Chiral Recognition of Diketopiperazine Cyclo(Pro-Gly) and Propranolol Using (-)-Epigallocatechin-3-O-gallate

Chem Pharm Bull (Tokyo). 2016;64(2):142-9. doi: 10.1248/cpb.c15-00712.

Abstract

In the (1)H-NMR spectrum of a solution containing an equimolecular amount of cyclo(L-Pro-Gly), cyclo(D-Pro-Gly) and (-)-epigallocatechin-3-O-gallate (EGCg) in a D2O, a difference in the chemical shift of (1)H-NMR signal for H7α, H7β,8α of the Pro residue was observed. Judging from the crystal structures of the 2 : 2 complexes of EGCg and cyclo(L-Pro-Gly), cyclo(D-Pro-Gly), the difference in the chemical shift resulted mainly from a magnetic anisotropic shielding effect by the ring current from the B ring of EGCg. Therefore, it was considered that chirality of cyclo(Pro-Gly) was recognized by EGCg in the D2O solution. Furthermore, in the (1)H-NMR spectrum of a solution containing an equimolecular amount of racemic propranolol ((R)- and (S)-propranolols) and EGCg in D2O, the (1)H-NMR signal for H2 of the naphthalene group was observed as two doublets, suggesting that the racemic propranolol formed diastereomers of complexes with EGCg; as a result, chirality of propranolol was recognized by EGCg in the D2O solution.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catechin / analogs & derivatives*
  • Catechin / chemistry
  • Diketopiperazines / analysis*
  • Diketopiperazines / chemistry*
  • Molecular Structure
  • Peptides, Cyclic / analysis*
  • Peptides, Cyclic / chemistry*
  • Propranolol / analysis*
  • Propranolol / chemistry*
  • Proton Magnetic Resonance Spectroscopy / standards
  • Reference Standards

Substances

  • Diketopiperazines
  • Peptides, Cyclic
  • Catechin
  • cyclo(prolylglycyl)
  • Propranolol
  • epigallocatechin gallate