ON THE STRUCTURE OF CALONYCTIN-A, A PLANT-GROWTH REGULATOR

The plant growth regulator calonyctin A, isolated from the dried leave s of Calonyction aculeatum L. House (Yue-Guang-Hua), was separated int o two pure components by high performance liquid chromatography. By us e of mass spectrometry based on various ionization techniques, one- an d two-dimensional NMR spectroscopy, IR spectrometry, and chemical meth ods the molecular structures of the two homologous glycosides were det ermined. Each molecule contains two hydroxy fatty acid residues and fo ur 6-deoxyhexose units. The fatty acids are 3-hydroxy-2-methylbutanoic acid and 11-hydroxytetradecanoic acid or 11-hydroxyhexadecanoic acid. The 6-deoxyhexose residues (three of quinovose and one of rhamnose) c omprise a tetrasaccharide having the following structure: [GRAPHICS] T he long-chain hydroxy acid is linked glycosidically through its 0-11 t o Qui D and esterified to 0-2 of Qui C, forming a macrocyclic lactone. The 3-hydroxy-2-methylbutanoic acid is ester-linked to 0-3 of Qui C.