flavonoids and compares them with calculated quantities characteristic of the hydrogen or electron donation. For that purpose, bond dissociation energies, ionization potentials and electron transfer enthalpies are computed by using DFT methods and the ONIOM procedure implemented in the ab initio program Gaussian. This process has been chosen because it can be extended to the study of large molecules. When acid dissociation and interaction with the solvent are taken into account, the results present very good concordance with experimental results, enlightening the complexity of the processes involved in the classical assays which measure the ability of compounds to scavenge the (2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt) radical cation (ABTS (+)) or the 2,2-diphenyl-1-picryl-hydrazyl radical (DPPH(·)). This study demonstrates the good accuracy of theoretical calculations in obtaining the relative energies involved in free radical scavenging abilities and its capacity for predictive behaviour. It also highlights the necessity to take into account the pK(a) of the compounds and the solvent interaction. The ability of the method to calculate the antioxidant properties of larger molecules are tested on glycosylated flavonoids and the effects of sugar substitution on the antioxidant properties of flavonoids are investigated, pointing out the importance of the charges on the oxygen atoms.

Topics: Antioxidants; Apigenin; Benzothiazoles; Biphenyl Compounds; Electrons; Flavonoids; Free Radical Scavengers; Glycosylation; Hydrogen; Hydrolysis; Kaempferols; Models, Chemical; Models, Molecular; Molecular Structure; Oxidation-Reduction; Picrates; Quercetin; Solvents; Structure-Activity Relationship; Sulfonic Acids; Thermodynamics

Free radicals and reactive oxygen species (ROS) caused by UV exposure or other environmental factors are critical players in cellular damage and aging. In order to develop a new anti-photoaging agent, this work focused on the antioxidant effects of the extract of tinged autumnal leaves of Acer palmatum. One compound was isolated from an ethyl acetate soluble fraction of the A. palmatum extract using silica gel column chromatography. The chemical structure was identified as apigenin-8-C-beta-D-glucopyranoside, more commonly known as vitexin, by spectral analysis including LC-MS, FT-IR, UV, 1H-, and 13C-NMR. The biological activities of vitexin were investigated for the potential application of its anti-aging effects in the cosmetic field. Vitexin inhibited superoxide radicals by about 70% at a concentration of 100 microg/mL and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals by about 60% at a concentration of 100 microg/mL. Intracellular ROS scavenging activity was indicated by increases in dichlorofluorescein (DCF) fluorescence upon exposure to UVB 20 mJ/cm2 in cultured human dermal fibroblasts (HDFs) after the treatment of vitexin. The results show that oxidation of 5-(6-)chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (CM-H2DCFDA) is inhibited by vitexin effectively and that vitexin has a potent free radical scavenging activity in UVB-irradiated HDFs. In ROS imaging using a confocal microscope we visualized DCF fluorescence in HDFs directly. In conclusion, our findings suggest that vitexin can be effectively used for the prevention of UV-induced adverse skin reactions such as free radical production and skin cell damage.

Topics: Acer; Antioxidants; Apigenin; Biphenyl Compounds; Carbohydrate Sequence; Cells, Cultured; Chromatography, Liquid; Fibroblasts; Flow Cytometry; Free Radical Scavengers; Humans; Magnetic Resonance Spectroscopy; Mass Spectrometry; Microscopy, Confocal; Molecular Sequence Data; Nitroblue Tetrazolium; Picrates; Plant Leaves; Spectrophotometry, Infrared; Spectrophotometry, Ultraviolet; Superoxides

An extract of Xanthosoma violaceum leaves was subjected to a polyphenol profile determination, including total polyphenols, and antioxidant activity evaluation. Analysis of the extract resulted in the isolation of a new flavone C-glycoside, apigenin 6-C-beta-D-glucopyranosyl-8-C-beta-D-apiofuranoside (1), as well as known flavone C-glycosides, including vitexin (2), isovitexin (3), isovitexin 4'-O-rhamnopyranoside (4), apigenin 6-C-[beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside] (5), and apigenin 6,8-diC-beta-D-glucopyranoside (6). The antioxidant activity of the extract was assessed by means of two different in vitro tests: bleaching of the stable 1,1-diphenyl-2-picrylhydrazyl radical (DPPH test) and peroxidation induced by the water-soluble radical initiator 2,2'-azobis(2-amidinopropane) hydrochloride, on mixed dipalmitoylphosphatidylcholine/linoleic acid unilamellar vesicles (LP-LUV test). In both tests used, the extract and a fraction II showed a significant antioxidant/free-radical scavenging effect (fraction II, EC(50) = 11.6 microg/mL) in comparison to alpha-tocopherol (EC(50) = 10.1 microg/mL).

Topics: Antioxidants; Apigenin; Biphenyl Compounds; Flavonoids; Free Radical Scavengers; Glycosides; Monosaccharides; Peroxides; Phenols; Picrates; Plant Extracts; Plant Leaves; Xanthosoma

Fractionation of a methanolic extract of the leaves of Anthurium versicolor has resulted in the isolation of two main fractions, I and II. Both the extract and the fractions were assayed for their radical-scavenging activity by means of an in vitro test (bleaching of the stable 1,1-diphenyl-2-picrylhydrazyl radical) and showed a significant radical-scavenging effect. Subsequent chromatographic fractionation of the most active fraction, II, has led to the isolation and characterization, as major constituents, of four new flavone glycosides, acacetin 6-C-[alpha-L-rhamnopyranosyl-(1-->3)-beta-D-glucopyranoside] (1), acacetin 6-C-[beta-D-xylopyranosyl-(1-->6)-beta-D-glucopyranoside] (2), acacetin 6-C-[beta-D-apiofuranosyl-(1-->3)-beta-D-glucopyranoside] (3), and acacetin 8-C-[alpha-L-rhamnopyranosyl-(1-->3)-beta-D-glucopyranoside] (4), as well as vitexin (apigenin-8-C-beta-D-glucopyranoside) and rosmarinic acid. The structures of 1-4 were determined using spectroscopic methods.

Topics: Antioxidants; Apigenin; Bepridil; Biphenyl Compounds; Chromatography, High Pressure Liquid; Cinnamates; Depsides; Ecuador; Flavonoids; Free Radical Scavengers; Glycosides; Magnetic Resonance Spectroscopy; Mass Spectrometry; Molecular Structure; Picrates; Plant Leaves; Plants, Medicinal; Rosmarinic Acid; Spectrophotometry, Ultraviolet