Synthesis and Antioxidant Properties of Organoselenium Compounds.

BACKGROUND: The chemistry of organoselenium reagents provides an asset for organic synthesis. The versatility of these reagents as electrophiles and nucleophiles makes them one of the key components of organic synthesis. Various synthetic transformations such as oxyselenenylations, selenocyclization and selenoxide elimination have been successfully achieved using organoselenium reagents under mild reaction conditions. The presence of selenocysteine in a few mammalian enzymes was the key information for selenium chemists to explore the biochemistry of selenium compounds. Glutathione peroxidase (GPx), a mammalian selenoenzyme, is well known for maintaining redox equilibrium by detoxifying reactive oxygen species. OBJECTIVE: The aim is to critically analyze the recent development and prospects of synthesis and antioxidant properties of organoselenium compounds. METHODS: In this review, we summarised research and review papers from the PubMed and Scopus databases. The primary themes were linked to the synthesis of organoselenium compounds and their capacity to maintain cellular redox equilibrium when exposed to oxidative stress. RESULTS: The study reveals that diselenide compounds synthesised by various methods showed a better antioxidant activity profile compared to selenides. In a few cases, the activity was found better than the standard compound ebselen. Moreover, the synthesis and antioxidant activity of Selenium-based nanoparticles have been also included. CONCLUSION: In the past two decades, various biological properties of organoselenium compounds have been extensively studied, including the antioxidant properties. This review article will give insight into the synthesis of different types of recently synthesised organoselenium compounds. The review would be helpful to the researchers working in the field of medicinal chemistry in directing the synthesis of new organoselenium compounds as antioxidants.

Palladium-Catalyzed Organic Reactions Involving Hypervalent Iodine Reagents.

The chemistry of polyvalent iodine compounds has piqued the interest of researchers due to their role as important and flexible reagents in synthetic organic chemistry, resulting in a broad variety of useful organic molecules. These chemicals have potential uses in various functionalization procedures due to their non-toxic and environmentally friendly properties. As they are also strong electrophiles and potent oxidizing agents, the use of hypervalent iodine reagents in palladium-catalyzed transformations has received a lot of attention in recent years. Extensive research has been conducted on the subject of C-H bond functionalization by Pd catalysis with hypervalent iodine reagents as oxidants. Furthermore, the iodine(III) reagent is now often used as an arylating agent in Pd-catalyzed C-H arylation or Heck-type cross-coupling processes. In this article, the recent advances in palladium-catalyzed oxidative cross-coupling reactions employing hypervalent iodine reagents are reviewed in detail.

Selenium-Based Fluorescence Probes for the Detection of Bioactive Molecules.

Chemistry of organoselenium reagents have now become an important tool of synthetic organic and medicinal chemistry. These reagents activate the olefinic double bonds and used to archive the number of organic transformations under mild reaction conditions. A number of organoselenium compounds have been identified as potent oxidants. Recently, various organoselenium species have been employed as chemical sensors for detecting toxic metals. Moreover, a number of selenium-based fluorescent probes have been developed for detecting harmful peroxides and ROS. In this review article, the synthesis of selenium-based fluorescent probes will be covered including their application in the detection of toxic metals and harmful peroxides including ROS.

The first synthesis of podocarflavone A and its analogs and evaluation of their antimycobacterial potential against Mycobacterium tuberculosis with the support of virtual screening.

The first synthetic route developed for Podocarflavone A reported from Podocarpus macrophyllus and its analogs in 7 steps. Computational analysis for binding with the pantothenate kinase (3AVO) of Mycobacterium tuberculosis showed their docking score (ds) in the range of -8.9 to -9.3 Kcal/mol. MD simulations delineated the stability of the protein-ligand complexes in the TIP3P model. MMGBSA and MMPBSA values of 8d were -42.46 Kcal/mol and -14.58 Kcal/mol, respectively. Further in-vitro antitubercular screening of compounds 8a, 8d, and 8e against M. tuberculosis H37Ra using XRMA protocol exhibited promising antimycobacterial activity with IC50 values 21.82 µg/mL, 15.55 µg/mL, and 16.56 µg/mL, respectively. Compounds 8a, 8d, and 8e showed antibacterial activity with IC50 values 41.56 µg/mL, 24.72 µg/mL, and 72.45 µg/mL respectively against the Staphylococcus aureus. 8a and 8d showed inhibition with IC50 values 39.6 µg/mL and 27.64 µg/mL, respectively, against Bacillus subtilis. The present study could help in the further development of lead molecules against tuberculosis.

Synthesis and in vitro antimalarial activity of tetraoxane-amine/amide conjugates.

A series of tetraoxanes, tetraoxane-amine and tetraoxane-amide conjugates have been synthesized and screened for in vitro antimalarial activity against chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum. Most of the conjugates showed slightly better antimalarial activity than the parent tetraoxanes. Three of the conjugate compounds were potentially active with IC(50) values in the range of 0.38-0.80µM. Cytotoxicity of four selected compounds was also evaluated in a panel of four cancer (SK-MEL, KB, BT-549, SK-OV-3) and two non-cancer (Vero and LLC-PK(11)) cell lines up to a concentration of 25µM and none of the compounds was found toxic to any of the cells.

Synthesis, thermal stability, antimalarial activity of symmetrically and asymmetrically substituted tetraoxanes.

Symmetrically and asymmetrically substituted 1,2,4,5-tetraoxanes were synthesized by the oxidative system H(2)O(2)/TFE in presence of MeReO(3) as a catalyst. All of the synthesized compounds were characterized spectroscopically, and evaluated for cytotoxicity, and antimalarial activity. Several of these tetraoxanes exhibited in vitro antimalarial activity without showing any cytotoxicity. Thermal stability of these compounds was studied by differential scanning calorimetry.