2058 research outputs found
Sort by
Chemical Investigation of Bioactive Substances from Medicinal Plants
No full textThis part deals with chemical investigation of compounds isolated from Anthocephalus cadamba (Roxb.) followed by DNA Topoisomerase IB activity pf the isolates. Chromatographic resolution of the methanolic and ethyl acetate extract of stem bark of Anthocephalus cadamba resulted in the isolation of a new indole alkaloid glycoside known as anthocephaline (1) with five known indole alkaloids (strictosamide, vincosamide, cadambine, 5-carboxystrictosidine and vallesiachotamine). Along with
these indole alkaloids four triterpenoids viz., ursolic acid, quinovic acid 3-O-β-Lrhamnopyranoside,
3-O-[α-L-rhamnopyranosyl]-quinovic acid -28-O-[β-Dglucopyranosyl] ester, 3-O-[β-D-glucopyranosyl-(2→1) O-β-D-glucopyranosyl]-quinovic acid-28-O-[β-D-glucopyranosyl] ester and one iridoid glucoside (diderroside) were also isolated. Anthocephaline (1) was found to be an amorphous solid. It gave IR absorptions
for hydroxyl and α, β-unsaturated carbonyl groups at 3420 cm-1 and 1653 cm-1 respectively. The UV spectrum exhibited absorptions which were found to be similar to
an indole chromophore. The structure was established from detailed 1H and 13C NMR spectroscopic data, along with 2D NMR experiments (COSY, NOESY, HSQC, HMBC). The 1H and 13C NMR data of anthocephaline were very similar to those of naucleomide C, except for the resonances of aromatic protons, and trisubstituted olefinic and enolic
protons. The 13C NMR data further indicated the presence of one carbomethoxy carbonyl group instead of an amide carbonyl
Microcalorimetry and spectroscopic studies on the binding of dye janus green blue to deoxyribonucleic acid
Get PDFThe interaction of the phenazinium dye janus green blue (JGB) with deoxyribonucleic acid was investigated using isothermal titration calorimetry and thermal melting experiments. The calorimetric data were supplemented by spectroscopic studies. Calorimetry results suggested the binding affinity of the dye to DNA to be of the order of 105 M-1. The binding was predominantly entropy driven with a small negative favorable enthalpy contribution to the standard molar Gibbs energy change.The binding became weaker as the temperature and salt concentration was raised. The temperature dependence of the standard molar enthalpy changes yielded negative values of standard molar heat capacity change for the complexation revealing substantial hydrophobic contribution in the DNA binding. An enthalpy–entropy compensation behavior was also observed in the system. The salt dependence of the binding yielded the release of 0.69 number of cations on binding of each dye molecule. The non-polyelectrolytic contribution was found to be the predominant force in the binding interaction. Thermal melting studies revealed that the DNA helix was stabilized against denaturation by the dye. The binding was also characterized by absorbance, resonance light scattering and circular dichroism spectral measurements. The binding constants from the spectral results were close to those obtained from the calorimetric data. The energetic aspects of the interaction of the dye JGB to double stranded DNA are supported by strong binding revealed from the spectral data
Molecular Details of Acetate Binding to a New Diamine Receptor by NMR and FT-IR Analyses
No full textAcetate anion plays an important role in several
biochemical functions such as enzyme reaction, antibody response, and action of receptor molecules. This investigation reports the synthesis and molecular details of a unique receptor, 2-amino-N-(2- amino-benzyl)-benzamide (R) that senses selectively acetate via simultaneous involvement of one aromatic amine group and an amide proton of the receptor molecule. Solution-state NMR, steady-state fluorescence, and FT-IR examinations established that
the acetate anion binds to the receptor with 1:1 ratio with high specificity. The binding was stabilized by two H-bond formations between the oxygen atoms of acetate anion and two H atoms, one from amide group and the other from the amine group of the receptor. The binding interaction caused significant changes in the chemical shift of the receptor protons, and the evaluated affinity constant, from the NMR measurements, was found to be 1.87 × 104 M−1. Density functional theory (DFT) analysis further showed a significant rotation of one of the two aromatic rings leading to formation of a 10-member ring involving the acetate anion, amide proton, and the one amine group attached to aromatic ring. The H-bond patterns observed in the crystal structure were significantly changed due to complex formation. However, the changes in the geometrical arrangement in the complex caused a small but significant increase of the fluorescence emission. Acetate geometry and unique positioning of the amide and amine groups of the receptor render the recognition feasible, and DFT analysis estimated ∼30 kJ M−1 stabilization due to 1:1 complexation. Such positioning and geometrical arrangement may make the receptor very specific to bind acetate anion, and as such R became a very relevant molecule in detection and function of the acetate anion present in complex biochemical system
