Macrolide analogs and methods for identifying macrolide analogs capable of unregulated inhibition of actin filament dynamics are provided. A method according to the invention includes the steps of: (a) contacting F-actin with a candidate compound; and (b) assaying the candidate compound's ability to sever the F-actin and cap resulting F-actin (+)-ends. The candidate compound is identified as a macrolide analog where said candidate compound displays an ability to sever F-actin and, following severing, the resulting F-actin (+)-end is capped by the candidate compound thusly preventing subsequent G-actin incorporation. Severing and capping activities are unregulated; i.e., independent of at least physiologically-meaningful concentrations of phosphatidyl inositol and calcium.