Mikhail V. Khvostov

Polysaccharide arabinogalactan from larch Larix sibirica as carrier for molecules of salicylic and acetylsalicylic acid: preparation, physicochemical and pharmacological study

Abstract Inclusion complexes of salicylic acid (SA) and acetylsalicylic acid (aspirin, ASA) with polysaccharide arabinogalactan (AG) from larch wood Larix sibirica and Larix gmelinii were synthesized using mechanochemical technology. In the present study, we have investigated physicochemical properties of the synthesized complexes in solid state and in aqueous solutions as well as their anti-aggregation and ulcerogenic activity. The evidence of the complexes formation was obtained by nuclear magnetic resonance (NMR) relaxation technique. It was shown that in aqueous solution the molecules of SA and ASA are in fast exchange between the complex with AG macromolecules and solution. The stability constant of aspirin complex was calculated. It was shown that mechanochemically synthesized complexes are more stable when compared to the complex obtained by mixing solutions of the components. Complexes of ASA show two-fold increase of anti-platelet effect. It allows to reduce the dose of the antithrombotic drug and its ulcerogenic activity. These results substantiate the possibility to design new preparations on the basis of ASA with increased activity and safety.

Arabinogalactan, a plant polysaccharide, as a new tool for pharmacon clathration.

The ability of the carbohydratecontaining naturalmetabolites to bind drugs by formation of complexes(clathration) attracts attention because this allows thepharmacon dose and toxicity to be reduced, with theirpleiotropic properties improved and the basic effectretained.We demonstrated previously that this ability wascharacteristic of glycosides of higher terpenoids, suchas glycyrrhizinic acid [1, 2], stevioside, and rebaudioside [3].In this study, we have demonstrated that thepolysaccharide arabinogalactan (AG), which is ametabolite of the endemics of Siberian forest floralarches

Alteration of Warfarins Pharmacologic Properties in Clathrates with Glycyrrhizic Acid and Arabinogalactan

The article describes the pharmacological examinations of clathrates of warfarin (WF) with glycyrrhizic acid (GA) and arabinogalactan (AG). A direct connection between the clathrate structure and the pharmacons anticoagulative properties was observed. A 20 mg/kg (WF 2 mg/kg) dose of WF: GA 1:10 clathrate causes the increase in prothrombin time (PT) only in 54 hours, after 3 administrations. In contrast, a 20 mg/kg (WF 2 mg/kg) dose of WF: AG 1:10 clathrate leads to an increase in PT in 24 and 48 hours after a single administration, which corresponds to the effect of a comparator agent WF (2 mg/kg).

Gel chromatographic and toxicological studies of the mechanochemical transformations of water-soluble polysaccharides

Changes in the molecular weight characteristics of polysaccharide macromolecules - arabinogalactan, hydroxyethyl starch 200/0.5, Fibregum, and dextrans 10, 40, and 70 - were studied during mechanochemical processing. A preference for “gentle” conditions for mechanical processing (~1 g) were established, as these conditions do not lead to destruction of polysaccharide macromolecules. An additional advantage of these mechanical processing regimes is that they can be scaled up to industrial flow mills. Mechanochemical processing had no adverse effect on the toxicity measures of the polysaccharides studied. Toxicological studies of mechanically processed arabinogalactan, hydroxyethyl starch 200/0.5, Fibregum, and dextrans 10, 40, and 70 showed that these polysaccharides and the products of their mechanochemical processing can be classified as class 4 (low-toxicity) substances.

Preparation of curcumin self-micelle solid dispersion with enhanced bioavailability and cytotoxic activity by mechanochemistry

Abstract An amorphous solid dispersion (SD) of curcumin (Cur) with disodium glycyrrhizin (Na2GA) was prepared by mechanical ball milling. Curcumin loaded micelles were self-formed by Na2GA when SD dissolved in water. The physical properties of Cur SD in solid state were characterized by differential scanning calorimetry, X-ray diffraction studies, and scanning electron microscope. The characteristics of the sample solutions were analyzed by reverse phase HPLC, UV–visible spectroscopy, 1H NMR spectroscopy, gel permeation LC, and transmission electron microscopy. In vitro cytotoxic tests demonstrated that Cur SD induced higher cytotoxicity against glioblastoma U-87 MG cells than free Cur. Besides, an improvement of membrane permeability of Cur SD was confirmed by parallel artificial membrane permeability assay. Further pharmacokinetic study of this SD formulation in rat showed a significant ∼19-fold increase of bioavailability as comparing to free Cur. Thus, Cur SD provide a more potent and efficacious formulation for Cur oral delivery.

