Hi Mandeep K.,
So look up "wollamide" on Google, pull up one of the several papers on the antibiotic material and its analogues, and wade your way through. You will note that the first "hit" on Google tells you all about how to choose a good candidate for an effective drug, what properties are relevant. For example, an excellent material must 1) dissolve and be carried through the body (and not all drugs meet this property!, many anticancer and antifungal drugs come to mind), 2) must not be broken down ("metabolized") by the body too rapidly, so that it has sufficient time to work -- and yet, must eventually disappear, and 3) must be effective at a very low concentration ("MIC" == minimum inhibitory concentration) so that it can do its antibiotic activity without messing up other things in the body.
If some of the papers out there don't discuss structure-activity relationships at the level of detail that you might want, that's likely b/c the investigation of analogs was scattershot, just a preliminary survey of part of the possible experimental drug "space" around wollamide, to be eventually followed by a more targeted inquiry based around analogs of proven superior effectiveness. These sorts of investigations frequently look at many diverse materials in parallel, since even if a particular analog looks good by some tests, it may fail to be useful in humans (usually, with toxic side-effects). Very few drug candidates make it all the way out to clinical use, and even less are marketed.
-- Cheers, -- Mr. d.