Background : Turmeric (Curcuma longa L.) and black pepper (Piper nigrum L.) have traditionally been used as Asian medicinal and culinary herb. Curcumin, a major compound of turmeric, has been known to have antitumor activity. However, curcumin is bioavailable because it is rapidly metabolized and released from the body. Therefore, the addition of adjuvants such as piperine, a potent inhibitor of drug metabolism, is one of the ways to increase the bioavailability of curcumin.
Methods and Results : The yields of turmeric and black pepper ethanolic extracts (TM and BP) are 18.2 and 8.2% (w/w), respectively. The EC50 values of A549 and NCI-H292 cells exposed to TM were 77.8 ㎍/㎖ and 92.0 ㎍/㎖, respectively. No significant cytotoxicity was observed up to the 400 ㎍/㎖ in the A549 and NCI-H292 exposed to BP. Based on the central composite design, the co-treatment of TM and BP enhanced the cytotoxicity of A549 and NCI-H292 cells. The optimal combination concentration (optimal EC50 value) of TM and BP calculated by the response surface methodology assay were 48.5 and 241.7 ㎍/㎖. The conbination index assay confirmed that the cytotoxic effect at optimal combinatino concentration was due to the synergistic effect.
Conclusion : We hypothesized that co-treatment of TM and BP enhanced cytotoxicity more than single treatment of TM against lung cancer cells, and cell death at this time may synergetic cytotoxicity effects associated with curcumin metabolism.