Characterization of the glycans involved in sea urchin Paracentrotus lividus reversible adhesion

Sea urchins have hundreds of specialized adhesive organs, the tube feet, which play a key role in locomotion, substrate attachment and food capture. Tube feet are composed by two functional units: a proximal cylindrical stem that is mobile and flexible, attached to a distal flattened disc that produces adhesive secretions. Oral tube feet discs possess a specialized duo-glandular epidermis that produces adhesive and de-adhesive secretions, enabling strong but reversible adhesion to the substrate. Due to the growing interest in biomimetic adhesives, several studies have been carried out to characterize sea urchin adhesives, and up to date, it has been shown that it is composed by proteins and glycans. The protein fraction has been the subject of several studies, that pin-pointed several adhesion-related candidates. Contrastingly, little is known about the glycans that compose sea urchin adhesives. This study aims at contributing to this topic by focusing on the characterization of the glycosidic fraction of the adhesive secreted by the sea urchin Paracentrotus lividus (Lamarck, 1816), using a battery of 22 lectins, applied to 3 complementary techniques. Our results show that five lectins label exclusively the disc adhesive epidermis and simultaneously the secreted adhesive, being, therefore, most likely relevant for sea urchin adhesion. In addition, it was possible to determine that the glycosidic fraction of the adhesive is composed by a high molecular weight glycoprotein containing N-acetylglucosamine oligomers.

Structure de l'opigénine: triterpène pentacyclique isolé d'Opilia celtidifolia

The structure of opigenin, an aglycone from the glycosidic fraction of Opiliaceltidifolia, has been established by study of the genin and its derivatives by means of ir, mass spectroscopy, and 1H and 13C nmr spectroscopy. This is a new triterpene whose skeleton resembles that of 3β-hydroxy lupane but with an isopropyl group in position 20 and an oxymethylene bridge in position 20–28.

New triterpenoid extractives from Lemaireocereus chichipe

Reinvestigation of the glycosidic fraction of the extracts of the giant cactus Lemaireocereus chichipe has resulted in the isolation of a new triterpene triol to which is assigned the structure olean-12-ene- 3β,16β,22α-triol (5a). Two triterpene esters were also isolated, hydrolysis of which gave the known isomeric 3β,16β,28-triol longispinogenin (1a) and a mixture of even-carbon content fatty acids (C10-C18).