Comprehensive characterisation of polyphenols in leaves and stems of three anti‐dengue virus type‐2 active Brazilian Faramea species (Rubiaceae) by HPLC‐DAD‐ESI‐MS/MS

Abstract

A comprehensive characterization of polyphenols by online high-performance liquid chromatography with diode array detection coupled to electrospray ionization and triple quadrupole mass spectrometry (HPLC-DAD-ESI-CID-MS/MS) of leaf and stem MeOH extracts from the Brazilian species Faramea bahiensis, F. hyacinthina and F. truncata (Rubiaceae) was performed. Structures have been assigned on the basis of the complementary information obtained from retention time, UV-visible spectra, scan mode MS spectra, and fragmentation patterns in product ion scan MS/MS spectra in different collision energies. The use of the mechanisms and fragmentation patterns established with phenolic standards led to successfully characterize thirty-one phenolic compounds. Flavanone O-mono- and diglycosides, flavonol O-mono- and diglycosides, flavone O-mono-, di- and tri-glycosides and flavone C-mono- and diglycosides were identified. Scopoletin, caffeic acid and syringic acid were also detected. The leaves of F. bahiensis showed to be the richest in phenolic compounds while the leaves of the other two species presented lower diversity and quantity, especially F. truncata. The stems revealed that in general have lower occurrence of these compounds than the leaves. The assay for in vitro cytotoxity and DENV serotype 2 (DENV-2) infected hepatocarcinoma cell lineage (HepG2) of the stem extracts showed that F. hyacinthina and F. bahiensis presented a similar anti-DENV-2 activity to those previously described to their leaves. However, a loss of cytoprotective activity of F. bahiensis and a higher cytotoxicity of F. truncata relative to those previously described to their leaves was observed.