Tyrokeradines C–F, New Bromotyrosine Alkaloids from the Verongid Sponges

Takaaki Kubota, Shinya Watase, Hiroya Mukai, Jane Fromont, Jun'ichi Kobayashi
2012 Chemical and pharmaceutical bulletin  
Four new bromotyrosine alkaloids, tyrokeradines C-F (1-4), have been isolated from Okinawan marine sponges of the order Verongidae. The structures of 1-4 were elucidated on the basis of spectroscopic data. Tyrokeradines C (1) and D (2) are new bromotyrosine alkaloids possesing an imidazole ring, while tyrokeradines E (3) and F (4) are new bromotyrosine alkaloids possesing a cyano group. Key words marine sponge; order Verongida; bromotyrosine alkaloid; tyrokeradine Marine sponges of the order
more » ... ges of the order Verongida have been found to contain a number of bromotyrosine alkaloids. 1) In our search for bioactive substances from marine sponges, a series of bromotyrosine alkaloids have been isolated from Verongid marine sponges. 2-4) Recently, we have investigated extracts of Okinawan Verongid sponges (SS-242 and SS-301) and isolated four new bromotyrosine alkaloids, tyrokeradines C-F (1-4). Here we describe the isolation and structure elucidation of 1-4. The sponges of the order Verongidae (SS-242 and SS-301) collected off Kerama Islands, Okinawa, were extracted with MeOH. BuOH-soluble materials of the extract of SS-301 were subjected to a C 18 column chromatography followed by C 18 HPLC to yield tyrokeradines C (1, 0.00006%, wet weight) and D (2, 0.00009%) with tyrokeradines A and B. 3) EtOAc-soluble materials of the extract of SS-242 were subjected to a LH-20 column followed by a SiO 2 column and C 18 HPLC to yield tyrokeradines E (3, 0.00007%) and F (4, 0.00002%). Tyrokeradine C (1) was obtained as a colorless amorphous solid. The electrospray ionization (ESI)-MS spectrum of 1 showed the molecular ion peaks at m/z 531, 533, 535 [(M) + , (1 : 2 : 1)], indicating the presence of two bromine atoms, and the molecular formula of 1 was revealed to be C 18 H 25 N 6 O 3 79
doi:10.1248/cpb.c12-00785 pmid:23207640 fatcat:4j7yiph6djfxlessiotcuhxbdi