1-1-diphenyl-2-picrylhydrazyl and methyl-gallate

Formulation of antioxidant agents is still a challenge that limits their application in the biomedical field. Pentablock copolymers obtained through modification of two common PEO-PPO-PEO copolymers (Pluronic F127 and F68) with poly(ε-carprolactone) (PCL) were evaluated regarding their capability to form nanocarriers suitable for gallic acid, methyl gallate, and ethyl gallate. Applying a dialysis method, PCL/F127/PCL and PCL/F68/PCL self-assembled into spherical micelles in 0.9% NaCl aqueous solution but notably differed in critical micellar concentration (CMC), micelle core hydrophobicity, and micelle size, as evidenced by pyrene fluorescence, transmission electron microscopy, and dynamic light scattering. Cytotoxicity studies showed that the copolymers were safe at concentrations well above the CMC. Transfer of gallic acid and derivatives from aqueous medium to the micelle phase was characterized in terms of distribution constant and free energy of transference, which were shown to be strongly dependent on the hydrophobicity of the gallate derivatives and the length of PCL in the pentablock copolymer. Antioxidant activity of gallates was challenged against DPPH previously loaded in PCL/F127/PCL and PCL/F68/PCL micelles. The more the hydrophobicity of the gallate derivative, the greater the capability to enter in the micelle and to consume free radicals. In vitro release studies of gallic acid, methyl gallate, and ethyl gallate from the pentablock copolymer micelles also evidenced the influence of the hydrophobicity of both the gallate derivative and the micelle core on release rate, recording a variety of release patterns. Overall, PCL/F127/PCL and PCL/F68/PCL appear as suitable nanocarriers of potent antioxidant agents in a wide range of polarities, which may be useful for diverse therapeutic applications.

Topics: Animals; Antioxidants; BALB 3T3 Cells; Biocompatible Materials; Biphenyl Compounds; Drug Liberation; Gallic Acid; Mice; Micelles; Particle Size; Picrates; Poloxamer; Polyesters; Solubility

In this study, a compound with antioxidant and anti-HIV activities designated as HEB was first isolated from the edible mushroom Pholiota adiposa by extraction with ethanol and ethyl acetate. HEB was then purified by high performance liquid chromatography (HPLC) and identified to be methyl gallate (C8H8O5, 184.1 Da) based on data from its mass spectrum (MS) and nuclear magnetic resonance (NMR) spectrum. HEB displayed strong antioxidant potency in inhibiting, at 1.36 mM concentration, erythrocyte hemolysis and scavenging DPPH radicals and superoxide anion (O2(-)) by 82.4%, 85.6% and 71.4%, respectively. Besides exhibiting a low cytotoxicity, compound HEB demonstrated significant anti-HIV activity in that it inhibited HIV-1 replication in TZM-BL cells infected by pseudovirus with an IC50 value of 11.9 μM. Further study disclosed that HEB inhibited the viral entry process and activities of key enzymes essential for the HIV-1 life cycle. HEB inhibited HIV-1 reverse transcriptase and integrase activities with an IC50 value of 80.1 μM and 228.5 μM, respectively, and at 10 mM concentration inhibited HIV-1 protease activity by 17.1% which was higher than that achieved by the positive control pepstatin A. Interestingly, this study first revealed that H2O2 stimulation not only activated cell oxidative stress responses, but also accelerated HIV-1 long terminal repeat (LTR) promotion in TZM-BL cells, which was significantly reduced by HEB from 18.2% to about 2%. It implied a direct relationship between the antioxidant and anti-HIV activities of the natural active constituent HEB. Nuclear transcription factor kappa B (NF-κB) signal pathways plays an important role in oxidative stress responses. Meanwhile, there is κB target sequence in HIV promoter LTR which is significant for virus replication and gene expression. In this study, Western Blot assay showed that HEB could inhibit the activation of NF-κB signal pathway stimulated by H2O2 in mouse spleen cells through suppressing NF-κB (p65) translocation into nucleus and NF-kappa-B inhibitor (IκB) degradation in cytoplasm. In summary, the antioxidant HEB from P. adiposa could inhibit HIV-1 replication through multiple target sites. The data suggest that natural antioxidant compounds might have a potential for treatment of AIDS.

Topics: Animals; Anti-HIV Agents; Antioxidants; Biological Products; Biphenyl Compounds; Erythrocytes; Gallic Acid; Hemolysis; HIV Reverse Transcriptase; Male; Mice, Inbred BALB C; NF-kappa B; Pholiota; Picrates; Reverse Transcriptase Inhibitors; Superoxides

The anti-DPPH radical effect as well as anti-peroxide activity of gallic acid, methyl gallate, and α-tocopherol in a bulk Kilka fish oil and its oil-in-water emulsion stabilized by soy protein isolate at 55°C were investigated. Gallic acid with the lowest hydrophobicity (log P=-0.28) was found to be the most active antiradical agent (IC50=29.5 μM), followed by methyl gallate (IC50=38.0 μM, log P=-0.23) and α-tocopherol (IC50=105.3 μM, log P=0.70). The anti-peroxide activity in the bulk oil system decreased in the order of methyl gallate>gallic acid>α-tocopherol. In the emulsion system, methyl gallate still behaved better than gallic acid, but the highest activity belonged to α-tocopherol. Based on the calculation of a number of kinetic parameters, the antioxidants, in general, showed better performances in the bulk oil system than in the emulsion system.

Topics: alpha-Tocopherol; Animals; Antioxidants; Biphenyl Compounds; Emulsions; Fish Oils; Fishes; Free Radical Scavengers; Gallic Acid; Hydrolyzable Tannins; Inhibitory Concentration 50; Lipids; Peroxides; Picrates; Triglycerides

The chromatographic separation of MeOH extract from the Quercus salicina Blume Stem led to the isolation of five phenolic compounds. Using spectroscopic methods, the structures of these compounds were determined as D-threo-guaiacylglycerol 8-O-beta-D-(6'-O-galloyl)glucopyranoside (1), 9-methoxy-D-threo-guaiacylglycerol 8-O-beta-D-(6'-O-galloyl)glucopyranoside (2), 6''-O-galloyl salidroside (3), methyl gallate (4), quercetin (5). We measured radical scavenging activity with the DPPH method and the anti-lipid peroxidative efficacy on human LDL with TBARS assay, with the result that all these compounds exhibited the antioxidative activity.

Topics: Antioxidants; Biphenyl Compounds; Chromatography; Free Radical Scavengers; Gallic Acid; Glucosides; Glycerol; Humans; Lipid Peroxidation; Lipoproteins, LDL; Magnetic Resonance Spectroscopy; Picrates; Plant Stems; Quercetin; Quercus; Thiobarbituric Acid Reactive Substances