Helmoz R. Appelt

Facilitation of long-term object recognition memory by pretraining administration of diphenyl diselenide in mice

Selenium compounds display antioxidant and neuroprotective properties. Diphenyl diselenide (PhSe)(2) is an organic selenium compound that affects a number of neuronal processes. The aim of the present study was to evaluate the effects of the systemic administration of (PhSe)(2) on novel object recognition memory in mice. Adult male CF1 mice were given an i.p. injection of (PhSe)(2) (0.2, 1.0, 5.0, or 25.0 micromol/kg) 30 min before training in an object recognition task. (PhSe)(2) did not affect short-term memory or the total time exploring both objects, but induced a facilitation of retention measured 24 h after training. The present findings show that systemic administration of (PhSe)(2) induces a facilitation of formation of long-term object recognition memory.

Facile and practical enantioselective synthesis of propargylic alcohols by direct addition of alkynes to aldehydes catalyzed by chiral disulfide–oxazolidine ligands

Abstract The enantioselective alkynylation reaction of aldehydes with alkynes and diethylzinc, catalyzed by chiral disulfide–oxazolidine ligands, provides a simple, practical and inexpensive method to access chiral propargylic alcohols in good yields and satisfactory ees.

A new functionalized, chiral disulfide derived from (L)-cysteine: R,R-bis[(3-benzyloxazolan-4-yl)-methane] disulfide as a catalyst in the diethylzinc addition to aldehydes

Abstract A new, easily accessible, chiral disulfide 3 was prepared from l -cysteine in a short synthetic sequence ( Scheme. 1 ) and applied successfully as a highly efficient catalyst for the enantioselective addition of diethyl zinc to aromatic and aliphatic aldehydes to afford the product alcohols in up to more than 99% ee. In contrast to the more common amino alcohols used in similar reactions, catalyst 3 does not have a protic hydrogen in the form of a free hydroxy group.

New C2-symmetric chiral disulfide ligands derived from (R)-cysteine

Abstract Several sulfur-containing optically active C 2 -symmetrical ligands have been synthesized from ( R )-cysteine and applied successfully as chiral catalysts in the asymmetric addition of diethylzinc to aldehydes. The resulting secondary alcohols could be obtained in good yields and excellent enantiomeric excess.

Synthesis and Antimicrobial Activity of Carbohydrate Based Schiff Bases: Importance of Sugar Moiety

A series of D-glucosamine derivatives were synthesized (2–4) and evaluated for their antimicrobial activity. Some of the compounds investigated have shown significant antimicrobial activity against Gram-positive and Gram-negative bacterial strains as well as a few fungal strains. The results suggest that the presence of sugar moiety is necessary to biological activity.