Although erythromycin A contains five hydroxyl groups, regioselective methylation at the C-6 hydroxyl group was achieved to the extent of 90%when a 9-0-substituted erythromycin A 9-oxime was employedas substrate. The methylation and its selectivity are dependent on an O-protecting group at the 9-oxime, solvent, base, and methylating reagent. In particular, the use ofa polar aprotic solvent is i...

A common structure of substrates of lignostilbenedioxygenases was investigated using synthesized stilbenes. Cell-free extracts of Sphingomonas paucimobilis TMY1009 degraded only trans-4-hydroxystilbene and trans-4-hydroxy-3-methoxystilbene. Other stilbenes that had no 4-hydroxyl group and had a cis structure were not substrates for lignostilbenedioxygenases. These results indicate that a 4-hydr...

going reduction. However, the carbonyl group of the larger, and more polar, 178-0(3-carboxypropanoyl)glycollyl side chain was not reduced. A 17/3-carboxyl or 178-methoxycarbonyl side chain was not reduced, probably for electronic reasons. In this respect, the reducing power of cortisone reductase resembled that of NaBH4 or lithium tri-t-butoxyaluminium hydride, and was less than that of LiAIH4....

BACKGROUND The redox imbalance between nitric oxide and superoxide generated in the endothelium is thought to play a pivotal role in the development of endothelial dysfunction. A third reactive oxygen species (ROS), H2O2, is known to have both beneficial and detrimental effects on the vasculature. Nonetheless, the influence of the hydroxyl radical, a byproduct of H2O2 decay, is unclear, and the...

A series of isoflavone and tyrphostin compounds were found to inhibit the degradation of cAMP by several cyclic nucleotide phosphodiesterase (PDE) isozymes. Specific hydroxyl groups on the isoflavone structure were critical for PDE isozyme-selective inhibition. Replacement of the C-7 hydroxyl group of the isoflavone with a methoxy group raised the IC(50) for PDE1, PDE3, and PDE4. The absence of...

The intermediate metabolism of androgens has been the subject of many investigations by incubation of liver slices and homogenates with testosterone or other suitable (319 compounds (l-4). The enzymatic reduction of the a,Bunsaturated ketone in ring A (4) and the oxidation of the C-17 hydroxyl group (1, 4) have been the major transformations demonstrated. However, Schneider and Mason (5) have s...

Our previous results elucidated that the leaves of Eriobotrya japonica possessed the potential to suppress ovariectomy-induced bone mineral density deterioration, and ursolic acid, the major bioactive component in these leaves, suppressed the osteoclast differentiation. The aim of this study was to discover more candidates for development of novel antiosteoclastogenesis agents from the leaves o...