Agesamines A and B, New Dibromopyrrole Alkaloids from the Sponge Agelas sp.

New dibromopyrrole alkaloids, agesamines A (1) and B (2), were obtained as an inseparable epimeric mixture from a marine sponge Agelas sp., collected in Indonesia.The planar structures were elucidated by analysis of spectroscopic data, and the absolute configuration was determined by the calculated ECD spectrum.Marine sponges contain structurally diverse metabolites with interesting biological activities. 1 In our research to discover new biologically active compounds from natural sources, an extract of the marine sponge Agelas sp., collected in Indonesia, showed cytotoxicity in HeLa cells.We here describe the elucidation of the structures of agesamines A (1) and B (2).The sponge was extracted with EtOH and the extract was partitioned between EtOAc and H 2 O.The EtOAc fraction was partitioned between n-hexane and 90% MeOH, and the H 2 O fraction was partitioned between n-BuOH and H 2 O.The 90% MeOH and n-BuOH fractions showed cytotoxicity toward HeLa cells.The fractions were combined and subjected to column chromatography and HPLC, yielding new dibromopyrrole alkaloids (1 and 2) as an inseparable epimeric mixture, along with the known bromopyrrole alkaloids oroidin 2,3 (3) and manzacidin C 4,5 (4) (Figure 1).Despite repeated purification by HPLC using various columns, the 1 H NMR spectrum of the mixture of 1 and 2 revealed nine pairs of signals with the same intensity in the ratio of 1:1 (Table 1).This indicated that 1/2 was an inseparable mixture of structurally similar compounds or a dimeric compound composed of similar structures.ESIMS of 1/2 showed protonated ion peaks at m/z 403, 405, and 407 (1:2:1), indicating the presence of two bromine atoms, and HRESIMS revealed the molecular formula to be C 11 H 11 Br 2 N 5 O 2 .These data