Celenamides

Celenamides - peptides with unknown bioiogicai activity... 

Celenamide E (108), a tripeptide alkaloid from the Patagonian sponge Cliona chilensis, shows antibiotic activity against Bacillus subtilis, Staphylococcus aureus, Micrococcus luteus, and Enterococcus faecalis at 50 pg/disk. An unusual feature is the presence of a N-terminal dehydroamino acid [87]. 

Palermo JA, Brasco MFR, Cabezas E, Balzaretti V, Seldes AM (1998) Celenamide E, a Tripeptide Alkaloid from the Patagonian Sponge Cliona chilensis. J Nat Prod 61 488... 

Two brominated linear peptides that are found in the sponge Cliona celata, celenamide A (21 R = CH2CHMe2) and celenamide B (21 R = CHMe2), bear close structural relationships to the cyclic peptides integerrin and lasiodine A that occur in plants.16 A I3C n.m.r. analysis of cyclic peptide alkaloids has been reported and the chemical shifts of most of the carbon atoms in discarines A and B, lasiodines A and B, pandamine, pandaminine, and hymenocardine have been assigned.17... 

They exhibit fragments a-1, which are displayed in Fig. 21 (60, 61). We note the following i) The celenamides are marine natural products of sponge origin and usually bear a Br atom in R side chain ii) some of the fragments, due to the presence of Br, exhibit two isotope peaks which... 

Celenamides are the cyclopeptide alkaloids with the highest molecular weight (around 1000) and are isolated from sponges. The universal presence of fragment e, with m/z 319 is quite characteristic. The occurrence of fragments differing by 2 amu is due to the presence of Br in the R side chain. 

Recently the total synthesis of mucronine-B (150) 147), of the 4(15)-mucronine-A-type, and zizyphine-A (27) 148), the major representative of the 5(13)-type, was achieved. Total synthesis of dihydro derivatives of cyclopeptide alkaloids was more fruitful dihydro-zizyphine-A and -B 149) of the 5(13)-type, dihydro-mauritine-A 150) of the 5(14)-amphibine-B-type and dihydro-zizyphine-G 151, 152) of the 4(14)-amphibine-F-type were synthesized. The total synthesis of the linear peptide alkaloid hexaacetyl-celenamide-A was also achieved (156) 153). 

Stonard, R.J., and RJ. Andersen Linear Peptide Alkaloids from the Sponge Cliona celata (Grant). Celenamides C and D. Can. J. Chem., 58, 2121 (1980). 

Cliona celata has furnished a series of linear peptide alkaloids, the celenamides A to D (278-281), in addition to the previously known clionamide (282) (168, 169). These compounds were isolated in the form of their polyacetates after acetylation of the methanolic extract of the homogenized sponge. The celenamides contain a unique amino acid a,P-didehydro-3,4,5-trihydroxyphenylalanine, as a subunit. The configuration of the double bond in the dehydroamino acid residue has been determined by synthesis of the hexa-acetate of 278 (170). 

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