Wearing copper bracelets is an age-old folk remedy for rheumatoid arthritis. Now scientists too think that copper could help ease the painful symptoms of the disease.
"Jackson and his colleagues have synthesised an organic cage ligand that binds copper and improves its absorption and retention in the body."
In rheumatoid arthritis the body's own immune system attacks and destroys its joints, causing painful inflammation. This can be relieved with anti-inflammatory drugs. Graham Jackson from the University of Cape Town, South Africa, has suggested that copper has anti-inflammatory properties and can be used to treat the condition. With this in mind, Jackson and his colleagues have synthesised an organic cage ligand that binds copper and improves its absorption and retention in the body.
'We believe that the body naturally releases stored copper in response to inflammation,' said Jackson. 'In previous studies, we and others have shown that administering copper does have beneficial effects,' he said.
The designed ligand had to be stable in the body, but not so much that it would just be excreted. It also had to be lipophilic (fat-loving) enough to be absorbed through the skin; in earlier studies the copper was injected but this time the team wanted to develop a cream that could be self-applied in smaller doses as required.
Copper complexes are potential anti-inflammatory drugs
The group achieved this by incorporating a hydrocarbon cage into a diaminodiamide ligand, a strong chelator of copper. The large lipophilic nature of the cage means that the metal complex can cross the fatty cell membranes and dermal absorption studies showed that the complex was absorbed.
The team also carried out bio-distribution studies, showing that the copper complexes survive in vivo. According to the researchers, the rigid cage may help increase the stability of the metal complex by forcing the ligand into the ideal conformation for complexation.
Jackson expects that the future will involve a different approach to metals in medicine. 'We will become more aware of the body's own natural defence mechanisms,' he said, 'and try and supplement deficiencies, which may be quite subtle, rather than use metal-containing drugs directly.'