Fluorescent probes for the visualization of FtsZ in gram-positive and gram-negative bacterial pathogens

1. A compound of formula I:

or a salt thereof, wherein:

Y is H, halo, halo(C 1 -C 6 )alkyl, halo(C 1 -C 6 )alkoxy, or CN;

L is a linking group;

Z is halo, cyano, or halo(C 1 -C 6 )alkyl; and

W is a detectable group selected from the group consisting of:

2. The compound of claim 1 wherein L comprises 3-25 atoms.

3. The compound of claim 1 wherein L is a branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 1 to 25 carbon atoms, wherein one or more of the carbon atoms are optionally replaced independently by —O—, —S, —N(R a )—, 3-7 membered heterocycle, 5-6-membered heteroaryl or carbocycle and wherein each chain, 3-7 membered heterocycle, 5-6-membered heteroaryl or carbocycle is optionally and independently substituted with one or more substituents independently selected from the group consisting of (C 1 -C 6 )alkyl, (C 1 -C 6 )alkoxy, (C 3 -C 6 )cycloalkyl, (C 1 -C 6 )alkanoyl, (C 1 -C 6 )alkanoyloxy, (C 1 -C 6 )alkoxycarbonyl, (C 1 -C 6 )alkylthio, azido, cyano, nitro, halo, —N(R a ) 2 , hydroxy, oxo (═O), carboxy, aryl, aryloxy, heteroaryl, and heteroaryloxy, wherein each R a is independently H or (C 1 -C 6 )alkyl.

4. The compound of claim 1 wherein L is a branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 1 to 15 carbon atoms, wherein one or more of the carbon atoms is optionally replaced independently by —O— or N(R a )—, and wherein each carbon atom are optionally substituted with one or more substituents independently selected from the group consisting of (C 1 -C 6 )alkyl, (C 1 -C 6 )alkoxy, (C 3 -C 6 )cycloalkyl, (C 1 -C 6 )alkanoyl, (C 1 -C 6 )alkanoyloxy, (C 1 -C 6 )alkoxycarbonyl, azido, cyano, halo, —N(R a ) 2 , hydroxy, oxo (═O), and carboxy, wherein each R a is independently H or (C 1 -C 6 )alkyl.

5. The compound of claim 1 wherein L is a branched or unbranched, saturated hydrocarbon chain, having from 1 to 15 carbon atoms, wherein one or more of the carbon atoms are optionally replaced independently by —O— or N(R a )—, and wherein each carbon atom is optionally substituted with one or more substituents independently selected from the group consisting of halo and oxo (═O), wherein each R a is independently H or (C 1 -C 6 )alkyl.

6. The compound of claim 1 wherein L is —CH 2 CH 2 C(═O)O—CH 2 —, —CH 2 C(═O)O—CH 2 , —C(═O)O—CH 2 —, —O—CH 2 —, or —CH 2 —.

7. The compound or salt of claim 1 , which is a compound of formula (Ia):

or a salt thereof.

8. The compound or salt of claim 1 , which is a compound of formula (Ib):

or a salt thereof.

9. The compound or salt of claim 1 , which is a compound of formula (Ic):

or a salt thereof.

10. The compound or salt of claim 1 , which is a compound of formula (Id):

or a salt thereof, wherein:

Y is H, halo, CF 3 , OCF 3 , OCF 2 CF 3 , or CN;

X is —O—, —C(═O)—, —OC(═O)—, —C(═O)O—, —N(R a )C(═O)—, —C(═O)N(R a )—, —OC(═O)O—, —N(R a )C(═O)O—, —OC(═O)N(R a )—, —N(R a )—, —S—, —SC(═O)—, —C(═O)S—, —SC(═O)O—, —O C(═O)S—, —N(R a )SO 2 —, or —SO 2 N(R a )—;

n is 0, 1, 2, 3, 4, 5, or 6; and

each R a is independently H or (C 1 -C 6 )alkyl.

11. The compound or salt of claim 1 , which is a compound of the formula (Ie):

or a salt thereof, wherein X is —O—, —C(═O)—, —OC(═O)—, —C(═O)O—, —N(R a )C(═O)—, —C(═O)N(R a )—, —OC(═O)O—, —N(R a )C(═O)O—, —OC(═O)N(R a )—, —N(R a )—, —S—, —SC(═O)—, —C(═O)S—, —SC(═O)O—, —O C(═O)S—, —N(R a )SO 2 —, or —SO 2 N(R a )—.

12. The compound or salt of claim 1 , which is a compound of the formula (If):

or a salt thereof.

13. The compound or salt of claim 1 , which is a compound of the formula (Ig):

or a salt thereof.

14. The compound or salt of claim 1 , which is a compound of the formula (Ih):

or a salt thereof.

15. A composition comprising a compound of formula (I) as described in claim 1 or a salt thereof, and a pharmaceutically acceptable excipient.

16. A method for visualizing FtsZ in live Gram-positive or Gram-negative bacterial cells comprising treating the cells with a compound of formula (I) as described in claim 1 or a salt thereof, rinsing away unreacted compound, and measuring the fluorescence of the treated cells to provide fluorescence signals, wherein the fluorescence signals are indicators of where FtsZ is located and distributed in the cells.

17. A method for monitoring cell division live Gram-positive or Gram-negative bacterial cells comprising treating the cells with a compound of formula (I) as described in claim 1 or a salt thereof, rinsing away unreacted compound, and measuring the fluorescence of the treated cells to provide fluorescence signals, wherein the fluorescence signals are indicators of where FtsZ is located and distributed in the cells.

18. A method for identifying a FtsZ inhibitor comprising treating live Gram-positive or Gram-negative bacterial cells with a test FtsZ inhibitor, followed by treatment with a compound of formula (I) as described in claim 1 or a salt thereof, rinsing away unreacted compound, and measuring the fluorescence of the treated cells to provide a fluorescence signal pattern, wherein the fluorescence signal pattern in the cells treated with the test FtsZ inhibitor characterized by an enlarged phenotype and an absence of speta or septally-localized FtsZ is indicative of FtsZ inhibition and the disruption of cell division.