A facile one-step synthesis of cysteinyldopas using mushroom tyrosinase.

A convenient one-step procedure, based upon the tyrosinase co-oxidation of dopa and cysteine, is reported for the synthesis of 5-S-cysteinyldopa (I) in 74% yield. Secondary products of the reaction turned out to be 2-S-cysteinyldopa (II, 14%), 2,5-S, S-dicysteinyldopa (iv, 5%), and the hitherto unknown 6-S-cysteinyldopa (III, approximately 1%).     

Electrochemical synthesis of cysteinyldopas

Summary A fast and inexpensive method for the synthesis of mon- and dicysteinyldopas is described. Dopa is oxidized by electrochemical techniques, and cysteine is then added to give cysteinyldopas.Acknowledgment. This investigation has been supported by grants from the Swedish Cancer Society (project 626-B80-08XB and 626-B80-08P).     

A new one-step synthesis of hexahydrocannabinoid analogs

Summary A one-step synthesis of hexahydrocannabinoid analogs (HHC) is described making use of the condensation of phenolic ketones and aldehydes with citronellal in the presence of pyridine.Grateful thanks are accorded to Drs L. Chopard and S. Selvavinayakam for spectral measurements and Dr I. Fleming for useful discussion.R. Mechoulam and Y. Gaoni, Recent advances in the chemistry of Hashish, in: Progress in the Chemistry of Organic natural products, vol. 25, p. 175. Ed. L. Zechmeister. Springer Verlag, Wien 1967; R. Mechoulam, Marijuana Chemistry and Pharmacology, metabolism and clinical effects. Academic Press, New York 1973; R. Mechoulam, N. K. McCallum and S. Burstein, Chem. Rev.76, 75 (1976).     

A one-step synthesis of (-)-Δ1-Tetrahydrocannabinol from chrysanthenol

Zusammenfassung Eine Einschritt-Synthese von (—)-Tetrahydrocannabinol¹ (THC) ausgehend von Chrysanthenol mit möglichen biogenetischen Folgerungen wird beschrieben.     

Inhibition of mushroom tyrosinase by 3-amino-L-tyrosines: Molecular probing of the active site of the enzyme

Summary We report the ability of 3-amino-L-tyrosine to act as a fully reversible competitive inhibitor of mushroom tyrosinase. The inhibition is linked to the ortho-aminophenol structure, and a coppe bridging mechanism in the active site is proposed.     

Inhibition of mushroom tyrosinase by 3-amino-L-tyrosine: molecular probing of the active site of the enzyme

We report the ability of 3-amino-L-tyrosine to act as a fully reversible competitive inhibitor of mushroom tyrosinase. The inhibition is linked to the ortho-aminophenol structure, and a copper bridging mechanism in the active site is proposed.     

A facile approach to dihydrojasmone

Résumé La dihydrojasmone a été synthétisée en trois étapes à partir du pentanedione-2,4.

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This research was supported by NRCC, Ottawa.     

Activation of skin tyrosinase

Résumé L'activité de tyrosinase intégumentale est augmenté par un séjour de 10–18 jours à 0–4°C sous oxygène ou en plein air mais pas nitrogène. Les 3 espèces vertébrés qui montrent cette réaction sontMyxine glutinosa, Lepisosteus osseus etNeoceratodus fosteri.

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Contribution No. 194, Department of Biology.     

A simple one-step procedure for staining the nucleolus organizer regions

Summary A simple silver staining technique for routine use is described by which the nucleolus organizer regions of mammalian chromosomes, including those of mouse chromosomes, are stained selectively.Acknowledgment. We would like to thank Prof. Dr K. Sperling for critical and helpful discussion.     

A simple one-step procedure for staining the nucleolus organizer regions.

A simple silver staining technique for routine use is described by which the nucleolus organizer regions of mammalian chromosomes, including those of mouse chromosomes, are stained selectively.     

Inhibition of melanoma tyrosinase by fusaric acid

Zusammenfassung Nachweis, dass Fusarinsäure die DOPA-Oxydation durch Melanom-Tyrosinase kompetitiv mit DOPA hemmt.     

Alpha-hydrazinophloretic acid, competitive inhibitor of fungal tyrosinase]

alpha-Hydrazinophloretic acid, the hydrazino analogue of tyrosine, was shown to behave as a competitive inhibitor of tyrosinase. Some closely related compounds, especially the hydrazino analogue of phenylalanine as well as other hydrazine derivatives, will also inhibit the enzyme, but in these cases, the inhibition observed belonged to the non-competitive type.     

Effect of tryptophan on tyrosinase in relation to vitiligo

Summary Tryptophan can inhibit DOPA (3,4-dihydroxy phenylalanine) conversion to melanin both by the enzymatic and the nonenzymatic route. Its role has been studied in relation to vitiligo.Acknowledgments. The authors wishes to thank Dr S.C. Bhattacharyya, Bose Institute and Dr A. Sen, Department of Chemistry for their interest in the work.     

Inhibition of tyrosinase and uricase activity by ultraviolet radiation

Résumé L'activité de l'uricase et des tyrosinases d'origine végétale et animale est diminuée par irradiation UV (2537 Å). Il existe une relation exponentielle entre l'activité enzymatique relative et la quantité de rayonnement. Il n'a pas été possible de mettre en évidence une relation entre la perte d'activité de la tyrosinase végétale des échantillons irradiés et la teneur en cuivre de ces derniers.     

Integumental distribution of tyrosinase activity in the slow loris,Nycticebus coucang,and the presence of integumental tyrosinase inhibitor(s)

Résumé L'analyse radiométrique de la tyrosinase tégumentaire a montré que les régions de la peau deNycticebus coucang diffèrent enzymatiquement. Cette peau renferme un inhibiteur enzymatique de tyrosinase ainsi que des champignons.     

A new synthesis of dehydromunduserone

Zusammenfassung Eine einfache Synthese von Dehydromunduseron aus 7,2,4,5-Tetramethoxy-isoflavon wird beschrieben.     

A synthesis of anhydrobrazilic acid

Zusammenfassung Eine neue Synthese von Anhydrobrazilinsäure wird beschrieben. Es wird gezeigt, dass Arylidenchroman-on-4 zu Homoisoflavon isomerisiert werden kann.     

A new solid-phase synthesis of porcine vasoactive intestinal peptide using Nα-9-fluorenylmethyloxycarbonyl amino acids

Summary The solid-phase synthesis of an octacosapeptide amide corresponding to the amino acid sequence of porcine vasoactive intestinal peptide (VIP) is described. No final treatment with strong, anhydrous acid was employed, since the use of base-labile 9-fluorenylmethyloxycarbonyl amino acids bearing tert-butyl based side chain protection enabled the peptide chain assembly to be performed on p-benzyloxybenzyl amine resin, which was cleaved from the whole peptide amide at the end of the synthesis by diluted trifluoroacetic acid.