New N-Adducts of Thiadiazole and Thiazoline with Levoglucosenone and Evaluation of Their Significant Cytotoxic (Anti-Cancer) Activity.

The conjugate N-adducts of thio-1,3,4-diazole and 2-thiazoline with levoglucosenone were synthesized via a stereoselective, base-catalyzed conjugate N-Michael addition to levoglucosenone at C-4. Structural assignments were established using 1H and 13C NMR analysis, and X-ray single-crystal analysis for one of the compounds. The biological properties of the novel compounds were tested on a cell model. Cytotoxicity was analyzed via colorimetric assay. Two distinct types of cell death, apoptosis and necrosis, were analyzed by determining the phosphatidylserine levels from the outer leaflet of the plasma membrane, caspase activation, and lactate dehydrogenase release. We also evaluated DNA damage using an alkaline comet assay. The level of oxidative stress was measured with a modified comet assay and an H2DCFDA probe. The thio-1,3,4-diazole adduct (FCP23) and the 2-thiazoline adduct (FCP26) exhibit similar cytotoxicity values for cancer cells (ovarian (A2780), breast (MCF-7), cervix (HeLa), colon (LoVo), and brain (MO59J and MO59K)), but their mechanism of action is drastically different. While FCP23 induces oxidative stress, DNA damage, and necrosis, FCP26 induces apoptosis through caspase activation.

New syntheses of thiosaccharides utilizing substitution reactions.

Novel synthetic methods published since 2005 affording carbohydrates containing sulfur atom(s) are reviewed. The review is divided to subchapters based on the position of sulfur atom(s) in the sugar molecule. Only those methods that take advantage of substitution are discussed.

Carbohydrate-Based Micro/Nanocapsules With Controlled External Surface for Medical Applications.

Micro/nanocapsules would have many more applications if we were able to controllably populate their surface with various chemical moieties. The present review introduces a novel variant of interfacial polymerization (IP) as a very robust method of manufacturing reservoir micro/nanocapsules equipped with several different functionalities on the capsules' surface. We call the method-IPCESCO (Interfacial Polymerization for Capsules' External Surface Control). As always in IP, the capsules' forming reaction is between monomers dissolved in opposite phases (oil or water) and takes place at the interface. Each monomer carries two or more functionalities reacting with functional groups of the monomer dissolved in the other phase. IPCESCO requires that one or both monomers are additionally equipped with (protected) functional groups interfering neither with the payload nor with the polymer formation. These additional groups end up everywhere in the polymeric shell but most importantly they are present on the external surface of capsules. These "handles" allow for the introduction of various moieties onto the capsules' surface. Since carbohydrate chemists developed a plurality of protecting and deprotecting methods for various functional groups such as aldehyde and hydroxyl, modified mono, and oligosaccharides are particularly well-suited to act as monomers in IPCESCO. The article discusses possible monomers and their synthesis, the transformation of protected reactive groups on the external capsules' surface into the desired functionalities, the control of the number of moieties on the surface and the capsules surface's architecture. The most important application of the novel encapsulation technology is in drug delivery. Possible surface units facilitating capsules' transport in the body, delivery to specific locations and mechanisms of capsules rupture are also addressed. Other applications of novel capsules include an ultra-sensitive quantitation and removal of pathogens, transport of nutrients in plants, detection of various antigens and other parameters in single cells.

(1-4)-Thiodisaccharides as anticancer agents. Part 5. Evaluation of anticancer activity and investigation of mechanism of action.

(1-4)-Thiodisaccharides, thiosugars with the 1-4-thio bridge, were recently shown to induce oxidative stress, as well as, apoptosis in cancer cells in the low micromolar range; however, the detailed mechanism of their anticancer action still remains unknown. In order to clarify the mechanism of (1-4)- thiodisaccharides action, we performed a series of tests including cytotoxic, clonogenic and apoptosis assays using an in vitro glioma cancer model with one ATCC cell line U87 and two novel glioma cell lines derived from cancer patients - H6PX and H7PX. We also evaluated the ability of (1-4)-thiodisaccharides to interfere with protein folding and synthesis processes, as well as, the thioredoxin system. (1-4)-thiodisaccharides induced glioma cell death, which were found to be accompanied with endoplasmic reticulum stress, inhibition of global protein synthesis, reduced overall cellular thiol level and thioredoxin reductase activity. We also performed a RT-PCR and Elisa analysis of (1-4)-thiodisaccharides-treated glioma cells to identify any changes within the pathway affected by (1-4)-thiodisaccharides. We observed a significant increase of expression in key markers of endoplasmic reticulum stress and pro-apoptotic protein, FASLG. We proposed that (1-4)-thiodisaccharides react with cellular thiols and disturb any cellular thiol-depended processes like thioredoxin system or protein folding.

