A Ceramide and Cerebroside from the Starfish Asterias amurensis Lütken and Their Plant-Growth Promotion Activities

The new phytosphingosine-type ceramide asteriaceramide A (1) and glucocerebroside asteriacerebroside G (2), together with two known cerebrosides, asteriacerebrosides A and B, were isolated from lipophilic fractions of the whole bodies of the Northern Pacific starfish Asterias amurensis Lütken. The water-soluble fraction afforded two known asterosaponins, glycoside B(2) and asterosaponin-1. The structures of 1 and 2 were determined on the basis of chemical and spectroscopic evidence as (2S,3S,4R,13Z)-2-[(2'R)-2-hydroxyhexadecanoylamino]-13-docosene-1,3,4-triol (1) and 1-O-(beta-d-glucopyranosyl)-(2S,3R,4E,13Z)-2-[(2'R)-2-hydroxytetradecanoylamino]-4,13-docosadiene-1,3-diol (2). Compounds 1, 2, and asteriacerebrosides A and B promoted plant growth in sprouts of Brassica campestris.