How Plants Protect Us From Disease

At the Agricultural Research Service (ARS) Western Human Nutrition Research Center in Davis, Calif., research molecular biologist Daniel H. Hwang conducts studies to solve the complex puzzle of precisely how phytochemicals fight inflammation. His investigations with cells cultured in his laboratory have uncovered probable modes of action used by phytochemicals from red wine, green tea, garlic, curcumin and cinnamon.

Hwang's team has found, for example, that phytochemicals can interfere with the normal flow of certain chemical signals or messages sent to and from cells involved in chronic inflammation. The messages these cells send are in the form of proteins. In particular, his group is closely examining proteins known as TLRs (short for "Toll-Like Receptors") and NODs (an abbreviation for the tongue-twisting "nucleotide binding oligomerization domain containing proteins").

Their experiments show that certain phytochemicals can interfere with messages that, if unimpeded, could travel from TLRs and NODs, reaching and activating genes that can trigger an inflammatory response.

The studies suggest that different phytochemicals have different ways of interfering with these messages. For example, curcumin can undermine certain TLRs when a specific part of curcumin's chemical structure reacts with what are known as "sulfhydryl groups" in TLRs.

But resveratrol, found in red grapes, has a different set of targets. Hwang's experiments suggest that resveratrol interferes with molecules called "TBK1" and "RIP1." If unimpeded, these molecules would help convey signals to and from TLRs.