1,1,2-Tris-organoselenide alkene derivatives, but not 1,2-bis-organoselenide alkene derivatives, inhibited δ-aminolevulinate dehydratase activity from human erythrocytic cells in vitro

Atom Transfer Oxidative Radical Cascade of Aryl Alkynoates towards 1,1-Dichalcogenide Olefins

An oxidative trifunctionalization of aryl alkynoates has been devised via the chalcogenide radical triggered intramolecular 1,4-aryl migration/decarboxylation cascade to prepare 1,1-dichalcogenide tetrasubstituted alkenes in high yields (up to 98 %). This operationally simple reaction proceeds under metal-free conditions, can be executed on gram scale, and highlights formal 1,1-difunctionalization of alkynes. Synthetic potential of this protocol was demonstrated through a twofold cascade rearrangement to access highly conjugated tetra-selenylated alkenes along with a cross-dehydrogenative annulation to prepare fluorene derivative.

Copper-Catalyzed Decarboxylative/Click Cascade Reaction: Regioselective Assembly of 5-Selenotriazole Anticancer Agents

A simple and efficient Cu-catalyzed decarboxylative/click reaction for the preparation of 1,4-disubstituted 5-arylselanyl-1,2,3-triazoles from propiolic acids, diselenides, and azides has been developed. The mechanistic study revealed that the intermolecular AAC reaction of an alkynyl selenium intermediate occurred. The resulting multisubstituted 5-seleno-1,2,3-triazoles were tested for in vitro anticancer activity by MTT assay, and compounds 4f, 4h, and 4p showed potent cancer cell-growth inhibition activities.

Delta-ALA-D inhibitory potential and protective action of Syzygium jambos and Solanum guaraniticum leaf extracts on oxidatively stressed erythrocytes

OBJECTIVE

This study aimed to investigate the effect of the leaf extracts of Syzygium jambos and Solanum guaraniticum on the δ-aminolevulinate dehydratase (δ-ALA-D) activity, their antioxidant activity and potential protective action on oxidatively stressed erythrocytes, in order to demonstrate the safety or toxicity of the plant.

METHODS

In erythrocyte samples, the effect of both extracts on δ-ALA-D activity, H2O2-induced oxidative stress, and 2,2'azobis (2-amidinopropane) (AAPH)-induced hemolysis was evaluated, as well as some antioxidant mechanisms.

RESULTS

Both extracts inhibited δ-ALA-D activity (S. guaraniticum > S. jambos), and an involvement of the zinc ion of the δ-ALA-D structure on the inhibition of enzyme activity was verified. S. jambos leaf extract showed marked efficiency in countering H2O2-induced lipid peroxidation and in maintaining cellular integrity against AAPH-induced hemolysis. Furthermore, S. jambos exhibited greater H2O2 scavenging activity and stronger reduction power than S. guaraniticum.

DISCUSSION

Both extracts bear potent antioxidant property as an important beneficial effect. However, the inhibition of δ-ALA-D activity suggests a possible harmful effect of these vegetal preparations and indicates the need for further investigation regarding their toxicological properties. All together, these data represent a significant contribution to the knowledge of these plants, both to the scientific community and to the folk medicine.

Fe(II) and sodium nitroprusside induce oxidative stress: a comparative study of diphenyl diselenide and diphenyl ditelluride with their napthyl analog

Here, we compare the influence of molecular structural modifications of diphenyl diselenide (DPDS) and diphenyl ditelluride (DPDT) with their naphthalene analogs, 1-dinapthyl diselenide (1-NapSe)2, 2-dinapthyl diselenide (2-NapSe)2, 1-dinapthyl distelluride (1-NapTe)2, and 2-dinapthyl ditelluride (2-NapTe)2. Fe(II)-induced hepatic thiobarbituric acid reactive species (TBARS) was in the order [(2-NapTe)2] > [(2-NapSe)2] > [(DPDS)] > [(1-NapSe)2] > [(1-NapTe)2]> [(DPDT)]. For sodium nitroprusside (SNP)-induced hepatic TBARS, the order was [(2-NapTe)2] > [(DPDT)] > [(1-NapSe)2] > [(2-NapSe)2] > [(1-NapTe)2] > [(DPDS)]. For Fe(II) and SNP-induced renal TBARS, the orders were [(2-NapTe)2] > [(1-NapTe)2] = [(DPDT)] > [(1-NapSe)2] > [(2-NapSe)2] > [(DPDS)] and [(2-NapTe)2] > [(1-NapTe)2] > [(1-NapSe)2] > [(2-NapSe)2] > [(DPDS)] > [(DPDS)], respectively. The present investigation shows that DPDS was less potent and the change in the organic moiety from an aryl to napthyl group dramatically changed the potency of diselenides. These results suggest that minor changes in the organic moiety of aromatic diselenides can profoundly modify their antioxidant properties. In view of the fact that the pharmacological properties of organochalcogens are linked, at least in part, to their antioxidant properties, it becomes important to explore the pharmacological properties of dinaphtyl diselenides and ditellurides.

Acute exposure of rabbits to diphenyl diselenide: a toxicological evaluation

The simple organoselenium compound diphenyl diselenide (PhSe)(2) is a promising new pharmacological agent. However, few toxicological evaluations of this molecule have been reported. We evaluated the effects of acute administration of (PhSe)(2) on toxicological parameters in rabbits. Adult New Zealand rabbits were exposed to (PhSe)(2) (5-500 micromol kg(-1) , intraperitoneally) once a day for 5 days. Exposure to 500 micromol kg(-1) caused 85% mortality. Exposure to 50 micromol kg(-1) of (PhSe)(2) increased the glutathione levels in the hippocampus, kidney, heart, muscle and blood, whereas lipoperoxidation (TBARS) decreased in the cerebellum and kidney after exposure to 5 micromol kg(-1) . The activity of glutathione peroxidase increased in the heart and muscle of rabbits treated with 50 micromol kg(-1) of (PhSe)(2) and glutathione reductase activity was reduced in the cerebellum, cerebral cortex and kidney. Treatment with (PhSe)(2) reduced the activity of δ-aminolevulinate dehydratase in the hippocampus and increased this activity in the heart, but did not alter the activity of complexes I and II of the respiratory chain in the liver and brain. Hepatic and renal biochemical and histological parameters were not modified by (PhSe)(2) and apoptosis was not detected in these tissues; however, the hepatic cells tended to accumulate fat vacuoles. These results indicated that acute toxicology to (PhSe)(2) in rabbit is dependent on the dose, which should motivate further experiments on the therapeutic properties of this compound.