Tin protoporphyrin

Tin protoporphyrin, when administered in conjunction with UVA irradiation, has been reported to be of possible benefit in the treatment of psoriasis.404... 

Synthetic tin protoporphyrin is a specific inhibitor of heme oxygenase and reduces plasma bilirubin concentrations in both adults and neonates, thereby preventing jaundice (1-3). A variety of heme analogues, such as tin, zinc, chromium, and manganese metalloporphyrins, act by competitive inhibition of cleavage of heme to biliver-din and carbon monoxide. Stannic porphyrins seem to be the most effective. The adverse effects are few, with only occasional erythema attributable to the phototoxicity of the metalloporphyrins. 

Drummond GS, Kappas A. Chemoprevention of neonatal jaundice potency of tin-protoporphyrin in an animal model. Science 1982 217(4566) 1250-2. 

Treatment of neonatal jaundice is usually by phototherapy. A decrease in bilirubin production in the neonatal period can also be achieved by inhibiting the rate-limiting enzyme of bilimbin formation from heme, namely, the heme oxygenase. A potent competitive inhibitor of heme oxygenase is the synthetic heme analogue tin (Sn" +) protoporphyrin. When administered parenterally, the tin protoporphyrin safely decreases bilimbin formation. Exchange transfusions also rapidly decrease plasma bilimbin levels. 

Tin protoporphyrin (SnPP) Formulated as liposomes rv administration increased drug accumulation in spleen due to its high concentration of reticuloendothelial cells... 

Tin(IV)-protoporphyrin (254), Ga-deuteroporphyrin (255), and Co-mesoporphyrin (256) complexes are potent inhibitors of heme oxygenase. The Sn(IV) complex significantly inhibits bilirubin production... 

Iron as a cofactor in catalysis is receiving increasing attention. The most common oxidation states of iron are Fe2+ and Fe3+. Iron complexes are nearly all octahedral, and practically all are paramagnetic (as a result of unpaired electrons in the 3d orbital). The most common form of iron in biological systems is heme. Heme groups (Fe2+) and hema-tin (Fe3+) most frequently involve a complex with protoporphyrin IX (fig. 10.19). They are the coenzymes (prosthetic... 

It is apparent that more than one oxygen activation pathway exists. The excited triplet state of tin porphyrins is known to be quenched in the presence of 2, suggesting a possible direct mechanism of O2 activation by the photosensitizer. We have examined reactions of both singlet O2 and superoxide anion under our reaction conditions. Chemically-produced superoxide (K02/18-crown-6) is not reactive under our experimental conditions. On the other hand, singlet oxygen, produced by irradiation of free base protoporphyrin (H2ProtoP), is reactive in the presence of tertiary amines and gives about the same hexanol to hexanone ratio (2.7, see Table 1) as is observed in the presence of the SnP photosensitizer. 

Dichloro(protoporphyrin IX)tin(IV) (Sn-heme, 6) is undergoing clinical trials for the treatment of neonatal jaundice. It is a potent inhibi-... 

A photoelectrochemical sensing platform was fabricated, based on the composition of protoporphyrin IX, tungsten trioxide, WO3, and RGO on an indium tin oxide (ITO) electrode for detecting cysteine in aqueous solution, with a 25 nM detection limit [133]. 

Along with blood lead and urine, effects on the heme system can be used as indicators of exposure to lead. Elevations of zinc protoporphyrin (ZPP) or free erythrocyte protoporph)Tin (FEP) can indicate past lead exposures while blood lead will indicate a recent exposure. As shown in Table 22.2, OSFIA requires action when blood lead is 40 pg/100 g of whole blood and removal from lead exposure when the blood lead reaches or exceeds 60 tg/100 g of whole blood or if the average of three consecutive blood lead levels are over 50 pg/lOO g of whole blood. 

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