Two jacalin-related lectins from seeds of the African breadfruit (Treculia africana L.)

Anti-plasmodial, Cytotoxic and Antioxidant Activities of Selected Ghanaian Medicinal Plants

Malaria affects about half of the world's population. The sub-Saharan African region is the most affected. Plant natural products have been a major source of antimalarial drugs; the first (quinine) and present (artemisinin) antimalarials are of natural product origin. Some secondary metabolites demonstrate adjuvant antioxidant effects and selective activity. The focus of this study was to investigate the anti-plasmodial activity, cytotoxicities and antioxidant properties of eight (8) Ghanaian medicinal plants. The anti-plasmodial activity was determined using the SYBR green assay and the tetrazolium-based colorimetric assay (MTT) was employed to assess cytotoxicity of extracts to human RBCs and HL-60 cells. Antioxidant potential of plant extracts was evaluated using Folin-Ciocalteu and superoxide dismutase assays. Phytochemical contstituents of the plant extracts were also assessed. All the extracts demonstrated anti-plasmodial activities at concentrations <50 μg/ml. Parkia clappertoniana and Terminalia ivorensis elicited the strongest anti-plasmodial activities with 50% inhibitory concentrations (IC₅₀) of 1.13 μg/ml and 0.95 μg/ml, respectively. This is the first report on anti-plasmodial activities of Baphia nitida, Tabernaemontana crassa and Treculia Africana. T. Africana showed moderate anti-plasmodial activity with IC₅₀ value of 6.62 µg/mL. Extracts of P. clappertoniana, T. Africana and T. ivorensis (0.4 mg/mL) showed >50% antioxidant effect (SOD). The extracts were not cytotoxicity towards RBCs at the concentration tested (200 μg/ml) but were weakly cytotoxic to HL-60 cell. Selectivity indices of most of the extracts were greater than 10. Our results suggest that most of the plant extracts have strong anti-plasmodial activity and antioxidant activity which warrants further investigations.

Evaluation of Glycan-Binding Specificity by Glycoconjugate Microarray with an Evanescent-Field Fluorescence Detection System

Glycan microarray is an essential tool to study glycan-binding proteins called lectins. Using glycan microarrays, glycan-binding specificity can be analyzed by incubation with an array in which a series of glycans are immobilized. Various research groups in the world have developed glycan microarray. Among them, our glycan microarray has two unique points: one is the incorporation of the evanescent-field fluorescence detection system, and another is the use of multivalent glycopolymers. These two unique properties allow high-sensitive detection from a relatively limited amount of only nanograms of lectins, which could even be applied in crude samples such as cell lysates and cell culture media. Thus, this system is suitable for the first screening of lectins, lectin-like molecules, lectin candidates, and lectin mutants. Here we describe the protocols to analyze glycan-binding specificity of lectins using our glycan microarray system.