Cytotoxicity of xyloglucan from Copaifera langsdorffii and its complex with oxovanadium (IV/V) on B16F10 cells.

The aim of this study was to investigate the effects of xyloglucan extracted from Copaifera langsdorffii seeds (XGC) and its complex with oxovanadium (XGC:VO) in murine melanoma B16F10 cells. The formation of complexes was followed by potentiometric titration and further demonstrated by 51V RMN. The viability and proliferation of B16F10 cells were reduced up 50% by the xyloglucan and its complex, both at 200 µg/mL, from 24 to 72 h. Cytotoxic effects of XGC and XGC:VO do not involve changes in cell cycle progression. Only XGC:VO (200 µg/mL) promoted the cell death evidenced by annexin V stain. XGC increased the respiration and lactate levels in melanoma cells, while XGC:VO reduced about 50% the respiration and levels of pyruvate, without alter the lactate levels, indicating that both xyloglucan preparations interfere with the metabolism of B16F10 cells. No change in activity of the enzyme hexokinase and expression of pyruvate kinase M2 was observed. XGC:VO (200 µg/mL) negatively modulated the expression of the ß subunit of ATP synthase. The results demonstrate that the cytotoxicity of XGC and XGC:VO on murine melanoma B16F10 cells can be related to the impairment of the mitochondrial functions linked to energy provision.

Toxicity of native and oxovanadium (IV/V) galactomannan complexes on HepG2 cells is related to impairment of mitochondrial functions.

Polysaccharides and vanadium compounds have been studied due to their antitumor potential. In this study, the cytotoxic effects of galactomannan preparations on HepG2 cells were investigated. Native galactomannan from S. amazonicum (SAGM) and its modified form (MSAGM) were complexed with oxovanadium resulting in SAGM:VO and MSAGM:VO, respectively. The complexation was confirmed by NMR, FTIR, and AAS. SAGM and MSAGM:VO (250µg/mL) after 72h decreased viability by 51% and 58%, respectively, while the inhibition of the HepG2 cell proliferation was of ∼27% and ∼46%, respectively. SAGM and MSAGM:VO (250µg/mL) significantly inhibited all states of respiration (basal: 85% and 63%; uncoupled: 90% and 70%; and leak: 30% and 58%) after 72h. ROS levels increased by ∼149% after the treatment with MSAGM:VO (250µg/mL) for 72h, while ΔΨm decreased by ∼50%. Our results indicate that galactomannan preparations from S. amazonicum, especially SAGM and the MSAGM:VO complex, could be considered as potential antitumor drugs for further investigations, once they have the ability to make HepG2 cells susceptible to death by affecting vital cellular processes such as respiration and ROS generation.

Leishmanicidal activity of polysaccharides and their oxovanadium(IV/V) complexes.

The parasites of the genus Leishmania cause a range of leishmaniasis diseases, whose treatment is impaired due to intramacrophage parasites living in the mammalian host. Immunostimulation has been considered an important strategy to leishmaniasis treatment. The immunomodulatory effects of the polysaccharides arabinogalactan (ARAGAL), galactomannan (GMPOLY), and xyloglucan (XGJ), as well as their oxovanadium (IV/V) complexes (ARAGAL:VO, GMPOLY:VO, and XGJ:VO) were evaluated on peritoneal macrophages. At 25 µg/mL of GMPOLY:VO and of XGJ:VO, and 10 µg/mL of ARAGAL:VO, nitric oxide (NO) production by the macrophages was not altered compared with the control group. All polymers increased the production of interleukins 1 beta and 6 (IL-1ß and IL-6), but the oxovanadium complexes were more potent activators of these mediators. ARAGAL:VO 10 µg/mL, GMPOLY:VO and XGJ:VO 25 µg/mL led to an increase of 562%, 1054%, and 523% for IL-1ß, respectively. For IL-6 at the same concentration, the levels increased by 539% and 794% for ARAGAL:VO and GMPOLY:VO, respectively. Polysaccharides and their oxovanadium complexes exhibited important leishmanicidal effects on amastigotes of Leishmania (L.) amazonensis. The native and complexed polymers reduced the growth of promastigote-form Leishmania by ∼60%. This effect was reached at concentrations 12 times lower than that observed for Glucantime (300 µg/mL promoted an inhibition of ∼60%). The 50% inhibitory concentration (IC50) values for the complexes were determined. XGJ:VO showed the lowest IC50 value (6.2 µg/mL; 0.07 µg/mL of vanadium), which for ARAGAL:VO was 6.5 µg/mL (0.21 µg/mL of vanadium) and 7.3 µg/mL (0.06 µg/mL of vanadium) for GMPOLY:VO. The upregulation of IL-1ß and IL-6 release and downregulation of NO production by macrophages and the important leishmanicidal effect are essential to stablish their potential use against this pathology.

Macrophage activation and leishmanicidal activity by galactomannan and its oxovanadium (IV/V) complex in vitro.

