Protocatechuic acid, isolated from

Among the derivates of HBAs, further compounds have been identified. GUntert et al. (1986) identified ethyl esters of vanillic acid and p-hydroxybenzoic acid, and methyl esters of vanillic acid and protocatechuic acid. Ethyl esters of protocatechuic acid and vanillic acid, as well as the glucose ester of vanillic acid, were isolated from a German Riesling wine (Baderschneider and Winterhalter 2001). Analytically, HBA are mostly determined as trimethylsilane derivatives by using... 

In 1806 Vauquelin isolated from cinchona bark an acidic crystalline substance which he named acide kinique. Later the same substance was reported in the coffee bean, in hay and in various other substances. The ready conversion of quinic acid to aromatic substances early demonstrated its carbocyclic nature. Treatment with aqueous bromine gave protocatechuic acid with phosphorus pentachloride, m-chlorobenzoyl... 

Biller et al. (22) isolated the pyrrolizidine alkaloids 7-and 9-angeloylretronecine, intermedine, rinderine and 3 -acetylrinderine. The concentrations of these hepatotoxic alkaloids were high in the roots and mature flower heads, but negligible in the leaves and stems. This finding is noteworthy since the leaves are mostly used in traditional medicine. Phenolic acids including protocatechuic, />-hydroxybenzoic, />-coumaric, femlic and vanillic acids have also been isolated from the plant (29). 

The products accumulated and isolated from the cultures of mutants are sometimes not those of the actual pathway, but modified products derived from intermediates involved. For example, in Neurospora mutants blocked after the formation of dehydroshikimic acid, only protocatechuic and vanillic acids (derived from dehydroshikimic acid) accumulate. In other instances, an intermediate or a derivative of an intermediate may be converted by a pathway that usually... 

The microorganism used was obtained from the culture collection of Dr. Martin Alexander at Cornell University, where it was originally isolated on protocatechuic acid. It was grown in a salts medium with phenol as sole carbon source, and was maintained at pH 7.2 in a phosphate buffer. None of the chlorophenols supported growth of the organism. 

Protocatechuic acid, 3,4-dihydroxybenzoic acid, has long been known as a constituent of plants. Its biosynthesis was first described by Evans (1947), who isolated the dihydroxy compound from cultures of Vibrio growing on p-hydroxybenzoic acid. Subsequently m-hydroxybenzoic... 

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