Structurally, the reducible compounds are aromatic derivatives or quinones having suitable substituents which promote varying amounts of moiety release at physiological pH. When reduced at about pH 7, the preferred compounds release at least 50% of {HEAD ~ the available detectable species} within {TAIL ~ 30 minutes} 
Structurally , the reducible compounds are aromatic derivatives or quinones having suitable substituents which promote varying amounts of moiety release at physiological pH. When reduced at about pH 7 , the preferred compounds release at least 50 % of { HEAD ~ the available detectable species } within { TAIL ~ 30 minutes }
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