Mechanistic Insight into the Reactivation of BCAII Enzyme from Denatured and Molten Globule States by Eukaryotic Ribosomes and Domain V rRNAs
Get PDFIn all life forms, decoding of messenger-RNA into polypeptide chain is accomplished by the ribosome. Several protein chaperones are known to bind at the exit of ribosomal tunnel to ensure proper folding of the nascent chain by inhibiting their premature folding in the
densely crowded environment of the cell. However, accumulating evidence suggests that ribosome may play a chaperone role in protein folding events in vitro. Ribosome-mediated folding of denatured proteins by prokaryotic ribosomes has been studied extensively. The
RNA-assisted chaperone activity of the prokaryotic ribosome has been attributed to the domain V, a span of 23S rRNA at the intersubunit side of the large subunit encompassing
the Peptidyl Transferase Centre. Evidently, this functional property of ribosome is unrelated to the nascent chain protein folding at the exit of the ribosomal tunnel. Here, we seek to scrutinize whether this unique function is conserved in a primitive kinetoplastid group of eukaryotic species Leishmania donovani where the ribosome structure possesses distinct additional features and appears markedly different compared to other higher eukaryotic
ribosomes. Bovine Carbonic Anhydrase II (BCAII) enzyme was considered as the model protein. Our results manifest that domain V of the large subunit rRNA of Leishmania ribosomes
preserves chaperone activity suggesting that ribosome-mediated protein folding is, indeed, a conserved phenomenon. Further, we aimed to investigate the mechanism underpinning the ribosome-assisted protein reactivation process. Interestingly, the surface plasmon resonance binding analyses exhibit that rRNA guides productive folding by directly interacting with molten globule-like states of the protein. In contrast, native protein shows no
notable affinity to the rRNA. Thus, our study not only confirms conserved, RNA-mediated chaperoning role of ribosome but also provides crucial insight into the mechanism of the process
Elucidation Of Regulation And Function Of WISP3
No full textWISP3 (Wnt Induced Signaling Protein 3) is a member of the CCN (Cysteine rich 61, Connective tissue growth factor, Nephroblastoma overexpressed protein) family proteins, and
expressed in cells and tissues of mesenchymal origin. As suggested and published by the International CCN Society, the alternative name of WISP3 is CCN6. WISP3 maps to human
chromosome 6q-22 and codes for a 354 amino acid multi-domain protein. Mutations of WISP3 are associated with Progressive Pseudo Rheumatoid Dysplasia (PPRD) which is characterized by degeneration of cartilage, narrowing of joint space and stunted bone growth at the onset of
puberty. Prior investigations suggest that most of these CCN proteins are mainly involved in the regulation of chondrogenesis and angiogenesis. In spite of a number of studies focusing on the functional characterization of WISP3 in context of chondrocyte differentiation and cartilage growth / development, the detailed molecular mechanism of WISP3 function remains incomplete. The goal of this thesis work is to explore the function and regulation of WISP3. Given that WISP3 has its influence on ROS accumulation and mitochondria are the major site of
ROS production, WISP3 may regulate mitochondrial ROS by influencing mitochondrial functions. Besides, the multi-domain architecture of WISP3 suggests that it may interact with mitochondrial protein HSP60 and ATP5A1, and the WISP3 interaction network may regulate mitochondrial functions. Here, for the first time we found that WISP3 localizes to mitochondria and depletion of WISP3 enhances mitochondrial ROS accumulation within physiological limit. Additionally, WISP3 depletion by siRNA enhances mitochondrial ATP synthesis, mitochondrial membrane potential, calcium uptake, ROS dependent PGC1α expression and mitochondrial
