The marine sponge Agelas citrina as a source of the new pyrrole–imidazole alkaloids citrinamines A–D and N-methylagelongine

Abstract

SummaryThe chemical investigation of the Caribbean sponge Agelas citrina revealed four new pyrrole–imidazole alkaloids (PIAs), the citrinamines A–D (1–4) and the bromopyrrole alkaloid N-methylagelongine (5). All citrinamines are dimers of hymenidin (6) which was also isolated from this sponge as the major metabolite. Citrinamines A (1) and B (2) are derivatives of the PIA dimer mauritiamine (7), whereas citrinamine C (3) is derived from the PIA dimer nagelamide B (8). Citrinamine D (4) shows an uncommon linkage between the imidazole rings of both monomeric units as it is only observed in the benzocyclobutane ring moiety of benzosceptrins A–C (9–11). Compound 5 is the N-methyl derivative of agelongine (12) which consist of a pyridinium ring and an ester linkage instead of the aminoimidazole moiety and the common amide bond in PIAs.

Bioactive Secondary Metabolites from the Marine Sponge Genus Agelas

“…The Caribbean specimen of Agelas citrina was firstly found to yield three new diterpene alkaloids, (−)-agelasidine E ( 8 ), (−)-agelasidine F ( 9 ) and agelasine N ( 10 ) [ 9 ]. Latter chemical investigation showed that this sponge also produces four new pyrrole-imidazole alkaloids, citrinamines A–D ( 11 – 14 ), and one bromopyrrole alkaloid N -methylagelongine ( 15 ) ( Figure 5 ) [ 10 ]. Compounds 12 – 14 had antimicrobial activities whereas no inhibitory effect on cell proliferation of mouse fibroblasts was found for 11 – 14 .…”

Marine Organisms from the Yucatan Peninsula (Mexico) as a Potential Natural Source of Antibacterial Compounds

“…Thus, agelasidines with antifungal activity against Candida albicans have been extracted from A. citrina, one of the most promising crude extracts in the present study, and (-)-agelasidine C (MIC 0.5 mg/L) was found to be the most active [34]. More recently, new pyrrole-imidazole alkaloids (denominated citrinamines) were isolated from the same species and were found to be able to inhibit the growth of the Gram-positive bacteria Micrococcus luteus and Mycobacterium phlei [35]. Inhibition of the growth of E. coli and Pseudomonas putida by extracts of this sponge has also been reported [36].…”

Recent Advances on Marine Alkaloids from Sponges

“…[59] Four novel compounds 87-90 classified as pyrrole alkaloids containing various imidazolidine-or imidazole-derived moieties were isolated from marine sponge Agelas citrina, of which compound 88 had a unique taurine group. [60] Six new bromopyrrole alkaloids 91-96 from South China Sea sponge Agelas sp. were obtained.…”

“…[59-65,68,69,74 -77] Most of them were collected from or near South China Sea at the depth of 30 m above [59,61,[63][64][65]68,69,[74][75][76][77] , while only the six compounds 87-90 and 97 and 98 were collected from Bahamas sea area nearby as well as the same range of depth. [60,62] The 23 alkaloids 39-44, 47-49 and 55-68 were isolated from the genus of Monanchora. They belonged to guanidine alkaloids, which took up 15.3 % of the total sponge alkaloids.…”