Abstract:

Macroporous resin HP-2MGL and SephadexLH-20 Gel was used to purify the proanthocyanidin from grape seed. Fraction GSPP3HP-2MGL was obtained by separation of crude grape seed extract through HP-2MGL and its proanthocyanidin content reached 96.5%. The fraction was further purified with SephadexLH-20 and two proanthocyanidin dipolymers GSPP3- SP1 and GSPP3-SP2 were resulted. HPLC analysis showed 4 peaks from GSPP3-SP1 and 7 peaks from GSPP3-SP2 were recognized. Mass spectrums revealed the abundance of the fragment ions like m/z 287, m/z 289, m/z 290, m/z 408, m/z 426, m/z 577, m/z 578 and m/z 580, suggesting this proanthocyanidin was a catechuic acid epigallocatechin--epicatechin dimer. The MW of GSP was determined to be 4.15×104 by laser light scattering combined with GPC and the coefficient of polydispersity was 1.65. The MW of GSPP3 was 4.26×103 with the average degree of polymerization of 13 and the coefficient of polydispersity of 1.56. The relative molecular weight curve showed a symmetrical distribution and this proanthocyanidin was highly polymerized. GSPP3-SP was found to lowly polymerized proanthocyanidin with the MW of 1.89×103, the average degree of polymerization of 6 and the coefficient of polydispersity of 1.45.

Key words: grape seed, proanthocyanidin, purification, structure