A New Indole Derivative from the Red Alga Chondria atropurpurea. Isolation, Structure Determination, and Anthelmintic Activity

Chondriamide C (3), a new bis(indole) amide, was isolated from the red alga Chondria atropurpurea, and its structure was established from spectroscopic data and chemical transformations. A new natural product, 3-indoleacrylamide (4), and the previously described chondriamides A and B (1, 2) and 3-indoleacrylic acid (5) were also isolated. The anthelmintic activities of compounds 1, 3, 4, and 6 (the O,N 1,N 1 ‘-trimethyl derivative of compound 2) against Nippostrongylus brasiliensis in vitro were evaluated.