Novel LC-MS/MS approaches for metabolite identification of natural compounds, such as curcumin and analogues, with anticancer activity

Curcumin (diferuloylmethane) a major component of the Curcuma species, used as a colouring and flavouring agent in foods, is a natural product well known for its antioxidative and anti-inflammatory properties as well as its anticancer potential [1]. It is well established that curcumin is rapidly and extensively metabolized. However it is crucial to understand its metabolism for the design of more stable/potent analogues. In this study we present a set of novel approaches for the identification of curcumin's metabolites following incubation with mouse and human liver microsomes, using a hybrid triple quadrupole linear ion trap mass spectrometer coupled with an HPLC system. Using the system's Information-Dependent Acquisition (IDA) feature allowed us to perform two or more scan modes in the same chromatographic run and in addition selective modes such as MS/MS/MS, enabled us to identify with confidence previously reported metabolites as well as newly identified ones, such as bisglucuronide and O-demethylated derivatives. The information acquired in this study lead to the proposal of a metabolic scheme for curcumin [2]. The same methodology has also been applied to curcumin's analogues with more promising anticancer activity and the results show that such analogues are metabolically significantly more stable than curcumin [3]. Finally, similar approaches have been extended to include other bioactive natural products that potentially play a role in the treatment of cancer, such as indirubin analogues.

References: 1. Sharma. et al. (2005) European Journal of Cancer 41:1955–68.

2. Tamvakopoulos, C. et al. (2007) Eur. J Drug Metab Pharmacokinet 32:51–57.

3. Tamvakopoulos, C. et al. (2007) Clin. Cancer Res. 13:1269–77.