Investigation of dioxygen activation by copper(ii)-iminate/aminate complexes.

The activation of dioxygen by metal ions is critical in chemical and bio-chemical processes. A scientific challenge is the elucidation of the activation site of dioxygen in some copper metalloproteins, which is either the metal center or the substrate. In an effort to address this challenge, we prepared a series of new copper(ii) complexes (1·2H2O, 2·CH3OH, 3) with bio-inspired amidate ligands and investigated their activity towards dioxygen activation.

Effect of conjugates of all-trans-retinoic acid and shorter polyene chain analogues with amino acids on prostate cancer cell growth.

In the present work, a series of conjugates of amino acids with all-trans-retinoic acid (ATRA) and shorter polyene chain analogues were rationally designed, synthesized by coupling the succinimidyl active esters of the acidic retinoids with appropriately protected amino acids or peptides followed by deprotection, and examined for their possible effect on viability of human prostate cancer LNCaP cells. In contrast to ATRA, all conjugates bearing amino acids with polar side chains showed no inhibitory effect on LNCaP cell proliferation, while conjugates with alpha-amino acids with lipophilic side chain, such as 7, or linear amino acids, such as 9, significantly decreased prostate cancer LNCaP cell number. Interestingly, while the effect of ATRA was RARalpha-dependent, the effect of its active analogues was not inhibited by a selective RARalpha antagonist.

Preparation of spermine conjugates with acidic retinoids with potent ribonuclease P inhibitory activity.

Novel mono- and diacylated spermines, readily obtained using isolable succinimidyl active esters of acidic retinoids for the selective acylation of free spermine or in situ activated acidic retinoids for acylating selectively protected spermine followed by deprotection, were shown to inhibit the ribozyme ribonuclease P more strongly than the parent retinoids.