Turmeric ethanolic extract possesses stronger inhibitory activities on colon tumour growth than curcumin – The importance of turmerones

Abstract

The active ingredient curcuminoid (including curcumin, demethoxycurcumin and bisdemethoxycurcumin) from the Asian medicinal and culinary herb turmeric possesses anti-tumour effects, but poor oral absorption in the intestine impedes its widespread clinical application. Our previous study showed that turmerones increased the accumulation of curcumin inside colonic cells. The present study demonstrates the enhanced anti-proliferative and anti-angiogenic activities of curcumin in the presence of turmerones in human colon cancer cells and endothelial cells, respectively. Furthermore, in HT29 tumour xenograft-bearing mice fed with curcumin alone or turmeric ethanolic extract (in which the concentration of curcumin was kept the same), the tumour burden of turmeric extract-fed mice was the lowest, suggesting turmeric extract provided better anti-tumour activities than the same amount of curcumin alone did. The superior anti-tumour effects of turmeric extract, which contains curcumin, turmerones and other constituents, were verified in tumour-bearing mice, indicating the potential use of turmeric for colorectal cancer adjuvant therapy.