Amino Alcohols from the Ascidian Pseudodistoma sp.

Abstract

Seven new amino alcohol compounds, pseudoaminols A–G (1–7), were isolated from the ascidian Pseudodistoma sp. collected off the coast of Chuja-do, Korea. Structures of these new compounds were determined by analysis of the spectroscopic data and from chemical conversion. The presence of an N-carboxymethyl group in two of the new compounds (6 and 7) is unprecedented among amino alcohols. Several of these compounds exhibited moderate antimicrobial activity and cytotoxicity, as well as weak inhibitory activity toward Na+/K+-ATPase.

The Ascidian-Derived Metabolites with Antimicrobial Properties

“…Pseudoaminols A–G ( 27 – 33 , Figure 5 ), obtained from a Pseudistoma sp. collected along the Korean coasts [ 55 ], possess structures closely related to those of crucigasterins. Pseudoaminols F ( 32 ) and G ( 33 ) are the first report of glycine-derived amino alcohols, as attested by the presence, in their structures, of a N -carboxymethyl group [ 55 ].…”

“…collected along the Korean coasts [ 55 ], possess structures closely related to those of crucigasterins. Pseudoaminols F ( 32 ) and G ( 33 ) are the first report of glycine-derived amino alcohols, as attested by the presence, in their structures, of a N -carboxymethyl group [ 55 ]. All compounds 27 – 33 were screened for their antibacterial activity against strains of Gram-positive and Gram-negative bacteria.…”

“…Pseudoaminols A and B (27 and 28) displayed significant activity against all the tested bacterial strains except for E. coli (Table 1); the effects were similar for the two compounds except for Salmonella typhimurium, where 27 was more potent than 28 ( Table 1). Both pseudoaminols A and B were slightly cytotoxic against pulmonary adenocarcinoma A549 and chronic myeloid leukaemia K562 cell lines, too [55].…”

“…The reduction of polarity and/or basicity of the amino and hydroxyl groups, for example, with the introduction of a N-carboxymethyl substituent, as in the inactive compounds 32 and 33, emphasizes the crucial role played by these functions in the bioactivity either for electronic effects or steric hindrance [55]. Moreover, the above data suggest that the number of double bonds in the amino alcohols alkyl chain strongly affects the antimicrobial activity, too; if within the group of pseudoaminols, it seems that, as the number of double bonds increases, the activity decreases [55], and the saturated amino alcohol (2S, 3R)-2-aminododecan-3-ol (34, Figure 5), isolated from a sample of Clavelina oblonga when tested on both oxacillin-resistant and sensitive strain of S. aureus, was Biosynthetic studies strongly suggested that these derivatives are produced starting from both fatty acids and either L-or d-alanine. The 2R absolute configuration in compounds 22-24 implied that they should derive from d-alanine, whereas crucigasterins B and E are L-alanine derivatives [53,54].…”

Amino Acid-Derived Metabolites from the Ascidian Aplidium sp.

“…In our continuing search for bioactive metabolites from Korean ascidians [ 19 , 20 , 21 , 22 ], we recently encountered the reddish orange Aplidium sp. off the coast of Chuja-do, Korea, whose organic extract exhibited significant cytotoxicity (IC 50 38.6 µg/mL) for the A549 cancer cell-line.…”