The ionophores were first recognized as being a separate class with the publication of the structure for monensin in 1967. Several members of the group have found commercial application as anticoccidials in poultry farming and as growth promoters for cattle, pigs and chickens. Polyether antibiotics are characterized by multiple tetrahydrofuran and tetrahydropyran rings connected by aliphatic bridges, direct C-C linkage, or spiro linkage. Other important features, also contributing to their mode of action include a free carboxyl function, many lower alkyl groups and a variety of functional oxygen groups. The ionophore antibiotics are fermentation products of various Streptomyces spp. (monensin, salinomycin) and Actinomadura spp. (maduramycin) and are active against both protozoa and bacteria. Consequently they are used as prophylactic and therapeutic anticoccidials and antibacterials and may also be used for growth promotion in cattle and swine.

  • Mode of Action:

An ionophore is a lipid-soluble molecule usually synthesized by microorganisms to transport ions across the lipid bilayer of the cell membrane. Ionophores disrupt transmembrane ion concentration gradients, required for the proper functioning and survival of microorganisms, and thus have antibiotic properties. They are produced naturally by a variety of microbes and act as a defense against competing microbes. Many antibiotics, particularly the macrolide antibiotics, are ionophores that exhibit high affinities for Na+ or K+.

monesin A chemical structure

Figure 1 The structure of the complex of sodium (Na+) and the antibiotic monensin-A.

valinomycin chemical structure

Figure 2 Left: Structure of ionophore Valinomycin, Right: Valinomycin is highly selective for K+ relative to Na+.

v-1013.uniport

Figure 3 The ionophore valinomycin is also a uniport carrier.

  • Antibacterial Activity:

The ionophore antibiotics are generally extremely hydrophobic with a molecular weight greater than 500 daltons. Consequently they cannot penetrate the outer membrane of gram-negative bacteria and this group of organisms is generally ionophore resistant. In contrast, gram-positive organisms, lacking the protective outer membrane are susceptible. The ionophores are active against both aerobic and anaerobic gram-positive organisms including Lactobacillus spp., Eubacterium spp., Peptococcus spp., Peptostreptococcus spp., Streptococcus bovis, as well as Acholeplasma and Mycoplasma spp. Both salinomycin and monensin have been shown to suppress Clostridium perfringens and therefore they may be considered important in the prevention of necrotic enteritis in broiler chickens. It has been suggested that the antibacterial activity of ionophores may result in overgrowth of gram-negative organisms in the gut, particularly Salmonella spp. but evidence for this is conflicting. In ruminants ionophores can be used to manipulate rumen fermentation and hence ruminal volatile fatty acid concentrations. This effect is thought to be the basis for improved feed efficiency when low concentrations of ionophores are included in ruminant feeds.

The susceptibility of bacteria to the ionophore antibiotics varies depending on cell wall structure. The gram negative organisms are more inherently resistant due to the inability of the ionophores to penetrate the cell membrane, although within this group of organisms differences in ionophore binding and permeability have been observed. Gram positive organisms are more susceptible as a group because of their cell wall structure and again, within the group differences in susceptibility have been observed.

 

There is little data in the literature concerning resistance in pathogenic organisms important in human health and the effects of the ionophore antibiotics on the bacterial flora of the gut of pigs and chickens are not readily available. However some limited studies have been performed which indicate resistance occurring in the following groups of organisms. It has also suggested that cross resistance to other ionophores may be a common feature of resistance to individual compounds.

Source: Monensin and Salinomycin in Veterinary Medicine - Overview, Membran Transport 1998-2007 by Joyce J. Diwan, Wikipedia.

