LC-MS Identification of Proanthocyanidins in Bark and Fruit of six Terminalia species

Abstract

Proanthocyanidins (PAs) are the most important and valuable polyphenolic compounds of Terminalia species (family Combretaceae) used for the treatment of several diseases. This study aims to seek identification and characterization of PAs in the ethanolic extracts of bark and fruit of six Terminalia species viz T. arjuna, T. bellerica, T. catappa, T. chebula, T. elliptica and T. paniculata. A high performance liquid chromatography with quadrupole time-of-flight tandem mass spectrometry (HPLC/ESI-QTOF-MS/MS) method was developed for the simultaneous identification and characterization of PAs. The chromatographic separation was carried on a Thermo Betasil C8 column (250 mmx4.5 mm, 5μm) operated with 0.1% formic acid aqueous solution and acetonitrile as the mobile phase. The MS/MS fragmentation study of [M-H]- ions obtained from these PAs showed distinguishable fragment ions with high mass accuracy. Heterocyclic ring fission (HRF), retro-Diels-Alder (RDA) fragmentation, quinone methide (QM) fragmentation and benzofuran formation (BFF) have been identified as the characteristic fragments. Total of 51 PAs were tentatively identified which include 28 dimers, 15 trimers and 8 other flavan-3-ols.