Publikationen - Natur- und Wirkstoffchemie

Selected species of the tribe Antidesmeae (Euphorbiaceae, subfamily Phyllanthoideae) have been screened for antidesmone occurrence and its content by quantitative HPLC (UV) and qualitative LC–MS/MS analysis. The LC–MS analysis allowing the additional detection of 17,18-bis-nor-antidesmone, 18-nor-antidesmone, 8-dihydroantidesmone and 8-deoxoantidesmone was carried out in the selected reaction monitoring (SRM) mode. Leaf material from herbarium specimens of 13 Antidesma spp., Hyeronima alchorneoides and Thecacoris stenopetala (all subtribe Antidesminae), as well as Maesobotrya barteri, Aporosa octandra (both Scepinae) and Uapaca robynsii (Uapacinae) were analysed. Additionally, freshly collected samples of different plant parts of two Antidesma spp. were investigated to ensure the significance of the results on herbarium specimens and to compare the antidesmone content in bark, root and leaves. Antidesmone could be unambiguously identified in 12 of 13 Antidesma spp., as well as in the two other investigated genera of subtribe Antidesminae, in levels of up to 65 mg/kg plant dry weight. Antidesmone was not found in specimens from other subtribes. Antidesmone-derived compounds occur in much lower concentrations than antidesmone.Selected species of the tribe Antidesmeae (Euphorbiaceae, subfamily Phyllanthoideae) have been screened for the occurrence of antidesmone and some derived compounds by HPLC and LC–MS/MS analysis, including selected reaction monitoring (SRM). Antidesmone could be identified in 12 of 13 Antidesma species as well as in the two other investigated genera of subtribe Antidesminae. It was not found in specimens from other subtribes.

Two novel alkaloidal glucosides derived from the recently discovered antidesmone (1 ), together with four known megastigmane and three lignan glucosides, two of which had not previously been described, were isolated from 1‐butanol extracts of Antidesma membranaceum (Euphorbiaceae). The structural elucidation of (17RS )‐17‐(β‐D ‐glucopyranosyloxy)antidesmone (2 ) and (17RS )‐8‐deoxo‐17‐(β‐D ‐glucopyranosyloxy)antidesmone (3 ) is based on 1H, 13C, COSY, NOESY, HMQC and HMBC NMR spectra, together with LC/ESI‐CIDMS and CD data. Determination of the absolute configuration at C‐17 was accomplished by comparison with 1H NMR spectroscopic data for alk‐2‐yl β‐D ‐glucopyranosides, an approach that also proved useful for the megastigmane glucosides blumenyl C β‐D ‐glucopyranoside (4 ), 3‐oxo‐α‐ionyl β‐D ‐glucopyranoside (5 ), blumenyl B β‐D ‐glucopyranoside (6 ) and blumenyl A β‐D ‐glucopyranoside (7 ). The lignan glucosides lyoniresin‐4‐yl β‐D ‐glucopyranoside (8 ), 4′‐O‐methyllyoniresin‐4‐yl β‐D ‐glucopyranoside (9 ) and secoisolariciresin‐4‐yl β‐D ‐glucopyranoside (10 ), featuring an unusual glucosylation position, were investigated with the aid of 1H and 2D NMR, CD and MS data.

The structure of antidesmone, an alkaloid from Antidesma membranaceum Müll. Arg. and A. venosum E. Mey. (Euphorbiaceae), was revised to be (S)-4,8-dioxo-3-methoxy-2-methyl-5-n-octyl-1,4,5,6,7,8-hexahydroquinoline [(S)-2], not the isoquinoline derivative 1, as assumed previously. The revision was initiated by biosynthetic feeding experiments of one of our groups.

A novel type of tetrahydroisoquinoline alkaloid, antidesmone (1), was isolated from Antidesma membranaceum Müll. Arg.. The structure of 1 was determined to be (5S)-1-hydroxy-4-methoxy-3-methyl-5-octyl-5,6,7,8-tetrahydroisoquinolin-8-one by spectroscopic methods (MS, 1H, 13C 2D NMR, CD) and chemical derivatisation. The absolute (S)-configuration was determined by quantumchemical calculation of CD spectra.Antidesmone (1), a novel type of tetrahydroisoquinoline alkaloid, was isolated from Antidesma membranaceum Müll. Arg. The structure of 1 was determined to be (5S)-1-hydroxy-4-methyl-5-octyl-5,6,7,8-tetrahydroisoquinolin-8-one.

From Antidesma membrananeum, besides three feruloyl amides and (−)-syringaresinol, new phenolic compounds have been isolated. Their structures were established as two series of 2-alkylated 5,7-dihydroxychromones and 2,5,7-trihydroxychromanones, and the dimeric compound, 8,8-bis-(dihydroconiferyl)-diferuloylate, respectively, from their spectroscopic data.