Protoberberine Alkaloids: Chiroptical Properties and Absolute Configuration

Abstract

Uv spectra were recorded in 957, ethanol with a Cary 14 instrument.

Bioactive Isoquinoline Alkaloids fromCorydalis saxicola

“…The known alkaloids (−)-tetrahydropalmatine (3) [21,28], (−)-corynoxidine (4) [29], (+)-1-nitroapocavidine (5) [3], (+)-cavidine (6) [26,27], (+)-thalictrifoline (7) [26,27,30], berberine (8) [31,32], palmatine (9) [33], dehydrocavidine (10) [34], sanguinarine (11) [31], and 8-acetonyldihydrochelerythrine (12) [35] were determined by comparison of their spectral data with those in the literature. The inhibitory activity of all compounds against AChE, BuChE, and canine parvovirus were evaluated.…”

“…Therefore, the planar structure of 1 was elucidated as 2,9-dihydroxy-3,11-dimethoxy-1,10-dinitrotetrahydroprotoberberine. The absolute configuration of 1 was determined as 14S according to the strong negative Cotton effect at 207 nm (Δε · -1.52) in the CD spectrum of 1 hydrochloride [21]. Compound 2 was obtained as yellow powder, which has the molecular formula of C 20 H 20 N 2 O 6 according to its HREIMS at m/z 384.1322 [M] + (calcd.…”

“…The absolute configuration of 2 was deduced as 13S, 14R by comparison of its CD spectrum with that of known (+)-cavidine (6) (see Supporting Information) [26,27]. Ringdahl et al have studied the CD spectra of a series of 14S-tetrahydroprotoberberines and suggested that the intense 206-210 nm negative Cotton effects correlate directly with the absolute configuration of 14S [21]. However, 14R-tetrahydroprotober- berines were not reported in the literature.…”

New Cytotoxic Tetrahydroprotoberberine-Aporphine Dimeric and Aporphine Alkaloids fromCorydalis turtschaninovii

“…NOESY correlations were observed from the H-1′, H-4′, and 2′-O-methyl resonances in the protoberberine subunit to the H-8 and 10-O-methyl resonances in the oxoaporphine portion of the structure, which established the structure of 1 as protoberberine, corypalmine linked at C-3′ to the oxoaporphine, oxoglaucine via the C-9 phenolic hydroxyl group. The absolute configuration of 1 was determined from its CD spectrum by comparison with those of the (−)-tetrahydropalmatine [16,17], because the diphenyl ether linkage of 1 would not prevent the two components from behaving as individual monomers conformationally [9]. The CD spectrum showed three Cotton effect maxima at 204, 235, and 280 nm (two negative and one positive), indicating that 1 has an S-configuration at C-14′ [16,17].…”

“…In the course of our continuing search for biologically active compounds from Korean medicinal plant sources, we performed a phytochemical investigation of tubers of C. turtschaninovii. The purification of the CHCl 3 -soluble fraction of its ethanol extract by repeated column chromatography led to the isolation of two new tetrahydroprotoberberine-aporphine dimeric alkaloids, corydaturtschines A (1) and B (2), and a new aporphine derivative, ethyl glausuccinate (3), together with 13 known protoberberine (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16) and nine known aporphine alkaloids (17)(18)(19)(20)(21)(22)(23)(24)(25). The structures of these new compounds were determined through spectral analysis, including extensive 2D-NMR data.…”