On the alkaloids from Aspidosperma discolor A. DC

From the stem bark of Aspidosperma discolor A. DC. (–)-reserpiline, (–)-isoreserpiline, (+)-yohimbine, (–)-10-methoxy-geissoschizol and (–)-10-methoxy-dihydrocorynantheol (major alkaloids) and (–)-isoreserpiline-ψ-indoxyl, AD-V (–)-β-yohimbine, (+)-haplocidine, (+)-desmethylaspidospermine and (–)-demethoxy-aspidospermine (minor alkaloids) have been isolated.     

Fragmentation of plumeran indole alkaloids from Aspidosperma spruceanum by electrospray ionization tandem mass spectrometry

The fragmentation of six plumeran indole alkaloids (PIAs) previously isolated from Aspidosperma spruceanum has been investigated by electrospray ionization tandem mass spectrometry (ESI‐MS/MS) in the positive ion mode. The fragmentation pathways have been established on the basis of MS/MS experiments using fragment ions generated in‐source and deuterium‐labeled alkaloids as precursor ions and on the basis of accurate mass measurements. Our results demonstrated that the fragmentation routes observed for the protonated PIAs are essentially derived from a pericyclic reaction and from the opening of rings D and E, followed by 1,4‐hydrogen rearrangements. Product ions resulting from radical eliminations were also observed, contrary to the ‘even‐electron rule’. Our data reveals that some product ions from protonated PIAs provide crucial information for the characterization of the acyl substituent at N‐1, the methoxyl and hydroxyl groups at the aromatic moiety, and give evidence of an ether bridge between C‐18 and C‐21. The data reported here were used for the dereplication of these compounds in a stem bark methanolic extract of Aspidosperma spruceanum. Copyright © 2010 John Wiley & Sons, Ltd.     

Buxus alkaloids. XII. Benzamide alkaloids from Buxus sempervirens L

The isolation and structural elucidation of ten new alkaloids from the “additional weak bases” fraction of Buxus sempervirens L. are reported. A structural feature common to eight of the new alkaloids is the presence of a secondary benzamide function at the C-3 position. Evidence is presented for assignment of structures for N-benzoylcycloxobuxine-F (I), N-benzoylcycloxobuxidine-F (Xa), N-benzoyldihydrocyclomicrophylline-F (XII), N-benzoylcycloxobuxoline-F (XF), N-benzoyl-O-acetylcycloxobuxoline-F (XVI), N-benzoylbuxidienine-F (XIX), N-benzoylcycloprotobuxoline-D (XXIIIa), N-benzoylcycloprotobuxoline-C (XXXIIIb), tigloycyclovirobuxeine-B (XXIXb), and N-acetylcyclopropotobuxine-D (XXXc).     

A new approach to the synthesis of pentacyclic indole derivatives related to Aspidosperma alkaloids

N-Indolylethyl-2-pyridones bearing appropriate β-dicarbonyl substituents in the 3-position have been cyclised to pentacyclic indoles via spirocyclic indolenines by catalysis with trifluoroacetic anhydride.     

A New Tricyclic Alkaloid from Portulaca oleracea L.

A new tricyclic alkaloid named portulacatone ( 1 ), i.e., 5,6‐dihydro‐8,9‐dihydroxy‐11H‐pyrrolo[2,1‐b] [3]benzazepin‐11‐one, together with eight known compounds, methyl 4‐hydroxyphenylacetate ( 2 ), p‐hydroxybenzaldehyde ( 3 ), vanillin ( 4 ), protocatechualdehyde ( 5 ), p‐hydroxybenzoic acid ( 6 ), iseluxine ( 7 ), oleracein E ( 8 ), and (+)‐(R)‐feruloyl malate ( 9 ) were isolated from aerial parts of Portulaca oleracea L. Their structures were elucidated based on spectroscopic analyses. Among them, compounds 1 – 7 and 9 were isolated from this medicinal plant for the first time. Compounds 1 and 7 showed dose‐dependent scavenging activities against DPPH (2,2‐diphenyl‐1‐picryl‐hydrazyl) free radical, with EC₅₀ values of 14.36 μM and 9.98 μM , respectively, more potent than the natural antioxidant vitamin C (EC₅₀ 20.72 μM ).     

Nagelamides K and L, dimeric bromopyrrole alkaloids from sponge Agelas species

Two new dimeric bromopyrrole alkaloids, nagelamides K (1) and L (2), have been isolated from Okinawan marine sponges Agelas species, and the structures and stereochemistry were elucidated from spectroscopic data. Nagelamide K (1) is a bromopyrrole alkaloid possessing a rare piperidinoiminoimidazolone ring with an aminoimidazole ring and a taurine unit, while nagelamide L (2) is a unique dimeric bromopyrrole alkaloid containing an ester linkage. Nagelamides K (1) and L (2) exhibited antimicrobial activity.     

A New Alkaloid from the Seeds of Sophora alopecuroides L.

Alopecurin A, an alkaloid with an unprecedented skeleton, was isolated from the seeds of Sophora alopecuroides L. The absolute configuration and structure of this compound was identified as (3S,12R)‐3‐hydroxy‐1,7‐diazatricyclo[10.4.0.1^3,7]heptadecane‐11,16,17‐trione (=(7S,15aR)‐decahydro‐7‐hydroxy‐6H‐7,11‐methano‐4H‐pyrido[1,2‐a][1,7]diazacyclododecine‐4,15,16(12H)‐trione). The structure and absolute configuration was elucidated by spectroscopic methods, mainly HR‐ESI‐TOF‐MS, IR, 1D‐NMR (¹H‐ and ¹³C‐NMR), 2D‐NMR (COSY, NOESY, HSQC, HMBC), and particularly X‐ray crystal‐diffraction and CD spectral analysis.     

Analysis of Danshen and twelve related Salvia species

Danshen is a commonly used traditional Chinese herb, but over twenty Salvia species are used as Danshen by local herbalists. In this study, twelve Salvia species from the plateau of Sichuan and Yunnan Provinces were collected, analyzed and compared with Danshen by HPLC. The results showed that most of the Salvia species were good sources of rosmarinic acid and tanshinones. The highest amount of both rosmarinic acid and tanshinone IIA were found in S. przewalskii Maxim. These results pave the way for a better therapeutic exploitation of these plants.