:Ansamycin
{{Short description|Group of chemical compounds}}
{{distinguish|Annamycin}}
File:Geldanamycin.svg, one of the benzoquinone ansamycins.]]
Ansamycins is a family of bacterial secondary metabolites that show antimicrobial activity against many Gram-positive and some Gram-negative bacteria, and includes various compounds, including streptovaricins and rifamycins.{{cite journal |author1=Wehrli, W. |author2=Staehelin, M. |journal= Bacteriological Reviews|title=Actions of the rifamycins |volume=35 |issue=3 |pages=290–309 |year=1971 |pmid=5001420 |pmc=378391|doi=10.1128/MMBR.35.3.290-309.1971 }} In addition, these compounds demonstrate antiviral activity towards bacteriophages and poxviruses.
They are somewhat similar in structure to macrolide antibiotics, but because they have a lactam instead of a lactone, they do not belong in the class of macrolides.
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Structure
They are named ansamycins (from the Latin ansa, handle) because of their unique structure, which consists of an aromatic moiety bridged by an aliphatic chain.{{cite journal |author1=Prelog, V. |author2=Oppolzer, W. |title=Rifamycins. 4. Ansamycins, a novel class of microbial metabolism products |journal=Helvetica Chimica Acta |volume=56 |pages=1179–1187 |year=1973 |issue=7 | doi = 10.1002/hlca.19730560716|pmid=4148590 }} The main difference between various derivatives of ansamycins is the aromatic moiety, which can be a naphthalene ring or a naphthoquinone ring as in rifamycin and the naphthomycins.{{cite journal |author1=Balerna, M. |author2=Keller-Schierlein, W. |author3=Martius, C. |author4=Wolf, H. |author5=Zähner, H. |journal= Archiv für Mikrobiologie|title=Metabolic products of microorganisms. 72. Naphthomycin, an antimetabolite of vitamin K |volume=65 |pages=303–17 |year=1969 |pmid=4988744 |issue=4 |doi=10.1007/bf00412210|s2cid=31145406 }} Another variation consists of benzene or a benzoquinone ring system as in geldanamycin or ansamitocin. Ansamycins were first discovered in 1959 by Sensi et al. from Amycolatopsis mediterranei, an actinomycete bacterium.{{cite journal |author1=Sensi, P. |author2=Margalith, P. |author3=Timbal, M. T. |journal=Il Farmaco, Edizione Scientifica|title=Rifomycin, a new antibiotic; preliminary report |volume=14 |issue=2 |pages=146–7 |year=1959 |pmid=13639988}}
Examples
Rifamycins are a subclass of ansamycins with high potency against mycobacteria. This resulted in their widespread use in the treatment of tuberculosis, leprosy, and AIDS-related mycobacterial infections.{{cite journal |author1=Floss, H. G. |author2=Yu, T. |journal= Current Opinion in Chemical Biology|title=Lessons from the rifamycin biosynthetic gene cluster |volume=3 |pages=592–7 |year=1999 |doi=10.1016/S1367-5931(99)00014-9 |pmid=10508670 |issue=5}} Since then various analogues have been isolated from other prokaryotes.{{cn|date=March 2023}}