How snake "urine" can help treat gout and kidney stones

Scientists suggest that snakes and lizards may help find new ways to prevent painful kidney stones and gout in humans - all thanks to their unusual way of excreting waste. HealthDay reports that.

Reptiles have a different excretory system than humans: they don't just excrete liquid urine, but crystallise waste to save water. An international team of researchers studied the solid "urine" of more than 20 reptile species and found that all samples contained microscopic spherical structures made of uric acid. The results are published in the Journal of the American Chemical Society.

"This study was inspired by a desire to understand how reptiles are able to safely excrete such substances, in the hope that this will prompt new approaches to preventing and treating disease," explains co-author of the paper, chemistry professor Jennifer Swift of Georgetown University.

In humans, excess nitrogen is excreted in the urine as urea, uric acid and ammonia. Reptiles, on the other hand, convert some of the same substances into solid crystals - called "urates" - which are then excreted through the cloaca. For them, crystal formation is a way of survival, but in humans a similar process becomes a problem: too high levels of uric acid lead to the formation of crystals in the joints (gout) and in the urinary tract (kidney stones).

Swift's team used powerful microscopes to study how these crystals are organised in different species. In pythons and Madagascar tree boa constrictors, for example, urates are made up of textured spheres no larger than 0.0004 inches. These microspheres, in turn, are built from even smaller nanocrystals of water and uric acid. Scientists have shown that uric acid in reptiles helps convert toxic ammonia into a safer solid form.

The researchers suggest that in humans, uric acid may play a similar protective role, but further work is needed to confirm this hypothesis. In any case, the chemistry behind crystallised reptile waste could suggest new approaches to treating diseases associated with uric acid accumulation.

The technique used in the study - analysing uric acid nanocrystals (uric acid monohydrate) - opens the way to a better understanding of how the body manages nitrogen and salts. In the long term, this could lead to the development of drugs or strategies that do not just reduce uric acid levels, but change its form and behaviour in the body, reducing the risk of gout and stone formation, according to the authors of the paper.