Tobacco field bacteria offers hope for buzz-kill smoking therapy

Subterranean 'baccy microbe guzzles down nicotine 'like Pac-Man'

Help may soon be at hand for those who have tried and failed to quit smoking, thanks to a bacterium that guzzles down nicotine.

Chemistry boffins reckon the organism may hold the key to a future anti-smoking therapy.

An enzyme from the Pseudomonas putida bacterium – originally isolated from soil in a tobacco field – consumes nicotine as its sole source of carbon and nitrogen. Research from not-for-profit The Scripps Research Institute (TSRI) shows that this NicA2 enzyme can be recreated in the lab while retaining its potency, thus making it a potential candidate for drug development.

The enzyme therapy would be used to seek out and destroy nicotine before it reaches the brain, depriving a smoker of the buzz from nicotine that can trigger a relapse into smoking.

“Our research is in the early phase of the drug development process, but the study tells us the enzyme has the right properties to eventually become a successful therapeutic,” said Kim Janda, a professor of chemistry and member of the Skaggs Institute for Chemical Biology at TSRI, in a statement.

Current smoking cessation aids fail in 80-90 per cent of cases. A drug based on the tobacco-burning bacterial enzyme could reduce the attraction of cigarettes, which might therefore be more effective than nicotine substitute therapies, such as patches and the like.

Early tests of the enzyme therapy, which have not as yet even progressed towards testing on live animals, have reportedly been encouraging.

The researchers first combined blood serum from mice with a dose of nicotine equivalent to one cigarette. When they added the enzyme, the nicotine's half-life dropped from two to three hours to just 9 to 15 minutes. A higher dose of the enzyme – and a few chemical modifications – could reduce the half-life of nicotine even further and keep it from ever reaching the brain, according to Janda and his team.

The enzyme stayed stable in the lab for more than three weeks at 98 degrees Fahrenheit. Even more importantly, the researchers detected no toxic metabolites produced when the enzyme degraded nicotine. The next step is to alter the enzyme's bacterial make-up, which will help mitigate potential immune liabilities, while maximising its therapeutic potential.

"Hopefully, we can improve its serum stability with our future studies, so that a single injection may last up to a month," according to Song Xue, a TSRI graduate student and first author of a new study on the putative therapy.

For more than 30 years, Janda and his colleagues have struggled to create a nicotine reward-suppressing biochemical in the lab. Now they have run across a potential enzyme in nature. "The bacterium is like a little Pac-Man," according to Janda. "It goes along and eats nicotine."

More early findings from the ongoing research were published in the Journal of the American Chemical Society this week. ®

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