Structural and Synthetic Investigations of Tanikolide Dimer, a SIRT2 Selective Inhibitor, and Tanikolide <i>seco</i>-Acid from the Madagascar Marine Cyanobacterium <i>Lyngbya majuscula</i>
作者:Marcelino Gutiérrez、Eric H. Andrianasolo、Won Kyo Shin、Douglas E. Goeger、Alexandre Yokochi、Jörg Schemies、Manfred Jung、Dennis France、Susan Cornell-Kennon、Eun Lee、William H. Gerwick
DOI:10.1021/jo900578j
日期:2009.8.7
Tanikolide seco-acid 2 and tanikolide dimer 3, the latter a novel and selective SIRT2 inhibitor, were isolated from the Madagascar marine cyanobacterium Lyngbya majuscula. The structure of 2, isolated as the pure R enantiomer, was elucidated by X-rayexperiment in conjunction with NMR and optical rotation data, whereas the depside molecular structure of 3 was initially thought to be a meso compound as established by NMR, MS, and chiral H PLC analyses. Subsequent total synthesis of the three tanikolide dimer stereoisomers 4, 5, and ent-5, followed by chiral GC-MS comparisons with the natural product, showed it to be exclusively the R,R-isomer 5. Tanikolide dimer 3 (= 5) inhibited SIRT2 with an IC50 = 176 nM in one assay format and 2.4 mu M in another. Stereochemical determination of symmetrical dimers such as compound 3 pose intriguing and subtle questions in structure elucidation and, as shown in the current work, are perhaps best answered in conjunction with total synthesis.