Bonabiline A, a Monoterpenoid 3α-Acyloxytropane from the Roots of Bonamia spectabilis showing M₃ Receptor Antagonist Activity

Abstract

Two 3α-acyloxytropanes with unique monoterpenoic acyl moieties, bonabiline A and its anhydro derivative bonabiline B, have been isolated from the roots of Bonamia spectabilis. Their structures were elucidated by detailed spectroscopic analysis. Due to the structural similarity of bonabiline A to atropine/hyoscyamine, the affinity of both bonabilines to the muscarinic M₃ receptor was studied in the isolated guinea-pig ileum. Bonabiline A (pA₂ 6.65 ± 0.03) proved to be a more potent antagonist than bonabiline B (pA₂ 5.50 ± 0.03).

Key words

Bonamia spectabilis - Convolvulaceae - 3α-tropanol esters - bonabiline A - monoterpenoic acids - bonabilic acid - apobonabilic acid - muscarinic M₃ receptor antagonist

References

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