ides . ▁( see ▁below ) ▁The ▁development ▁of ▁pen ic ill in ▁led ▁to ▁renew ed ▁interest ▁in ▁the ▁search ▁for ▁ant ib i otic ▁comp ounds ▁with ▁similar ▁effic acy ▁and ▁safety . ▁For ▁their ▁successful ▁development ▁of ▁pen ic ill in , ▁which ▁F lem ing ▁had ▁accident ally ▁discovered ▁but ▁could ▁not ▁develop ▁himself , ▁as ▁a ▁th era pe ut ic ▁drug , ▁Ch ain ▁and ▁Fl ore y ▁shared ▁the ▁ 1 9 4 5 ▁Nobel ▁Prize ▁in ▁Medicine ▁with ▁F lem ing . ▁ ▁Fl ore y ▁cred ited ▁R ene ▁Dub os ▁with ▁pione ering ▁the ▁approach ▁of ▁deliber ately ▁and ▁system atically ▁searching ▁for ▁ant ib acter ial ▁comp ounds , ▁which ▁had ▁led ▁to ▁the ▁discovery ▁of ▁gram ic id in ▁and ▁had ▁rev ived ▁Fl ore y ' s ▁research ▁in ▁pen ic ill in . ▁In ▁ 1 9 3 9 , ▁coinc iding ▁with ▁the ▁start ▁of ▁World ▁War ▁II , ▁Dub os ▁had ▁reported ▁the ▁discovery ▁of ▁the ▁first ▁naturally ▁derived ▁ant ib i otic , ▁ty ro th ric in , ▁a ▁comp ound ▁of ▁ 2 0 % ▁gram ic id in ▁and ▁ 8 0 % ▁ty roc id ine , ▁from ▁Bac ill us ▁bre vis . ▁It ▁was ▁one ▁of ▁the ▁first ▁commer cially ▁manufact ured ▁ant ib iot ics ▁and ▁was ▁very ▁effective ▁in ▁tre ating ▁w ounds ▁and ▁ul cers ▁during ▁World ▁War ▁II . ▁Gram ic id in , ▁however ,