Dimeric Bromopyrrole Alkaloids Research Articles

Agelanemoechine, a Dimeric Bromopyrrole Alkaloid with a Pro-Angiogenic Effect from the South China Sea Sponge Agelas nemoechinata.

One new dimeric bromopyrrole alkaloid, agelanemoechine, with an unprecedented imidazo [1,5-a] azepin nucleus together with one known dimeric bromopyrrole alkaloid sceptrin were isolated from the marine sponge Agelas nemoechinata. The structure elucidation and absolute configuration assignments were determined by extensive spectroscopic analyses and the comparison of experimental and calculated ECD. Agelanemoechine showed strong pro-angiogenic activity in zebrafish.

New bromopyrrole alkaloids from the marine sponge Agelas sp.

Chemical investigation of the marine sponge Agelas sp. collected from the South China Sea resulted in the isolation of four new dimeric bromopyrrole alkaloids, including hexazosceptrin (1) with a rare cyclohexane-fused-cyclobutane skeleton, agelestes A and B (2–3), the sceptrin analogues without any aminoimidazole substitution, and (9S, 10R, 9′S, 10′R)-nakamuric acid (4), of which the absolute configuration was confirmed for the first time. The structure elucidation and absolute configuration assignments were unambiguously determined via extensive spectroscopic analyses and the comparison of experimental and calculated electronic circular dichroic spectra. Compounds 1 and 4 exhibited moderate antimicrobial activity.

ChemInform Abstract: Bromopyrrole Alkaloids from Okinawan Marine Sponges Agelas spp.

AbstractReview: 26 refs.

Bromopyrrole Alkaloids from Okinawan Marine Sponges Agelas spp.

In our continuing study for structurally and biogenetically interesting natural products from marine organisms, Okinawan marine sponges Agelas spp. were investigated, resulting in the isolation of 18 unique alkaloids including five dimeric bromopyrrole alkaloids (1-5), ten monomeric bromopyrrole alkaloids (6-15), and three conjugates of monomeric bromopyrrole alkaloid and hydroxykynurenine (16-18). In this mini-review, the isolation, structure elucidation, and antimicrobial activities of these alkaloids are summarized.

Agelamadins A and B, dimeric bromopyrrole alkaloids from a marine sponge Agelas sp.

Two structurally unique dimeric bromopyrrole alkaloids, agelamadins A (1) and B (2), were isolated from a marine sponge Agelas sp. Agelamadins A (1) and B (2) have a structure consisting of an agelastatin-like tetracyclic moiety and an oroidin-like linear moiety in common. The structures of 1 and 2 were elucidated on the basis of spectroscopic analysis. The antimicrobial activity and cytotoxicity of agelamadins A (1) and B (2) were evaluated.

Nagelamides X–Z, Dimeric Bromopyrrole Alkaloids from a Marine Sponge Agelas sp.

Three new dimeric bromopyrrole alkaloids, nagelamides X-Z (1-3), were isolated from a marine sponge Agelas sp. Nagelamides X (1) and Y (2) possess a novel tricyclic skeleton consisting of spiro-bonded tetrahydrobenzaminoimidazole and aminoimidazolidine moieties. Nagelamide Z (3) is the first dimeric bromopyrrole alkaloid involving the C-8 position in dimerization. The structures of 1-3 were elucidated on the basis of spectroscopic data. Nagelamides X-Z (1-3) exhibited antimicrobial activity.

Benzosceptrin C, a new dimeric bromopyrrole alkaloid from sponge Agelas sp.

A new dimeric bromopyrrole alkaloid possessing a benzocyclobutane ring, benzosceptrin C ( 1), has been isolated from an Okinawan marine sponge of the genus Agelas (SS-956), and the structure and relative stereochemistry were elucidated from spectroscopic data. Benzosceptrin C ( 1) showed antimicrobial activity.

Nagelamides Q and R, Novel Dimeric Bromopyrrole Alkaloids from Sponges Agelas sp.

Two new dimeric bromopyrrole alkaloids, nagelamides Q (1) and R (2), have been isolated from Okinawan marine sponges of the genus Agelas (SS-1134 and SS-956, respectively), and the structures and stereochemistry were elucidated from spectroscopic data. Nagelamide Q (1) is a rare dimeric bromopyrrole alkaloid possessing a pyrrolidine ring, while nagelamide R (2) is the first bromopyrrole alkaloid having an oxazoline ring. Nagelamides Q (1) and R (2) showed antimicrobial activity.

