Vitamin C can kill drug-resistant TB bacteria: Study

Zee Media Bureau

New Delhi: In a breakthrough discovery, scientists have found that vitamin C can be used to effectively kill off the bacterium M. Tuberculosis. Scientists at the Albert Einstein College of Medicine of Yeshiva University chanced upon the finding during research into how TB bacteria become resistant to isoniazid, a first-line medication for TB. They observed that isoniazid-resistant strains were not producing a thiol compound called mycothiol. “We hypothesized that TB bacteria that can`t make mycothiol might contain more cysteine, an amino acid,” said Dr. William Jacobs, professor of microbiology & immunology and of genetics. “So, we predicted that if we added isoniazid and cysteine to isoniazid-sensitive M. tuberculosis in culture, the bacteria would develop resistance. Instead, we ended up killing off the culture- something totally unexpected.” The team suspected that cysteine was helping to kill TB bacteria by acting as a "reducing agent" that triggers the production of reactive oxygen species (sometimes called free radicals), which can damage DNA. "To test this hypothesis, we repeated the experiment using isoniazid and a different reducing agent- vitamin C," said Dr. Jacobs. "The combination of isoniazid and vitamin C sterilized the M. tuberculosis culture. We were then amazed to discover that vitamin C by itself not only sterilized the drug-susceptible TB, but also sterilized MDR-TB and XDR-TB strains," he explained. To justify testing vitamin C in a clinical trial, Dr. Jacobs needed to find the molecular mechanism by which vitamin C exerted its lethal effect. More research produced the answer: Vitamin C induced what is known as a Fenton reaction, causing iron to react with other molecules to create reactive oxygen species that kill the TB bacteria. "We don`t know whether vitamin C will work in humans, but we now have a rational basis for doing a clinical trial," said Dr. Jacobs. "It also helps that we know vitamin C is inexpensive, widely available and very safe to use. At the very least, this work shows us a new mechanism that we can exploit to attack TB," he added. (With ANI inputs)