Chlorin e₆ 13¹:15²-Anhydride: A Key Intermediate in Conjugation Reactions of Chlorin e₆.

ABSTRACT: Since the patent for the photodynamic therapy agent Talaporfin (mono-L-aspartylchlorin e₆) was issued in 1987, confusion has existed regarding which of the three carboxylic acid groups in the chlorophyll degradation product, chlorin e₆ (1), is modified in standard amino acid type conjugations (using DCC or EDC and an organic base) with amino acids and other biomolecules. Here it is shown that the site of conjugation is the central 15²-carboxylic acid, such reactions proceeding in numerous examples via a 13¹,15²-anhydride for which a high resolution X-ray structure is reported. Conjugation with eight oxygen and nitrogen nucleophiles, in every case, afforded the 15²-conjugate, reinforcing the earlier conclusion t

SUBMITTER: Chen H 

PROVIDER: S-EPMC4525479 | biostudies-literature | 2015 Jun

REPOSITORIES: biostudies-literature