Diospyrin inactivates a drug target for tuberculosis in new way

A compound from the South African toothbrush tree inactivates a drug target for tuberculosis in a previously unseen way. 

The compound under research, diospyrin (see below structure), binds to a novel site on a well-known enzyme, called DNA gyrase, and inactivates the enzyme. DNA gyrase is essential for bacteria and plants but is not present in animals or humans. It is established as an effective and safe drug target for antibiotics.

"The way that diospyrin works helps to explain why it is effective against drug-sensitive and drug-resistant strains of tuberculosis," said Professor Tony Maxwell from the John Innes Centre.

In traditional medicine the antibacterial properties of the tree are used for oral health and to treat medical complaints such bronchitis, pleurisy and venereal disease. Twigs from the tree are traditionally used as toothbrushes.

Most antibiotics originate from naturals sources, such as the soil bacteria Streptomyces. Antibiotics derived from plants are less common, but they are potentially rich sources of new medicines.

"Extracts from plants used in traditional medicine provide a source for novel compounds that may have antibacterial properties, which may then be developed as antibiotics," said Professor Maxwell.

Diospyrin inactivates a drug target for tuberculosis in new way

New Drug, Bedaquiline to Tackle Resistant TB

Johnson & Johnson said that it is seeking U.S. approval for the first new type of medicine to fight deadly tuberculosis in more than four decades.

The experimental drug, called bedaquiline (discovered by Koen Andries, see structure), also would be the first medicine specifically for treating multi-drug-resistant tuberculosis. That's an increasingly common form in which at least two of the four primary TB drugs don't work.

Mode of action : Bedaquiline affects the proton pump for ATP synthase, which is unlike the quinolones, whose target is DNA gyrase

Tuberculosis, caused by bacterial infection of the lungs and other body areas, is the world's No. 2 killer of adults among infectious diseases.

J&J's Janssen Research & Development unit created the drug, which was tested in several hundred patients with multidrug-resistant tuberculosis in two mid-stage studies lasting for six months. Some patients were studied for about 1 1/2 years.

The company this fall is to begin late-stage testing that will compare bedaquiline to dummy pills over nine months in about 600 patients; each will also take six other drugs that are the standard treatments for tuberculosis. That study is aimed at seeing whether treatment for resistant tuberculosis can be reduced to nine months from the current 18 to 24 months recommended by the World Health Organization.

Roughly one-third of the world's population is estimated to be infected with the bacteria causing tuberculosis. It remains latent in most people for many years but can be activated by another infection or serious health problem.

TB is rare in the U.S. but kills about 1.4 million people a year worldwide, with about 150,000 of those succumbing to the increasingly common multidrug-resistant forms.

Janssen's head of infectious diseases, Dr. Wim Pays, said the company will also apply for approval of bedaquiline in other countries where TB is very common.

The disease is a serious problem in developing countries because it takes so long to cure and many patients stop taking their pills once they begin to feel better. That helps bacteria still alive in the patient to develop resistance to the medicines already taken, making future treatment much more difficult.

Ref : http://www.inpharm.com/news/173302/janssen-submits-tuberculosis-pill-fda