PH Stability and Antioxidant Power of CycloDOPA and Its Derivatives.

Shiori Nakagawa,Fumina Ohashi,Natsumi Kurokawa,Takeyuki Suzuki,Yasuko Sakihama,Makoto Hashimoto,Yasuyuki Hashidoko,Zetryana Tachrim

doi:10.3390/molecules23081943

Shiori Nakagawa, Fumina Ohashi + Show 6 more

Open Access

https://doi.org/10.3390/molecules23081943

Copy DOI

Abstract

CycloDOPA (leukodopachrome), a well known metabolite of tyrosine, is a precursor of melanine in mammalian organisms and of the pigment betalain in plants. However, the isolation of cycloDOPA from natural sources has not been widely reported. In the present work, the stabilities of cycloDOPA and cycloDOPA methyl ester at various pH levels were studied. Both compounds were stable under acidic conditions. By contrast, both compounds were unstable when the pH was shifted from neutral to basic to form indole derivatives as major products. Based on the pH stability, cycloDOPA and its derivatives were subjected to the DPPH radical scavenging assay for the first time.

Highlights

IntroductionCycloDOPA (leukodopachrome), a major metabolite derived from tyrosine, is a precursor of melanin in animals [1] and of betalain pigment in plants [2]
CycloDOPA, a major metabolite derived from tyrosine, is a precursor of melanin in animals [1] and of betalain pigment in plants [2]
At neutral pH, in which the enzymatic reaction mixture was incubated for a longer period (>0.5 h), and the formation cycloDOPA decomposed within 2 h

Summary

Introduction

CycloDOPA (leukodopachrome), a major metabolite derived from tyrosine, is a precursor of melanin in animals [1] and of betalain pigment in plants [2]. In one of the most common methods, in situ-generated cycloDOPA has been derivatized to triacetyl-protected cycloDOPA [5] Another method has been developed by reacting the in situ-generated cycloDOPA with betalamic acid to form betalain [6], which has a high molar coextinction coefficient. To the best our knowledge, biosynthetic cycloDOPA has been detected by UHPLC¬Q¬TOF-MS [7], but studies have not reported the isolation and characterization of cycloDOPA from natural sources. These findings indicated that the chemical stability of cycloDOPA may hamper the isolation of pure cycloDOPA, especially in the case of quantitative analysis from.

Synthesis

(Supplementary Materials

General Procedures

Evaluation of The DPPH Radical Scavenging Activity for CycloDOPA Derivatives