Dimeric stilbenes of the wood of Maackia amurensis

Dimeric stilbenes have been isolated from the wood of Amur maackia for the first time. Two of them have been identified as the known scirpusins A and B. The structure of a new dimeric stilbene with a dioxane linkage, which has been called maackinin, has been established. The PMR and¹³C NMR spectra of the substances isolated have been studied in detail. Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 468–476, September–October, 1992.     

Determination of phenolic components in ethanolic extracts from wood of Maackia amurensis

The phenolic components in an ethanolic extract from the wood of Amur maackia were determined quantitatively by the HPLC method in the isocratic regime using a column with a C₁₉ reversed-phase sorbent and β-naphthol acetate as internal standard. Before injection into the chromatographic column, the extract was purified on a column of Florisil that had been treated with 30% acetic acid. The relative error in the determination of each component at a confidence level of 0.95 does not exceed 7%.     

Determination of phenolic components in ethanolic extracts from wood of Maackia amurensis

The phenolic components in an ethanolic extract from the wood of Amur maackia were determined quantitatively by the HPLC method in the isocratic regime using a column with a C₁₉ reversed-phase sorbent and -naphthol acetate as internal standard. Before injection into the chromatographic column, the extract was purified on a column of Florisil that had been treated with 30% acetic acid. The relative error in the determination of each component at a confidence level of 0.95 does not exceed 7%.Pacific Institute of Bioorganic Chemistry, Far Eastern Branch, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 801–804, November–December, 1988.     

Lupin alkaloids from Chinese Maackia amurensis

Two new alkaloids were isolated together with 16 known lupin alkaloids from the leaves and stems of Chinese Maackia amurensis. Their structures were determined by spectroscopic methods to be (-)-6alpha-methoxylupanine and (-)-5alpha-(12-cytisinylmethyl)-6alpha-hydroxylupan ine and identified by comparison with synthetic samples. The structures of lupin alkaloids were also related to the geographical distributions of the Maackia plants.     

Isoflavones and stilbenes of the heartwood ofMaackia amurensis

The isoflavin retusin, squalene, 3,4′,5-trihydroxystilbene (resveratrol), 3,3′,4′,5-tetrahydroxystilbene, and a new compound constructed of fragments of retusin and 3,3′,4′,5-tetrahydroxystilbene have been isolated for the first time from an ethanolic extract of the heartwood ofMaackia amurensis Rupr. et Maxim (Fabaceae) growing in Maritime Territory. The high-molecular-weight polyphenols that impart the characteristic coloration to macckia wood are present in an amount of 7%. The majority of the phenolic compounds isolated showed a high antiradical and antioxidant activity.     

A new isoflavonostilbene from the heartwood of Maackia amurensis

A new isoflavonostilbene which has been called maackiasin has been isolated from an ethanolic extract of the heartwood ofMaackia amurensis and its structure has been established by spectral methods. The maackiasin molecule is constructed of fragments of the isoflavone retusin and of 3,3,4,5-tetrahydroxystilbene linked by a diether bond. The dioxane grouping connecting the two fragments is constructed from the hydroxyls at C-7 and C-8 of the isoflavone and the vinyl grouping of the stilbene. Maackiasin is the first representative of a new type of natural polyphenols.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 39–42, January–February, 1986.     

Isoflavonoids from Heartwood of Maackia amurensis Rupr. et Maxim.

Orobol, tektorigenin, (-)-medicarpin, (±)-vestitol, and a new isoflavanone, the structure of which was established by chemical transformations and spectral data, were isolated from heartwood ofMaackia amurensis     

About native components of extracts fromMaackia amurensis wood

A new dimeric stilbene, the name for which is suggested as maackin A, is isolated from the wood ofMaackia amurensis. The structure of maackin A is determined by NMR, UV, and IR spectral methods. Thecis-isomers that are observed during fractionation of the extracts are not native components of the wood but are formed from thetrans-dimers under certain separation conditions. Pacific Institute of Bioorganic Chemistry, Far-East Branch, Russian Academy of Sciences, Vladivostok-22, pr.Stoletiya Vladivostoka, 159. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 664–669, September–October, 1999.     

Minor polyphenols from <Emphasis Type="Italic">Maackia amurensis</Emphasis> wood

The rare α,4,2′,4′-tetrahydroxydihydrochalcone, flavanones liquiritigenin and naringenin, isoflavones calycosin and 5-methoxydaidzein, and reduced stilbene dihydroresveratrol were isolated for the first time from Maackia amurensis wood. The structures of the pure compounds were established using 2D NMR COSY, NOE, HMBC, and HSQC experiments. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 575–577, November–December, 2008.     

Copolymerization of N-ethylmaleimide with stilbenes

Charge-transfer complexes in solutions of ethylmaleimide and stilbenes have been characterized by spectroscopy. The stoichiometric compositions of these complexes have been shown by Job's method to be 1:1 molar complexes. The value of the equilibrium constant K for complex formation of ethylmaleimide with stilbene derivative increases in the following probable order: ethylmaleimide–stilbene ? ethylmaleimide–dimethylaminostilbene (DMAS) < ethylmaleimide–aminodimethylaminostilbene (ADMAS). From the calculations of the electron density of the highest occupied level for the stilbenes, the charge transfer in ethylmaleimide–DMAS and ethylmaleimide–ADMAS is attributed to n → π transition, while the charge transfer in ethylmaleimide-stilbene is attributed to n → π transition. Copolymerization was carried out by γ-irradiation in benzene or THF solutions of the comonomer pairs. The alternating tendency of copolymerization was larger in the ethylmaleimide–DMAS system than in the ethylmaleimide–stilbene system. This can be explained by assuming resonance structures in the transition state of addition reaction of DMAS to the propagating ethylmaleimide unit. In the copolymerization of ethylmaleimide with ADMAS, the effect of the penultimate unit was more important than in that with DMAS.     

Synthesis of substituted stilbenes via the Knoevenagel condensation

Knoevenagel condensations between aldehydes and substrates containing active methylene groups were carried out in ethanol at room temperature, in the presence of potassium phosphate, to afford unsymmetrical olefins. These condensations have been shown to afford only the E-isomers in greater than 80% yields. Salicylaldehyde first produces the Knoevenagel condensation products, which undergo a subsequent heterocyclization to give coumarin derivatives. The structures of the synthesized compounds were established on the basis of UV, IR, MS and NMR spectroscopy.     

Oligomeric stilbenes from the root of Caragana stenophylla

Caragaphenol A (1), a new trimeric stilbene, was isolated from the roots of Caragana stenophylla (Leguminosae) along with three known oligomeric stilbenes: (+)-alpha-viniferin (2), miyabenol C (3) and kobophenol A (4). The stereostructure of 1 was elucidated by one- and two-dimensional (1D- and 2D-)-NMR spectral studies.     

The nematocidal activity and the structure-activity relationships of stilbenes

The pinewood nematode, Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle, is the causative agent of the pine wilt disease which has been devastating forests of Pinus densiflora Sieb.et Zucc. and P. thunbergii Parl. in Japan. To prevent the pine wilt disease, the development of nematocidal compound is required. Twenty-one synthesized stilbenes (1)-(20), (23), salicylic acid (21), and phenylsalicilate (22) were examined for their nematocidal activity against an isolate of B. xylophilus (T-4). Among the tested compounds, two fluorinated stilbenes (15) and (13), were found to be most potent compounds against T-4, demonstrating 99% and 98% lethality at 10 ppm concentration. The LD50 values of compounds 15 and 13 were 3 ppm, respectively.