Comparison of Bioactivities and Composition of Curcumin-free Turmeric (curcuma Longa L.) Oils from Different Sources

Composition, antioxidant capacities and cell inhibition properties of curcuminfree turmeric (Curcuma longa L.) oils from different sources were evaluated by chromatographic method, two different in vitro antioxidative activity assays (DPPH* free radical scavenging assay and reducing power assay) and two different cancer cell lines (Caco-2 and MCF-7). Turmeric oil A (TOA) contains zingiberene, turmerone, and arturmerone, while turmeric oil B (TOB) contains 1-phellandrene and α-terpinolene as the major compounds. The antioxidant tests showed that both turmeric oils possessed strong free radical scavenging activities in the DPPH* free radical scavenging assay and high reducing powers in the reducing power assay compared with standard antioxidants such as BHT and commercial rosemary oil (RO). The free radical scavenging effect of 20 μL/mL TOA is comparable to that of 70 μL/mL TOB, comparable to that of 10 mM BHT and better than that of 100 μL/mL RO (p<0.0001). The order of reducing powers is: 100 μL/mL TOA > 100 μL/mL TOB > 10 mM BHT > 100 μL/mL RO (p<0.0001). Among the complex constituents in the crude TOA, ar-turmerone, turmerone, curlone and αterpineol were isolated and found with strong antioxidant activities. The anticancer activity results showed that both turmeric oils possessed high inhibitive capacity against cancer cell lines (ie. Caco-2 and MCF-7) at 20 μL/mL.