Ionophore properties of monensin derivatives studied on human erythrocytes by 23Na NMR and K+ and H+ potentiometry: relationship with antimicrobial and antimalarial activities.
Eight derivatives of monensin with a modified C25-C26 moiety were synthesized. Their ionophore properties were studied on human erythrocytes by measuring Na+ influx with 23Na NMR and concomitant K+ and H+ efflux by potentiometry. Modification of OH-26 led to inversion of selectivity of transport in favor of K+/Na+ in comparison with monensin. This selectivity disappeared by suppression of the C26-OH moiety. Finally the ionophore ability was lost if the head-to-tail chelation of the monensin skeleton was prevented by blocking the terminal OH-25 and -26 functions. All the compounds were inactive on Gram-negative bacteria and fungi. MIC measured on Bacillus cereus showed that derivatives with increased K+/Na+ selectivity were clearly the most active against Bacillus growth. Most of the compounds showed potential antimalarial properties in the nanomolar range when tested in vitro against Plasmodium falciparum. The IC50S measured were correlated with the whole Na+ and K+ transport efficiency rather than with the ionic selectivity. In both cases determination of initial fluxes of transport for both cations (Na+ and K+) was necessary to investigate the relationship between biological and ionophore properties.
Rochdi
M
M
Université Blaise Pascal, U.R.A. 485 du C.N.R.S., Laboratoire de Synthèse et Etude de Systèmes à Intérêt Biologique, Aubière, France.
Delort
A M
AM
Guyot
J
J
Sancelme
M
M
Gibot
S
S
Gourcy
J G
JG
Dauphin
G
G
Gumila
C
C
Vial
H
H
Jeminet
G
G
D000328:Adult; D000818:Animals; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology*; D000962:Antimalarials / Q000737:chemistry / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006801:Humans; D006859:Hydrogen / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D017136:Ion Transport; D007476:Ionophores / Q000737:chemistry / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D008826:Microbial Sensitivity Tests; D008985:Monensin / Q000737:chemistry / Q000494:pharmacology*; D010963:Plasmodium falciparum / Q000187:drug effects; D011188:Potassium / Q000378:metabolism*; D011199:Potentiometry; D012975:Sodium Isotopes; D013237:Stereoisomerism
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D000962:Antimalarials; D007476:Ionophores; D012975:Sodium Isotopes; D006859:Hydrogen; D008985:Monensin; D011188:Potassium