Ansamycins is a family of secondary metabolites that show antimicrobial

Antimicrobial

An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...

 activity against many gram-positive

Gram-positive

Gram-positive bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink...

 and some gram-negative

Gram-negative

Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...

 bacteria and includes various compounds, among which: streptovaricins and rifamycins. In addition, these compounds demonstrate antiviral activity towards bacteriophages and poxviruses.

Structure

They are named ansamycins (from the Latin ansa, handle) because of their unique structure, which comprises an aromatic moiety bridged by an aliphatic chain. The main difference between various derivatives of ansamycins is the aromatic moiety, which can be a naphthalene

Naphthalene

Naphthalene is an organic compound with formula . It is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromatic hydrocarbon, naphthalene's structure consists of a fused pair of benzene rings...

 ring or a naphthoquinone

Naphthoquinone

Naphthoquinone is a class of natural phenols based on the C6-C4 skeleton.1,4-Naphthoquinone can be viewed as derivatives of naphthalene through the replacement of two hydrogen atoms by two ketone groups....

 ring as in rifamycin

Rifamycin

The rifamycins are a group of antibiotics that are synthesized either naturally by the bacterium Amycolatopsis mediterranei or artificially. They are a subclass of the larger family Ansamycin...

 and naphthomycin. Another variation comprises benzene or a benzoquinone ring system as in geldanamycin

Geldanamycin

Geldanamycin is a benzoquinone ansamycin antibiotic that binds to Hsp90 and inhibits its function. HSP90 client proteins play important roles in the regulation of the cell cycle, cell growth, cell survival, apoptosis, angiogenesis and oncogenesis.Geldanamycin induces the degradation of proteins...

 or ansamitocin. Ansamycins were first discovered in 1959 by Sensi et al. from Amycolatopsis mediterranei, an Actinomycete.

Examples

Rifamycins are a subclass of ansamycins with high potency against mycobacterial activity. This resulted in their wide use in the treatment of tuberculosis

Tuberculosis

Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...

, leprosy

Leprosy

Leprosy or Hansen's disease is a chronic disease caused by the bacteria Mycobacterium leprae and Mycobacterium lepromatosis. Named after physician Gerhard Armauer Hansen, leprosy is primarily a granulomatous disease of the peripheral nerves and mucosa of the upper respiratory tract; skin lesions...

, and AIDS-related mycobacterial infections. Since then various analogues have been isolated from other prokaryotes.