mass. We demonstrated that WISP3 associates with mitochondrial proteins including HSP60. Upon depletion of WISP3 expression by siRNA, interaction of HSP60 with mitochondrial Complex I subunit NDUFB8 changes, concomitant with enhanced Complex I activity of mitochondrial electron transport chain (ETC). Enhanced ETC activity is documented by elevated Complex I assembly. A similar outcome of WISP3 depletion using CRISPR-Cas9 validates that WISP3 modulates Complex I assembly and thereby mitochondrial function. Transcription factor Nrf2 counter regulates WISP3 function through repressing WISP3 expression. Taken together,
our results document for the first time that WISP3 plays an inhibitory role appropriately balanced by Nrf2 in mitochondrial ETC complex assembly and activity
GSH Induced Controlled Release of Levofloxacin from a Purpose-Built Prodrug: Luminescence Response for Probing the Drug Releasein Escherichia coli and Staphylococcus aureus
No full textFluoroquinolones are third-generation broad spectrum bactericidal antibiotics and work against both Grampositive
and Gram-negative bacteria. Levofloxacin (L), a fluoroquinolone, is widely used in anti-infective chemotherapy and treatment of urinary tract infection and pneumonia. The main pathogen for urinary tract infections is Escherichia coli, and Streptococcus pneumoniae is responsible for pneumonia, predominantly a lower respiratory tract infection. Poor permeability of L
leads to the use of higher dose of this drug and excess drug in the outer cellular fluid leads to central nervous system (CNS) abnormality. One way to counter this is to improve the lipophilicity of the drug molecule, and accordingly, we have synthesized two new Levofloxacin derivatives, which participated in the spatiotemporal release of drug via disulfide bond cleavage induced by
glutathione (GSH). Recent studies with Streptococcus mutants suggest that it is localized in epithelial lining fluid (ELF) of the normal lower respiratory tract and the effective [GSH] in ELF is ∼430 μM. E. coli typically cause urinary tract infections and the concentration of GSH in porcine bladder epithelium is reported as 0.6 mM for a healthy human. Thus, for the present study we have chosen two important bacteria (Gram + ve and Gram − ve), which are operational in regions having high extracellular GSH
concentration. Interestingly, this supports our design of new lipophilic Levofloxacin based prodrugs, which released effective drug on reaction with GSH. Higher lipophilicity favored improved uptake of the prodrugs. Site specific release of the drug (L) could be achieved following a glutathione mediated biochemical transformation process through cleavage of a disulfide bond of these
purpose-built prodrugs. Further, appropriate design helped us to demonstrate that it is possible also to control the kinetics of the drug release from respective prodrugs. Associated luminescence enhancement helps in probing the release of the drug from the prodrug in bacteria and helps in elucidating the mechanistic pathway of the transformation. Such an example is scarce in the
contemporary literatur
Biomolecules from living sources used as immunostimulants: their Identification, mechanism of actions and molecular interactions
No full textOur environment contains innumerable infectious microbes such as viruses, bacteria, fungi, protozoa and multi cellular parasites which can cause disease or can damage by
inducing stress and DNA damage. If they remain unchecked, eventually kill their host. Moreover, there are some other physical as well as chemical agents can damage proper
functioning of human system. Thus to combat such infectious agents and to repair injuries, body requires a system known as immune syste
Vesicular (liposomal and nanoparticulated) delivery of curcumin: a comparative study on carbon tetrachloride–mediated oxidative hepatocellular damage in rat model
