Binding Characteristics of Drugs to Synthetic Levodopa Melanin

Shimada, Kenji; Baweja, Raman; Sokoloski, Theodore D.; Patil, Popat N.

doi:10.1002/jps.2600650725

Cited by 54 publications

(26 citation statements)

References 6 publications

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“…This result indicates that competitive binding is nonstereoselective. The observations with the stereoisomers of amphetamine are consistent with the previous studies where the binding of each labeled isomer was investigated (10).…”

Section: Discussionsupporting

confidence: 80%

“…Preparation of Levodopa Melanin-The melanin was prepared as reported previously (10). The yield resulting was 4.38 g using exactly the same amounts and procedures.…”

Section: Methodsmentioning

confidence: 99%

“…Unlabeled cocaine was added to the labeled compound whose concentration was fixed at 5.83 X 10-6 M (5.8 nCi/ml). Ratios (unlabeled-labeled) of between 5 1 and.7501 were used, and the systems were analyzed for free and bound drug as outlined previously (10).…”

Section: Methodsmentioning

confidence: 99%

“…An earlier study (10) attempted to quantify the drug interactions with synthetic melanin by assuming that the process involved was analogous to adsorption on a solid, permitting a calculation of affinity and capacity constants to characterize binding. It was observed (10) that (&)-cocaine hydrochloride had an affinity for melanin of a magnitude and reproducibility that suggested it might be used to study the binding of various drugs; the approach suggested was the measurement of the tendency of drugs to compete with labeled cocaine for melanin sites.…”

mentioning

confidence: 99%

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Competitive Binding between Cocaine and Various Drugs to Synthetic Levodopa Melanin

Baweja

Sokoloski

Patil

1977

Journal of Pharmaceutical Sciences

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Section: Discussionsupporting

confidence: 80%

“…Preparation of Levodopa Melanin-The melanin was prepared as reported previously (10). The yield resulting was 4.38 g using exactly the same amounts and procedures.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Competitive Binding between Cocaine and Various Drugs to Synthetic Levodopa Melanin

Baweja

Sokoloski

Patil

1977

Journal of Pharmaceutical Sciences

Self Cite

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“…Many investigators have demonstrated the affinity of natural and synthetic melanins for various drugs by in vivo and in vitro studies [1,3,5,30,31,32,39,49,50,58,62,63]. It is generally accepted that the ability of melanin-containing tissue to accumulate and retain these drugs is remarkable [18].…”

Section: Introductionmentioning

confidence: 99%

A comparison of 3 H-cocaine binding on melanin granules and human hair in vitro

Pötsch

Skopp

Rippin

1997

International Journal of Legal Medicine

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The in vitro experiments on the interaction of 3H-cocaine and melanin from Sepia officinalis confirmed the existence of drug binding sites on melanin granules. The results suggested that the binding of 3H-cocaine to melanin could be analyzed by assuming that the binding to the surface of pigment granules is analogous to the adsorption of a drug on a solid and follows Langmuir adsorption isotherm type I. Scatchard analysis indicated heterogeneity of binding sites. Structural and chemical alterations caused by isolation of the melanoproteins, which are heterogeneous in nature and show different physico-chemical properties, are considered to be most crucial. The studies on hair samples confirmed that melanin-drug interaction occur on the surface of melanin granules. These seem to be of minor importance compared to the drug-melanoprotein loading during melanogenesis for the observed influence of pigmentation on the drug content of hair fibers. From the results it was concluded that in vitro studies on melanin provide limited information and even drug-soaked hair must be regarded as inappropriate for the study of melanin-drug-binding in hair.

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Stoichiometry of interaction between soluble (—)‐dopa melanin and enantiomers of ephedrine by NMR spectroscopy

1992

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Synthetic soluble ( -)-dopa melanin was prepared in deuteriated buffer, pH 8, by autooxidation of the precursor. At 6 mM of the precursor, the incorporation was over 90%. The changes in the line width measurements of N-CH, protons of enantiomers of ephedrine in the soluble melanin were quantified by NMR spectroscopy. The dissociation constants of ( -)-1R,2S-ephedrine, ( + )-lS,BR-ephedrine, ( -)-1R,2R-+-ephedrine, and ( + )-lS,2S-$-ephedrine were 11.7, 4.20, 3.60, and 4.80 mM, respectively. Since the concentration of ( -)-dopa was known and since the conversion of ( -)-dopa to indole units of melanin was considered as 1 : 1, the stoichiometry of the interaction between the drug and the indole unit was calculated. Based on the dissociation constants of the enantiomers, it appears that up to four molecules of ( -)-ephedrine can interact with one indole unit of the melanin, while such a ratio for other isomers appear to be 2: 1. The preference by indole units of melanin is stereoselective.0 1992 Wiley-Liss, Inc.

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Binding Characteristics of Drugs to Synthetic Levodopa Melanin

Cited by 54 publications

References 6 publications

Competitive Binding between Cocaine and Various Drugs to Synthetic Levodopa Melanin

Competitive Binding between Cocaine and Various Drugs to Synthetic Levodopa Melanin

A comparison of 3 H-cocaine binding on melanin granules and human hair in vitro

Stoichiometry of interaction between soluble (—)‐dopa melanin and enantiomers of ephedrine by NMR spectroscopy

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