Three decahydroisoquinoline alkaloids, lepadins I-K, were isolated from a specimen of Didemnum sp. collected in the Bahamas. The structures of the new compounds were assigned by an integrated analysis of MS, IR, and 1H, 13C, and 2D NMR spectra. Like previously reported lepadins, the structures of the new compounds contain a decahydroquinoline heterocyclic core in lepadin I, and a new variation, an octahydroquinoline in lepadin J, but differ from earlier reported compounds by acylation of the 3-hydroxyl group by a rare 3'-methylthioacrylate. The absolute configuration of lepadin I was solved by interpretation of NOE measurements, and exciton coupled circular dichroism (ECCD) of the corresponding N- p-bromobenzoyl derivative. The latter constitutes a general method for determination of absolute configuration of the entire lepadin family. The configuration of the remote side-chain secondary carbinol was solved by the modified Mosher's esters method. Lepadin I inhibited butyrylcholineesterase (BuChE, IC50 3.1 μM), but only weakly inhibited acetylcholineesterase (AChE) (10% at 100 μM).
Three decahydroisoquinoline alkaloids, lepadins I-K, were isolated from a specimen of n class="Species">Didemnum sp. collected in the Bahamas. The structures of the new compounds were assigned by an integrated analysis of MS, IR, and 1H, 13C, and 2DNMR spectra. Like previously reported lepadins, the structures of the new compounds contain a decahydroquinoline heterocyclic core in lepadin I, and a new variation, an octahydroquinoline in lepadin J, but differ from earlier reported compounds by acylation of the 3-hydroxyl group by a rare 3'-methylthioacrylate. The absolute configuration of lepadin I was solved by interpretation of NOE measurements, and exciton coupled circular dichroism (ECCD) of the corresponding N- p-bromobenzoyl derivative. The latter constitutes a general method for determination of absolute configuration of the entire lepadin family. The configuration of the remote side-chain secondary carbinol was solved by the modified Mosher's esters method. Lepadin I inhibited butyrylcholineesterase (BuChE, IC50 3.1 μM), but only weakly inhibited acetylcholineesterase (AChE) (10% at 100 μM).
Authors: James B McAlpine; Shao-Nong Chen; Andrei Kutateladze; John B MacMillan; Giovanni Appendino; Andersson Barison; Mehdi A Beniddir; Maique W Biavatti; Stefan Bluml; Asmaa Boufridi; Mark S Butler; Robert J Capon; Young H Choi; David Coppage; Phillip Crews; Michael T Crimmins; Marie Csete; Pradeep Dewapriya; Joseph M Egan; Mary J Garson; Grégory Genta-Jouve; William H Gerwick; Harald Gross; Mary Kay Harper; Precilia Hermanto; James M Hook; Luke Hunter; Damien Jeannerat; Nai-Yun Ji; Tyler A Johnson; David G I Kingston; Hiroyuki Koshino; Hsiau-Wei Lee; Guy Lewin; Jie Li; Roger G Linington; Miaomiao Liu; Kerry L McPhail; Tadeusz F Molinski; Bradley S Moore; Joo-Won Nam; Ram P Neupane; Matthias Niemitz; Jean-Marc Nuzillard; Nicholas H Oberlies; Fernanda M M Ocampos; Guohui Pan; Ronald J Quinn; D Sai Reddy; Jean-Hugues Renault; José Rivera-Chávez; Wolfgang Robien; Carla M Saunders; Thomas J Schmidt; Christoph Seger; Ben Shen; Christoph Steinbeck; Hermann Stuppner; Sonja Sturm; Orazio Taglialatela-Scafati; Dean J Tantillo; Robert Verpoorte; Bin-Gui Wang; Craig M Williams; Philip G Williams; Julien Wist; Jian-Min Yue; Chen Zhang; Zhengren Xu; Charlotte Simmler; David C Lankin; Jonathan Bisson; Guido F Pauli Journal: Nat Prod Rep Date: 2018-07-13 Impact factor: 13.423
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