Antibiotic sensitivity-restoring and photosensitive agents

A method of treating a condition, the method comprising administering to a subject in need thereof a therapeutically-effective amount of a compound and a therapeutically-effective amount of a second agent, wherein the compound is of the formula:

• wherein:
• R1 is hydrogen or an ester group;
• R2 is hydrogen, halogen, or L1-Ar1;
• R3 is hydrogen, halogen, or L2-Ar2;
• each L1 and L2 is independently alkylene, alkenylene, O, S, SO2, CO, N2 or a bond;
• Ar1 is a substituted or unsubstituted aryl group;
• Ar2 is a substituted or unsubstituted aryl group wherein Ar2 is not substituted with an amide, amine, nitro, imine, or ester group;
• each A1, A2, A3, and A4 is independently C(R1a), C(R1a)(R1b), N, or N(R1a);
• each R1a and R1b is independently hydrogen, halogen, hydroxyl, sulfhydryl, nitro, nitroso, cyano, azido, a sulfoxide group, a sulfone group, a sulfonamide group, a sulfonic acid group, an imine group, an acyl group, an acyloxy group, alkyl, alkenyl, alkynyl, an alkoxy group, an ether group, a carboxylic acid group, a carboxaldehyde group, an ester group, an amine group, an amide group, a carbonate group, a carbamate group, a thioether group, a thioester group, a thioacid group, aryl, aryloxy, arylalkyl, arylalkoxy, heterocyclyl, heterocyclylalkyl, heteroaryl, or heteroarylalkyl, any of which is substituted or unsubstituted;
• and
• each is independently a single or double bond,
• or a pharmaceutically-acceptable salt thereof, wherein the compound is not:

The method of claim 1, wherein the compound is of the formula:

• wherein:
• R1 is hydrogen;
• R2 is hydrogen or L1-Ar1;
• R3 is L2-Ar2;
• and
• each A1, A2, A3, and A4 is independently C(R1a) or N,
• or a pharmaceutically-acceptable salt thereof.