POLYETHER IONOPHORE ANTIBIOTIC EXAMPLES:

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39 Items

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  1. 4-Bromo-A23187
    4-Bromo-A23187
    A-1130

    Starting at $98.72

  2. A23187, Free Acid | CAS 52665-69-7 | Calcium Ionophore | AG Sci.
    A23187, Free Acid
    A-1020

    Starting at $78.34

  3. A23187, Mixed Calcium-Magnesium Salt
    A23187, Mixed Calcium-Magnesium Salt
    A-1128

    Starting at $60.52

  4. Ionomycin, Free Acid
    Ionomycin, Free Acid
    I-1014

    Starting at $89.34

  5. Monensin Sodium Salt
    Monensin Sodium Salt
    M-1211

    Starting at $72.02

  6. Ferutinin
    Ferutinin
    F-1140

    Starting at $40.20

  7. Nonactin | Cyclic Ionophore | CAS # 6833-84-7 | AG Scientific, Inc.
    Nonactin
    N-1155

    Starting at $114.99

  8. Enniatin B
    Enniatin B
    E-2024

    Starting at $156.34

  9. Nigericin Sodium Salt
    Nigericin Sodium Salt
    N-1103

    Starting at $73.71

  10. Valinomycin | CAS 2001-95-8 | Potassium ionophore | AG Scientific, Inc.
    Valinomycin
    V-1013

    Starting at $140.67

  11. CA 1001 | CAS 58801-34-6 | Calcium Ionophore | IBOS optical sensor | AG Scientific, Inc.
    CA 1001 (Calcium Ionophore I)
    E-2026

    Starting at $301.51

  12. 5,10,15,20-Tetraphenyl-21H,23H-porphine manganese(III) chloride
    5,10,15,20-Tetraphenyl-21H,23H-porphine manganese(III) chloride
    C-1472

    Starting at $0.00

  13. Monensin EIA
    Monensin EIA
    M-1183

    Starting at $0.00

  14. Lithium Ionophore VIII chemical structure | CAS 13338-85-9 | AG Scientific, Inc.
    Lithium Ionophore VIII
    L-1185

    Starting at $2,160.88

  15. A-39183A
    A-39183A
    A-2573

    Starting at $335.02

  16. Avenaciolide
    Avenaciolide
    A-2649

    Starting at $281.41

  17. Deethylindanomycin
    Deethylindanomycin
    D-2477

    Starting at $335.02

  18. Dinactin
    Dinactin
    D-2521

    Starting at $395.32

  19. Enniatin A
    Enniatin A
    E-2423

    Starting at $225.58

  20. Enniatin A1
    Enniatin A1
    E-2425

    Starting at $225.58

  21. Enniatin B1
    Enniatin B1
    E-2427

    Starting at $225.58

  22. Indanomycin
    Indanomycin
    I-2561

    Starting at $335.02

  23. Lasalocid
    Lasalocid
    L-2527

    Starting at $145.17

  24. Lasalocid sodium
    Lasalocid sodium
    L-2529

    Starting at $145.17

  25. Leucinostatin A
    Leucinostatin A
    L-2539

    Starting at $189.37

  26. Maduramicin
    Maduramicin
    M-2553

    Starting at $212.19

  27. Maduramicin ammonium
    Maduramicin ammonium
    M-2555

    Starting at $145.17

  28. Monactin
    Monactin
    M-2603

    Starting at $395.32

  29. Monensin A
    Monensin A
    M-2607

    Starting at $145.17

  30. Narasin
    Narasin
    N-2589

    Starting at $212.19

  31. Narasin sodium
    Narasin sodium
    N-2591

    Starting at $145.17

  32. Salinomycin chemical structure | CAS 53003-10-4 | Polyether Ionophore | AG Scientific, Inc.
    Salinomycin
    S-2747

    Starting at $79.99

  33. Tetranactin
    Tetranactin
    T-2617

    Starting at $335.02

  34. Trinactin
    Trinactin
    T-2657

    Starting at $395.32

  35. Tropodithietic acid [TDA]
    Tropodithietic acid [TDA]
    T-2795

    Starting at $243.48

  36. Carbonate Ionophore VII
    Carbonate Ionophore VII
    C-8991

    Starting at $215.00

  37. Magnesium Ionophore I
    Magnesium Ionophore I
    M-4100

    Starting at $0.00

  38. Magnesium Ionophore III
    Magnesium Ionophore III
    M-4300

    Starting at $0.00

  39. Sodium Ionophore X
    Sodium Ionophore X
    S-7777

    Starting at $0.00

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