Secondary-emission mass spectrometry of hederagenin glycosides and medicagenic acid glycosides

The secondary emission (SE) spectra of six glycosides of medicagenic acid (MA) and of hederagenin have been studied. The (M + H)⁺ ions were observed in the secondary ion spectra (LSIMS) of mono- and biosides of MA and also of a triand a tetraoside of hederagenin in a glycerol matrix. The (M + Na)⁺ ions were recorded in the spectra of tri- and tetraosides of MA. In the majority of cases processes involving the successive splitting out of the carbohydrate units were revealed. Positive- and negative-ion spectra have been obtained on the ionization by bombardment with fast atoms — FAB + and FAB – — of a trioside and a tetraoside of MA. The FAB – spectra are the most characteristic: They show intense peaks of the (M - H)^– ions and of the products of the sequential elimination of the sugar residues.Institute of the Chemistry of Plant Substances, Uzbekstan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 98–102, January–February, 1992.     

Spectrophotometry of glycosides of oleanolic acid and hederagenin in concentrated sulfuric acid

Summary The UV spectra in concentrated sulfuric acid of hederagenin and oleanolic acid and their glycosides has been studied. For analytical purposes it is proposed to use the extremum at a wavelength of 405 nm, which is distinguished by constancy of position and intensity of absorption for the genins and their glycosides.A spectrophotometric method is proposed for the determination of the triterpene glycosides in a preparation from the bulbs ofLeontice ewersmannii Bge.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 220–227, March–April, 1977.     

Color reactions of pyridines with pentacyanoamminoferrate

Trisodium pentacyanoamminoferrate is proposed as a spot test, chromatographic spray or spectrophotometric reagent for pyridines. A 1:1 colored complex of the reagent and pyridine derivative is formed in aqueous solution. The intensity and stability of the color varies with the pH.     

Effect of hydrolysis on the yield of hederagenin and High-performance thin-layer chromatography densitometric quantification of hederagenin in fruit pericarp of Sapindus spp

Fruit pericarp of Sapindus species are reported to contain glycosides with hederagenin as an aglycone. To free the aglycone from the glycosides, they need to be hydrolyzed, and the commonly used method is hydrolysis with either hydrochloric or sulfuric acid. In the present work, we studied the effect of hydrolysis on the yield of hederagenin from the fruit pericarp of 3 species of Sapindus, viz., S. mukorossi, S. laurifolius, and S. emarginatus. A high-performance thin-layer chromatography densitometric method for the quantification of hederagenin was developed and validated. It involved automated application of samples as bands onto silica gel 60F254 plates, development with toluene-ethyl acetate-formic acid (7 + 3 + 5, v/v/v) mobile phase, detection with anisaldehyde-sulfuric acid reagent, and scanning at 595 nm. The yield of hederagenin ranged from 0.035 to 1.29% (w/w) with different methods of hydrolysis. Hydrolysis with 3.5 M aqueous sulfuric acid under reflux for 6 h gave the maximum yield of hederagenin in all 3 species, with the highest amount in S. emarginatus (1.29%, w/w).     

Maleimide polymers. III. Color reactions and kinetics

We have shown previously that the free-radical polymerization kinetics of maleimide can be explained by a scheme for retarded polymerization. The steps involve tautomerization of a growing maleimidyl chain to succinimidyl, the retarded addition of maleimide to the latter, and termination solely by resonance-stabilized succinimidyl radicals. Combination termination is preferred, since this yields a very stable N,N′-bisuccinimidyl structure. Other authors also invoke tautomerization to succinimidyl radicals which they believe terminate by disproportionation with growing maleimidyl chains to generate polymer with unsaturated endgroups. Free-radical-initiated polymaleimides are colored in the presence of base. Our measurements of the absorbance of polymaleimides at 387 and 500 nm in the presence of excess strong organic base show there is essentially no dependence on molecular weight. This suggests that the chromophoric groups are intramolecular and that color does not arise from the ionization of allylic protons associated with terminal double bonds. The near-ultraviolet spectra of polymaleimides in slightly acidic media contain absorption bands at about 288, 320, and 360 nm. The structural impurities that account for these bands cannot be terminal unsaturation. We propose that the origin of these bands is pyrrolinone type structures which are formed by a retarded polymerization step through succinimidyl oxygen.     

