Bioassay-guided isolation of cytotoxic constituents from the flowers of Aquilaria sinensis

Abstract

Bioassay-guided fractionation of the EtOH extract from the flowers of Aquilaria sinensis (Lour.) Spreng. (Thymelaeaceae) led to the isolation of a new cucurbitane-type triterpenoid, aquilarolide A (1), along with five known compounds (2–6). The structure of 1 was elucidated by extensive 1D and 2D nuclear magnetic resonance (NMR) experiments and mass spectrometry (MS) data and theoretical calculations of its electronic circular dichroism (ECD) spectra. Aquilarolide A, cucurbitacin E (3), cucurbitacin B (4), and 7-hydroxy-6-methoxy-2-[2-(4-methoxyphenyl)ethyl]-4H-1-benzopyran-4-one (6) showed significant cytotoxicity against human lung adenocarcinoma SPC-A-1, human lung squamous cell carcinoma NCI-H520, human lung adenocarcinoma A549, and paclitaxel-resistant A549 (A549/Taxol) cell lines. All four active compounds, with IC50 values ranging from 0.002 to 0.91 μM, had better inhibitory activities against A549/Taxol cells than paclitaxel (IC50 = 1.80 μM). Among them, cucurbitacin E (IC50 = 0.002 μM) is the most active. Further studies are needed to evaluate their in vivo antitumor activities and to clarify their mechanisms. Graphical Abstract

Phytochemistry and Cytotoxic Activity of Aquilaria crassna Pericarp on MDA-MB-468 Cell Lines

“…Cucurbitacin triterpenoids found in the fruits and flowers of A. sinensis have been identified as the main constituents contributing to the cytotoxic activities against different cancer cell lines. − Recent studies have shown that the extract of A. crassna’s agarwood induces apoptosis and inhibits cancer angiogenesis in breast cancer models, specifically MDA-MB-231 and MCF-7 cells .…”