Enantioselective Syntheses of Lignin Models: An Efficient Synthesis of ß-O-4 Dimers and Trimers by Using the Evans Chiral Auxiliary.

We describe an efficient five-step, enantioselective synthesis of (R,R)- and (S,S)-lignin dimer models possessing a ß-O-4 linkage, by using the Evans chiral aldol reaction as a key step. Mitsunobu inversion of the (R,R)- or (S,S)-isomers generates the corresponding (R,S)- and (S,R)-diastereomers. We further extend this approach to the enantioselective synthesis of a lignin trimer model. These lignin models are synthesized with excellent ee (>99 %) and high overall yields. The lignin dimer models can be scaled up to provide multigram quantities that are not attainable by using previous methodologies. These lignin models will be useful in degradation studies probing the selectivity of enzymatic, microbial, and chemical processes that deconstruct lignin.

Development of an adrenocorticotropin-responsive human adrenocortical carcinoma cell line.

CONTEXT: The molecular mechanisms regulating adrenal steroidogenesis continue to be defined. The only current human adrenocortical cell line is the NCI-H295 and its substrains. One of the strains, H295R, has retained the ability to respond to angiotensin II (Ang II); however, it lacks ACTH responsiveness. An ACTH-responsive human adrenocortical model would add significantly to studies directed at defining the molecular control of corticosteroid biosynthesis. OBJECTIVE: The objective of the study was to develop a human adrenal cell line that retained both Ang II- and ACTH-regulated corticosteroid production. DESIGN: Human adrenocortical carcinoma (HAC) cells were isolated from an adrenal tumor removed from a girl presenting with virilization and hypertension. Clonal populations of cells were established and characterized. HAC cells were treated with ACTH, Ang II, and forskolin, followed by examination of steroidogenic enzyme mRNA expression using quantitative real-time PCR and steroid production. RESULTS: HAC clone 15 (HAC15) cells responded to treatment with ACTH, Ang II, and forskolin, with increased cortisol and aldosterone production. ACTH, Ang II, and forskolin also increased expression of mRNA, encoding all enzymes needed for cortisol and aldosterone biosynthesis, namely steroidogenic acute regulatory protein, cholesterol side-chain cleavage, cytochrome P450 17alpha-hydroxylase-17, 20-lyase, 3beta-hydroxysteroid dehydrogenase type II, 21-hydroxylase, 11beta-hydroxylase, and 11beta-aldosterone synthase. In addition, the cells expressed mRNA for ACTH receptor (MC2R) and Ang II receptor. MC2R protein was also expressed in HAC15 cells. CONCLUSION: The current study describes the development and characterization of an ACTH- and Ang II-responsive human adrenal cell line. The HAC15 cell line should provide an important model system for defining the molecular mechanisms regulating aldosterone and cortisol production.