S. V. Sysolyatin

Shikimic acid: review of its analytical, isolation, and purification techniques from plant and microbial sources

Shikimic acid properties and its available analytical techniques are discussed. Plants having the highest content of shikimic acid are shown. The existing isolation methods are analyzed and the most optimal approaches to extracting this acid from natural sources (plants and microorganisms) are considered.

New syntheses of [1,2,5]oxadiazolo[3,4-e][1,2,3,4]tetrazine 4,6-dioxide

New methods were developed for the synthesis of [1,2,5]oxadiazolo[3,4-e][1,2,3,4]tetrazine 4,6-dioxide from 4-(tert-butyl-NNO-azoxy)-N-nitro-1,2,5-oxadiazol-3-amine or its alkali metal salts and acid anhydrides (or chlorides) in the presence of strong acids. The yield of [1,2,5]oxadiazolo[3,4-e][1,2,3,4]tetrazine 4,6-dioxide in acetic anhydride in the presence of sulfuric acid or sulfuric anhydride at 20°C in 20 min attained 83%. A general mechanism was proposed for the reactions under study. Acetyl group behaved for the first time as departing group in the synthesis 1,2,3,4-tetrazine 1,3-dioxides, and [1,2,5]oxadiazolo[3,4-e][1,2,3,4]tetrazine 4,6-dioxide was obtained in 47% yield from N-[4-(acetyl-NNO-azoxy)-1,2,5-oxadiazol-3-yl]acetamide.

Neuroprotective effects of p-tyrosol after the global cerebral ischemia in rats.

BACKGROUND Salidroside is a biologically active compound derived from Rhodiola rosea L. Studies showed that salidroside after i.v. injection is extensively metabolized to p-tyrosol and only trace amounts of salidroside are found in the brain tissue. OBJECTIVE The aim of the study was to investigate the neuroprotective effects of p-tyrosol in the global cerebral ischemia-reperfusion (GCI) model. STUDY DESIGN A total of 103 Wistar rats were assigned to groups of sham-operated (n=10), control (n=42), p-tyrosol-treated (n=36), and pentoxifylline-treated (n=15) animals. The rats of control, p-tyrosol-treated, and pentoxifylline-treated groups received intravenously 0.9% NaCl solution, 2% solution of p-tyrosol in doses of 5mg/kg, 10mg/kg, and 20mg/kg, and pentoxifylline in a dose of 100mg/kg, respectively, daily for 5 days. Rats were examined at days 1, 3, and 5 after GCI. After evaluation of neurological deficit, animals were euthanized for morphological and biochemical characterization. METHODS Rats of control, p-tyrosol-treated, and pentoxifylline-treated groups were exposed to three-vessel model of GCI. Neurological deficit, numeric density of neurons in hippocampal CA1 region, and percentage of neurons with focal and total chromatolysis were studied. Biochemical study assessed contents of conjugated dienes and fluorescent products in brain homogenate. RESULTS In control group, only 50.0% of rats survived by day 5 after the GCI; 38.1% of survived animals had severe neurologic deficit. In brain tissue of PTX-treated rats, the levels of diene conjugates and fluorescent products were 79% and 73%, respectivley, at day 5 compared with control. Differences in diene conjugates were statistically significant compared with control. The survival rate of animals treated with 20mg/kg p-tyrosol was 82.3% at day 5 after GCI. In p-tyrosol-treated GCI rats, the numeric density of neurons in the hippocampal CA1 region was higher by 31% compared with control. The percentage of neurons with focal and total chromatolysis decreased by 27% and 43%, respectively. At day 5 after GCI, the levels of conjugated dienes and fluorescent products were significantly lower (by 37% and 45%, respectively) in group of animals treated with 20mg/kg p-tyrosol compared with control. Moderate neuroprotective effects of 5mg/kg p-tyrosol administration were documented only at day 5 after GCI. In case of 10mg/kg p-tyrosol administration, neuroprotection was documented sooner: at day 1 or 3 after GCI. However, administration of 5 and 10mg/kg p-tyrosol did not affect animal survival. CONCLUSION Course administration of intravenous p-tyrosol in a dose of 20mg/kg increased survival, reduced neurological deficit after GCI, attenuated neuronal damage in the hippocampus, and attenuated lipid peroxidation in brain tissue in animals subject to GCI with reperfusion.

