Process development for the enrichment of curcuminoids in turmeric spent oleoresin and its inhibitory potential against LDL oxidation and angiotensin-converting enzyme.

Turmeric (Curcuma longa) contains biologically active colouring constituents, curcuminoids, which are isolated from the turmeric rhizome by solvent extraction. The mother liquor left after the separation of curcuminoids is known as turmeric spent oleoresin (SOT). The present study developed a method for the enrichment of curcuminoids in SOT. By using this method, curcuminoids in the SOT (8.4%) were doubled (17.5%). Presence of curcuminoids in enriched fraction was confirmed by high performance liquid chromatography (HPLC) and liquid chromatography coupled with mass spectroscopy analysis. Further studies on this fraction showed that it can effectively inhibit angiotensin-converting enzyme and low-density lipoprotein oxidation with IC(50) values of 19.45 µg/ml and 30.52 µg/ml, respectively. The results showed that curcuminoids enriched fraction (CEF) can reduce the risk of hypertension and cardiovascular diseases. In addition to this fraction, a turmerone-rich hexane fraction was also separated from the spent oleoresin.