Ionophores in Society
Ionophores are not only chemically interesting in their own right but have important medical and economic roles in our society.
A selection of ionophores for study in chemistry courses for pre-med, vet, pharma, biochemistry, and other science students is presented below.
The use of ionophore 'growth promoters' in the animal feedstock industry is also relevant to environmental chemistry concerns about their presence in manure and sewerage sludges used as fertiliser for human and animal crops.
The ability of these materials to transport ions across phospholipid bilayer cell membranes, which is usually the key to understanding their mode of action, can be easily studied using tethered membrane technology.
Contents
Amphotericin B
Amphotericin B is an antibiotic used to treat serious fungal infections. It forms ion channels in the fungal cell membrane with the assistance of ergosterol which is a naturally occurring lipid in fungal membranes. As a medicine it is administered intravenously as a liposomal preparation.
While its affinity for ergosterol makes it target fungal cells, Amphotericin can also interact, though to a lesser extent, with the cholesterol in mammalian cells. This limits its therapeutic dosage because of toxicity.
Amphotericin B is similar both in structure and in action to Nystatin.
http://www.drugs.com/pro/amphotericin-b.html
Beauvericin
Beauvericin is closely related to the enniatins, having three benzyl groups in place of the aliphatic chains of enniatins. It is a potentially toxic agent found in grain crops affected by fungus.
Occurrence of Beauvericin and Enniatins in Wheat Affected by Fusarium avenaceum Head Blight. A. Logrieco, A. Rizzo, R. Ferracane, and A. Ritieni, Applied Environmental Microbiology, 68, 82-85, 2002. doi: 10.1128/AEM.68.1.82-85.2002
Gramicidin
Gramicidin is used as a topical antibiotic. It is often regarded as the archetypal ion channel despite its unusual dimer arrangement that can form across the cell membrane. It was one of the first commercially available antibiotics.
Gramicidin is usually sold as a mixture of related linear polypeptides (principally A, B and C) by Sigma-Aldrich and many other suppliers. The main component is Gramicidin A.
Gramicidin S is an unusual macrocyclic variant.
http://www.drugs.com/search.php?searchterm=Gramicidin
Enniatin complex
Enniatins are produced by fungal species that commonly infect wheat and other grains. High levels are potentially toxic.
A complex mixture of at least six variants is commonly encountered.
There have also been some reports of Enniantins having promise as antibiotics and anti-cancer drugs..
http://toxinology.nilu.no/Researchareas/Fungaltoxins/Factsheets/Enniatins/tabid/4536/Default.aspx
Lasalocid
Lasalocid is commonly used as an antibiotic for control of coccidiosis, a protozoan parasite of poultry and livestock.
http://www.drugs.com/search.php?searchterm=Lasalocid
Maduramicin
Maduramicin is used as an antibiotic for control of coccidiosis, a protozoan parasite of poultry and livestock.
http://www.drugs.com/search.php?searchterm=Maduramicin
Monensin A
Monensin is used in the livestock industry as a food supplement, where it can alter the gut flora (bacteria populations) of the animal so that animal growth rates are improved.
http://www.bioagrimix.com/haccp/html/ionophores.html
http://www.drugs.com/search.php?searchterm=Monensin
Narasin
Narasin is a derivative of salinomycin, and has similar properties.
http://www.drugs.com/search.php?searchterm=narasin
Nystatin
Nystatin is an antifungal antibiotic often prescribed for the treatment of Candida infections. It forms ion channels in the fungal cell membrane with the assistance of ergosterol which is a naturally occurring lipid in fungal membranes. As a medicine Nystatin is taken orally or topically.
While its affinity for ergosterol makes it target fungal cells, it can also interact, though to a lesser extent, with the cholesterol in mammalian cells. This can limit its therapeutic dosage because of toxicity.
It is similar both in structure and in action to Amphotericin B.
http://www.drugs.com/search.php?searchterm=nystatin
Salinomycin
Salinomycin is used in the livestock industry as a food supplement, where it can alter the gut flora (bacteria populations) of the animal so that animal growth rates are improved.
It is also being investigated as an anti-cancer agent.
http://www.bioagrimix.com/haccp/html/ionophores.html
http://www.merck-animal-health-usa.com/binaries/intp1069_SACOX_tcm96-86731.pdf
http://www.drugs.com/search.php?searchterm=salinomycin
Persistence of antibiotics such as macrolides, tiamulin and salinomycin in soil. Michael P. Schlüsener, Kai Bester, Environmental Pollution, 143, 565–571, 2006. doi: 10.1016/j.envpol.2005.10.049
Effects of the veterinary pharmaceutical salinomycin and its formulation on the plant Brassica rapa. V. Furtula, G. L. Stephenson, K. M. Olaveson, P. A. Chambers, Archives of Environmental Contamination and Toxicology, 63, 513-522, 2012. doi: 10.1007/s00244-012-9807-y
Valinomycin
Valinomycin is historically one of the best known ionophores, especially for its 105 fold selectivity for potassium over sodium ions. It is being investigated for use as an antibiotic.
It is used in the manufacture of potassium ion selective electrodes.
