Artemisia absinthium and Artemisia vulgaris: A comparative study of infusion polysaccharides

AbstractThe aerial parts of Artemisia absinthium and Artemisia vulgaris are used in infusions for the treatment of several diseases. Besides secondary metabolites, carbohydrates are also extracted with hot water and are present in the infusions. The plant carbohydrates exhibit several of therapeutic properties and their biological functions are related to chemical structure. In this study, the polysaccharides from infusions of the aerial parts of A. absinthium and A. vulgaris were isolated and characterized. In the A. absinthium infusion, a type II arabinogalactan was isolated. The polysaccharide had a Gal:Ara ratio of 2.3:1, and most of the galactose was (1→3)- and (1→6)-linked, as typically found in type II arabinogalactans. In the A. vulgaris infusion, an inulin-type fructan was the main polysaccharide. NMR analysis confirmed the structure of the polymer, which is composed of a chain of fructosyl units β-(2←1) linked to a starting α-d-glucose unit

Chemical structure and biological activity of the (1 → 3)-linked β-D-glucan isolated from marine diatom Conticribra weissflogii

Several polysaccharides are considered to be "biological response modifiers" (BRM) - these refer to biomolecules that augment immune responses and can be derived from a variety of sources. Microalgae produce a diverse range of polysaccharides and could be an excellent source of BRM. Here, we describe the chemical structure and biological activity of water-soluble polysaccharide isolated from the marine diatom Conticribra weissflogii. Using chemical and NMR spectroscopic methods, the polysaccharide was identified as a (1 → 3)-linked β-D-glucan with a low proportion of C-6 substitution by single β-glucose units. The biological activity of this low molecular weight β-glucan (11.7 kDa) was investigated with respect to glioblastoma cell lines (U87 MG and U251) and macrophages (RAW 264.7). We observed that this β-D-glucan did not exhibit cytotoxic activity against glioblastoma cells, but did enhance the phagocytic activity of macrophages, suggesting that it possesses immunomodulatory properties.</p

Hypoxia protects against the cell death triggered by oxovanadium–galactomannan complexes in HepG2 cells

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Preparation and characterization of 4-nitrochalcone-folic acid-poly(methyl methacrylate) nanocapsules and cytotoxic activity on HeLa and NIH3T3 cells

Chalcones of natural origin are plant metabolites which have been explored because of the cytotoxic effects towards tumor cells. In this study, the synthetic chalcone 4-nitrochalcone (4NC) and its encapsulated form in folic acid-poly(methyl methacrylate) (PMMA) nanocapsules (4NC-FA-PMMA) were investigated towards the cytotoxic effects on erytrocytes, mouse embryonic fibroblasts cells (NIH3T3), and tumor cells (HeLa cells). Characterization of 4NC-FA-PMMA presented spherical morphology with nanocapsule-type structure, a mean size of 170 ± 6 nm, a negative zeta potential of (−40 ± 4 mV), and an entrapment efficiency of ~80%. In HeLa cells, 4NC induced a dose-dependent reduction in cell viability, with an IC value of 46.7 μM. The cytotoxicity was confirmed by morphological alterations, cell death, and an increase in the population of hypodiploid cells. When 4NC-FA-PMMA nanocapsules were employed at concentrations of 15 and 30 μM the reduction in cell viability was higher than that of 4NC. In addition, 4NC and 4NC-FA-PMMA nanocapsules did not present any cytotoxic effect on the NIH3T3 cells and human erythrocytes up to 50 μM. These results demonstrated that the 4NC encapsulation in PMMA nanocapsules with folic acid-modified surface is a better system to promote selective cytotoxic effects to HeLa cells. Therefore, this formulation could be considered a promising preparation with potential chemotherapeutic action

Selective Cytotoxicity of 1,3,4-Thiadiazolium Mesoionic Derivatives on Hepatocarcinoma Cells (HepG2).

In this work, we evaluated the cytotoxicity of mesoionic 4-phenyl-5-(2-Y, 4-X or 4-X-cinnamoyl)-1,3,4-thiadiazolium-2-phenylamine chloride derivatives (MI-J: X=OH, Y=H; MI-D: X=NO2, Y=H; MI-4F: X=F, Y=H; MI-2,4diF: X=Y=F) on human hepatocellular carcinoma (HepG2), and non-tumor cells (rat hepatocytes) for comparison. MI-J, M-4F and MI-2,4diF reduced HepG2 viability by ~ 50% at 25 μM after 24-h treatment, whereas MI-D required a 50 μM concentration, as shown by 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. The cytotoxicity was confirmed with lactate dehydrogenase assay, of which activity was increased by 55, 24 and 16% for MI-J, MI-4F and MI-2,4diF respectively (at 25 μM after 24 h). To identify the death pathway related to cytotoxicity, the HepG2 cells treated by mesoionic compounds were labeled with both annexin V and PI, and analyzed by flow cytometry. All compounds increased the number of doubly-stained cells at 25 μM after 24 h: by 76% for MI-J, 25% for MI-4F and MI-2,4diF, and 11% for MI-D. It was also verified that increased DNA fragmentation occurred upon MI-J, MI-4F and MI-2,4diF treatments (by 12%, 9% and 8%, respectively, at 25 μM after 24 h). These compounds were only weakly, or not at all, transported by the main multidrug transporters, P-glycoprotein, ABCG2 and MRP1, and were able to slightly inhibit their drug-transport activity. It may be concluded that 1,3,4-thiadiazolium compounds, especially the hydroxy derivative MI-J, constitute promising candidates for future investigations on in-vivo treatment of hepatocellular carcinoma

Effects of 1,3,4-thiadiazolium derivatives on HepG2 cell morphology (the experimental conditions are described in the Materials and Methods section 2.6).

<p>The cells were seeded with or without 1,3,4-thiadiazolium derivatives at 5 μM for 3 h. The images were captured with a 100X magnification; they correspond to control (A), MI-D (B), MI-J (C), MI-4F (D) and MI-2,4diF (E). The scale is indicated by black bars representing 0.02 mm. The arrows show morphological modifications as blebs, increased volume and vacuolization. The photographs represent three different experiments in triplicate.</p

Annexin V-FITC and propidium iodide staining of HepG2 treated with 1,3,4-thiadiazolium derivatives (the experimental conditions are described in the Materials and Methods section 2.5.3).

<p>The cells were seeded with or without 1,3,4-thiadiazolium derivatives at 25 μM for 18–24 h. Then, the cells were collected with trypsin and 10.000 events were analyzed by flow cytometry by FL2 and FL1 filters. (A) control, (B) MI-D, (C) MI-J, (D) MI-4F and (E) MI-2,4diF. The figures show representative dot-plot with the different cell populations: left-bottom = labeled cells; left-top = PI labeled; right-top = doubly labeled; right-bottom = annexin V labeled. The results were expressed as mean ± SD of three independents experiments.</p