One-Step Isolation of Monoterpene Indole Alkaloids from Psychotria leiocarpa Leaves and Their Antiviral Activity on Dengue Virus Type-2

摘要

The leaf MeOH extract of Psychotria leiocarpa (Rubiaceae) showed in vitro non-cytotoxic and anti-dengue virus serotype 2 (DENV2) activity in human hepatocarcinoma cell lineage (HepG2). A one-step and cost-effective reversed-phase solid-phase extraction method based on high-performance liquid chromatography (HPLC) parameters allowed the isolation, directly from this bioactive extract, of the monoterpene indole alkaloids: N -glucopyranosyl vincosamide ( 1 ), vincosamide ( 2 ) and strictosidinic acid ( 3 ). The chemical structures were characterized based on 1D and 2D nuclear magnetic resonance (NMR), UV and high-resolution mass spectra (HRMS). The methodology has also allowed yielding a polyphenolic-rich fraction that was analyzed by high-performance liquid chromatography coupled to diode array detection and electrospray ionization tandem mass spectrometry (HPLC-DAD-ESI-MS/MS) revealing two flavonol triglycosides ( 4 , 5 ) and three caffeoylquinic acid isomers ( 6 - 8 ). Compound 3 is reported for the first time in P. leiocarpa and all the phenolic compounds ( 4-8 ) are described for the first time in the genus Psychotria . Compounds 1 - 3 showed to be non-cytotoxic and anti-dengue active towards DENV2, highlighting vincosamide ( 2 ).