US researchers have developed a synthetic form of good cholesterol known as HDL they hope will be able to keep levels of bad cholesterol in check.

The compound, which has a tiny core of gold, is manufactured using nanotechnology, and its developers think it has the potential to rid the body of excess bad cholesterol.

"The idea is you take this and effectively just urinate it out," said Chad Mirkin of Northwestern University in Chicago, whose study was published on Monday in the Journal of the American Chemical Society.

Mirkin, director of Northwestern's International Institute for Nanotechnology, said the molecule mirrors the size and structure of high-density lipoprotein, or HDL.

It comprises a carefully sized gold particle swathed in fat molecules known as lipids and capped off with a protein layer. It is designed to attract and trap low-density lipoprotein, or LDL, the bad kind of cholesterol that can build up in arteries and cause heart attacks and strokes.

Powerful drugs known as statins can help lower LDL levels, but they do little to raise levels of protective HDL cholesterol.

"The hope is this will be a material that doesn't have side effects, that allows you to do what the statins don't do. That is raise the HDL level, which might be able reverse a lot of the damage and plaques that are already there," Mirkin said.

Current drugs that raise natural levels of HDL, such as niacin, cause unpleasant side effects such as flushing. And while many drug companies are working to develop better HDL-raising drugs, few have succeeded.

"HDL is a natural nanoparticle, and we've successfully mimicked it," Mirkin said in a statement.

Mirkin said gold is an ideal scaffolding material because its shape can be easily tailored, and it is non-toxic, making it a good drug candidate.

"Gold is already used in therapies for arthritis and as contrast agent in imaging," Mirkin said. "From an FDA approval standpoint, we think the bar will be a lot lower than with other materials," he said, referring to the US Food and Drug Administration.

Mirkin is testing the synthetic HDL molecules in animals. "Will they bind to cholesterol and effectively lower cholesterol, and will they reverse the damage of plaques? That would be absolutely spectacular," he said.

Analysts believe the market potential for HDL-raising drugs is well over $10 billion.

Current HDL-raising drugs include Abbott Laboratories Inc's Niaspan, which also lowers a type of blood fat called triglycerides. In Europe, Merck & Co markets a drug called Tredaptive that combines niacin with an anti-flushing agent. The drug was rejected by US health regulators.

Merck is already well into development of an HDL-raising drug called anacetrapib and plans to start late-stage trials in humans this year.

The drug, also called MK-859, has a similar mechanism of action to a failed compound by Pfizer Inc called torcetrapib that was linked with deaths. So far, Merck has not seen any safety problems in mid-stage trials.

Mirkin, who has founded a number of nanotechnology start-ups including Nanosphere Inc, said the university plans to license the technology. -Reuters