Publikation
Anh, N. T. H.; Sung, T. V.; Wessjohann, L.; Some homoisoflavonoidal compounds from Ophiopogon Japonicus Ker-gawler Vietnam J. Chem. 41, 117-121, (2003)
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Anh, N. T. H.; Sung, T. V.; Franke, K.; Wessjohann, L. A.; Phytochemical studies of Rehmannia glutinosa rhizomes Pharmazie 58, 593-595, (2003)
2,4-Dimethoxy-2-methyl-6H-pyran-3-one (1), a hitherto unknown natural product, and the calcium salt of rehmapicroside (2) have been isolated from rhizomes of the Vietnamese variety of Rehmannia glutinosa Libosch together with a series of known compounds: norcarotenoids (3–5), 2-formyl-5-hydroxymethylfurane (6), the iridoid rehmaglutin D (7), iridoid glycosides (8–12) and phenylethyl alcohol glycosides (13–17). Their structures were determined by mass and NMR spectroscopy.
Publikation
Anh, N. T. H.; Sung, T. V.; Porzel, A.; Franke, K.; Wessjohann, L. A.; Homoisoflavonoids from Ophiopogon japonicus Ker-Gawler Phytochemistry 62, 1153-1158, (2003) DOI: 10.1016/S0031-9422(02)00515-0
From the ethyl acetate extract of the tuberous roots of Ophiopogon japonicus (Liliaceae) eight known and five new homoisoflavonoidal compounds were isolated. The new compounds are 5,7-dihydroxy-8-methoxy-6-methyl-3-(2′-hydroxy-4′-methoxybenzyl)chroman-4-one (1), 7-hydroxy-5,8-dimethoxy-6-methyl-3-(2′-hydroxy-4′-methoxybenzyl)chroman-4-one (2), 5,7-dihydroxy-6,8-dimethyl-3-(4′-hydroxy-3′-methoxybenzyl)chroman-4-one (3), 2,5,7-trihydroxy-6,8-dimethyl-3-(3′,4′-methylenedioxybenzyl)chroman-4-one (4) and 2,5,7-trihydroxy-6,8-dimethyl-3-(4′-methoxybenzyl)chroman-4-one (5). Their structures have been elucidated by mass and NMR spectroscopy. Compounds 4 and 5 are the first isolated homoisoflavonoids with a hemiacetal function at position 2.Five new and eight known homoisoflavonoids were isolated from the tuberous roots of the medicinal plant Ophiopogon japonicus (Liliaceae) and identified by spectroscopic data.
Publikation
Samappito, S.; Page, J. E.; Schmidt, J.; De-Eknamkul, W.; Kutchan, T. M.; Aromatic and pyrone polyketides synthesized by a stilbene synthase from Rheum tataricum Phytochemistry 62, 313-323, (2003) DOI: 10.1016/S0031-9422(02)00545-9
A cDNA encoding a stilbene synthase, RtSTS, was isolated from the rhizomes of Tatar rhubarb, Rheum tataricum L. (Polygonaceae), a medicinal plant containing stilbenes and other polyketides. Recombinant RtSTS was expressed in E. coli and assayed with acetyl-coenzyme A (CoA), n-butyryl-CoA, isovaleryl-CoA, n-hexanoyl-CoA, cinnamoyl-CoA and p-coumaroyl-CoA as primers of polyketide synthesis. RtSTS synthesized resveratrol and a trace amount of naringenin chalcone from p-coumaroyl-CoA, supporting the enzyme's identification as a resveratrol-type stilbene synthase (EC 2.3.1.95). Bis-noryangonin and p-coumaroyl triacetic acid lactone (CTAL)-type pyrones were observed in minor amounts in the reaction with p-coumaroyl-CoA and as major products with cinnamoyl CoA. As well, such pyrones, and not aromatic polyketides, were identified as the only products in assays with aliphatic and benzoyl CoA esters. Acetonyl-4-hydroxy-2-pyrone, a pyrone synthesized from acetyl-CoA, was identified as a new product of a stilbene synthase. Using Northern blot analysis, RtSTS transcript was found to be highly expressed in R. tataricum rhizomes, with low transcript levels also present in young leaves. This expression pattern correlated with the occurrence of resveratrol, which was detected in higher amounts in R. tataricum rhizomes compared with leaves and petioles using HPLC. Few stilbene synthases have been found in plants, and the identification of RtSTS provides additional sequence and catalytic information with which to study the evolution of plant polyketide synthases.A cDNA encoding a plant polyketide synthase was isolated from Rheum tataricum and functionally charactarized as a resveratrol-forming stilbene synthase.
