Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P47989 (xanthine oxidase)
 8,633 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pyrroloquinoline quinone (PQQ) inhibited the chemiluminescence (CL) from mouse peritoneal cells initiated by zymosan, carrageenin and N-formyl-methionyl-leucyl-phenylalanine and CL generated by the xanthine-xanthine oxidase reaction and the lipid peroxidation in the rat brain homogenate. The inhibitory activity of PQQ was more potent than that of idebenone, alpha-tocopherol and ascorbic acid in all the three assay systems. In the xanthine-xanthine oxidase reaction, PQQ had no effect on the formation of uric acid at the concentration of CL inhibition. These results suggest that PQQ might have a radical scavenger-like activity. Structure-activity relationship of PQQ and its six related compounds showed that the 7- and 9-carboxyl groups of PQQ as well as the orthoquinone structure are responsible for the radical scavenger-like activity. In addition, the -NH group in the pyrrole ring of PQQ seemed to be essential for the antilipid peroxidative activity in the rat brain homogenate. When administered i.p., PQQ inhibited the development of 0.1% carrageenin-induced paw edema in rats. These results suggest that PQQ might have therapeutic effects on various diseases, of which development or exacerbation has been known to be associated with radical oxygens.
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PMID:New biological properties of pyrroloquinoline quinone and its related compounds: inhibition of chemiluminescence, lipid peroxidation and rat paw edema. 217 8

Our laboratory recently isolated free PQQ (2,7,9-tricarboxy-pyrroloquinoline quinone, methoxatin), a bacterial redox cofactor, from red cells, neutrophils, serum and milk and found free PQQ in CSF, synovial fluid and bile. The metabolism and functions of PQQ and ascorbate may be coupled. Physiologically, free PQQ catalyzes dioxygen-superoxide interconversion, and participates in both superoxide generation (respiratory burst) and scavenging (cell protection). Using a labeled aromatic o-diamine, superoxide formation by activated neutrophils was inhibited and the labeled phenazine adduct of PQQ could be isolated from the inhibited cells (Karnovsky et al., 1992). PQQ may convert xanthine oxidase to xanthine dehydrogenase (XD) and could be the physiological coenzyme of XD. PQQ plus copper, form a potent amine-oxidizing system. Shah et al., 1992 found that PQQ-Cu2+ catalyzes the oxidation of epsilon-amino groups in collagen and elastin. Rucker's lab (Smidt et al., 1991) has found that PQQ may be a vitamin for mouse pups. Watanabe et al., 1988 and Nishigori et al., 1989, showed that injected PQQ protects animals against oxidative stress injury. PQQ's in vivo antioxidant action, spares reduced glutathione. PQQ, as an actively transported organic anion, concentrates in cells. In other experiments (Aizenman et al., 1992), PQQ protected neurons against the neurotoxin action of the glutamate-receptor against NMDA. We shall consider possible roles for PQQ in the biosynthesis of nitric oxide (NO, endothelium-derived relaxing factor, EDRF) from L-arginine and in NO removal by superoxide. NO has now been linked to the inhibition of osteoclastic bone resorption.
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PMID:Is the antioxidant, anti-inflammatory putative new vitamin, PQQ, involved with nitric oxide in bone metabolism? 840 96