Dereplication of a Dichloromethane Extract of Goniothalamus lanceolatus Leaves using UHPLC-ESI-ORBITRAP HRMS

Abstract

In our continuing search for bioactive compounds in Goniothalamus lanceolatus, we scrutinized the chemical constituents present in the leaves of this plant. As these leaves are traditionally used to repel mosquitoes, we were inspired to examine the plant for potential anti-dengue activity. Our preliminary screening showed that at a concentration of 50 µg/ml, the dichloromethane extract of these leaves was able to inhibit 90.9% of Dengue Virus Type-2 (DENV-2). Dose-dependent plaque assays gave an IC50 of 4.16 µg/ml with a selectivity index (SI) of 5.82. Thus, this extract was selected for in-depth phytochemical analysis. This paper reports an efficient chemical profiling of the G. lanceolatus leaf dichloromethane extract using high-resolution mass spectrometry (UHPLC-ESI-Orbitrap), via data-dependent MS/MS experiments. We used MZmine2 software version 2.50 (MZmine2) for data processing and peak deconvolution. The dereplication strategy began with the determination of molecular formula from accurate mass measurements (m/z). Data mining using MZmine2 followed by cross-search filters against the Dictionary of Natural Products (DNP) produced several hits consisting of styryl-lactones, alkaloids, and acetogenins. A further search of the molecular formula of isolated compounds from different parts of G. lanceolatus using an in-house library unambiguously identified seven compounds including goniolanceolatin A, goniolanceolatin E, (6S,7S,8S)-goniodiol, 1S,5S,7R,8S,3-exo,7-endo-(+)-8-epi-9-deoxygoniopypyrone, goniofupyrone B, parvistone D, and deoxygoniopypyrone B.