Phenolic glycosides of Juncus acutus and its anti-eczematic activity

The total alcohol extract of Juncus acutus L. showed significant anti-eczematic activity. The isolation of the five phenolic glycosides which responsible for this activity were isolated and identified as oxyresveratrol 2-O-β-D-glucopyranoside (1), resveratrol 3′,4′-O,O′-di-β-D-glucopyranoside (2), markhamioside F (3), canthoside B (4), and caffeic acid glucorhamnoside (5). The toxic effect of the alcohol extract of the plant was studied on mice to determine their LD₅₀, which proved to be nontoxic up to 3000 mg/kg body weight. The anti-eczematic activity of the isolated compounds was tested in mice and showed variable effect. Compounds 3 and 4 were found to have the highest activity; they cured eczema by 90 and 100% respectively. Published in Khimiya Prirodnykh Soedinenii, No. 2, pp. 125–127, March–April, 2006.     

Regio- and stereoselective synthesis of 2-deoxy-C-aryl glycosides via palladium catalyzed decarboxylative reactions

An efficient and versatile approach for the synthesis of 2-deoxy-C-aryl glycosides is reported. This strategy is based on a palladium-catalyzed decarboxylative Heck coupling reaction of benzoic acids and glycals. A wide variety of glycals and benzoic acids have been screened, and all these reactions could afford the desired C-aryl glycoside products in moderate to good yields with exclusive regio- and stereoselectivities.     

Color reactions of polyarylenesulfophthalides in aniline-cyclohexanone mixtures in air

Slow color reactions occur when some polyarylenesulfophthalides are dissolved in an aniline—cyclohexanone mixture; these reactions involve generation of triarylmethyl type radicals that were characterized by ESR and UV spectroscopy. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 389–391, February, 1997.     

Color reactions of aldehydes and ketones with vanillin in alkaline medium

Vanillin in alkaline medium is a very useful reagent for the detection of carbonyl-bearing compounds, especially ketones, yielding yellow, orange or red colorations in the reaction mixture. he intensity of the reaction and the particular color produced depends upon the constitution of the compound and its concentration. The reaction works best with aliphatic ketones, especially when these contain a methyl group. Acetone with two methyl radicals yields the maximal color. As the carbon chains in the ketone radicals lengthen, reactivity diminishes. Aromatic ketones are least reactive or do not react at all.     

曲利本蓝-氨基糖苷类抗生素的显色反应及其分析应用

曲利本蓝 (TB)与硫酸卡那霉素 (KANA)和硫酸妥布霉素 (TOB)等氨基糖苷类抗生素在pH 2 .0～ 7.0的条件下反应生成蓝色离子缔合物。其最大显色波长位于 680nm(TOB)和 686nm(KANA) ,线性范围分别是 0～ 1 1 .0 μg mL(TOB)和0～ 1 3.0 μg mL(KANA) ,摩尔吸光系数 (ε)分别为 5 .32× 1 0 3(TOB)和 3.64× 1 0 3(KANA)L·mol-1·cm-1;最大褪色波长位于 5 88nm(TOB)和 5 90nm(KANA) ,线性范围均为 0～ 1 1 .0 μg mL ,摩尔吸光系数 (ε)分别为 1 .84× 1 0 4 (TOB)和 1 .1 1× 1 0 4(KANA)L·mol-1·cm-1。当用双波长叠加法时 ,ε值分别为 2 .37× 1 0 4 (TOB)和1 47× 1 0 4 (KANA)L·mol-1·cm-1。探讨了适宜的反应条件及主要的分析化学性质。该方法用于市售药物中氨基糖苷类抗生素的测定。     

Carbon suboxide and some of its reactions

The reaction of carbon suboxide with a number of 2-amino-1,3,4-thiadiazoles has given the corresponding pyrimido[1,2-b]-1,3,4-thiadiazoles     

Carbon suboxide and some of its reactions

Reaction of carbon suboxide with a number of 2-aminopyrimidines gives compounds which are considered to be 2, 3-(dioxotetrahydropyrimido)pyrimidines or 1, 2-(dioxotetrahydropyrimido)pyrimidines.For Part XX see [4].     

Carbon suboxide and some of its reactions

Reaction of carbon suboxide with some 2-aminobenzimidazoles is investigated, and some corresponding 2, 3-(dioxotetrahydropyrimido) benzimidazoles obtained, which arylate to enol form derivatives.For Part XXIII see [3].