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A lectin-like protein from the seeds of Acacia farnesiana was isolated from the albumin fraction, characterized, and sequenced by tandem mass spectrometry. The albumin fraction was extracted with 0.5 M NaCl, and the lectin-like protein of A. farnesiana (AFAL) was purified by ion-exchange chromatography (Mono-Q) followed by chromatofocusing. AFAL agglutinated rabbit erythrocytes and did not agglutinate human ABO erythrocytes either native or treated with proteolytic enzymes. In sodium dodecyl sulfate gel electrophoresis under reducing and nonreducing conditions, AFAL separated into two bands with a subunit molecular mass of 35 and 50 kDa. The homogeneity of purified protein was confirmed by chromatofocusing with a pI = 4.0 +/- 0.5. Molecular exclusion chromatography confirmed time-dependent oligomerization in AFAL, in accordance with mass spectrometry analysis, which confers an alteration in AFAL affinity for chitin. The protein sequence was obtained by a liquid chromatography quadrupole time-of-flight experiment and showed that AFAL has 68% and 63% sequence similarity with lectins of Phaseolus vulgaris and Dolichos biflorus, respectively.

Ethnopharmacological relevance Himatanthus drasticus (Mart.) Plumel – Apocynaceae is a medicinal plant popularly known as Janaguba. Its bark and latex have been used by the public for cancer treatment, among other medicinal uses. However, there is almost no scientific research report on its medicinal properties. Aim of the study The aim of this study was to investigate the antitumor effects of Himatanthus drasticus latex proteins (HdLP) in experimental models. Materials and methods The in vitro cytotoxic activity of the HdLP was determined on cultured tumor cells. HdLP was also tested for its ability to induce lysis of mouse erythrocytes. In vivo antitumor activity was assessed in two experimental models, Sarcoma 180 and Walker 256 carcinosarcoma. Additionally, its effects on the immunological system were also investigated. Results HdLP did not show any significant in vitro cytotoxic effect at experimental exposure levels. When intraperitoneally administered, HdLP was active against both in vivo experimental tumors. However, it was inactive by oral administration. The histopathological analysis indicates that the liver and kidney were only weakly affected by HdLP treatment. It was also demonstrated that HdLP acts as an immunomodulatory agent, increasing the production of OVA-specific antibodies. Additionally, it increased relative spleen weight and the incidence of megakaryocyte colonies. Conclusion In summary, HdLP has some interesting anticancer activity that could be associated with its immunostimulating properties.

The effects of a lectin (AaL) from seeds of Araucaria angustifolia were investigated in the model of rat paw edema. In vivo anti-and pro-inflammatory activities, role of sugar residues, inflammatory mediators and systemic toxicity were assessed. Intravenous injection of AaL (0.1-1 mg/kg) dose-dependently inhibited the dextran-induced increase in edema and vascular permeability, which were prevented by association of the lectin with its binding sugar N-acetyl-glucosamine (Glyc-Nac). AaL also significantly inhibited edema induced by serotonin (18%) and compound 48/80 (33%), but not edema induced by histamine. In contrast, when applied by the s.c. route, AaL evoked a paw edema that peaked 1 h later and was partially prevented by association with Glyc-Nac (59%) or by prior i.v. administration of the lectin itself (38.8%). This AaL edematogenic activity was significantly inhibited by pentoxifylline (44.4%) or dexamethasone (51%) and also by depletion of rat paw mast cells (45.6%), but not by L-N-nitro-arginine methyl ester or indomethacin, excluding involvement of nitric oxide and prostaglandins. Treatment of animals with a single anti-inflammatory dose of AaL (1 mg/kg, i.v.) for 7 days did not affect rat corporal mass, liver, kidney, spleen or stomach wet weight, blood leukocyte count, and urea, creatinine or serum transaminase activity. Systemic toxicity was apparent only at much higher doses (LD50=88.3 mg/kg) than those required for the anti-inflammatory effect. Summarizing, AaL exerts anti-and pro-edematogenic actions via interaction with its specific lectin domain. These actions may share a common pathway involving either activation or inhibition of inflammatory mediators from resident mast cells.