Callipeltin A, an Anti-HIV Cyclic Depsipeptide from the New Caledonian Lithistida Sponge Callipelta sp.

Callipeltin A ( 1 ) is a cyclic depsidecapeptide from a shallow water sponge of the genus Callipelta (order Lithistida), collected in the waters off New Caledonia. The structure of callipeltin A ( 1 ), which possesses the N-terminus blocked with a β-hydroxy acid, and the C-terminus lactonized with a threonine residue, was determined by interpretation of spectral data, chemical degradation, and evaluation of the amino acids obtained by acid hydrolysis. Along with four common l -, one d -, and two N -methyl amino acids, it contains three new amino acid residues: β-methoxytyrosine (βOMeTyr), (2 R,3 R,4 S )-4-amino-7-guanidino-2,3-dihydroxyheptanoic acid (AGDHE), and (3 S,4 R )-3,4-dimethyl- l -glutamine. Callipeltin A ( 1 ) has been found to protect cells infected by human immunodeficiency (HIV) virus.