Absolute stereostructures of cell-adhesion inhibitors, macrosphelides C, E–G and I, produced by a Periconia species separated from an Aplysia sea hare

Macrosphelides E–I have been isolated, along with known macrosphelides A and C, from a strain of Periconia byssoides originally separated from the sea hare Aplysia kurodai, and the absolute stereostructures of macrosphelides E–G and I have been elucidated on the basis of spectroscopic analyses using 1D and 2D NMR techniques and some chemical transformations. In addition, the absolute configuration of macrosphelide C, previously undetermined, has been established by X-ray analysis and application of the modified Mosher method. Macrosphelides E–H inhibited the adhesion of human-leukaemia HL-60 cells to HUVEC.