Hamburg -- Tests in laboratory animals have resulted in a major breakthrough in Alzheimer's research, though the German scientists involved in the tests warn that a cure is still years off.

The scientists at Germany's Max Planck Institute synthesized a compound that targets a key biological pathway essential to the development of the disease.

In tests on mouse and fruit fly animal models, the molecule reduced changes in the brain associated with Alzheimer's by more than 50 percent.

Although the work is at an early stage, the German researchers hope it will pave the way for pioneering and more effective Alzheimer's treatments.

The disease is the most common form of dementia, causing a progressive loss of memory and mental faculties, which can be devastating for the patients concerned and those around them.

A range of drugs is available to alleviate the symptoms of Alzheimer's, but the medications do not halt the condition and can have serious side effects.

One of the hallmarks of Alzheimer's is the formation of amyloid protein deposits or plaques that eventually kill off brain cells. Their main component is the beta-amyloid peptide, a protein building block.

The new compound targets an enzyme, beta-secretase, involved in the production of beta-amyloid peptide.

Allowed to float freely inside the affected cells, it only had a limited ability to inhibit the enzyme. The breakthrough came when scientists used another molecule to anchor the inhibitor to specific sites where the enzyme is active.

These are "rafts," tiny compartments built into the fatty cell membrane that play a central role in complex biological processes, including immune responses.

Once the therapeutic compound was anchored it became far more potent. Microscopic concentrations were enough to block the appearance of beta-amyloid peptide completely.

In the animal experiments, beta-amyloid formation was halved in the space of four hours. The free inhibitor, on the other hand, proved ineffective.

Professor Dr. Kai Simons, from the Max Planck Institute of Molecular Cell Biology and Genetics, who led the research reported in the journal Science, said: "Our data provide proof-of-principle of a new approach for directing small molecule inhibitors to disease- causing raft targets in cellular membranes.

"In this instance, by directing inhibition to the sub-compartment where the enzyme is active, the approach has the potential to be used in the design of more effective beta-secretase inhibitors for the treatment of Alzheimer's disease."

He said the same strategy might prove effective against other conditions in which rafts play a role, including allergic disorders and infectious diseases.

Professor Simons is co-founder of JADO Technologies, a German biotech company dedicated to investigating new raft treatments.

Chief Executive Officer Charl van Zyle said the company was building a pipeline of therapeutic compounds.

"This data support our belief that the raft approach...has potential in a diverse number of indications," he said.

In infectious disease, rafts are hijacked by harmful invaders to gain entry to cells.

DPA