Leishmanicidal activities and cytotoxicities of bisnaphthoquinone analogues and naphthol derivatives from Burman Diospyros burmanica

A methanol extract of the wood of Diospyros burmanica, collected in Burma (Myanmar), was found to exhibit significant activity against Leishmania major. Subsequent chromatographically resolved fractionation led to the isolation of three novel bisnaphthoquinone analogues, burmanin A, B, and C (1-3), together with nine known compounds (4-12). The structure of 1 was confirmed by X-ray crystallography, and those of 2 and 3 by spectroscopic techniques, including 1D and 2D NMR. The inhibitory activities of the isolates were evaluated against the promastigote forms of Leishmania major and the murine macrophage-like cell line, RAW264.7.     

Biogenic Polyamines Capture CO2 and Accelerate Extracellular Bacterial CaCO3 Formation

Bacteria, including cyanobacteria, as well as some fungi, are known to deposit calcium carbonate (CaCO₃) extracellularly in calcium-containing artificial medium. Despite extensive investigation, the mechanisms involved in extracellular formation of CaCO₃ by bacteria have remained unclear. The ability of synthetic amines to remove carbon dioxide (CO₂) from natural gas led us to examine the role of biogenic polyamines in CaCO₃ deposition by bacteria. Here, we demonstrated that biogenic polyamines such as putrescine, spermidine, and spermine were able to react with atmospheric CO₂ and the resultant carbamate anion was characterized by using nuclear magnetic resonance (NMR) analysis. Biogenic polyamines accelerated the formation of CaCO₃, and we artificially synthesized the dumbbell-shaped calcites, which had the same form as observed with bacterial CaCO₃ precipitates, under nonbacterial conditions by using polyamines. The reaction rate of calcification increased with temperature with an optimum of around 40 °C. Our observation suggests a novel scheme for CO₂ dissipation that could be a potential tool in reducing atmospheric CO₂ levels and, therefore, global warming.     

Visualisation of Phosphate in Subcalicoblastic Extracellular Calcifying Medium and on a Skeleton of Coral by Using a Novel Probe,Fluorescein-4-Isothiocyanate-Labelled Alendronic Acid

Marine Biotechnology - The overload of nutrients of anthropogenic origin, including phosphate, onto coastal waters has been reported to have detrimental effects on corals. However, to the best of...