Compounds that activate macrophage antimicrobial activity are potential targets for treatment of leishmaniasis. The present study investigated the in vitro immunomodulatory effects of a galactomannan (GALMAN-A) isolated from seeds of Mimosa scabrella and its oxovanadium (IV/V) complex (GALMAN-A:VO(2+)/VO(3+)) on macrophage activity. GALMAN-A increased nitric oxide levels by ~33% at a concentration of 250µg/ml, while GALMAN-A:VO(2+)/VO(3+) decreased nitric oxide levels by ~33% at a concentration of 50µg/ml. Furthermore, GALMAN-A increased interleukin-1 beta (IL-1ß) and interleukin-6 (IL-6) levels by 5.5 and 2.3 times, respectively, at a concentration of 25µg/ml; at the same concentration, GALMAN-A:VO(2+)/VO(3+) promoted an increase in IL-1ß and IL-6 production by 8 and 5.5 times, respectively. However, neither GALMAN-A nor GALMAN-A:VO(2+)/VO(3+) affected tumor necrosis factor alpha (TNF-α) or interleukin-10 (IL-10) levels. Importantly, both GALMAN-A and GALMAN-A:VO(2+)/VO(3+) exhibited leishmanicidal activity on amastigotes of Leishmania (L.) amazonensis, reaching ~60% activity at concentrations of 100 and 25µg/ml, respectively. These results indicate that GALMAN-A is three times more potent and its oxovanadium complex is twelve times more potent than Glucantime (300µg/ml), which is the drug of choice in leishmaniasis treatment. The IC50 value for GALMAN-A:VO(2+)/VO(3+) was 74.4µg/ml (0.58µg/ml of vanadium). Thus, the significant activation of macrophages and the noted leishmanicidal effect demonstrate the need for further studies to clarify the mechanisms of action of these compounds.

Two galactomannan preparations from seeds from Mimosa scabrella (bracatinga): Complexation with oxovanadium(IV/V) and cytotoxicity on HeLa cells.

Two galactomannans, GALMAN-A and GALMAN-B, were isolated from seeds of Mimosa scabrella (bracatinga), with deactivation and exposure to native enzymes, respectively. They were treated with oxovanadium(IV) and oxovanadium(V), designated (VO(2+)/VO(3+)) to form GALMAN-A:VO(2+)/VO(3+) and GALMAN-B:VO(2+)/VO(3+) complexes, respectively. The potentiometric studies provided the binding constants for the complexes and the resulting complexed species were a function of pH. (51)V NMR spectra of GALMAN-A:VO(2+)/VO(3+) and GALMAN-B:VO(2+)/VO(3+) at pH 7.8 and at 30 degrees C indicated the occurrence of two types of complexes formed by oxovanadium ions and galactomannans. GALMAN-A:VO(2+)/VO(3+) and GALMAN-B:VO(2+)/VO(3+) caused loss of HeLa cells viability at concentrations of 50-200microg/mL. GALMAN-A:VO(2+)/VO(3+) exhibited low toxicity for 24h, although GALMAN-B:VO(2+)/VO(3+) was extremely toxic, since 50microg/mL was sufficient to decrease HeLa cell viability after 48h by 60%. GALMAN-A gave rise to a slight increase in cell proliferation after 48h at 100microg/mL, whereas GALMAN-B promoted a slight decrease at concentrations of 50-100microg/mL. GALMAN-A:VO(2+)/VO(3+) and GALMAN-B:VO(2+)/VO(3+) exhibited a significant decrease in cell proliferation after 48h, each reaching 60% inhibition at 5-10microg/mL. The complexes which caused this effect were at concentrations 10 times lower than the uncomplexed polymers.

Properties of complexes of galactomannan of Leucaena leucocephala and Al3+, Cu2+ and Pb2+.

The use of biopolymers in many industrial processes is on the increase. The different interactions of biopolymers and electrolytes either in aqueous solutions or in solid state provide different physico-chemical properties and a simple correlation cannot be established. In this study, in order to determine the properties of the complexes of galactomannan of Leucaena leucocephala (gal) with the metal ions Al3+ and Pb2+, toxic elements and Cu2+, essential, the logs of the binding constants of the complexes formed in the aqueous solutions were calculated. Their rheological properties, their thermal behavior, the infrared characteristics and shape and form of the films formed by those complexes in solid state were also determined. The aqueous solutions properties have shown a better complexation between gal and Al3+. The species distribution diagrams have shown an existence of complex species going from acidic to basic pH values. Infrared spectra have proved the complexations as well as the viscosity studies. Thermal stabilities in general were smaller in the complexed species than in the native biopolymers and the films obtained from aqueous solutions showed for Cu2+ the most different morphology compared to the biopolymer itself. A use can be suggested of this biopolymer in environmental remediations besides its already established industrial uses.

Aqueous and solid complexes of iron(III) with hyaluronic acid. Potentiometric titrations and infrared spectroscopy studies.

The coordination of iron(III) ion to hyaluronic acid (Hyal) in aqueous solutions and solid state was accomplished by potentiometric titrations and infrared spectroscopy. The potentiometric titration studies provided the binding constants for the complexes found in the systems and the speciation of these species according to the variation of pH values. The complexes found presented a complexing ability through both the chelating moieties of Hyal (via the N-glucosamine and D-glucoronic acid), showing no special preference for either one while in solid state, but when in aqueous solution the complexation via the N-glucosamine moiety was the preferred, forming two complexed species, ML and ML(2) (log K(ML)=8.2 and log K(ML2)=7.9). The presence of a mu-oxo complex via the D-glucoronic acid was also detected in both aqueous (log K=6.7) and solid states via the N-glucosamine and D-glucoronic acid simultaneously linked to two Hyal chains. A structure for this latter complex was suggested. The results indicated that these complexes could be used in eliminating the excess iron(III) in living organisms.