A concise synthesis of marine natural product (-)-15-oxopuupehenol from (+)-sclarelide.

A step-economical synthesis of (-)-15-oxopuupehenol from cheap and readily available (+)-sclarelide is achieved with 20.3% overall yield in 9 steps. The key features of this synthetic mythology include a palladium catalyzed tandem carbine migratory insertion reaction to construct the key skeleton, a DDQ-mediated isomerization/oxidation of allyl alcohol to afford α, ß-unsaturated ketone, and a NaOH-induced intramolecular Michael addition followed by acetonide deprotection to give (-)-15-oxopuupehenol.

A novel fluorogenic substrate for dinuclear Zn(II)-containing metallo-ß-lactamases.

In an effort to prepare a fluorogenic substrate to be used in activity assays with metallo-ß-lactamases, (6R,7R)-8-oxo-7-(2-oxo-2H-chromene-3-carboxamido)-3-((4-(2-oxo-2H-chromene-3-carboxamido)-phenylthio)methyl)-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid (CA) was synthesized and characterized. CA exhibited a fluorescence quantum yield (φ) of 0.0059, two fluorescence lifetimes of 3.63×10(-10) and 5.38×10(-9)s, and fluorescence intensity that is concentration-dependent. Steady-state kinetic assays revealed that CA is a substrate for metallo-ß-lactamases (MßLs) L1 and CcrA, exhibiting Km and kcat values of 18µM and 5s(-1) and 11µM and 17s(-1), respectively.

[Study on the culture of crown gall from Panax quinquefolium and the prouction of its secondary metabolites--Ginsenosides Re and Rg1].

It was clearly demonstrated that T-DNA of Agrobacterium tumefeciens Ti plasmid was integrated into the cells of crown gall in our experiment. This paper reported the influences of some kinds of physical-chemistry factors on the growth of crown gall of Panax quinquefolium and the production of its main active compounds--ginsenoside Re and ginsensoside Rg1. The results showed that White medium was the best one for ginsensoside Rg1 accumulation (0.095%) among the six media, but ginsensoside Re accumulation (0.194%) was the highest on the MS medium; The highest contents of ginsensoside Re (0.147%) and ginsensoside Rg1 (0.061%) were on the culture 36d and 32d after innoculum respectively; The optimum pH was 5.6 for ginsensoside Rg1 synthesis(0.054%), and 5.8 for ginsensoside Re synthesis(0. 184% ); The contents of ginsensoside Re and ginsensoside Rg1 was the highest in the inoculum of 4 g and 2 g/flask (FW) respectively. The result also indicated that the concentration of inositol in 0.05 g/L could obviously promote ginsensoside Re synthesis (0.182%), and in 0.30 g/L for ginsensoside Rg1 (0.055%).