Global Challenges/Chemistry Solutions

Combating Disease: Leaves of carob tree, source of chocolate substitute, fight virulent food-poisoning bacteria

January 14, 2013

Leaves of carob tree
The leaves of the carob tree, source of
chocolate substitute, fight virulent
food-poisoning bacteria.

Credit: iStockphoto/Thinkstock


Leaves of the plant that yields carob — the substitute
for chocolate that some consider healthier than
chocolate — are a rich source of antibacterial
substances ideal for fighting the microbe responsible
for listeriosis, a serious form of food poisoning,
according to a report in ACS’ Journal of Agricultural
and Food Chemistry

Today’s solution is an antibacterial extract from the leaves of the carob tree (the source of a popular chocolate substitute) that could fight the microbe responsible for the serious form of food poisoning called listeriosis. The research appears in ACS’ Journal of Agricultural and Food Chemistry.

Nadhem Aissani, a graduate student at the University of Cagliari in Italy, led the research. Here’s his advisor, Pierluigi Caboni, Ph.D.:

“The increase in antibiotic-resistant bacteria has fostered a search for new natural substances to preserve food and control disease-causing microbes. In particular, we need new substances to combat Listeria monocytogenes, bacteria that have caused food poisoning outbreaks in a dozen states in the U.S., with three deaths so far this year.”

As Caboni states, Listeria infections are serious. In 2012, three people died in the U.S. from this type of food poisoning. Carob has attracted attention as a potential antibacterial substance, but until now, scientists had not tested it against Listeria. Carob may be best-known as a substitute for chocolate that does not contain caffeine or theobromine, which makes chocolate toxic to dogs.

Nadhem Aissani
Nadhem Aissani,
graduate student
University of Cagliari, Italy

In their tests, carob leaf extracts proved effective in inhibiting the growth of Listeria bacteria growing in laboratory cultures. Further, the study offers a possible explanation for the antibacterial action. Because of these promising results, they next plan to test carob extracts on Listeria growing in meat and fish samples.

Smart Chemists/Innovative Thinking

Smart chemists. Innovative thinking. That’s the key to solving global challenges of the 21st Century. Please check out more of our full-length podcasts on wide-ranging issues facing chemistry and science, such as promoting public health, developing new fuels and confronting climate change, at Today’s podcast was written by Sam Lemonick. I’m Katie Cottingham at the American Chemical Society in Washington.

Pierluigi Caboni, Ph.D.
Pierluigi Caboni, Ph.D.,
Professor of Chemistry,
University of Cagliari, Italy