Topic
Phenols
About: Phenols is a research topic. Over the lifetime, 4719 publications have been published within this topic receiving 218472 citations. The topic is also known as: phenol & phenol compound.
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TL;DR: The antiradical properties of various antioxidants were determined using the free radical 2,2-Diphenyl-1-picrylhydrazyl (DPPH*) in its radical form as discussed by the authors.
Abstract: The antiradical activities of various antioxidants were determined using the free radical, 2,2-Diphenyl-1-picrylhydrazyl (DPPH*). In its radical form. DPPH* has an absorption band at 515 nm which dissappears upon reduction by an antiradical compound. Twenty compounds were reacted with the DPPH* and shown to follow one of three possible reaction kinetic types. Ascorbic acid, isoascorbic acid and isoeugenol reacted quickly with the DPPH* reaching a steady state immediately. Rosmarinic acid and δ-tocopherol reacted a little slower and reached a steady state within 30 min. The remaining compounds reacted more progressively with the DPPH* reaching a steady state from 1 to 6 h. Caffeic acid, gentisic acid and gallic acid showed the highest antiradical activities with a stoichiometry of 4 to 6 reduced DPPH* molecules per molecule of antioxidant. Vanillin, phenol, γ-resorcylic acid and vanillic acid were found to be poor antiradical compounds. The stoichiometry for the other 13 phenolic compounds varied from one to three reduced DPPH* molecules per molecule of antioxidant. Possible mechanisms are proposed to explain the experimental results.
18,907 citations
Book•
01 Jan 1973
TL;DR: In this article, the authors present methods of extraction and isolation of plant components and methods of separation, and methods for identification and analysis of the results of the extraction and separation of these components.
Abstract: 1 Methods of Plant Analysis.- 1.1 Introduction.- 1.2 Methods of extraction and isolation.- 1.3 Methods of separation.- 1.4 Methods of identification.- 1.5 Analysis of results.- 1.6 Applications.- 2 Phenolic Compounds.- 2.1 Introduction.- 2.2 Phenols and phenolic acids.- 2.3 Phenylpropanoids.- 2.4 Flavonoid pigments.- 2.5 Anthocyanins.- 2.6 Flavonols and flavones.- 2.7 Minor flavonoids, xanthones and stilbenes.- 2.8 Tannins.- 2.9 Quinone pigments.- 3 The Terpenoids.- 3.1 Introduction.- 3.2 Essential oils.- 3.3 Diterpenoids and gibberellins.- 3.4 Triterpenoids and steroids.- 3.5 Carotenoids.- 4 Organic Acids, Lipids and Related Compounds.- 4.1 Plant acids.- 4.2 Fatty acids and lipids.- 4.3 Alkanes and related hydrocarbons.- 4.4 Polyacetylenes.- 4.5 Sulphur compounds.- 5 Nitrogen Compounds.- 5.1 Introduction.- 5.2 Amino acids.- 5.3 Amines.- 5.4 Alkaloids.- 5.5 Cyanogenic glycosides.- 5.6 Indoles.- 5.7 Purines, pyrimidines and cytokinins.- 5.8 Chlorophylls.- 6 Sugars and their Derivatives.- 6.1 Introduction.- 6.2 Monosaccharides.- 6.3 Oligosaccharides.- 6.4 Sugar alcohols and cyclitols.- 7 Macromolecules.- 7.1 Introduction.- 7.2 Nucleic acids.- 7.3 Proteins.- 7.4 Polysaccharides.
8,090 citations
TL;DR: A microplate-adapted colorimetric total phenolics assay that utilizes Folin–Ciocalteu (F–C) reagent is described that eliminates approximately 85% of ascorbic acid and other potentially interfering compounds.
Abstract: Non-structural phenolic compounds perform a variety of functions in plants, including acting as antioxidants. We describe a microplate-adapted colorimetric total phenolics assay that utilizes Folin-Ciocalteu (F-C) reagent. The F-C assay relies on the transfer of electrons in alkaline medium from phenolic compounds to phosphomolybdic/phosphotungstic acid complexes, which are determined spectroscopically at 765 nm. Although the electron transfer reaction is not specific for phenolic compounds, the extraction procedure eliminates approximately 85% of ascorbic acid and other potentially interfering compounds. This assay is performed in microcentrifuge tubes and assessed in a 96-well plate reader. At least 64 samples can be processed in 1 d.
2,047 citations
TL;DR: This study provides direct comparative data on antioxidant capacity and total and individual phenolics contents of the 26 spice extracts and showed that phenolic compounds in the tested spices contributed significantly to their antioxidant capacity.
Abstract: Total equivalent antioxidant capacity (TEAC) and phenolic content of 26 common spice extracts from 12 botanical families were investigated. Qualitative and quantitative analyses of major phenolics in the spice extracts were systematically conducted by reversed-phase high-performance liquid chromatography (RP-HPLC). Many spices contained high levels of phenolics and demonstrated high antioxidant capacity. Wide variation in TEAC values (0.55−168.7 mmol/100 g) and total phenolic content (0.04−14.38 g of gallic acid equivalent/100 g) was observed. A highly positive linear relationship (R2 = 0.95) obtained between TEAC values and total phenolic content showed that phenolic compounds in the tested spices contributed significantly to their antioxidant capacity. Major types of phenolic constituents identified in the spice extracts were phenolic acids, phenolic diterpenes, flavonoids, and volatile oils (e.g., aromatic compounds). Rosmarinic acid was the dominant phenolic compound in the six spices of the family La...
1,315 citations
Book•
01 Jan 1957
TL;DR: The covalent bond and shapes of molecules are discussed in detail in this paper, where Amino acids and proteins are represented as nucleophilic aliphatic substitution, and the reaction of benzene and phenols.
Abstract: The covalent bond and shapes of molecules. Alkanes and cycloalkanes. Alkenes and alkynes. Chirality and optical isomerism. Alcohols, ethers and thiols. Nucleophilic aliphatic substitution. Aromaticity. Reactions of benzene and phenols. Amines. Aldehydes and ketones. Carboxylic acids. Carbohydrates. Lipids. Amino acids and proteins. Nucleic acids. Spectroscopy.
1,233 citations