Polysaccharides and their vanadium complexes: new therapeutic perspectives by their ability of modulating macrophages

Abstract

Certain polysaccharides and their derivatives have been used in different applications including in medicine. As biological response modifiers, activities as immunomodulator, antitumor and antileishmanial are researched. Leishmaniasis is a very epidemiologically important disease and the World Health Organization (WHO)classifies it as a neglected disease. In mammal hosts, the Leishmania parasites live inside mononuclear phagocytes, which impair the action of drugs. The pentavalent antimonials sodium stibogluconate and meglumine antimoniate make up the primary treatment for leishmaniasis, which is associated with serious side effects and resistance to antimony. Since the survival of Leishmania parasites in the host cells is associated with the immune system modulation, compounds able to activate these cells to produce cytotoxic mediators could have great potential of promoting leishmanicidal effects. Therefore, immunomodulation is considered a promising strategy to cure leishmaniasis with fewer side effects. The polysaccharides that activate macrophages for proinflammatory activity have been studied aiming at leishmanicidal effect. When complexed with vanadium, galactomannans, arabinogalactans, and xyloglucans, polysaccharides had greater leishmanicidal effects and were more effective than the antimonials currently used in leishmaniasis treatment. Polysaccharides of various sources have been the target of study for applications in technological, food, and pharmaceutical industries and medicine [1,2] . In addition to the studies with native polymers, different types of chemically modified polysaccharides, including the complexation with metals aiming at different applications, has been investigated [3] . The complexation of carbohydrate biopolymers with different metals is facilitated mainly due to the presence of hydroxyl groups in these polymers and, in some instances, the presence of charged groups such as carboxyl or sulfate [4][5][6][7][8] .Vanadium exhibits several important biological effects [9,10] and has been suggested to be an excellent target for antiparasitic purposes, including antileishmanial action [11][12][13][14] .Plant polysaccharides have received great interest in medicine mainly due to their availability, low cost, and low toxicity [15] . Many of these biopolymers are biological response modifiers, in particular able to modulate macrophages to produce immunomodulatory mediators like cytokines and nitrogen and oxygen radicals such as nitric oxide (NO) and superoxide anion, respectively. These mediators are involved in activities such as antitumoral [15,16] , antimicrobial, and antileishmanial [11,13,18,19] . The action of polysaccharides on macrophages occurs by the interaction of these polymers with specific receptors on the cell surface. In addition to complement receptor 3 (CR3), scavenger receptor (SR), dectin-1, manose, fucose, β-glucans, Toll-like receptors RESEARCH HIGHLIGHTMacrophage 2015; 2: e746. doi: 10.14800/Macrophage.746; © 2015 by Guilhermina Rodrigues Noleto, et al.Page 2 of 5 ...