Induction of secretory and tumoricidal activities in peritoneal macrophages activated by an acidic heteropolysaccharide (ARAGAL) from the gum of Anadenanthera colubrina (Angico branco).

The immunomodulatory and anti-tumoral effects of an acidic heteropolysaccharide containing mainly galactose and arabinose (ARAGAL), isolated from the gum of the leguminous tree Anadenanthera colubrina (Angico branco) native to Brazil, were studied. It has been demonstrated that activation of mice peritoneal macrophages both in vivo and in vitro, increases phagocytic ability and anion superoxide production. In order to obtain further insights on the biological effects of ARAGAL, the capacity of eliciting peritoneal macrophages and tumor necrosis factor-alpha (TNF-alpha) production, and anti-tumoral effect against Sarcoma 180 (S-180), are now evaluated. Cell eliciting activity was observed in ARAGAL-treated animals in a dose dependent manner. Treatment of animals with 50, 100 or 200 mg/kg of ARAGAL increased peritoneal exudate cell (PEC) numbers by approximately 18, approximately 44 and approximately 88%, respectively. ARAGAL also increased 26-fold TNF-alpha production by peritoneal macrophages. Macrophages, treated in vitro for 18 h with ARAGAL, were able to kill Sarcoma 180 cells, as observed by their structures inside the macrophage cytoplasm. ARAGAL (100 mg/kg) showed anti-tumoral activity against S-180 in ascites or solid tumors, the tumoral inhibition being 63 and 38%, respectively. The results suggest a possible role as a BRM for ARAGAL.

Effect of an acidic heteropolysaccharide (ARAGAL) from the gum of Anadenanthera colubrina (Angico branco) on peritoneal macrophage functions.

Brazilian flora are a source of interesting polysaccharides which, either in their native state or when submitted to structural modifications, might have potential applications as biological response modifiers (BRM). A complex acidic heteropolysaccharide, containing mainly galactose and arabinose (ARAGAL), isolated from the gum of the native leguminous tree Anadenanthera colubrina (Angico branco), was studied for its immunological properties on peritoneal exudate cells, namely their superoxide anion production, phagocytic activity, morphological alterations and percentage content of activated macrophages. Activation of macrophages showing increased cytoplasm, bright and large nuclei, various cytoplasmatic projections and spreading ability, was detected following in vitro cell exposure to ARAGAL or in cells obtained from treated animals. In vitro exposure to ARAGAL increased the occurrence of activated macrophages in a time- and a dose-dependent pattern, since approximately 82% of the cells were activated in the presence of 300 microg/ml of ARAGAL after 24 h of incubation and approximately 91% after 48 h. The occurrence of activated macrophages was also evident in cell preparations from ARAGAL-treated mice, their percentage showing a dose-dependent pattern. There were approximately 60, 75 and 75% following treatment with 100, 250 and 500 mg/kg of ARAGAL, respectively. A phagocytic assay showed that 25 microg/ml ARAGAL was sufficient to impose a maximum phagocytic ability, although this effect was dose-dependent. O(2)(-) production by macrophages from ARAGAL-treated mice was 70% higher than that of cells from untreated mice. Moreover, cells from treated mice responded to PMA, the effect being 25% higher than that of the control using untreated mice. These results thus suggest a possible role of ARAGAL from A. colubrina as a BRM.

Histological and immunohistochemical evaluation of sarcoma 180 in mice after treatment with and alfa-D-glucan from the lichen Ramalia celastri

The antitumoral activity of an alfa-D-glucan from the lichen Ramalia celastri was investigated using the tumor Sarcoma 180 (S-180). Mice were inoculated with the tumor and 24 h later received a single dose of alfa-D-glucan (200 mg/kg). Thirty-five days after inoculation the mice were sacrificed and the tumors were examined histopathologically. Morphological analyses showed that the tumor was invasive and that it produced typical and atypical mitoses, neovascularization and an infiltration of inflammatory cells. In treated mice, inflammatory cells were more frequent and the presence of nuclear fragments suggested tumor cell death by apoptosis. The tumors of control and alfa-D-glucan treated mice were negative for laminin but expressed fibronectin, the intensity and distribution of which varied in the connective tissue surrounding the tumor mass, in treated mice than in control mice, but in tumor cells, the expression was greater in control mice. The results indicate that alfa-D-glucan can inhibit tumor growth and affect host defense cell responses. The differences in fibronectin distribution between the control and alfa-D-glucan treated mice, suggest that this protein may play an important role in limiting the invasiveness of malignant cells.