Aronia melanocarpa (Michx.) Elliott’s (chokeberry) besides anthocyanins contains significant amounts of hydroxycinnamic acids: Chlorogenic and its isomer neochlorogenic acid. They exhibit antioxidant, anti-inflammatory, antidiabetic, and antibacterial activities, thus they can have a significant impact on the health-promoting properties of Aronia. The aim of our research was to determine the changes in the content of chlorogenic acids (CGAs) and anthocyanins during fruit development and ripening, with a particular emphasis on acids. Aronia fruit samples were collected from July to October on two organic farms in Poland. The chemical composition of the extracts was determined by NMR spectroscopy and HPLC-DAD. 1H-NMR and HPLC data were analyzed using chemometric analysis and multivariate statistics (PCA). The results showed that the content of chlorogenic acids and anthocyanins changes during ripening and depends on the time of harvest and the region of cultivation. A correlation between the time of CGAs reduction and the appearance of anthocyanins was also noticed. The result of our research was also a database in the form of NMR parameters, which allows analysis of the metabolite profile and tracking of its changes. The 1H-NMR spectrum showing anthocyanin and CGA resonance can be considered the Aronia berry fingerprint.
9 October 2014 in Organic & Biomolecular Chemistry
A-type procyanidin trimers cinnamtannin B-1, cinnamtannin D-1, lindetannin, and aesculitannin B were studied in terms of their conformation and interaction with four solvents: methanol, acetone, DMSO and pyridine. The experiments demonstrated that for each trimer there are two principal conformers observable in the NMR. The ratio of the conformers (rotamers) depends on the structure of a given trimer as well as on the solvent used for NMR measurements. The DFT calculations (B3LYP/6-31G(d,p)) proved the presence of two main conformers to be the result of a steric hindrance that prevents free rotation along the B-type interflavan bond. An analysis of the solvent–procyanidin interactions showed that the strong electron donating solvents, pyridine and DMSO, favor different conformers from methanol and acetone, which prefer the lowest-energy gas phase conformer. These findings are in line with predictions of DFT/M06-2X calculations with the inclusion of the thermal corrections. The variations in the rotamer ratios in the studied solvents correlate with the solvent's capacity to induce local changes in the electron density of the particular procyanidin trimer.
Two, well defined binary crystals with 1-Hydroxy-4,5-Dimethyl-Imidazole 3-Oxide (HIMO) as coformer and thiobarbituric acid (TBA) as well barbituric acid (BA) as Active Pharmaceutical Ingredients (APIs) were obtained by cocrystallization (from methanol) or mechanochemically by grinding. The progress of cocrystal formation in a ball mill was monitored by means of high-resolution, solid state NMR spectroscopy. The 13C CP/MAS, 15N CP/MAS and 1H Very Fast (VF) MAS NMR procedures were employed to inspect the tautomeric forms of the APIs, structure elucidation of the coformer and the obtained cocrystals. Single crystal X-ray studies allowed us to define the molecular structure and crystal packing for the coformer as well as the TBA/HIMO and BA/HIMO cocrystals. The intermolecular hydrogen bonding, π–π interactions and CH-π contacts responsible for higher order organization of supramolecular structures were determined. Biological studies of HIMO and the obtained cocrystals suggest that these complexes are not cytotoxic and can potentially be considered as therapeutic materials.
Novel octakis-2[(6-hydroxyhexyl)thio]ethyl-octasilsesquioxane (POSS-S-OH) as well as heptaisobutyl-2[(6-hydroxyhexyl)thio]ethyl-octasilsesquioxane (iBu-POSS-S-OH) were synthesized. POSS structures, bearing both types of groups i.e., 2[(6-hydroxyhexyl)thio]ethyl and the vinyl ones, pendant from the octahedral cage are also described. The synthetic pathway involved thiol-ene click reaction of 6-mercapto-1-hexanol (MCH) to octavinyloctasilsesquioxane (POSS-Vi), and heptaisobutylvinyloctasilsesquioxane (iBu-POSS-Vi), in the presence of 2,2′-azobisisobutyronitrile. The functionalized silsesquioxane cages of regular octahedral structure were used further as initiators for ring opening polymerization of L,L-dilactide, catalyzed by tin (II) 2-ethylhexanoate. The polymerization afforded biodegradable hybrid star shape and linear systems with an octasilsesquioxane cage as a core, bearing polylactide arm(s).
Cancer is a global health problem being the second worldwide cause of deaths right after cardiovascular diseases. The main methods of cancer treatment involve surgery, radiation and chemotherapy with an emphasis on the latter. Thus development of nanochemistry and nanomedicine in a search for more effective and safer cancer treatment is an important area of current research. Below, we present interaction of doxorubicin and acriflavine and the cytotoxicity of these drug nano-complexes towards cervical cancer (HeLa) cells. Experimental results obtained from NMR measurements and fluorescence spectroscopy show that the drugs' interaction was due to van der Waals forces, formation of hydrogen bonds and π–π stacking. Quantum molecular simulations confirmed the experimental results with regard to existing π–π stacking. Additionally it was shown that, at the level of theory applied (DFT, triple zeta basis set), the stacking interactions comprise the most preferable interactions (the lowest ΔG ca. −12 kcal mol−1) both between the molecules forming the acriflavine system and between the other component – another drug (doxorubicin) dimer. Biological tests performed on HeLa cells showed high cytotoxicity of the complexes, comparable to free drugs (ACF and DOX), both after 24 and 48 hours of incubation. For non-cancerous cells, a statistically significant difference in the cytotoxicity of drugs and complexes was observed in the case of a short incubation period. The results of the uptake study showed significantly more efficient cellular uptake of acriflavine than doxorubicin, whether administered alone or in combination with an anthracycline. The mechanism determining the selective uptake of acriflavine and ACF : DOX complexes towards non-cancer and cancer cells should be better understood in the future, as it may be of key importance in the design of complexes with toxic anti-cancer drugs.