Zhijun Liu | 4/26/2005 12:13:25 AM
A succulent plant grown in a remote, mountainous region of southwestern China, where it’s used as a tea and herbal remedy, has become the latest plant being studied for its medicinal properties by researchers at the LSU AgCenter and Pennington Biomedical Research Center in Baton Rouge.
Dr. Zhijun Liu in the LSU AgCenter’s School of Renewable Natural Resources and Dr. Jianping Ye at Pennington are investigating a plant called Sinocrassula indica, which they call SLH in verbal shorthand.
"Its use is localized – in no other part of the world," Liu said.
SLH is one of the plants from which the researchers hope to isolate compounds that address metabolic syndrome – a group of metabolic risk factors in one person. The underlying causes of this syndrome are overweight/obesity, physical inactivity and genetic factors.
The LSU AgCenter is a partner with the Pennington Biomedical Research Center in a nearly $8 million grant from the National Institutes of Health to establish a national center of excellence to study the effects of botanical products, or plant extracts, on human health and diseases. As the AgCenter’s representative, Liu’s research program is receiving $500,000 over five years.
The center’s mission is to evaluate conditions in humans that lead to development of obesity and Type 2 diabetes and to determine whether plant extracts can effectively treat these conditions.
The research team will study the effects of specific botanical compounds and their components and how they may influence molecular and cellular processes associated with metabolic syndrome.
People with the metabolic syndrome are at increased risk of coronary heart disease, other related diseases such as stroke and peripheral vascular disease and type 2 diabetes.
Metabolic syndrome has become increasingly common in the United States, where the American Heart Association estimates about 47 million U.S. adults have it. The syndrome is closely associated with a generalized metabolic disorder called insulin resistance – in which the body can’t use insulin efficiently. That is why the metabolic syndrome also is called the insulin resistance syndrome. Some people are genetically predisposed to insulin resistance, and most people with insulin resistance have central obesity, according to experts.
Ye, who has been studying medicinal plants for several years, used an SLH extract Liu prepared. When he tested it on mice models, he observed weight loss.
"He also saw insulin-like activity," Liu said. "The compounds act like insulin and reduce blood sugar levels. That was very exciting, because we showed response in mice."
Liu took the extract to his laboratory and began refining it, using what he calls a fractionation process. First, he developed a crude extract that separated solids and fibers, and then further fractionation narrowed down the compounds in each fraction to exclude inactive components.
Using this preliminary data, the researchers applied for an NIH grant, which was awarded April 1.
Now, the scientists are testing the various fractions to evaluate their biomedical activity. They’re hoping to isolate the active ingredients and work toward standardization.
"There may be more than one compound," Liu said of the search for responsible ingredients that affect insulin-resistant symptoms associated with type 2 diabetes.
"The project will support identification of active principals of SLH and lead to future medical applications," Liu said.
The current five-year study will identify compounds and complete pre-clinical studies, Liu said. That may pave the way for eventual clinical studies.
"When we find a compound or combination of compounds, we’ll look at similar plants to see if any others have it," he said.
The LSU AgCenter researcher said the resulting compound or compounds may be effective in treatment of obesity and diabetes.
"This is bioassay-guided fractionation and isolation of active principals – compounds," he said. "We want to identify bioactive principals from natural sources."
Liu emphasized that the compounds aren’t synthetic – they exist in nature.
Ye identified the SLH plant from among several commercial products he collected in nutrient or Chinese herbal medicine stores in San Francisco’s Chinatown.
Natural products from such plants, however, are difficult to use as medicines because of inconsistencies in how they’re produced, Liu said.
"Botanical extracts are either not standardized or standardized without reference to the active ingredients," he said. "This has been a key flaw in the quality control of botanical extracts."
Manufacturing without knowing what is responsible for therapeutic activities risks the loss of the key ingredients in the process and results in inconsistent clinical effects, Liu explained.
"To be effective, the active ingredients must be concentrated enough to achieve a therapeutic effect," the researcher said.
"This work adds new dimensions to LSU AgCenter research," Liu said. "We’re taking the focus on foods and herbs and contributing to collaboration to do our part and fully use our plant resources. It’s another dimension – beyond nutrition."