1.Enantioselective synthesis of the ABC ring motif of norzoanthamine based on asymmetric Robinson annulation reactions.
Nguyen TX1, Dakanali M, Trzoss L, Theodorakis EA. Org Lett. 2011 Jul 1;13(13):3308-11. doi: 10.1021/ol200966z. Epub 2011 May 26.
An enantioselective strategy for the synthesis of tetracyclic motif 5, representing the northern fragment of norzoanthamine, is presented. Key to the strategy is the use of two asymmetric Robinson annulation reactions that produce the tricyclic ABC ring system with excellent stereoselectivity. Further functionalization at the periphery of the C ring produces compound 5 containing six contiguous stereocenters of the natural product.
2.Synthetic studies of the zoanthamine alkaloids: total synthesis of zoanthenol based on an isoaromatization strategy.
Yoshimura F1, Takahashi Y, Tanino K, Miyashita M. Chem Asian J. 2011 Mar 1;6(3):922-31. doi: 10.1002/asia.201000552. Epub 2010 Dec 23.
The total synthesis of zoanthenol, a unique aromatic member of the zoanthamine alkaloids, which has exhibited potent anti-platelet activities on human platelet aggregation, is described in full detail. The key step involves a Brønsted acid-promoted isoaromatization in the AB ring system to install the crucial aromatic ring. We have not only succeeded in the first total synthesis of zoanthenol, but also established an alternative efficient synthetic route from the commercially available norzoanthamine hydrochloride to zoanthenol.
3.Extracts of marine algae show inhibitory activity against osteoclast differentiation.
Koyama T1. Adv Food Nutr Res. 2011;64:443-54. doi: 10.1016/B978-0-12-387669-0.00034-X.
Osteoclasts are multinucleated cells that play a crucial role in bone resorption. The imbalance between bone resorption and bone formation results in osteoporosis. Therefore, substances that can suppress osteoclast formation are potential candidate materials for drug development or functional foods. There have been reports that extracts or purified compounds from marine micro- and macroalgae can suppress osteoclast differentiation. Symbioimine, isolated from the cultured dinoflagellate Symbiodinium sp., had suppressive effects against osteoclast differentiation in osteoclast-like cells. Norzoanthamine, isolated from the colonial zoanthid Zoanthas sp., has been shown to have antiosteoporosis activity in ovariectomized mice. With regard to marine extracts, the fucoxanthin-rich component from brown algae has been shown to have suppressive effects against osteoclast differentiation. An extract of Sargassum fusiforme has recently been shown to have antiosteoporosis activity.
4.New oxidized zoanthamines from a Canary Islands Zoanthus sp.
Cen-Pacheco F1, Martín MN2, Fernández JJ3, Hernández Daranas A4. Mar Drugs. 2014 Oct 14;12(10):5188-96. doi: 10.3390/md12105188.
Three new norzoanthamine-type alkaloids, named 2-hydroxy-11-ketonorzoan thamide B (1), norzoanthamide B (2) and 15-hydroxynorzoanthamine (3), were isolated from Zoanthus sp. specimens collected at the Canary Islands. Their structures were determined by interpretation of NMR and HR-ESIMS data. Relative configurations of their chiral centers were proposed on the basis of ROESY spectra and by comparison of their spectroscopic data with those of the well-known compound, norzoanthamine.