The present invention is directed to compounds of the general formula I and pharmaceutically acceptable salts thereof: ##STR1## wherein: R.sup.1 =HO or HOOC(CH.sub.2).sub.x CHR.sup.2 NH--;R.sup.2 =H, lower alkyl, benzyl or --CH.sub.2 OH;x=0 or 1;A=--(CH.sub.2).sub.n -- or ##STR2## n=1 to 5; and Y=H, Cl or OCH.sub.3Z=H or Clm=0 or 1R=lower alkyl;with the proviso that where R.sup.1 =OH, Y is H or Cl and m is 1, n is 4 or 5.The present invention is also directed to an antisickling pharmaceutical carrier and an antisickling agent of the general formula (I) (without the proviso) and pharmaceutically acceptable salts thereof.