Tauropinnaic acid

The cytostolic phospholipase A2 inhibitor tauropinnaic acid (229) was isolated from the Okinawan bivalve Pima muricata (pen shell). The structure and stereochemistry at all but one centre were elucidated by interpretation of spectroscopic data [234]. 

Three novel related marine alkaloids, halichlorine (1148) from the sponge Halichondria okadai (1177, 1178) and pinnaic acid (1149) and tauropinnaic acid (1150) from the bivalve Pinna muricata (1179), have been the objects of much synthetic interest in view of their pronounced biological activity (inhibition of the vascular cell adhesion molecule-1) (1180). Synthesis of these alkaloids led to both revision and confirmation of the original structures (1181,1182). The syntheses of the previously known chlorine-containing cylindricines have been reviewed (1183). 

Chou T, Kuramoto M, Otani Y, Shikano M, Yazawa K, Uemura D (1996) Pinnaic Acid and Tauropinnaic Acid Two Novel Fatty Acids Composing a 6-Azaspiro[4.5]decane Unit from the Okinawan Bivalve Pinna muricata. Tetrahedron Lett 37 3871... 

The fatty acid-derived alkaloids halichlorine (112) [99,100], pinnaic acid (113), and tauropinnaic acid (114) [101,102] have novel structures and unique anti-inflammatory activity. 

Tong, C., Kuramoto, M., Otani, Y, Shikano, M., Yazawa, K. and Uemura, D, 1996. Pinnaic acid and tauropinnaic acid two novel fatty acids composing a 6-azaspiro[4.5]decane unit from the Okinawan bivalve Pinna muricata.. Tetrahedron Lett 37, 3871-3874. 

Pinnaic acid (24) and tauropinnaic acid (25) were isolated from the viscera of P. muricata [45]. Both 24 and 25 have a imique 6-azaspiro[4.5]decane moiety. The gross structure of 24 was also confirmed by a comparison of the EI-MS fragment peaks with the corresponding peaks of 25. The relative stereochemistry of 25 was deduced from phase-sensitive NOE correlations. 

Pinnaic acid (24) and tauropinnaic acid (25) inhibited CPLA2 activity in vitro with IC50 values of 0.2 mM and 0.09 mM, respectively. The activities of pinnaic acids were not so strong, but were still interesting, since CPLA2 inhibitors are rare. 

Christie, H.S. and Heathcock, C.H. (2004) Total synthesis of ( )-halichlorine, ( )-pinnaic acid, and ( )-tauropinnaic acid. Proc. Natl Acad. Sci. USA, 101,12079-12084. 

A total of3000 shellfish produced 10 kg of digestive glands, from which was extracted 1 mg of pinnaic acid and 4 mg of tauropinnaic acid. 

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