Disubstituted Dithiolethione ACDT Exerts Neuroprotective Effects Against 6-Hydroxydopamine-Induced Oxidative Stress in SH-SY5Y Cells

Neurochemical Research - Parkinson’s disease (PD) is a prevalent, progressive, neurodegenerative disorder with no known cure. Oxidative stress has been found to play a significant role in its...     

Substrate modulates compound I formation in peroxide shunt pathway of Pseudomonas putida cytochrome P450(cam)

The active oxygenating intermediate, a ferryl-oxo-(II) porphyrin cation radical (compound I), in substrate-bound cytochrome P450(cam) (P450(cam)) has eluded detection and kinetic analysis for several decades. Upon rapid mixing of peroxides-H(2)O(2) and m-CPBA with substrate-bound forms of P450(cam), we observed an intermediate with spectral features characteristic of compound I. Unlike in H(2)O(2), kinetic investigation on the reaction of m-CPBA with various substrate (camphor, adamantone, and norcamphor)-bound P450(cam) and its Y96A mutant shows a preferential binding of the aromatic end group of m-CPBA to the active-site of the enzyme and modulation of compound I formation by the local environment of heme active-site. The results presented in this paper describe the importance of heme environment in modulating formation of compound I, and form the first kinetic analysis of this intermediate in the peroxide shunt pathway of substrate-bound P450(cam).     

Peganine hydrochloride dihydrate an orally active antileishmanial agent

Protozoic infections caused by genus Leishmania pose an enormous public health threat in developing countries, compounded by the toxicity and resistance to current therapies. Under the aegis of our ongoing program on drug discovery and development on antileishmanial agents from plants, we carried out bioassay guided fractionation on Peganum harmala seeds which resulted in the isolation of 1 as an antileishmanial agent. 2D-NMR spectral data and single crystal X-ray crystallography data indicated 1 as peganine hydrochloride in dihydrated form. The compound 1 exhibited in-vitro activity against both extracellular promastigotes as well as intracellular amastigotes residing within murine macrophages in Leishmania donovani. Furthermore, 1 also exhibited in-vivo activity, 79.6 (±8.07)% against established VL in hamsters at a dose of 100 mg/kg b.wt.     

Immunolocalization and functional role of Sclerotium rolfsii lectin in development of fungus by interaction with its endogenous receptor

Many fungi are known to secrete lectins, but their functional roles are not clearly understood. Sclerotium rolfsii, a soilborne plant pathogenic fungus capable of forming fruiting bodies called sclerotial bodies, secrete a cell wall-associated Thomsen-Friedenreich antigen-specific lectin. To understand the functional role of this lectin, we examined its occurrence and expression during development of the fungus. Furthermore, putative endogenous receptors of the lectin were examined to substantiate the functional role of the lectin. Immunolocalization studies using FITC-labeled lectin antibodies revealed discrete distribution of lectin sites at the branching points of the developing mycelia and uniformly occurring lectin sites on the mature sclerotial bodies. During development of the fungus the lectin is expressed in small amounts on the vegetative mycelia and reaching very high levels in mature sclerotial bodies with a sudden spurt in secretion at the maturation stage. Capping of the lectin sites on the sclerotial bodies by lectin antibodies or haptens inhibit strongly the germination of these bodies, indicating functional significance of the lectin. At the maturation stage the lectin interacts with the cell wall-associated putative endogenous receptor leading to the aggregation of mycelium to form sclerotial bodies. The lectin-receptor complex probably acts as signaling molecule in the germination process of sclerotial bodies. Using biotinylated lectin, the receptors were identified by determining the specific lectin binding to lipid components, extracted from sclerotial bodies, and separated on thin-layer chromatograms. Preliminary characterization studies indicated that the receptors are glycosphingolipids and resemble inositolphosphoceramides. These findings together demonstrate the importance of lectin-receptor interactions to explain hitherto speculated functional role of the lectins and also the glycosphingolipids of fungi.     

Two new bacterial DNA primase inhibitors from the plant Polygonum cuspidatum

The 70% aqueous methanolic extract of the Peruvian plant Polygonum cuspidatum sp. was found to contain two novel phenolic saccharides 1 and 2, which were identified as inhibitors of the bacterial DNA primase enzyme. Structures of these two compounds were established based on high resolution NMR studies. Compound 1 and 2 inhibited the primase enzyme with an IC(50) of 4 and 5 microM, respectively.     

Three new compounds from the plant Lippia alva as inhibitors of chemokine receptor 5 (CCR5)

The 70% aqueous methanol extract of the Peruvian plant Lippia alva (Verbenaceae) was found to contain three novel compounds, 1, 2, and 3, which were identified as inhibitors of the chemokine receptor CCR5. The structures of 1-3 were established based on extensive NMR studies. Compounds 1-3 inhibited CCR5 receptor signaling as measured by a calcium mobilization assay with IC(50) values of 5.5, 6.0, and 7.2 microg/mL, respectively.     

Synthesis and biological evaluation of 2,3-diarylpyrazines and quinoxalines as selective COX-2 inhibitors

Several 2,3-diaryl pyrazines and quinoxalines with 4-sulfamoyl (SO(2)NH(2))/methylsulfonyl (SO(2)Me)-phenyl pharmacophores have been synthesized and evaluated for the cyclooxygenase (COX-1/COX-2) inhibitory activity. Smaller groups such as methoxy, methyl and fluoro when substituted at/around position-4 of the adjacent phenyl ring, have great impact on the selective COX-2 inhibitory activity of the series. Many potential compounds were obtained from a brief structure-activity relationship (SAR) study. Two of these, compounds 11 and 25 exhibited excellent in vivo activity in the established animal model of inflammation. Since compound 25 possessed an amenable sulfonamide group, two of its prodrugs 48 and 49 were also synthesized. Both of them have excellent in vivo potential, and represent a new class of COX-2 inhibitor.     

Compound heterozygosity at the FMR1 gene

Individuals affected with Fragile X syndrome are usually characterized at the DNA level by the presence of at least 200 CGG repeats in the 5' untranslated region of the FMR1 gene; this number of repeats is defined as a full mutation. Repeats that number 50-200 usually define those with premutations and are termed unaffected carriers. We report here a compound heterozygous female who carried CGG repeats in the FMR1 gene that fall within the premutation and full mutation ranges. The former appears to have been inherited from the father, whereas the latter is an expansion of the premutation carried by the proband's mother. Therefore, the offspring of the proband will carry a significant risk of being affected with Fragile X syndrome, and the paternal uncle and any cousins should be counselled for being at risk for this syndrome.     

Conformational control through translocational regulation: a new view of secretory and membrane protein folding

We suggest a new view of secretory and membrane protein folding that emphasizes the role of pathways of biogenesis in generating functional and conformational heterogeneity. In this view, heterogeneity results from action of accessory factors either directly binding specific sequences of the nascent chain, or indirectly, changing the environment in which a particular domain is synthesized. Entrained by signaling pathways, these variables create a combinatorial set of necessary-but-not-sufficient conditions that enhance synthesis and folding of particular alternate, functional, conformational forms. We therefore propose that protein conformation is productively regulated by the cell during translocation across the endoplasmic reticulum (ER), a concept that may account for currently poorly understood aspects of physiological function, natural selection, and disease pathogenesis.