Axinellin A and B: Two New Pyrrolactam Alkaloids from Axinella sp.
Two new pyrrolactam alkaloids, axinelline A (1) and B (2), were isolated from the n-BuOH extract of marine sponge Axinella sp. The structures of these compounds were elucidated on the basis of spectroscopic methods (HR-ESI-MS, 1D and 2D NMR).
Isolation and structure of axinastatin 5 from a republic of comoros marine sponge
Abstract The new cancer cell growth (human and murine) inhibitory (GI 50 0.3 to 3.3 μg/ml) cyclo -octapeptide axinastatin 5 ( 2 ) was isolated in 3.8 x 10 −7 % yield from the Western Indian Ocean marine sponge Axinella cf. carteri . Structural elucidation was achieved by high field (400 and 500 MHz) 2 D-NMR techniques and the amino acid sequence was confirmed by results of NMR and high resolution mass spectral MS/MS interpretations. Other peptide cancer cell growth inhibitory constituents of this orange sponge were found to be the cyclic hepta- and octapeptides axinastatin 1 and hymenistatin 1 (1).
Effects of the mineral phase and valence of vanadium on vanadium extraction from stone coal
The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal. Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when the raw ore is leached by 4 mol/L H2SO4 at 90°C for 2 h. After the sample is roasted at 900°C for 2 h, the leaching rate of vanadium reaches the maximum, and more than 70% of vanadium can be leached. The crystal of vanadium-bearing mica minerals decomposes and the content of V(V) increases with the rise of roasting temperature from 600 to 900°C, therefore the leaching rate of vanadium increases significantly with the decomposition of the mica minerals. Some new phases, anorthite for example, form when the roasting temperature reaches 1000°C. A part of vanadium may be enwrapped in the sintered materials and newly formed phases, which may impede the oxidation of low valent vanadium and make the leaching rate of vanadium drop dramatically. The leaching rate of vanadium is not only determined by the valence state of vanadium but also controlled by the decomposition of vanadium-bearing minerals and the existence state of vanadium to a large extent.