O-Allyl decoration on α-glucan isolated from the haloalkaliphilic Halomonas pantelleriensis bacterium

Statistical optimization of levan: Influence of the parameter on levan structure and angiotensin I-converting enzyme inhibitory

Based on Plackett-Burman design, steepest ascent method, and Box-Behnken design, statistical optimization for B. subtilis AF17 for levan production was carried out. Sucrose, tryptone and initial pH were found to be the most significant parameter (P < 0.05) for levan production. Result showed that the optimum condition was sucrose 162.5 g/L, tryptone 10 g/L, initial pH 7 and maximum yield was 7.9 ± 0.18 g/L in 72 h fermentation. Purified levan was characterized using various physicochemical techniques such as GC-MS, 1H NMR, 13C NMR spectroscopy and SEC/TDA. Based on this data, the structure of levan was independent of initial culture conditions. The biomedical potential of the isolated Bacillus subtilis A17 levan for its angiotensin-I converting enzyme (ACE) inhibition activities was exploited in vitro. Interestingly, levan possessed an important angiotensin I converting enzyme (ACE) inhibitory 81.1 ± 4.1% at 4 mg/mL. The overall, data suggested that levan presents a promising natural source of antihypertensive agents.

New (99m)Tc(CO)(3) mannosylated dextran bearing S-derivatized cysteine chelator for sentinel lymph node detection

The aim of the present study is to synthesize new mannosylated dextran derivative that can be labeled with Tc-99m for potential use in sentinel lymph node detection (SLND). The compound was designed to have a dextran with molecular weight of 10 kDa as a backbone, mannose for binding to mannose receptors of the lymph node and S-derivatized cysteine as a suitable chelator for labeling with [(99m)Tc(H(2)O)(3)(CO)(3)](+) precursor. Reaction of allyl bromide with dextran (MW 11800) yielded the intermediate allyl-dextran (1) with about 40% coupling. Addition of cysteine to allyl-dextran resulted in the S-derivatized cysteine, compound DC15 (2). The final product DCM20 (3) was obtained in good yield after in situ hydrolysis and activation of cyanomethyl tetraacetyl-1-thio-d-mannopyranoside and coupling to DC15. All derivatives were purified by ultrafiltration and characterized by NMR. DC15 and DCM20 were quantitatively labeled with (99m)Tc (>95% radiochemical purity) using the fac-[(99m)Tc(OH(2))(3)(CO)(3)](+) precursor and ligand concentration of 1.5 × 10(-6) M at neutral pH. Both (99m)Tc-labeled compounds (99m)Tc(CO)(3)-DC15 (6) and (99m)Tc(CO)(3)-DCM20 (7) remained stable after 6 h incubation at 37 °C in the presence of excess histidine or cysteine, as well as even after 20-fold dilution and incubation for 24 h at room temperature. The characterization of the compounds 6 and 7 was performed by comparing their HPLC radiochromatograms with those of their rhenium surrogates Re(CO)(3)-DC15 (4) and Re(CO)(3)-DCM20 (5) respectively that were prepared using the precursor [NEt(4)](2)fac-[ReBr(3)(CO)(3)] and characterized by IR and NMR spectroscopy. When injected subcutaneously from the foot pad of mice, (99m)Tc-labeled mannosylated dextran (7) showed accumulation in the popliteal lymph node (SLN in this model) higher than that of non-mannosylated analogue (6) and the (99m)Tc-phytate serving as standard. Compound 7 also exhibited lower radioactivity levels at the injection site compared to (99m)Tc-phytate. The SPECT/CT studies in mice confirmed that 7 accumulated in the popliteal lymph node allowing its clear visualization. The present findings demonstrate that compound 7 ((99m)Tc(CO)(3)-DCM20) is promising and merits further evaluation as a radiopharmaceutical for sentinel lymph node detection.

Molecules derived from the extremes of life

In order to survive extremes of pH, temperature, salinity and pressure, organisms have been found to develop unique defences against their environment, leading to the biosynthesis of novel molecules ranging from simple osmolytes and lipids to complex secondary metabolites. This review highlights novel molecules isolated from microorganisms that either tolerate or favour extreme growth conditions.