Hydroxycinnamic acids mediated modulation of α-Synuclein fibrillation: Biophysical insights.

The fibrillation of α-synuclein (α-Syn) is considered a major contributor to Parkinson's disease (PD). Recent therapeutic measures have focused on inhibiting the fibrillation of α-Syn using various small molecules. We report here the effects of two different hydroxycinnamic acids; chlorogenic acid and sinapic acid on α-Syn fibrillation and have also discussed the mechanistic insights into their mode of modulation.

Molecular insights into the aspartate protease Plasmepsin II activity inhibition by fluoroquinolones: A pathway to antimalarial drug development.

Plasmepsin II (PlmII) belongs to the aspartate proteases and is involved in hemoglobin degradation in Plasmodium falciparum. Due to its critical role in the survival of the Plasmodium, PlmII is considered as a potent drug target for antimalarial therapy. We have done recombinant protein production of pro-plasmepsin II (Pro-plmII).

Targeting disorders in unstructured and structured proteins in various diseases.

Intrinsically disordered proteins (IDPs) and intrinsically disordered protein regions (IDPRs) are proteins and protein segments that usually do not acquire well-defined folded structures even under physiological conditions. They are abundantly present and challenge the "one sequence-one structure-one function" theory due to a lack of stable secondary and/or tertiary structure. Due to conformational flexibility, IDPs/IDPRs can bind with multiple interacting partners with high-specificity and low-affinity and perform essential biological functions associated with signalling, recognition and regulation.

Modulation of α-synuclein fibrillation by plant metabolites, daidzein, fisetin and scopoletin under physiological conditions.

The aggregation of α-synuclein is linked to neurological disorders, and of these, Parkinson's disease (PD) is among the most widely studied. In this background, we have investigated here the effects of three α, β-unsaturated carbonyl based plant metabolites, daidzein, fisetin and scopoletin on α-Syn aggregation. The ThT and light scattering kinetics studies establish that these compounds have ability to inhibit α-Syn fibrillation to different extents; this is confirmed by TEM studies.

Natural compound safranal driven inhibition and dis-aggregation of α-synuclein fibrils.

Self-assembly of α-synuclein (α-Syn) is linked with a variety of neurodegenerative diseases collectively called as α-synucleiopathies. Therefore, discovering suitable inhibitors for this self-association process of α-Syn is a subject of intense research. In this background, we have demonstrated here that the natural compound, Safranal, delays/inhibits α-Syn fibrillation/aggregation, and we have also characterized its mode of action.

Triphala inhibits alpha-synuclein fibrillization and their interaction study by NMR provides insights into the self-association of the protein.

The process of assembly and accumulation of the intrinsically disordered protein (IDP), alpha-synuclein (αSyn) into amyloid fibrils is a pathogenic process leading to several neurodegenerative disorders such as Parkinson's disease, multiple system atrophy and others. Although several molecules are known to inhibit αSyn fibrillization, the mechanism of inhibition is just beginning to emerge. Here, we report the inhibition of fibrillization of αSyn by Triphala, a herbal preparation in the traditional Indian medical system of Ayurveda.

Deciphering the anti-Parkinson's activity of sulphated polysaccharides from Chlamydomonas reinhardtii on the α-Synuclein mutants A30P, A53T, E46K, E57K and E35K.

Parkinsonism-linked mutations in alanine and glutamic acid residues of the pre-synaptic protein α-Synuclein (α-Syn) affect specific tertiary interactions essential for stability of the native state and make it prone to more aggregation. Many of the currently available drugs used for the treatment of Parkinson's disease (PD) are not very effective and are associated with multiple side effects. Recently, marine algae have been reported to have sulphated polysaccharides which offers multiple pharmaceutical properties.

Unravelling the inhibitory activity of Chlamydomonas reinhardtii sulfated polysaccharides against α-Synuclein fibrillation.

α-Synuclein (α-Syn) is an intrinsically disordered presynaptic protein, whose aggregation is critically involved in Parkinson's disease (PD). Many of the currently available drugs for the treatment of PD are not sufficiently effective in preventing progress of the disease and have multiple side-effects. With this background, efficient drug candidates, sulfated polysaccharides from Chlamydomonas reinhardtii (Cr-SPs) were isolated and investigated for their effect on inhibition of α-Syn fibrillation and dissolution of preformed α-Syn fibrillar structures through a combination of spectroscopic and microscopic techniques.

Aqueous extract of Triphala inhibits cancer cell proliferation through perturbation of microtubule assembly dynamics.

