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Phthalideisoquinoline hemiacetal alkaloids from Corydalis decumbens that inhibit spontaneous calcium oscillations, including alkyl derivatives of (+)-egenine that are strikingly levorotatory

TitlePhthalideisoquinoline hemiacetal alkaloids from Corydalis decumbens that inhibit spontaneous calcium oscillations, including alkyl derivatives of (+)-egenine that are strikingly levorotatory
Publication TypeJournal Article
Year of Publication2019
AuthorsZhang C.L, Huang Q.L, Chen J., Zhang W.J, Jin H.X, Wang H.B, Naman C.B, Cao Z.Y
Volume82
Pagination2713-2720
Date Published2019/10
Type of ArticleArticle
ISBN Number0163-3864
Accession NumberWOS:000500026300005
KeywordsPharmacology & Pharmacy; Plant Sciences
Abstract

The new phthalideisoquinoline hemiacetal alkaloids (2-7) and the known analogues (1 and 8) were isolated from the bulbs of Corydalis decumbens. The new compounds were characterized by analysis of their NMR spectroscopic data, chemical degradation syntheses, X-ray crystallography, and comparison of experimental and calculated ECD data. All the isolates were screened in vitro for inhibitory activity of spontaneous calcium oscillations in primary cultured neocortical neurons. Compounds 1-3 and 5-7 were found to be active in the suppression of spontaneous calcium oscillations with IC50 values of 6.8, 5.6, 11.6, 10.2, 8.3, and 3.1 mu M, respectively. It was also observed that the presence of hydroxy, methoxy, and ethoxy groups at the remote stereogenic center C-7' of some isolated phthalideisoquinoline hemiacetal alkaloids could alter the preferred conformation and invert the sign of optical rotation, rather than this resulting from configurational isomerism at C-1 or C-9, and that the (3)J(1,9) coupling constants of these analogues varied accordingly. For example, compounds 1 and 6 are levorotatory, despite these molecules having the same carbon skeleton and absolute configuration as (+)-egenine. This emphasizes the potential risk of incorrectly assigning absolute configuration based only on observed coupling constants or optical rotation when comparing the data of new compounds with literature values for known analogues, especially within this class of molecules.

DOI10.1021/acs.jnatprod.9b00247
Student Publication: 
No
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