An unusual reduction route of 2,4,6-trinitrobenzoic acid under conditions of aqueous-phase hydrogenation over Pd/Sibunit catalyst

For the first time it was established that the catalytic hydrogenation of 2,4,6-trinitrobenzoic acid to 1,3,5-triaminobenzene can proceed via the formation of aromatic hydroxyamines and cyclohexane-1,3,5-trione trioxime. As a result of aqueous-phase hydrogenation of sodium salt of 2,4,6-trinitrobenzoic acid in the presence of 5%Pd/Sibunit catalyst at a temperature of 323 K and pressure of 0.5 MPa, a trioxime in high yield (about 70 %) was obtained. Due to high selectivity to cyclohexane-1,3,5-trione trioxime the catalytic hydrogenation of sodium salt of 2,4,6-trinitrobenzoic acid can be considered as a new method for its synthesis.

Facile method for the synthesis of oseltamivir phosphate

A ten-step scheme for the preparation of an antiviral agent, ethyl (3R,4R,5S)-4-acetylamino-5-amino-3-(pent-3-yloxy)cyclohex-1-enecarboxylate phosphate, from (-)-shikimic acid was studied. The main parameters of the synthesis were determined and the optimal conditions for the preparation of the intermediate compounds were selected. The total yield of oseltamivir phosphate calculated based on (-)-shikimic acid was 27%.

An Acid-Catalyzed Cascade Synthesis of Oxaazatetracyclo [5.5.0.03,11.05,9]dodecane Derivatives

ABSTRACT A condensation between mesylamide and glyoxal under highly acidic conditions was studied. A series of new compounds whose structures contain a moiety of oxaazatetracyclo[5.5.0.03,11.05,9]dodecane were synthesized. The synthesis processes were optimized and main factors affecting the assembling of cage products were revealed. Assumptions are made regarding the formation mechanism of these chemical entities. For the first time, compounds have been obtained that include moieties of 2,6,8-trioxa-4,10,12-triazatetracyclo[5.5.0.03,11.05,9]dodecane and 2,4,6-trioxa-8,10,12-triazatetracyclo[5.5.0.03,11.05,9]dodecane. An X-ray diffraction analysis of the new compounds was performed.

Improved synthesis of 2,7-dihydroxyfluorenone in the manufacture of tilorone with application of a rotor—stator system

A method for improving the quality and increasing the yield of 2,7-dihydroxyfluorenone by using a rotor– stator apparatus in the process technology is described. The results can be used in the manufacturing of tilorone.

A search for raw materials for the isolation of shikimic acid

The content of shikimic acid in the vegetative parts of a number of plants growing in the Altai Territory has been studied. The greatest content of shikimic acid (about 1.5%) was found in the coniferous needles of Scots pine. Shikimic acid accumulated in buckwheat cells cultivated in vitro on glyphosate-containing medium. The best results were obtained with buckwheat explants cultivated in vitro on Murashige and Skoog nutrient medium in the presence of 0.5 × 10−3 mg/L of glyphosate.

Anti-Ischemic Activity of n-Tyrozol under Conditions of Repeated Transient Myocardial Ischemia in Rats

We studied anti-ischemic activity of n-tyrozol under conditions of repeated transient myocardial ischemia in rats caused by repeated (5×3 min) occlusion of the left coronary artery. n-Tyrozol administered intraperitoneally in a dose of 20 mg/kg daily over 4 days before the ischemia modeling (the last injection 15 min prior to the start of the experiment) produced a clear-cut anti-ischemic effect: it reduced ST elevation and promoted more complete recovery of ECG during reperfusion. During reperfusion periods, n-tyrozol significantly decreased the risk of ventricular fibrillation and shortened the duration of tachyarrhythmia episodes (ventricular tachycardia and fibrillation).

Synthesis of new N-polysubstituted oxaazaisowurtzitanes by acid-catalyzed condensation of sulfonamides with glyoxal

By application of acid-catalyzed condensation of propane-2-, benzene- and methanesulfonamides with glyoxal a series of new derivatives of oxaazaisowurtzitanes were obtained, in particular, new heterocyclic systems: 2,4,6,8,12-pentaoxa-10-aza- and 2,4,8,12-tetraoxa-6,10-diazatetracyclo[5.5.0.03,11.05,9]-dodecanes.