Structural and Synthetic Investigations of Tanikolide Dimer, a SIRT2 Selective Inhibitor, and Tanikolide seco-Acid from the Madagascar Marine Cyanobacterium Lyngbya majuscula
摘要:
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.
Structural and Synthetic Investigations of Tanikolide Dimer, a SIRT2 Selective Inhibitor, and Tanikolide seco-Acid from the Madagascar Marine Cyanobacterium Lyngbya majuscula
摘要:
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.