Publikation
Nguyen, T. H. A.; Sung, T. V.; Wessjohann, L.; Steroidal glycosides from Ophiopogon Japonicus Vietnam J. Chem. 41, 136-142, (2003)
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Münzenberger, B.; Hammer, E.; Wray, V.; Schauer, F.; Schmidt, J.; Strack, D.; Detoxification of ferulic acid by ectomycorrhizal fungi Mycorrhiza 13, 117-121, (2003) DOI: 10.1007/s00572-003-0226-9
The ectomycorrhizal fungi Laccaria amethystina and Lactarius deterrimus grown in liquid culture were used to study the fate of added ferulic acid. Laccaria amethystina degraded ferulic acid to the major metabolite vanillic acid. The intermediate vanillin was not detected. Lactarius deterrimus showed a completely different detoxification pattern. Two dimers and one trimer of ferulic acid could be identified as polymerization products of this fungus. A bioassay of the possible biological activities of ferulic acid and vanillic acid on these fungi revealed that vanillic acid was less toxic than ferulic acid for Laccaria amethystina but that both phenolic acids were toxic for Lactarius deterrimus. The results are discussed with respect to ectomycorrhizal fungal growth in the organic layer of forest soils and between living root cells of ectomycorrhizas.
Publikation
Kolbe, A.; Porzel, A.; Schmidt, J.; Adam, G.; A new synthesis of [26,28-2H6]brassinolide and [26,28-2H6]castasterone via an unusual methyl migration J. Label. Compd. Rad. 46, 231-242, (2003) DOI: 10.1002/jlcr.662
Deuterium‐labelled brassinosteroids, namely [26,28‐2H6]castasterone, 8 , and [26,28‐2H6]brassinolide, 9 , were synthesized starting from 6,6‐ ethylenedioxy‐20‐formyl‐2α,3α‐isopropylidenedioxy‐5α‐pregnane, 1 , and 3‐[2H3]methyl‐but‐1‐yne‐[4,4,4‐2H3], 11 . Upon alkylating cleavage of the epoxide 6 with trimethylaluminium‐n‐butyllithium an unusual migration of a neighbouring [2H3]methyl group takes place to afford deuteriation at positions 26 and 28.
Publikation
Jarry, H.; Spengler, B.; Porzel, A.; Schmidt, J.; Wuttke, W.; Christoffel, V.; Evidence for Estrogen Receptor β-Selective Activity of Vitex agnus-castus and Isolated Flavones Planta Med. 69, 945-947, (2003) DOI: 10.1055/s-2003-45105
Recent cell culture experiments indicated that extracts of Vitex agnus-castus (VAC) may contain yet unidentified phytoestrogens. Estrogenic actions are mediated via estrogen receptors (ER). To investigate whether VAC compounds bind to the currently known isoforms ERα or ERß, ligand binding assays (LBA) were performed. Subtype specific ER-LBA revealed a binding of VAC to ERß only. To isolate the ERß-selective compounds, the extract was fractionated by bio-guidance. The flavonoid apigenin was isolated and identified as the most active ERß-selective phytoestrogen in VAC. Other isolated compounds were vitexin and penduletin. These data demonstrate that the phytoestrogens in VAC are ERß-selective.
Publikation
Thuy, T. T.; Sung, T. V.; Wessjohann, L.; Chemical constituents of the roots of Codonopsis pilosula Vietnam J. Chem. 41, 119-123, (2003)
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Spiteller, P.; Arnold, N.; Spiteller, M.; Steglich, W.; Lilacinone, a Red Aminobenzoquinone Pigment from Lactarius lilacinus J. Nat. Prod. 66, 1402-1403, (2003) DOI: 10.1021/np0303052
A red pigment, lilacinone (1), was isolated from fruit bodies of the toadstool Lactarius lilacinus. Its structure was established by 2D NMR and APCIMS methods. Compound 1 is a novel type of fungal aminobenzoquinone pigment and may be biosynthetically derived from three molecules of anthranilic acid.
