One from the vine

Kudzu is a vine weed that has overgrown almost 10 million acres of land in the southeastern United States. However, it could one day sprout into a dietary supplement to help reduce metabolic syndrome in millions of people. Mass spectrometry and UV spectroscopy have now been used to identify and quantify the putatively active isoflavones in extracts of the vine by US scientists.

A well-known nuisance in the southeastern USA could soon make a nutrient of itself. Researchers in Alabama and Iowa have published preliminary evidence that root extracts from kudzu (Pueraria lobata) could be a useful dietary supplement for combating the high-risk condition known as metabolic syndrome, which affects almost 50 million people in the US alone. The team published details in the current issue of the Journal of Agricultural and Food Chemistry.

Metabolic syndrome, also known as insulin resistance, is actually a combination of medical problems associated with an increased risk of developing cardiovascular disease and diabetes. Obesity, a sedentary lifestyle, age, and genetics are considered to be the major risk factors although the precise causative mechanisms are not yet fully understood.

Nevertheless, Michael Wyss of the Department of Cell Biology University of Alabama at Birmingham and colleagues Ning Peng, Jeevan Prasain, Yanying Dai, Ray Moore, Alireza Arabshahi, and Stephen Barnes, working with Scott Carlson of the Department of Biology, at Luther College, in Decorah, Iowa, note in their paper that people with metabolic syndrome have obesity, high blood pressure, high blood cholesterol, and problems with their body's ability to use insulin. This in turn gives rise to an increased risk to sufferers of having a heart attack, a stroke, or developing other associated diseases.

Researchers have spent many years looking for natural products that might help treat metabolic syndrome or that may be used as leads in the drug-discovery process. People in China and Japan have used kudzu supplements as a health food for many years, so Wyss and colleagues decided to evaluate kudzu root extracts, which are known to contain health-giving isoflavones, as one such putative treatment.

The researchers were able to demonstrate that kudzu root extract had a positive effect on laboratory rodents used as a model of human metabolic syndrome. Within two months of adding the extract to the animals' diet they were found to have lower cholesterol, reduced blood pressure, and lower blood sugar (plasma glucose), as well as insulin levels much closer to normal compared with the control group not given the extract.

In order to determine the isoflavone content of the kudzu root extract, team member Jeevan Prasain analysed a dietary supplement powder by extracting with acetonitrile in water and using beta-naphthoflavone as an internal standard for high-performance liquid chromatography (HPLC) and recording the UV-vis spectra at 225 to 400 nm.

They also used liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine the same compounds in plasma samples from the animals. Puerarin, daidzin, and daidzein are the major isoflavones they found in the kudzu root extracts.

"Strategies currently recommended for decreasing hypertension and, thereby, reducing cardiovascular disease and stroke depend primarily on pharmacological treatments but also include increasing daily activity and dietary interventions," the researchers explain. They point out that physiologically active foods have become the focus of much recent research and that polyphenols are commonly regarded as beneficial to health.

The team's findings with a rodent model of metabolic syndrome suggest that such compounds found in kudzu root might offer a non-pharmacological complement to conventional medical approaches to treating type 2 diabetes and hypertension. "Both of these conditions were reduced in the rodent model by supplementation," Wyss told SpectroscopyNOW, "As a complement to pharmaceutical treatment, botanicals like kudzu root could reduce effective dosages of the pharmaceutical, thereby reducing potential toxicity."

Kudzu root "may provide a dietary supplement that significantly decreases the risk and severity of stroke and cardiovascular disease in at-risk individuals," the researchers add. Given that kudzu is widespread and unwanted, it could provide an inexpensive and convenient intervention.