Monday, 22 January 2018

The Persian Shallot and Multidrug-Resistant Tuberculosis

The Persian shallot is a plant that is greatly appreciated for its culinary and ornamental benefits. It may also have important medical uses. It's classified in the same genus as the onion and has the scientific name Allium stipitatum. The plant is native to Asia and grows from a bulb with a strong flavour. Researchers have discovered that the plant contains chemicals that may be useful in fighting tuberculosis, or TB.

Allium stipitatum by KENPEI, CC BY-SA 3.0 License

The Persian Shallot

The Persian shallot has a basal group of strap-shaped leaves and a tall flowering stalk that extends far above the ground. The pretty star-shaped flowers are white to lilac in colour. They're borne in an umbel, which is a structure consisting of multiple flowers emerging from a common point. Although an individual flower of a shallot is small, the umbel as a whole is large and attractive. The plant is sold by nurseries for ornamental use. The bulb is a popular food in Iran.


Tuberculosis is an infectious disease caused by a bacterium named Mycobacterium tuberculosis. The bacterium is best known for its effects on the lungs, but it may also affect other parts of the body. The patient experiences a cough and releases sputum, which is a mixture of mucus from the lungs and saliva from the mouth. The sputum may be bloody. There may be additional symptoms, including chest pain, fever, fatigue, and unexpected weight loss.

TB may be serious. In some cases it's a latent (hidden and dormant) condition due to the inactivity of the bacteria in the body. In other cases the bacteria become active and the person develops symptoms of the disease.

Tuberculosis is generally treated by a mixture of antibiotics. These often need to be taken for months in order to be effective. A worrying trend is the development of antibiotic resistance in M. tuberculosis. Antibiotics that once killed bacteria quickly now either take longer to work or are ineffective. This is not only unfortunate for the patient but also a problem for the community because tuberculosis is infectious. It's spread by droplets of liquid released during coughing and sneezing. Antibiotic resistance is becoming a serious problem in many other bacterial infections besides TB.

As many as 50 million people worldwide are currently infected with multi-drug resistant TB, which means it's vital to develop new antibacterials. Quote from Dr. Sanjib Bhakta of the University of London

Possible symptoms of tuberculosis by Mikael Haggstrom, public domain image
It should be noted that the symptoms mentioned above are not unique to tuberculosis and that a patient may not experience all of them. Anyone who suspects that they have the disease or who has unexplained symptoms should visit a doctor.

Potentially Useful Compounds in the Persian Shallot

We need to find new ways to fight bacteria, including the species that causes tuberculosis. The Persian shallot may be very useful in improving the action of some present antibiotics used to treat TB.

A team of researchers from British universities recently studied chemicals found in an extract from Persian shallot bulbs. They made synthetic copies of some of the chemicals. When used with antibiotics, four of the synthetic chemicals increased the effectiveness of the antibiotics in killing multidrug-resistant tuberculosis bacteria. The addition of one of the synthetic chemicals "inhibited growth of the isolated TB cells by more than 99.9%". The shallot chemicals appear to interfere with activities in the bacteria that protect them from antibiotics.

The results described above sound fantastic, but they were done with isolated cells in lab equipment. The chemicals may not be so effective inside the human body. Absorption, dilution, and inactivation may all be a problem for medicinal drugs that enter the body. It's possible that the chemicals could be useful, however. The researchers hope to use the synthesized  chemicals as templates for new drugs that will be effective in humans.

Medicines From Plants

Plants are a wonderful resource. Many pharmaceutical drugs originally came from nature. Conservation of wild plants is important for many reasons. One of these is the likelihood of finding medicinal chemicals inside them. These may become increasingly important if antibiotic resistance spreads, as it's doing at the moment.


Information about Allium stipitatum from the Royal Horticultural Society, or RHS
Onions could hold key to fighting antibiotic resistance from the Medical Xpress news site
Facts about tuberculosis from the National Institutes of Health, or NIH

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