Biological properties of ristocetin-ps-aglycone.

Ristocetin-ps-aglycone obtained by acid hydrolysis of ristocetin A, has a substantially greater antimicrobial activity against Gram-positive bacteria than the parent compound. None of the substances are active against Gram-negative bacteria, yeast or fungi. The ps-aglycone is several times more toxic than ristocetin A when administered intravenously. Both substances are well-tolerated when given subcutaneously, intraperitoneally and perorally. Both ristocetin A and the ps-aglycone have a very low absorption after oral administration. Plasma levels following intravenous administration of ristocetin A and the ps-aglycone are comparable, with both showing a rapid decline during the first 60 minutes followed by a somewhat slower elimination. The aggregating properties of the ps-aglycone could not be determined due to its low solubility at neutral pH.