Kinetic study of the inhibition of the honeybee haemolymph apha-glucosidase in vitro by BAYe 4609, BAYg 5421 and BAYn 5595.

Three therapeutic inhibitors of vertebrate alpha-glucosidases recently assayed in research on diabetes control, show high inhibitory potencies towards the p-NP-alpha-D-glucosidase activity of honeybee haemolymph. BAYe 4609 is an allosteric V-type (pure non-competitive) inhibitor with: Ki congruent to K'i congruent to I50 congruent to 180 micro M; n = 1.17; ni = 1.15 BAYg 5421, an hydrolysis derivative of the former, is a mixed allosteric inhibitor with: Ki congruent to 0.17 micro M; K'i congruent to 0.85 micro M; I50 congruent to 0.38 micro M; n = 1.19; ni = 1.25. BAYn 5595 isd a pure competitive Michaelian inhibitor with: Ki = 15 micro M; I50 congruent to 23 micro M. All these properties reveal similarities to and differences from those of the natural inhibitors of the enzyme and analogies with their action on vertebrate enzymes. Accordingly, correlations have been emphasized between the structure and the activity of these inhibitors which finally lead to propositions of structures for new active molecules.