J. Schmidt

Synthesis of N-(jasmonoyl)amino acid conjugates

Abstract Both racemic jasmonic acid [(±)-JA] and the naturally occurring (-)-enantiomer [(-)-JA] have been reacted with aliphatic, aromatic as well as acidic amino acids to form amide-linked derivatives. The diastereoigomeric products of (±)-jasmonic acid with S-Val, S-Leu, S-Ile, S-Phe, S-Trp, R-Val, and R-Phe could be separated by silica gel chromatography. The synthesized N-(jasmonoyl)-conjugates have been structurally characterized by MS, 1H NMR, IR and ORD.

ANTIDESMONE, A NOVEL TYPE ISOQUINOLINE ALKALOID FROM ANTIDESMA MEMBRANACEUM (EUPHORBIACEAE)

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

Acyl-conjugated metabolites of brassinosteroids in cell- suspension cultures of Ornithopus-sativus

Abstract Exogenously applied 24-epi-brassinolide and 24-epi-castasterone were transformed by a cell suspension culture of Ornithopus sativus to give fatty acid conjugates of 3,24-bisepi-brassinolide and 3,24-bisepi-castasterone, respectively, esterified at the 3β-position. The conjugates were identified by means of 1 H NMR and mass spectrometry. Lauric acid, myristic acid and palmitic acid were the acyl components for both brassinosteroid conjugate types. Non-conjugated 3,24-bisepi-brassinolide was also found for the first time in a plant system.

β-Carboline alkaloids from Hedyotis capitellata

Three new β-carboline alkaloids were isolated from Hedyotis capitellata (Rubiaceae). Their structures were elucidated by spectroscopic data and X-ray analysis.

Alkaloidal, Megastigmane and Lignan Glucosides from Antidesma membranaceum (Euphorbiaceae)

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.

Sterols and triterpenoids from the cyanobacterium Anabaena hallensis

The sterol pattern of the cyanobacterium Anabaena hallensis has been investigated. Several sterols and triterpenes were found for the first time in the genus Anabaena.

Fissistigmatins A–D: Novel Type Natural Products with Flavonoid–Sesquiterpene Hybrid Structure from Fissistigma bracteolatum

Abstract From Fissistigma bracteolatum Chatt. (Annonaceae), a Vietnamese folk medicinal plant, the novel type natural products fissistigmatin A–D (1–4), being composed of a flavonoid and a sesquiterpene moiety, were isolated. Their structures were elucidated by extensive NMR techniques, MS, CD, molecular modelling calculations and X-ray analysis.

Lupeol long-chain fatty acid esters and other triterpenoid constituents from Plumeria obtusifolia

Abstract From the bark of Plumeria obtusifolia was isolated a series of lupeol fatty esters with the carbon numbers 16, 18,20 and 21–28 in the fatty acid part. Furthermore, lupeol, lupeol acetate, sitosterol, stigmasterol and campesterol were also identified.

A monoterpenoid peroxide from Adenosma caeruleum

Abstract A new monoterpenoid peroxide was isolated from the aerial parts of Adenosma caeruleum . Its structure has been elucidated on the basis of spectroscopic data, especially 2D NMR spectroscopy.

Apotirucallane triterpenoids from Luvunga sarmentosa (Rutaceae)

The leaves of Luvunga sarmentosa (Bl.) Kurz. yielded eight apotirucallane triterpenoids named luvungins A-G, and 1alpha-acetoxyluvungin A. Characteristic of the structure are the seven-membered lactone-ring A, the alpha-hydroxyl or alpha-acetoxyl group at C-7 and an oxygen bridge in the side chain giving five-, six- or seven-membered rings, respectively. Because of a hemiacetal function at C-21, luvungin C occurred as a mixture of 21-epimers. The structures have been elucidated on the basis of MS and NMR spectral data. In addition, two known coumarins ostruthin (6-geranyl-7-hydroxycoumarin) and 8-geranyl-7-hydroxycoumarin as well as five known triterpenes friedelin, flindissone, melianone, niloticin and limonin were isolated.