Abstract: The present invention comprises a compound of formula I: ##STR1## R.sub.1 of Formula I is substituted amino represented by formula NR.sup.5 R.sup.6 wherein R.sup.5 and R.sup.6 are independently selected from the group consisting of hydrogen, C.sub.1-4 alkyl, and unsubstituted amino with the proviso that R.sup.5 and R.sup.6 are not both hydrogen, and further that R.sup.5 and R.sup.6 are not both amino. R.sub.2 and R.sub.3 of Formula I are independently selected from the group consisting of hydrogen; C.sub.1-4 alkyl; amino; substituted or unsubstituted thiol; and halogen. Moreover, R.sub.4 of Formula I is represented by the formula R.sup.12 -X.sup.12 wherein R.sup.12 is a saturated or unsaturated linear hydrocarbon chain of 5-20 carbons optionally containing one or more interruptions within the chain by a heteroatom, and optionally substituted with one or more .dbd.O, or .dbd.S. Finally, X.sup.12 is selected from the group consisting of hydroxy, an aminoalkyl group, and a known amino acid bound by its .alpha.