IN-VITRO INHIBITION OF ADENOSINE-DEAMINASE BY A GROUP OF STEROID AND TRITERPENOID COMPOUNDS

The effects of several sapogenins and saponins of the steroid and trit erpenoid classes, as well as of a few common phytosterols, have been t ested for their inhibitory action towards adenosine deaminase (ADA). I t was found that the acidic sapogenins strongly inhibit the enzyme. Th e mean inhibitory concentration (IC50) was in the range 10(-3) to 10(- 2) mg/mL, while the inhibitor constants (K(i)) have been estimated as about 10(-6) M. In contrast to this finding is the complete absence of any influence on the enzyme of the neutral sapo(ge)nins and the phyto sterols. It is suggested that ADA is a worthwhile therapeutic target a nd that the (acidic) sapogenins, which are regular constituents of man y medicinal plant species, presumably contribute their activity throug h an interaction with this enzyme.