Identification and anti-tumour activities of phenolic compounds isolated from defatted adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) seed meal

Abstract

In this work, four phenolic compounds, N1,N5-di-[(E)-p-coumaroyl]-spermidine (1), p-coumaric acid (2), ferulic acid (3), and rutin (4) were isolated from n-butanol fraction of acetone extract of defatted adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) seed meal. Compound 1 was identified from adlay for the first time. The structures of these compounds were characterised by ESI-MS, 1H NMR, 13C NMR and UV–vis techniques. These compounds were evaluated for their anti-tumour activities against HepG-2, MCF-7 and CaCo-2 cancer cell lines by MTT assay. Of all purified compounds, compound 1 possessed the highest anti-tumour activity than other compounds with IC50 values between 46.34 ± 3.99 and 92.69 ± 5.63 µg/ml. Furthermore, activation of the caspase cascade in HepG-2 cells for intrinsic pathways caused by compound 1 were observed using western blot analysis. The result also showed that the expression of caspase-3, caspase-9, cytochrome c and Bax protein increased and the protein level of Bcl-2 decreased.

Keywords

• Defatted adlay seed meal
• Phenolic compounds
• Anti-tumour activity
• N1,N5-di-[(E)-p-coumaroyl]-spermidine
• Western blot analysis