Synthesis of 1,8-dioxooctahydroxanthene C-nucleosides

Since reactions between carbohydrates and cyclic 1,3-dicarbonyl compounds do not produce 1,8-dioxooctahydroxanthenes in general, reaction strategies have been devised to generate new 1,8-dioxooctahydroxanthene C-nucleosides by reacting sugars masked with acid-labile protecting groups and with free hydroxyl groups with 1,3-cyclohexanedione or dimedone. Some of these compounds are more cytotoxic to the cancer cells than against normal fibroblasts

Cell cytotoxicity and serum albumin binding capacity of the morin–Cu(ii) complex and its effect on deoxyribonucleic acid

The dietary components, flavonoids, are important for their anti-oxidant properties and the ability to act as metal ion chelators. The characterization of the morin–Cu(II) complex is executed using elemental analysis, FTIR and mass spectroscopy. DNA cleaving and cell cytotoxicity properties followed by serum albumin binding have been investigated in this report. The morin–Cu(II) complex was found to cleave plasmid pBR322 DNA via an oxidative pathway as revealed by agarose gel based assay performed in the presence of some scavengers and reactive oxygen species. The breaking of the deoxyribose ring of calf thymus DNA (ct-DNA) was also confirmed by the formation of thiobarbituric acid reacting species (TBARS) between thiobarbituric acid and malonaldehyde. The morin–Cu(II) complex is able to inhibit the growth of human HeLa cells. Fluorescence studies revealed that the morin–Cu(II) complex can quench the intrinsic fluorescence of serum albumins (SAs) via a static quenching method. The binding constants were found to be in the order of 105 M−1 and observed to increase with temperature. Both ΔH° and ΔS° are positive for the binding of the morin–Cu(II) complex with serum albumins which indicated the presence of hydrophobic forces. Site-selectivity studies reveal that the morin–Cu(II) complex binds to both site 1 (subdomain IIA) and site 2 (subdomain IIIA) of human serum albumin (HSA) and bovine serum albumin (BSA). Circular dichroism (CD) studies showed the structural perturbation of SAs during binding with the morin–Cu(II) complex. The results from binding studies confirmed that after complexation with the Cu(II) ion, morin alters its mode of interaction with SAs which could have differential implications on its other biological and pharmaceutical properties

A novel encystation specific protein kinase regulates chitin synthesis in Entamoeba invadens

Phosphorylation is an important post-translational modification of proteins and is involved in the regulation of a variety of cellular events. The proteome of Entamoeba invadens, the reptilian counterpart of Entamoeba histolytica consists of an overwhelming number of putative protein kinases, and some may have a role to play in Entamoeba encystation. In this study, we have identified a novel protein kinase named as EiCSpk (Entamoeba invadens cyst specific protein kinase) which expressed almost exclusively during encystation. It is an active Protein kinase C with a characteristic substrate phosphorylation and auto-phosphorylation property. Gene silencing study has unveiled its role as a regulator of chitin synthesis through transcriptional activation of the chitin synthesis pathway genes along with glycogen phosphorylases that are involved in the influx of glucose from glycogen breakdown for chitin synthesis