Purification, characterization and toxicity of a mannose-binding lectin from the seeds of Treculia africana plant

In this study, a mannose-specific, homodimeric lectin from the seeds of Treculia africana was purified, characterized and its adverse effects were investigated in mice. The purification protocol involved anionic exchange chromatography on DEAE-Cellulose followed by gel filtration on Sephadex G-100. The hemagglutinating activity of lectin towards human erythrocytes was sensitive to inhibition by D-mannose. Treatment of the protein with EDTA exerted no inhibitory effect; however, analysis of metal content by atomic absorption spectroscopy revealed the presence of Cu2+, Fe3+, and Mg2+. The results obtained showed that the lectin possesses maximum hemagglutinating activity towards human erythrocytes activity over the pH range 3–7.2 and is relatively thermostable up to 50°C. Periodic acid Schiff's (PAS) reagent staining showed that the protein was non-glycosylated while its amino acid composition analysis revealed that the protein contained 155 residues per subunit. The subunit had a minimal molecular weight of 22,139 Daltons, while the native molecular weight was estimated to be 41,000 Daltons. The lectin was found to be moderately toxic to mice with an LD50 of 47.21 µg g−1 body weight while, histopathological analysis showed no treatment related effects in any of the organs examined

A NEW BIOACTIVE THIOPHENOLIC GLYCOSIDE FROM THE LEAF OF MASSULARIA ACUMINATA (G. DON BULLOCK) EX HOYLE (RUBIACEAE)

Background: Massularia acuminata is a small tree or shrub of tropical rainforest. The leaves are used in Nigerian ethno-medicine for the treatment of microbial infections and pharmacological report suggested the leaf extract as possessing antioxidant activity. This study was therefore carried out to determine the most antioxidant and antimicrobial active fraction(s) of Massularia acuminata leaf and the constituent(s) responsible for the activities. Matherials and Methods: The leaf of Massularia acuminata was investigated for in vitro antioxidant and antimicrobial activities, using a 2,2- diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and agar dilution method respectively. Results: The ethyl acetate fraction demonstrated the best activities among the partitioned fractions tested. Bioassay guided purification of the most active ethyl acetate fraction led to isolation of a new thiophenolic glycoside, characterized as 4-(3´,3´-dihydroxy-1-mercaptopropyl)phenyl glycosylpyranoside. Conclusion: The isolated compound from the leaf of Massularia acuminata demonstrated antioxidant and antimicrobial activities and may be responsible for the activities of leaf extract and its ethyl acetate fraction, hence this may justify its ethnomedicinal use