Curcuminoids from the Vietnamese Curcuma longa: Phytochemical analysis and biological activities

A phytochemical investigation on the ethanolic (EtOH) extract of the Vietnamese Curcuma longa (C. longa) rhizomes has led to the isolation of four curcuminoids including curcumin (1), demethoxycurcumin (2), bisdemethoxycurcumin (3), and cyclocurcumin (4). The chemical structure of compounds 1-4 was elucidated by Nuclear magnetic resonance (NMR) and Mass spectrometry (MS) spectral data. Based on High-performance liquid chromatography (HPLC) quantitative analysis, the amounts of three major compounds 1-3 in the C. longa extract were calculated and reached 7.215±0.101, 3.927±0.031, and 2.255±0.049 mg/g, respectively. Curcuminoids 1-4 have induced IC50 values of 9.23-14.6 µg/ml in a 2,2-diphenyl-1- picrylhydrazyl (DPPH) radical scavenging assay as compared with that of the positive control resveratrol (IC50 11.5 µg/ ml). Compounds 1-4 with IC50 values ranging between 8.7-15.54 µg/ml were better than the positive control acarbose (IC50 169.14 µg/ml) in α-glucosidase inhibitory examination. In addition, the EtOH extract and compounds 1-4 were also responsible for inhibitions against enzyme acetylcholinesterase and four cancer cell lines including including epidermoid carcinoma (KB), hepatocellular carcinoma (HepG2), lung cancer (SK-LU-1), and breast cancer (MCF7).