Get PDFThe liver plays a vital role in biotransforming and extricating xenobiotics and is thus prone to their toxicities. Short-term administration of carbon tetrachloride (CCl4) causes hepatic inflammation by enhancing cellular reactive oxygen species (ROS) level, promoting mitochondrial dysfunction, and inducing cellular apoptosis. Curcumin is well accepted for its antioxidative and anti-inflammatory properties and can be considered as an effective therapeutic agent against hepatotoxicity. However, its therapeutic efficacy is compromised due to its insolubility in water. Vesicular delivery of curcumin can address this limitation and thereby enhance its effectiveness. In this study, it was observed that both liposomal and nanoparticulated formulations of curcumin could increase its efficacy significantly against hepatotoxicity by preventing cellular oxidative stress. However, the best protection could be obtained through the polymeric nanoparticle-mediated delivery of curcumin. Mitochondria have a pivotal role in ROS homeostasis and cell survivability. Along with the maintenance of cellular ROS levels, nanoparticulated curcumin also significantly (P,0.0001) increased cellular antioxidant enzymes, averted excessive mitochondrial destruction, and prevented total liver damage in CCl4-treated rats. The therapy not only prevented cells from oxidative damage but also arrested the intrinsic apoptotic pathway. In addition, it also decreased the fatty changes in hepatocytes, centrizonal necrosis, and portal inflammation evident from the histopathological analysis. To conclude, curcumin-loaded polymeric nanoparticles are more effective in comparison to liposomal curcumin in preventing CCl4-induced oxidative stress–mediated hepatocellular damage and thereby can be considered as an effective therapeutic strategy
Biophysical Studies on the Interaction of the Akaloid Chelerythrine with Nucleic Acids
No full textDNA-deoxyribonucleic acid is the blueprint for life. It is present in organisms ranging from the smallest bacterium to the largest whale. DNA carries most of the genetic instructions used in the development, functioning and reproduction of well known living organisms.
James Dewey Watson and Francis Harry Compton Crick had revolutionized the field of molecular biology and medicine by proposing the structure of deoxyribonucleic acid through model building studies in their celebrated paper published in the Nature magazine of April
23 (Watson and Crick, 1953). Although the Watson and Crick was known as father of DNA the preliminary research on DNA was started many decades ago on 1868 by Swiss chemist Friedrich Miescher. Miescher in 1868 detected a phosphorus-containing substance from the nuclei of pus cells obtained from discarded surgical bandages. He named it ‘nuclein’ consisting of an acidic portion which we know today as DNA. In 1878, Albrecht Kossel isolated the nonprotein component of “nuclein”, the nucleic acid, and later isolated its five primary nucleobases (Albrect, 1879). In 1919, Phoebus Levene identified the base, sugar and phosphate nucleotide unit (Levene, 1919). Levene suggested that DNA consisted of a string of nucleotide
units linked together through the phosphate groups. Levene thought the chain was short and the bases repeated in a fixed order. In 1937, William Astbury produced the first X-ray diffraction pattern that showed that DNA had a regular structure (Astbury and Florence, 1938). In 1944
Oswald Avery and his coworkers discovered that DNA carries a cell’s genetic material and can be altered through transformation
Ultrafast differential flexibility of Cro-protein binding domains of two operator DNAs with different sequences
No full textThe nature of the interface of specific protein–DNA complexes has attracted immense interest in contemporary
molecular biology. Although extensive studies on the role of flexibility of DNA in the specific interaction
in the genetic regulatory activity of lambda Cro (Cro-protein) have been performed, the exploration of
quantitative features remains deficient. In this study, we have mutated (site directed mutagenesis: SDM)
Cro-protein at the 37th position with a cysteine residue (G37C) retaining the functional integrity of the
protein and labelled the cysteine residue, which is close to the interface, with a fluorescent probe
(AEDANS), for the investigation of its interface with operator DNAs (OR3 and OR2). We have employed
picosecond resolved polarization gated fluorescence spectroscopy and the well known strategy of
solvation dynamics for the exploration of physical motions of the fluorescent probes and associated
environments, respectively. Even though this particular probe on the protein (AEDANS) shows marginal
changes in its structural flexibility upon interaction with the DNAs, a non-covalent DNA bound probe
(DAPI), which binds to the minor groove, shows a major differential alteration in the dynamical flexibility
in the OR3–Cro complex when compared to that of the OR2 complex with the Cro-protein. We attempt
to correlate the observed significant structural fluctuation of the Cro-protein binding domain of OR3 for
the specificity of the protein to the operator DN