HPLC/ESI-MS and NMR Analysis of Chemical Constitutes in Bioactive Extract from the Root Nodule of Vaccinium emarginatum

Abstract

Vaccinium emarginatum Hayata is a medicinal plant that has been historically used in ethnopharmacy to treat diseases in Taiwan. The objective of this study is to evaluate the anti-cancer and anti-bacterial constitutes from the root nodule extract of V. emarginatum. The chemical composition of V. emarginatum fractions was analyzed by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) and the chemical constitutes were isolated and structurally identified by nuclear magnetic resonance (NMR) spectroscopy. Bioassay-guided chromatography showed that the ethyl acetate (EA) fraction was bioactive on the hepatocellular carcinoma (HepG2). By LC-ESI-MS/MS analysis, twenty peaks of EA fraction were partially identified and the phytochemical investigation of the fractions led to the isolation and identification of protocatuchuic acid (1), epicatechin (2), catechin (3), procyanidin B3 (4), procyanidin A1 (5), hyperin (6), isoquercetin (7), quercetin (8), lupeol (9), beta-amyrin (10), and alpha-amyrin (11). Both procyanidin B3 and A1 exhibited anti-proliferative activity against HepG2 and gastric adenocarcinoma (AGS) cells at IC50 values between 38.4 and 41.1 μM and 79.4 and 83.8 μM, respectively. In addition, isoquercetin displayed the strongest anti-proliferative activity against the HepG2, lung carcinoma (A549), and AGS cell at 18.7, 24.6 and 68.5 μM, respectively. Among the triterpenoids, only lupeol showed the inhibitory activity against all tested tumor cell lines at IC50 values between 72.9 and 146.8 μM. Furthermore, procyanidins B3, A1 and isoquercetin displayed moderate anti-bacterial activity against Staphylococcus aureus. In conclusion, this study provides background information on the exploitation of V. emarginatum as a potential natural anti-cancer and anti-bacterial agent in pharmaceutical research.