Vitamin C Kills Drug-Resistant TB Bacteria

Vitamin C kills drug-resistant tuberculosis (TB) bacteria in laboratory culture, according to researchers at Albert Einstein College of Medicine of Yeshiva University.

The new finding suggests that adding vitamin C to the existing TB drugs helps in reducing the duration of TB therapy, also highlighting a new area of drug design.

TB occurs due to infection caused by the bacterium M tuberculosis. Data according to the World Health Organization reveals that in 2011, more than 8.7 million people were sick with TB, and nearly 1.4 million people died.

Researchers came across this finding while conducting research on how TB bacteria becomes resistant to the potent first-line TB drug 'isoniazid'.

"We hypothesized that TB bacteria that can't make mycothiol might contain more cysteine, an amino acid," said William Jacobs, Jr., Ph.D., professor of microbiology & immunology and of genetics at Einstein. "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 researchers believe that cysteine assisted in killing TB bacteria by playing the role of a reducing agent, which causes the production of reactive oxygen species that are capable of destroying DNA.

To test the hypothesis, the researchers conducted a repeated experiment with the help of isoniazid and another reducing agent: vitamin C. The mixture of isoniazid and vitamin C sterilized the M.tuberculosis culture. The researchers were surprised to see that vitamin C alone did not sterilize the drug-susceptible TB, but also sterilized MDR-TB and XDR-TB strains.

Vitamin C provoked the Fenton reaction: triggering iron to react with other molecules to produce reactive oxygen species that destroy 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.  

The study appears in the journal Nature.