Chemical Transformation of Terpenoids. X. Ionophoretic Activities of Macrocyclic Lactone Epoxides Synthesized from Geraniol

抄録

Two coronand-type 18-membered lactone epoxides, i.e., geranyl dimeric lactone diepoxide (GL₂E₂, 10) and tetraepoxide (GL₂E₄, 11), were synthesized from geraniol as diastereomeric mixtures. Among them, GL₂E₄ (11) was shown to exhibit ion-transport activity for Ca²⁺ ion in the test using a W-07 (liquid-membrane type) apparatus and ion-permeation activities for Ca²⁺ and K⁺ ions across the human erythrocyte membrane. Isolation of six component diastereomers of GL₂E₄ (11) [GL₂E₄-1 (11c), -2 (11d), -3 (11e), -4 (11f), -5 (11g), -6 (11h)], was effected by HPLC separation of two diastereomeric tetraepoxides (11a, 11b) which were prepared from two diepoxides (GL₂E₂-1, 10a and GL₂E₂-2, 10b). The relative stereostructures of these diastereomers were determined by a combination of X-ray diffraction and ¹H-NMR analyses. Among the six diastereomers, S₂-symmetrical GL₂E₄-4 (11f) exhibited the strongest ion-transport activity for Ca²⁺ ion while C₂-symmetrical GL₂E₄-6 (11h) exhibited the strongest ion-permeation activity for Ca²⁺ ion across the human erythrocyte membrane.