Diverse Aromatic Metabolites in the Solitary Tunicate Cnemidocarpa irene

Abstract

Fourteen aromatic metabolites (6–19) were isolated from an aqueous extract of the solitary tunicate Cnemidocarpa irene collected in Hokkaido, Japan. The structures of the metabolites were determined based on the spectroscopic interpretations, including one- and two-dimensional NMR, mass spectra, UV, and circular dichroism data. The biopterin analogue 10 modulated the behavior of mice after intracerebroventricular injection and showed a weak affinity to ionotropic glutamate receptor subtypes. Analyses of fluorescent coelomic fluid of the tunicate revealed that pterin 12 was responsible for the fluorescence of the blood cells, while β-carbolines 1 and 3 were fluorescent compounds in the serum. The metabolic profiles in adults, juveniles, larvae, and eggs of the animal differed substantially, suggesting that the metabolism of the animal, especially biosynthesis of aromatic secondary metabolites, changes over different life stages.

Marine natural products

“…An extensive range of metabolites, including amidotaurines 1413–1415 , pterins 1416–1418 and 1419 , guanine 1420 , cytidine analogue 1421 and tyramines 1422–1424 were reported from Cnemidocarpa irene , 686 while specimens of the genus Synoicum afforded new examples of butenolide-containing rubrolides T 1425 , ( Z )-U 1426 and ( E )-U 1427 ( S. kurani ) 687 and the related isocadiolides A–H 1428–1435 and cadiolide N 1436 ( Synoicum sp.). 688 The coelomic fluid of C. irene has been previously reported to exhibit blue fluorescence when irradiated at 365 nm: pterin 1419 was responsible for blood cell fluorescence, while previously reported irenecarboline A was the source of serum fluorescence.…”

Synthesis, Redox and Spectroscopic Properties of Pterin of Molybdenum Cofactors

“…This useful property of pterins can see them utilized as fluorophores [ 56 , 57 ] and easily detected as biomarkers for viral infection, inflammation and cancer [ 58 ]. It was also reported that the fluorescence of red blood cells in tunicate, Cnemidocarpa irene, can be attributed to a pterin derivative [ 59 ]. The compounds highlighted in Scheme 2 and Scheme 10 also fluoresce similarly to that of oxidized MPT.…”

Chemical and Biological Aspects of Water-Soluble Heterocyclic Marine Natural Products

“…Further isolation work resulted in identification of fifteen more aromatics with various structures [53]. These compounds can be categorized into tauroamides [54].…”

“…These compounds commonly contain 2-amino imidazole groups as found in KB343. Zoanthoxantin (53) and pseudozoanthoxantin (54) form 14π aromatic system with liner and angular arrangement of two aminoimidazole via 7-membred ring, respectively. Terrazoanthine (55) also has two aminoimidazole units without fused aromatic system [74].…”