Nagelamides K and L, Dimeric Bromopyrrole Alkaloids from Sponge Agelas Species

Two new dimeric bromopyrrole alkaloids, nagelamides K (1) and L (2), have been isolated from Okinawan marine sponges Agelas species, and the structures and stereochemistry were elucidated from spectroscopic data. Nagelamide K (1) is a bromopyrrole alkaloid possessing a rare piperidinoiminoimidazolone ring with an aminoimidazole ring and a taurine unit, while nagelamide L (2) is a unique dimeric bromopyrrole alkaloid containing an ester linkage. Nagelamides K (1) and L (2) exhibited antimicrobial activity.

Nagelamide J, a Novel Dimeric Bromopyrrole Alkaloid from a Sponge Agelas Species

A novel dimeric bromopyrrole alkaloid, nagelamide J (1), with antimicrobial activity has been isolated from an Okinawan marine sponge Agelas species, and the structure and stereochemistry were elucidated from spectroscopic data. Nagelamide J (1) is the first bromopyrrole alkaloid possessing a cyclopentane ring fused to an amino imidazole ring.

Nagelamides A-H, new dimeric bromopyrrole alkaloids from marine sponge Agelas species.

Eight new dimeric bromopyrrole alkaloids, nagelamides A-H (1-8) and a monomeric one, 9,10-dihydrokeramadine (9), have been isolated from the Okinawan marine sponge Agelas sp., and the structures were elucidated from spectroscopic data. Nagelamides A-H (1-8) exhibited antibacterial activity against Gram-positive bacteria. Nagelamide G (7) inhibited protein phosphatase 2A activity.

Bromosceptrin, an alkaloid from the marine sponge Agelas conifera.

Six dimeric bromopyrrole alkaloids (1-6) were isolated from a Florida Keys specimen of Agelas conifera. One of the constituents was identified as a new bromopyrrole metabolite, bromosceptrin (1). The structure of 1 was established from MS spectrometry and 1D and 2D NMR spectrocopy.

Chemical defenses of the Caribbean sponges Agelas wiedenmayeri and Agelas conifera

Previous studies have determined that Caribbean reef sponges of the genus Agelas are chemically defended from fish predation by brominated pyrrole alkaloids, and that the compounds responsible for this defense have been elucidated for 1 species, A. clathrodes. In this study, we ex- pand our understanding of chemical defense in this common sponge genus to include the character- ization of defensive metabolites in the tissues of A. wiedenmayeri and A. conifera. Bioassay-directed isolation of defensive metabolites was undertaken using fish feeding assays carried out in laboratory aquaria and in the field. A. wiedenmayeri contained the same 2 major metabolites as A. clathrodes, 4, 5-dibromopyrrole-2-carboxylic acid (1), and oroidin (2), in addition to a small amount of bromoage- liferin (7). The 2 major metabolites were present at higher concentrations in samples of A. wieden- mayeri than in A. clathrodes, and their relative concentrations were reversed, with A. wiedenmayeri on average containing more 4,5-dibromopyrrole-2-carboxylic acid (1) (2.0 mg ml -1 ) than oroidin (2) (0.8 mg ml -1 ). A. conifera contained a mixture of dimeric bromopyrrole alkaloids dominated by scep- trin (3), with <10% each of dibromosceptrin (5), bromoageliferin (7), dibromoageliferin (8), ageliferin (6), and bromosceptrin (4). Mean concentration of sceptrin (3) in sponge tissue was 5.3 mg ml -1 ; this compound deterred feeding of reef fish in aquarium assays at 1.0 mg ml -1 , the lowest concentration assayed. Sceptrin (3) concentrations were higher in sponges collected in the southern Bahama Islands than in those collected in the middle Bahamas, but the reasons for this variation remain unclear. The structure-activity relationship of the pyrrole group was investigated by assaying derivatives of the active metabolites. Feeding deterrent activity of the molecule was enhanced by the addition of bro- mine to the pyrrole group, but not affected by exchange of the heteroatom from N to O or S. Com- bining an understanding of the structure-activity relationship of Agelas metabolites with an under- standing of the variation in these metabolites across the genus may provide insight into the evolution of defensive chemistry in this highly successful taxa of pan-tropical sponges.

New bromopyrrole alkaloids from the Indopacific sponge Agelas nakamurai.

Two new dimeric bromopyrrole alkaloids, nakamuric acid (1) and its corresponding methyl ester (2), have been isolated from the Indopacific sponge Agelas nakamurai along with the known metabolites sceptrin (3), debromosceptrin (4), and ageliferin (5). Their structures were identified by analysis of spectral data. All compounds inhibited the growth of several Gram-positive and Gram-negative bacteria in the agar plate diffusion assay.