Phenolic acids naturally occurring

Phenolic compounds naturally occurring in plants have induced many physiological responses that duplicate those reported for ozone and/or peroxyacetylnitrate (PAN). Chlorogenic acid is a competitive inhibitor of lAA-oxidase (35) and plant growth is adversely affected by increased concentrations of auxins (36). Concentrations of chlorogenic acid are increased in tobacco tissue exposed to ozone ( ) Phenols inhibit ATP synthesis (37), oxidative phosphorylation ( ) and SH enzyme activity (27) they increase respiration (38), reduce CO2 fixation (22), modify both membrane permeability (40) and oxidation rate of reduced NADH... 

For the measurement a moderate reduction potential between — 100 and + 100 mV vs. Ag/AgCl is appUed (Fig. 2.12). In this region the potential for electrochemical interferences is very low. However, the biggest problems arise from the high reactivity of compormds I and II with reducing substrates (electron donors), which compete with the electrode for the reduction of peroxidase. Ascorbic acid, naturally occurring phenolics and aromatic amines are among those compounds. The competitive reaction of reductants should be... 

Shimp J, FK Pfaender (1985b) Influence of naturally occurring humic acids on biodegradation of monosubstituted phenols by aquatic bacteria. Appl Environ Microbiol 49 402-407. 

Phenolic acids and polyphenols are natural plant constituents which impart flavor and textural components to beverages made from these plants. In order to better understand the role of these easily oxidized compounds in the flavor and stability of beverages, it is necessary to determine them at the low concentrations they occur. LCEC has been shown to be quite effective at these trace determinations... 

The CF sheet is prepared by coating an acidic coreactant such as naturally occurring reactive clay, zinc salt of salicylic acid derivatives and zinc modified phenolic resin. 

Incorporation of some xenobiotics (herbicides) into soil humus-complexes occurs via pathways analogous to those for incorporation of naturally occurring phenolic and benzoic acids and do indeed involve phenolic and humus-like constituents... 

The solubility of most metals is much higher when they exist as organometallic complexes.4445 Naturally occurring chemicals that can partially complex with metal compounds and increase the solubility of the metal include aliphatic acids, aromatic acids, alcohols, aldehydes, ketones, amines, aromatic hydrocarbons, esters, ethers, and phenols. Several complexation processes, including chelation and hydration, can occur in the deep-well environment. 

Iodine water is added to an acetic acid sodium acetate buffered sample to reoxidise to iodate any iodine-containing substances produced by reduction of iodate by naturally occurring reducing substances present in the sample. Total iodate (i.e., iodate present in the original sample as iodate plus additional iodate produced by iodine water treatment) is then reacted with phenol solution at... 

For the synthesis of perfectly dendronized sohd-phase polymers (Fig. 7.4) various dendritic structures were prepared based on amide connections [6]. For example, the naturally occurring amino acid lysine was used as a building block in creating a dendritic scaffold [33]. The synthesis of symmetrical tri-branching den-drimers on aminomethyl polystyrene macrobeads was also described in literature [34]. Recently, aryl ether dendrimers were prepared on hydroxymethyl polystyrene using a Mitsunobu reaction with 3,5-bis(acetoxymethyl)phenol [35]. 

Phenylpropanes are aromatic compounds with a propyl side chain attached to the benzene ring, which can be derived directly from phenylalanine. Naturally occurring phenylpropanoids often contain oxygenated substituents, e.g. OH, OMe or methylenedioxy, on the benzene ring. Phenylpropanoids with hydroxyl substituent(s) on the benzene ring belongs to the group of phenolics, e.g. caffeic acid and coumaric acid. 

Phenol is produced through both natural and anthropogenic processes. It is naturally occurring in some foods, human and animal wastes, and decomposing organic material, and is produced endogenously in the gut from the metabolism of aromatic amino acids. Phenol has been isolated from coal tar, but it is now synthetically manufactured (EPA, 2002). Currently, the largest use of phenol is as an intermediate in the production of phenolic resins, which are used in the plywood, adhesive, construction, automotive, and appliance industries. Phenol is also used in the production of synthetic fibers such as nylon and for epoxy resin precursors such as bisphenol-A. 

J. Kendall, J. E. Booze, and J. C. Andrews 3 have shown that the formation of hydrates, in the sense of water of crystallization, with the weak acids very seldom occurs, and when hydrates are formed, the acid has the amphoteric character of a phenol. There is also a regular increase in the tendency of an acid to form hydrates, as the strength of the acid increases, until, with the strong acids, well-defined stable hydrates appear. The complexity and stability of the hydrates increase with the strength of the acid. These facts are in harmony with the weak acid nature of water. 

Most alkaloids exist in nature not in their free-base form but rather as the salt of naturally occurring acids known as tannins, a group of phenol-based organic acids that have complex structures. The alkaloid salts of these acids are usually much more soluble in hot water than in cold water. The caffeine in coffee and tea exists in the form of the tannin salt, which is why coffee and tea are more effectively brewed in hot water. As Figure 12.19 relates, tannins are also responsible for the stains caused by these beverages. 

The nature of the association between membrane and teichoic acid is unknown, and it is possible that these teichoic acids are chemically attached to other components of the cell. Samples obtained by extraction with phenol appear to have appreciably higher molecular weight than has the purified teichoic acid obtained by extraction with trichloroacetic acid, and it is likely that the prolonged, acid treatment used in earlier work may have caused hydrolysis of some of the phosphodiester linkages. It is noteworthy that this comment on earlier studies does not apply to ribitol teichoic acids. Detailed examination of preparations of membrane teichoic acid obtained by less drastic conditions is highly desirable, in order to confirm the supposed size of the naturally occurring polymers, as well as... 

ABSTRACT Chlorogenic acids are polyphenolic compounds that occur ubiquitously in foods of plant origin. They are quinic acid esters of hydroxycinnamic acid. Recently, naturally occurring plant phenolics have attracted considerable attention in relation to their physiological potential. Depending upon the conditions, phenolic compounds can be either beneficial or detrimental to biological processes. 

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