Luteolin stars in study of healthful plant compounds

July 9, 2010

Natural compounds in plants may protect us against unwanted inflammation. However, human nutrition researchers agree that many questions remain about exactly how these compounds, known as phytochemicals, do that. Studies led by USDA Agricultural Research Service (ARS) Molecular Biologist Daniel H. Hwang are providing some of the missing details.

Certain kinds of inflammation can increase risk of cancer and of some other disorders, including heart disease and insulin resistance, according to Hwang. Some of Hwang’s on-going studies build upon earlier research in which he and colleagues teased out precise details of how six natural compounds in plants—luteolin, quercetin, chrysin, eriodicytol, hesperetin, and naringenin—apparently act as anti-inflammatory agents.

Hwang’s team showed, for the first time, that all six plant compounds target an enzyme known as “TBK1.” Each compound inhibits, to a greater or lesser extent, TBK1’s ability to activate a specific biochemical signal. If unimpeded, the signal would lead to formation of gene products known to trigger inflammation.

Of the six compounds, luteolin was the most effective inhibitor of TBK1. Luteolin is already known to have anti-inflammatory properties. However, Hwang and his colleagues were the first to provide this new, mechanistic explanation of how luteolin exerts its anti-inflammatory effects.

The approaches that the researchers developed to uncover these compounds’ effects can be used by scientists elsewhere to identify additional anti-inflammatory compounds present in fruits and vegetables.

Agriculture Research magazine article