Hydroxyquinoline inhibition

Metal-binding agents (118-120) Oxalate, citrate, 1,10-phenanthroline, azide, diethyldithiocarbamate, cyanide, and 8-hydroxyquinoline inhibit, suggesting the metalloenzyme nature of the catalyst... 

In acidic solution, the degradation results in the formation of furfural, furfuryl alcohol, 2-furoic acid, 3-hydroxyfurfural, furoin, 2-methyl-3,8-dihydroxychroman, ethylglyoxal, and several condensation products (36). Many metals, especially copper, cataly2e the oxidation of L-ascorbic acid. Oxalic acid and copper form a chelate complex which prevents the ascorbic acid-copper-complex formation and therefore oxalic acid inhibits effectively the oxidation of L-ascorbic acid. L-Ascorbic acid can also be stabilized with metaphosphoric acid, amino acids, 8-hydroxyquinoline, glycols, sugars, and trichloracetic acid (38). Another catalytic reaction which accounts for loss of L-ascorbic acid occurs with enzymes, eg, L-ascorbic acid oxidase, a copper protein-containing enzyme. 

Elimination of a cofactor needed for luminescence. The chelators EDTA and EGTA efficiently quench the luminescence of Ca2+-activated systems such as aequorin, obelin and mnemiopsin. The luminescence systems that require ferrous ions, such as extracts of the polychaete Chaetopterus, can be inhibited by 8-hydroxyquinoline and... 

The enzyme activity is significantly inhibited by Tiron and 8-hydroxyquinoline, but not by a,a -dipyridyl and o-phenanthroline. The addition of thiol compounds such as cysteine, 2-mercaptoethanol and glutathione, and thiol inhibitors such as p-chloromercuribenzoate, N-ethylmaleimide and HgCl2 also markedly decreases the enzyme activity. The Michaelis constants of the enzyme are as follows 2-nitropropane (2.13 x 10-2M), nitroethane (2.43 x 10-2M), 3-nitro-2-pentanol (6.8 x 10 3M), 1-nitropropane (2.56 x 10-2 M) and oxygen (3.63 x 10 4M with 2-nitropropane)199. ... 

The phenol used for RNA extraction should be of the highest purity (double distilled), as oxidation products of phenol can cause degradation of RNA. Before use, the phenol is saturated with DEPC-treated water, and the phases are allowed to separate. The pH of the top aqueous layer is tested with pH paper. If phenol is acidic, it is equilibrated with Tris buffer by mixing it with a volume of 1 M Tris-Cl, pH 7.0. After phase separation, the top buffer layer is removed and the phenol is equilibrated twice with water. Additives such as 8-hydroxyquinoline (0.1%) are used in phenol to inhibit the activity of nucleases. Caution should be exercised in the use of phenol, as it is corrosive and a suspected carcinogen. Use in a chemical hood is recommended. Phenol chloroform extraction should be carried out in con-... 

Hydroxyquinoline 7-carboxylic acid (structure shown in Fig. 2) derivatives have been shown to be useful for producing integrase-inhibiting medica-... 

Phenol is redistilled under nitrogen, saturated with water or 10 mM Tris-HCl, 0.5 mM EDTA, pH 8.0, and stored frozen in small aliquots at -20°C. The addition of 0.1 % hydroxyquinoline to the phenol inhibits atmospheric oxidation. Also, the strong yellow colour helps in defining the interface between the phenol and aqueous layers after small-scale extractions. 

The previous review noted the formation of Reissert compounds from less than half the quinolines investigated and stated that ... the ease of formation of Reissert compounds is dependent upon steric as well as electronic factors, since the presence of substituents in the 2- and 8-positions of quinoline inhibits the formation of. .. Reissert compounds. That a steric factor does indeed exist is evidenced by the fact that from a total of seven 2-substituted and nine 8-substituted quinolines subjected to the reaction none has yielded a Reissert compound. Using the methylene chloride-water solvent system, however, Reissert compounds have been prepared from 3-, 4-, 5-, 6-, and 7-substituted quinolines and from disubstituted quinolines. Quinolines having various substituents in these positions, including all those previously reported as not giving Reissert compounds, gave positive results in this solvent system. In addition to Reissert compound formation, hydroxyquinolines were esterified and aminoquinolines were converted to the amides. 

In H. salinarium (cutinibnim), NADH is oxidized through c-type cytochromes and an cytochrome a oxidase. 2-heptyl-4-hydroxyquinoline-yV-oxide (HOQNO) inhibits electron transport chain at the level of the NADH dehydrogenase. The salt dependence of the NADH oxidase system indicates that the salt dependence of the NADH oxidase system is a reflection of the sensitivity of the NAD dehydrogenase [95]. 

An antimicrobial denture adhesive, denture cleansing cream or denture soaking or brushing composition comprises a combination of 8-hydroxyquinoline (or its salt) and at least one copper(II) salt. The composition fights denture stomatitis by inhibiting Candida albicans. 

In 1944, Albert, Gibson and Rubbo [541] found that Cu(II)(8-hydroxy-quinoline)2 was much more effective as a bactericidal and fungicidal agent than 8-hydroxyquinoline (8-HQ). Copper complexes of halo-substituted 8-HQ have been found by Gershon [542] to be even more effective than Cu(II)(8-HQ)2. In addition, both 8-HQ [543] and its copper complex [544] have been found to have antiviral activity. It was suggested that the parent compound inhibited the RNA-dependent DNA polymerase of chick myeloblastosis virus and its copper complex produced the same effect with the RNA-dependent DNA polymerase of the tumourogenic Rous sarcoma virus. 

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