Novel redox derivatives of tryptophan

The design, synthesis and study of some physicochemical properties of several potential brain targeting chemical delivery systems (CDS) of D,L-tryptophan (Trp) are described. CDS's are based on a 1,4-dihydropyridine ↔ pyridinium salt-type redox system. The dihydropyridine moiety was chemically attached to the amino group of Trp by either substituted amide or substituted carbamate linkages. While the amide bond-containing derivatives are known to be rather stable toward in vivo hydrolysis, the parent Trp can be readily released from the substituted carbamate-type combinations. Lipophilicity and chemical oxidation studies performed on the new derivatives indicated that some of the new CDSs possess the properties required for an improved and specific brain delivery of Trp.