Ohta et al. have already reported that the low moleculer fraction (L.M.F.) of the oyster extract possessed inhibitory effects on platelet aggregation. Some fractions of L.M.F. indicating such strong effects included nucleic substances, i.e. 5’-AMP, Inosine and cyclicAMP. In this study, we investigated and focused on the type and amount of the nucleic related substances in O.E. and their corresponding biological effects. The O.E. was abundant in 5’-AMP, 5’-IMP, Inosine, 5’-GMP, Adenosine and Guanosine. The inhibiting effects on the platelet aggregation of 5’-AMP, Adenosine and Inosine were confirmed. From the results it was suggested that at least the structure of the purine base plus ribose was needed to exhibit such effect.
