Vitamin C Kills Drug-Resistant TB Bacteria in Lab

Lisa Franchi May 24, 2013

Whilst studying how TB bacteria become resistant to a potent first-line drug for TB, scientists at Albert Einstein College of Medicine of Yeshiva University have found that vitamin C kills drug-resistant tuberculosis (TB) bacteria.

Tuberculosis is a lung infection caused by a bacterium called M. tuberculosis. According to the World Health Organisation, TB has affected some 8.7 million people and killed some 1.4 million. Whilst treatments are widely available, around 650,000 people worldwide have developed multi-drug resistant, making TB hard to cure. The WHO added that more than 95 percent of TB-related deaths are due to extensive resistance to potent drugs.

The current study which appears in the journal Nature Communications suggests that vitamin C added to existing anti-TB drugs could shorten the treatment period. Moreover, it can be used in developing a new drug design targeting patients that are resistant to traditional drugs.

Unexpected Findings

Dr William Jacobs, Jr., professor of microbiology & immunology and of genetics at Einstein and his colleagues observed that TB bacteria that are resistant to isoniazid, a drug used to treat TB, were deficient in a molecule called mycothiol. "We hypothesized that TB bacteria that can’t make mycothiol might contain more cysteine, an amino acid," said Dr. Jacobs. "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 was helping kill the bacteria by acting as a ‘reducing agent’ that triggers the production of free radicals that cause DNA damage. To test whether their theory was correct, Dr Jacobs and his colleagues repeated the experiment, this time using vitamin C as the reducing agent. The team discovered that vitamin C did not only sterilise the drug-resistant bacteria but also MDR-TB and XDR-TB strains.

They found that vitamin C induced a process called Fenton reaction, triggering iron to react with other molecules that create reactive oxygen species that kill TB bacteria.

"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." Dr Jacobs said they don’t know whether vitamin C will work in humans but he argued that they have a rational basis for conducting a clinical trial.

The surprise discovery may open up the possibility of tackling an increasingly hard-to-treat infection that affects millions of people worldwide.

Source of this article:

Mycobacterium tuberculosis is extraordinarily sensitive to killing by a vitamin C-induced Fenton reaction