Triphala (Trl) is an ayurvedic formulation used for treating disorders of the digestive, respiratory, and nervous systems. Its anticancer properties have also been documented. We studied effects of Trl on tubulin, a target protein for several anticancer drugs, and systematically elucidated a possible antiproliferative mechanism of action of Trl.

Safranal Inhibits HeLa Cell Viability by Perturbing the Reassembly Potential of Microtubules.

Saffron, a spice from Crocus sativus, has been known for its health benefits and medicinal properties. Safranal is a component of saffron and is known for its antioxidant and anticancer properties. In this study, we elucidated a possible tubulin-targeted antiproliferative mechanism of action of safranal.

Elucidation of the Tubulin-targeted Mechanism of Action of 9-(3-pyridyl) Noscapine.

We have recently reported the synthesis and antiproliferative potential of a series of biaryl type α-noscapine congeners. Among them, 9-(3-pyridyl) noscapine 3f (9-PyNos, henceforth), which was synthesized by adding pyridine unit to the tetrahydroisoquinoline part of natural α-noscapine core, was found to be the most effective one to inhibit proliferation of a variety of cancer cell lines. However, details of its interactions with its cellular target, tubulin, remain poorly understood.

Elucidation of the anticancer potential and tubulin isotype-specific interactions of β-sitosterol.

Beta-sitosterol (β-SITO), a phytosterol present in many edible vegetables, has been reported to possess antineoplastic properties and cancer treatment potential. We have shown previously that it binds at a unique site (the 'SITO-site') compared to the colchicine binding site at the interface of α- and β-tubulin. In this study, we investigated the anticancer efficacy of β-SITO against invasive breast carcinoma using MCF-7 cells.

Synergistic Inhibition of Protein Fibrillation by Proline and Sorbitol: Biophysical Investigations.

We report here interesting synergistic effects of proline and sorbitol, two well-known chemical chaperones, in the inhibition of fibrillation of two proteins, insulin and lysozyme. A combination of many biophysical techniques has been used to understand the structural morphology and modes of interaction of the chaperones with the proteins during fibrillation. Both the chaperones establish stronger polar interactions in the elongation and saturation stages of fibrillation compared to that in the native stage.

Competitive binding of anticancer drugs 5-fluorouracil and cyclophosphamide with serum albumin: Calorimetric insights.

Background: Isothermal titration calorimetry (ITC) has emerged as an excellent method to characterize drug-protein interactions. 5-Fluorouracil and cyclophosphamide have been used in combination for the treatment of breast carcinoma, though individually these drugs have also been useful in treating other types of cancer. A quantitative understanding of binding of these drugs with the transport protein under different conditions is essential for optimizing recognition by the protein and delivery at the target.

Inhibition of insulin fibrillation by osmolytes: Mechanistic insights.

We have studied here using a number of biophysical tools the effects of osmolytes, betaine, citrulline, proline and sorbitol which differ significantly in terms of their physical characteristics such as, charge distribution, polarity, H-bonding abilities etc, on the fibrillation of insulin. Among these, betaine, citrulline, and proline are very effective in decreasing the extent of fibrillation. Proline also causes a substantial delay in the onset of fibrillation in the concentration range (50-250 mM) whereas such an effect is seen for citrulline only at 250 mM, and in case of betaine this effect is not seen at all in the whole concentration range.

Thermodynamic insights into drug-surfactant interactions: Study of the interactions of naporxen, diclofenac sodium, neomycin, and lincomycin with hexadecytrimethylammonium bromide by using isothermal titration calorimetry.

The success of drug delivery depends on the efficiency of the route of administration, which in turn relies on properties of the drug and its transport vehicle. A quantitative knowledge of association of drugs with transport vehicles is lacking when the latter are in the category of self assembled structures. The work reported in this manuscript addresses the mechanism of partitioning of naproxen, diclofenac sodium, neomycin and lincomycin in the micelles of hexadecytrimethylammonium bromide and that is quantitatively based on the measurement of thermodynamic parameters of interactions by using isothermal titration calorimetry.

Ribosomal Protein P2 from apicomplexan parasite Toxoplasma gondii is intrinsically a molten globule.

Toxoplasma gondii is an apicomplexan parasite, which causes toxoplasmosis. Toxoplasma P2 (TgP2) is a ribosomal protein and exists as supramolecular assembly with other proteins in the ribosome. It is also shown that TgP2 is involved in some extra ribosomal functions.