The induction of oxidative stress in cervix carcinoma cells by levoglucosenone derived 4-S-salicyl derivative and (1-4)-S-thio-disaccharides. Part 4.

(1-4)-S-thiodisaccharides were shown to kill various cancer cell lines, including cervix, lung, mammary-gland and colon by unknown mechanisms. Here we identified two actions of levoglucosenone derived (1-4)-S-thiodisaccharides against cervix cancer cells: induction of oxidative stress and DNA damage. In consequence, (1-4)-S-thiodisaccharides lowered the cellular GSH level and changed the expression profile of genes encoding key proteins involved with oxidative stress response. We also observed that (1-4)-S-thiodisaccharides induced DNA damage and interfered with the thioredoxin (Trx) system. Both actions, as induced by FPC6, were stronger when dihedral angles of sulfur bridge were set to 110°, 100° and 109°, clearly indicating differences when compared to FPC8. These findings demonstrate that the 1-4-thio bridge of disaccharide is a powerful anticancer pharmacophore, and its potential use needs further studies.

A potential CARB-pharmacophore for antineoplastic activity: part 1.

Diverse functionalized representatives of various classes of sugars, such as thio-, anhydro-, and sulfamido-sugars and myo-inositol oxide, were synthesized and assessed for cytotoxicity against human cancer cell lines (A549, LoVo, MCF-7 and HeLa). The inositol oxide (4) was more active against MCF-7 cells (i.e., an estrogen-dependent breast cancer line), whereas all 3 sulfur-containing compounds showed strongest activity against A549 cells (i.e., a lung adenocarcinoma line). We propose to use a concept of functional 'CARB-pharmacophores' when evaluating a potential for the compounds' general antineoplastic activity. Future studies will determine the reasons for cell-type specificity of these compounds. The thio-sugar motif appears to be a promising lead for future developments.

Mechanical resolution of chiral objects in achiral media: where is the size limit?

Macroscopic chiral objects (boats and planes with turned rudders, shoes, etc.) get separated from their mirror-image counterparts by motion in achiral media. However, chiral molecules are not enantio-differentiated without the presence of a chiral environment, which may be due to other chiral molecules in the medium. This article explores the reasons of this micro/macro difference as well as the size borderline between the two regimes. There are two major demarcation lines, both related to the object's chaotic thermal motion. The first one is due to destruction of the necessary spatial orientation by the fast rotational diffusion. Only particles larger than 1 µm can maintain their original orientation for 1 sec or longer. For smaller particles, an additional external orienting factor, e.g., a strong electric field has to be applied. The second limitation is defined by the ratio of the hydrodynamic separation of the enantiomers (which is directly proportional to time) to their displacement due to the translational Brownian motion (which is proportional to square root of time). On the laboratory time scales (up to a year), the chiral objects have to be larger than 0.25 µm to be resolved. On evolutionary time scales, much smaller object could be resolved. For enantiomers approaching the molecular size, periods comparable to the age of the universe would be required.

A possible path to the RNA world: enantioselective and diastereoselective purification of ribose.

A theoretical mechanism resulting in the prebiotic appearance of enantiopure ribose, which would be needed for the origin of RNA and the "RNA world" is proposed. The mechanism simultaneously explains the emergence of biological homochirality and could answer the question of why nucleic acids are based on ribose rather than another sugar. Cleavage of certain non-chiral mineral crystals is known to lead to formation of chiral surfaces. In a chromatography-like process a mixture of racemic carbohydrates originating from the formose reaction is proposed to have been separated on such a chiral surface. Monosaccharides interact with surfaces through their hydroxyl groups, either by hydrogen bond formation or complex formation with metal ions. alpha-Ribopyranose, which has all hydroxyl groups on one side of the ring, is known to interact more strongly than other sugars with surfaces, as corroborated by certain chromatographic and electrophoresis data. A similar scenario leading to enantiopure ribose is separation on a flat, but not necessarily chiral surface in the presence of a strong electric field capable of orienting highly polar derivatives of sugars.

Absolute enantioselective separation: optical activity ex machina.

The paper describes methodology of using three independent macroscopic factors affecting molecular orientation to accomplish separation of a racemic mixture without the presence of any other chiral compounds, i. e., absolute enantioselective separation (AES) which is an extension of a concept of applying these factors to absolute asymmetric synthesis. The three factors may be applied simultaneously or, if their effects can be retained, consecutively. The resulting three mutually orthogonal or near orthogonal directors constitute a true chiral influence and their scalar triple product is the measure of the chirality of the system. AES can be executed in a chromatography-like microfluidic process in the presence of an electric field. It may be carried out on a chemically modified flat surface, a monolithic polymer column made of a mesoporous material, each having imparted directional properties. Separation parameters were estimated for these media and possible implications for the natural homochirality are discussed.