The mechanism of oleanolic acid monoglycosides transport into vacuoles isolated from Calendula officinalis leaf protoplasts

The uptake of [3-3H]-oleanolic acid 3-O-monoglucoside and 3-O-monoglucuronide into vacuoles isolated from Calendula officinalis leaf protoplasts was investigated under various conditions. The transport of monoglucoside was stimulated by ATP and pyrophosphate, and sensitive to protein-modifying agent as well as dissipaters of the membrane potential. On the contrary, the transport of monoglucuronide was not dependent on tonoplast energization and was affected only by a protein-modifying factor. Moreover, the kinetics of tonoplast transport of both monoglycosides was characterized as concentration-dependent with saturation phase. The obtained results indicate that oleanolic acid monoglucoside is transported to isolated vacuoles by an active, carrier-mediated and energy-dependent mechanism, whereas the transport of monoglucuronide is a passive, carrier-mediated process.