Molten globule nature of P2 homo-tetramer.

The P2 protein in has a high tendency to oligomerize, which seems to drive many of its non-ribosomal functions. During nuclear division of the parasite inside RBC, P2 translocates to the RBC surface as a tetramer. From a systematic study using variety of biophysical techniques, NMR spectral characteristics and relaxation dispersion measurements under different conditions of pH and/or urea concentrations, we deduce that (i) PfP2, an almost entirely helical protein, forms a molten globule monomer at low pH, (ii) at physiological pH, and at micro-molar concentrations, PfP2 is a stable tetramer wherein two dimmers associate sideways with close packing of helices at the interface, and (iii) the molten globule characteristic of the monomer is preserved in the tetramer.

Effects of hesperidin, a flavanone glycoside interaction on the conformation, stability, and aggregation of lysozyme: multispectroscopic and molecular dynamic simulation studies?

Hesperidin (HESP), a flavanone glycoside, shows high antioxidant properties and possess ability to go through the blood-brain barrier. Therefore, it could be a potential drug molecule against aggregation based diseases such as Alzheimer's, Parkinson's, and systemic amyloidoses. In this work, we investigated the potential of HESP to interact with hen egg-white lysozyme (HEWL) monomer and prevent its aggregation.

Addressing mechanism of fibrillization/aggregation and its prevention in presence of osmolytes: spectroscopic and calorimetric approach.

Understanding the mechanism of protein fibrillization/aggregation and its prevention is the basis of development of therapeutic strategies for amyloidosis. An attempt has been made to understand the nature of interactions of osmolytes L-proline, 4-hydroxy-L-proline, sarcosine and trimethylamine N-oxide with the different stages of fibrillization of hen egg-white lysozyme by using a combination of isothermal titration calorimetry, differential scanning calorimetry, fluorescence spectroscopy, and transmission electron microscopy. Based on thioflavin T fluorescence emission intensities and microscopic images, the nucleation, elongation, and saturation phases of fibrillization have been identified.

Drug-protein interactions in micellar media: thermodynamic aspects.

Devising directions for surfactant assisted effective controlled release of drugs requires a quantitative and qualitative understanding of the drug-protein, drug-surfactant, and surfactant-protein interactions. In this work, the effect of micellar environment on the binding of naproxen and diclofenac sodium with bovine serum albumin has been studied. The isothermal titration calorimetric (ITC) results suggest that the binding of naproxen is reduced with the protein when it is delivered from micellar media.

Unraveling the energetics and mode of the recognition of antibiotics tetracycline and rolitetracycline by bovine serum albumin.

An understanding of the detailed energetics and mechanism of the binding of drugs with target proteins is essential for devising guidelines to synthesize new drugs. Binding of the antibiotic drugs tetracycline and rolitetracycline with serum albumin has been studied by a combination of isothermal titration calorimetry, differential scanning calorimetry, steady-state and time-resolved fluorescence, and circular dichroism spectroscopies. Both tetracycline and rolitetracycline bind to bovine serum albumin in a sequential manner with first binding being the major binding event with an association constant of the order of 10(4) for tetracycline and 10(3) for rolitetracycline, respectively.

Insights into the binding of the drugs diclofenac sodium and cefotaxime sodium to serum albumin: calorimetry and spectroscopy.

Understanding physical chemistry underlying drug-protein interactions is essential to devise guidelines for the synthesis of target oriented drugs. Binding of a non-steroidal anti-inflammatory drug, diclofenac sodium (DCF) and an antibiotic drug, cefotaxime sodium (CFT) belonging to the family of cephalosporins with bovine serum albumin (BSA) has been examined using a combination of isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC), steady state and time resolved fluorescence and circular dichroism spectroscopies. Binding affinity of both DCF and CFT with BSA is observed to be of the order of 10(4)M(-1), with the binding profiles fitting well to the single set of binding site model.

Interaction of weakly bound antibiotics neomycin and lincomycin with bovine and human serum albumin: biophysical approach.

The thermodynamics of interaction of neomycin and lincomycin with bovine serum albumin (BSA) and human serum albumin (HSA) has been studied using isothermal titration calorimetry (ITC), in combination with UV-visible, steady state and time resolved fluorescence spectroscopic measurements. Neomycin is observed to bind weakly to BSA and HSA whereas lincomycin did not show any evidence for binding with the native state of these proteins, rather it interacts in the presence of surfactants. The ITC results suggest 1 : 1 binding stoichiometry for neomycin in the studied temperature range.