Curcumin, one of the polyphenols present in Turmeric, has a long track record of positive research relating to its anti-inflammatory, anti-cancer, and liver-protective effects. It is a mild and generally well-tolerated addition to the diet, and even concentrated extracts of the Turmeric rhizome (like New Chapter's TurmericForce) work well without having to take multiple daily tablespoons of the spice (see here for my articles on this spice).
Now, Japanese researchers have gone in and chemically modified curcumin, which is already an isolated constituent of Turmeric and contains none of its beneficial mucilage and fewer aromatic constituents, and given these modified chemicals to rats with colorectal cancer. The results: the new chemicals seem to work better.
My main comment on this research, other than the fact that it was performed on rats, is that it continues the misguided trend of taking botanical substances, refining them, and modifying them for an 'enhanced' effect in the human physiology. Historically, my favorite example of this trend is the opium -> morphine -> heroin chain, which has certainly done wonders for the human race. The problem with this approach is that we have no understanding of, and therefore no way to predict, the effects of long-term supplementation with substances our physiology hasn't ever seen. This is in contrast with unaltered, whole-plant preparations, which are not only familiar to our metabolic pathways, but probably created those pathways to begin with.
In the long run, many modified chemicals, while potent in the short term, leave the body with unwanted side-effects and often further weaken the system. I am fully in support of ongoing research into the chemistry and effects of plant constituents, but please, let's wait a little until applying them to humans in refined, or modified, forms.