The morphofunctional and biochemical characteristics of opisthorchiasis-associated cholangiocarcinoma in a Syrian hamster model

The validity of the experimental models of pathologies is one of the key challenges in translational medicine. Cholangiocarcinoma, or bile duct cancer, ranks second among oncological diseases of the liver. There is a strong association between bile duct cancer and parasitic infestation of the liver caused by trematodes in the Opisthorchiidae family. We recently demonstrated that cholangiocarcinoma can develop in Syrian hamsters (Mesocricetus auratus) infected by Opisthorchis felineus and administered with dimethylnitrosamine. However, there is still no description of how this experimental model can be used in translational research. The aim of this work was to study the morphological, functional, and biochemical characteristics during cholangiocarcinoma development in Syrian hamsters infected by O. felineus and administered with dimethylnitrosamine. The experiment lasted 30 weeks with combined administration of dimethylnitrosamine in drinking water at a dose of 12.5 ppm and a single injection of 50 metacercariae O. felineus. It was shown that the development of cholangiocarcinoma (18 weeks) increased the total number of basophils, eosinophils, and monocytes; the relative number of granulocytes, as well as the amount of total and direct bilirubin; and the cholesterol and ALT levels; however, it reduced the relative number of lymphocytes. Based on pathological, morphometric, and biochemical analyses, our model has characteristics similar to those in patients with opisthorchiasis-associated cholangiocarcinoma. Thus, this model can be used to test anticancer drugs, to study the mechanisms of cholangiocarcinogenesis, and to search for molecular markers for early diagnosis of bile duct cancer.

Effect of complexation with arabinogalactan on pharmacokinetics of "guest" drugs in rats: for example, warfarin.

A pharmacokinetic study of the warfarin (WF) : arabinogalactan (AG) complex with the 1 : 10 mass ratio after its intragastric introduction to Wistar rats at a dose of 5 mg/kg (WF dose in the complex was 0.5 mg/kg) once a day for three days was conducted. It was found that C max, T 1/2, and AUC of WF in the complex form were lower than after the introduction of blank WF at the same dose, but its elimination (Cl, MRT) was much faster. Significant accumulation (C min) and an abrupt increase in plasma concentration after the third introduction were observed for blank WF, whereas the complex showed a much more moderate increase in concentration at this point. However, despite obvious differences in pharmacokinetic parameters, the efficacies of both agents were virtually identical; the complex differed from blank WF by only 15%. This value is rather insignificant and does not impair its anticoagulant activity. Thus, we can conclude that introduction of the WF : AG complex is safe in terms of reduction of the bleeding risk and accumulation.

Development and validation of ultrafast LC–MS/MS method for quantification of anti-influenza agent camphecene in whole rat blood using dried blood spots and its application to pharmacokinetic studies

A fast, selective and sensitive procedure for quantitation of the camphor-based anti-influenza agent camphecene in whole rat blood was developed and validated using dried blood spots and LC-MS/MS. The method was validated according to recommendations of the FDA and EMA in terms of selectivity, linearity, accuracy, precision, recovery, matrix factor, stability, and carry-over. Sample preparation included spotting 20μL of whole blood taken from the tail vein onto the paper, drying and extracting the analyte, followed by evaporation of the solvent and analysis of the residue. HPLC separations were run on a reversed-phase microcolumn; the time of analysis was less than 2min. MS/MS detection was performed on a triple quadrupole mass-spectrometer using multiple reaction monitoring (MRM) mode. Transitions 196.4→122.2/153.3 and 152.2→93.1/107.2 were monitored for camphecene and 2-adamantylamine hydrochloride (internal standard), respectively. The intra- and inter-day precisions and accuracies, matrix factor, carry-over and recovery were within acceptable limits. Despite low extraction recovery (less than 2%), the sensitivity of the method was enough to detect the analyte in the concentration range 50-2500ng/mL. The application of the method was shown in pharmacokinetic studies of camphecene in rats at a dose of 10mg/kg.

Physicochemical properties and anti-opisthorchosis effect of mechanochemically synthesized supramolecular complexes of Albendazole with the polysaccharide Arabinogalactan from Larix sibirica and Larix gmelinii.

212 Opisthorchosis provoked by trematodes Opisthorchis felineus is one of the most widely spread helminthiasis in Russia, which affects at least 50–80% of the population of Western Siberia [1]. In the past decades, opisthorchosis has been treated with large action spectrum drugs, such as Praziquantel and Albendazole (ABZ). One of significant disadvantages of these preparations is their high toxicity [2]. More over, risks of teratogenic and carcinogenic effects of these preparations should also be taken into account. Praziquantel exhibited positive effects upon treatment of acute opisthorchosis, though it was not sufficiently effective in cases of most widely spread chronic opisthorchosis. Therefore, the development of novel antihelminthic agents and/or increase in efficiency of the existing ones is considered to be a challenging problem.

Rebaudioside, a novel agent of glycoside clathration of pharmacons.

205 Glycyrrhizinic acid and stevioside, glycosides of higher terpenoids, are capable of in vivo formation of clathrates with pharmacons with various types of activity. This property of glycosides allows the effective dose to be substantially decreased (by a factor of 10– 100), with the basic activity being preserved and novel pharmacological effects appearing [1–6]. The plant Stevia rebaudiana Bertoni is known to produce not only stevioside I, but also rebaudioside A II, which can be obtained in an individual state. The carbon chain of rebaudioside is more branched than the corresponding structural fragment of stevioside. Considering the high capacity of stevioside for clathrate formation, it is conceivable that rebaudioside also forms clathrates. Note that rebaudioside, like stevioside, is nontoxic (LD 50 8000 mg/kg) and is included in food compositions as a sweetener [7, 8]. Our study described below has confirmed that rebaudioside has the aforementioned capacity for glycoside clathrate formation.