Ankaflavin and Monascin Prevent Fibrillogenesis of Hen Egg White Lysozyme: Focus on Noncovalent and Covalent Interactions

Misfolding and amyloid fibrillogenesis of proteins have close relationships with several neurodegenerative diseases. The present work investigates the inhibitive activities of ankaflavin (AK) and monascin (MS), two yellow pigments separated from Monascus-fermented rice, on hen egg white lysozyme (HEWL) fibrillation. The results demonstrated that AK/MS suppressed HEWL fibrillation through interfering with the nucleation period and AK was more potent. Fluorescence quenching and in silico docking studies revealed that AK/MS bond to HEWL by the formation of noncovalent forces with some critical amino acid residues that tend to form fibrils. Compared to those of AK, hydrogen bonding interactions between MS and Asn46, Trp62, and Trp63 residues in HEWL were slightly weaker. Besides, the covalent interaction between MS and HEWL with the binding site of Arg68 was found. These observations offered reasonable explanations for the difference in the mechanisms of AK and MS inhibiting HEWL fibrillogenesis. In a word, all data acquired herein indicated AK/MS as potent candidates for the improvement and treatment of neurological disorders.

Exploring the Specific Role of Iron Center in the Catalytic Activity of Human Serum Transferrin: CTAB-Induced Conformational Changes and Sequestration by Mixed Micelles

Conformational changes play a seminal role in modulating the activity of proteins. This concept becomes all the more relevant in the context of metalloproteins, owing to the formation of specific conformation(s) induced by internal perturbations (like a change in pH, ligand binding, or receptor binding), which may carry out the binding and release of the metal ion/ions from the metal binding center of the protein. Herein, we investigated the conformational changes of an iron-binding protein, monoferric human serum transferrin (Fe-hTF), using several spectroscopic approaches. We could reversibly tune the cetyltrimethylammonium bromide (CTAB)-induced conformation of the protein, exploiting the concept of mixed micelles formed by three sequestrating agents: (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate) hydrate (CHAPS) and two bile salts, namely, sodium cholate (NaC) and sodium deoxycholate (NaDC). The formation of mixed micelles between CTAB and these reagents (CHAPS/NaC/NaDC) results in the sequestration of CTAB molecules from the protein environment and aids the protein in reattaining its native-like structure. However, the guanidinium hydrochloride-induced denatured Fe-hTF did not acquire its native-like structure using these sequestrating agents, which substantiates the exclusive role of mixed micelles in the present study. Apart from this, we found that the conformation of transferrin (adopted in the presence of CTAB) displays pronounced esterase-like activity toward the para-nitrophenyl acetate (PNPA) substrate as compared to native transferrin. We also outlined the impact of the iron center and amino acids surrounding the iron center on the effective catalytic activity in the CTAB medium. We estimated ∼3 times higher specific catalytic efficiency for the iron-depleted Apo-hTF compared to the fully iron-saturated Fe2-hTF in the presence of CTAB.

Exploration of the impact of graphene oxide, acetylenic gemini, and CTAT on the photophysical and aggregation properties of dipolar coumarin 153

Advanced spectroscopic techniques have been utilized to study the interaction between the laser dye coumarin 153 (C153) and graphene oxide (GO) nanoparticles. GO was synthesized using a modified Hummers' method and characterized by UV-vis spectroscopy, Raman laser spectroscopy, FTIR-ATR spectroscopy, FESEM, HR-TEM, and XRD techniques. The GO@C153 composite was formed by mixing two aqueous solutions of GO and C153 due to their strong interaction through stacking and hydrophobic interactions. In this case, GO acts as an effective fluorescence quencher for C153 molecules, which undergo H-type aggregation in the presence of GO. The Stern-Volmer equation and time-dependent fluorescence studies were utilized to analyse the mechanism of fluorescence quenching. According to the findings, both static and dynamic quenching processes are responsible for the reduction in fluorescence intensity. The effect of surfactants (both cetyltrimethylammonium p-toluenesulfonate (CTAT) and synthesized N,N'-dihexadecyl-N,N,N',N'-tetramethyl-N,N'-but-2-ynediyl-di-ammonium chloride (16-4-16)) on the aggregation and photophysical properties of the dye was investigated using surface tensiometry, conductometry, UV-vis absorption spectroscopy, steady-state fluorescence measurements, DLS, and time-dependent fluorescence spectroscopy. Surfactants change the microenvironment of the C153 dye, leading to spectrum shifting and a higher quantum yield, which causes a rapid rise in fluorescence intensity in the micellar medium. It has been noted that in a micellar medium rather than in an aqueous one, the luminous intramolecular charge transfer (ICT) state of C153 stabilises. Lastly, we investigated the photophysical behavior of the GO-C153-micelle ternary system and discovered that, in the presence of a micellar medium, the quenched and blue-shifted (H-type aggregation) fluorescence peak of C153 (in the presence of GO) began to intensify once more. The main goal of this work is to create an effective and fairly cost powerful fluorescence sensor. Additionally, the ternary system (GO-C153-micelle) analytical idea can be employed to identify the onset of micelle formation. In wastewater treatment analysis, the GO-C153-surfactant ternary system concept can also be used to regenerate the adsorbent (in this case, GO) from dye molecules by allowing the dye molecules to exit the adsorbent and enter the micellar medium.

Insight into the Effect of Submicellar Concentrations of Sodium Deoxycholate on the Structure, Stability, and Activity of Bovine and Human Serum Albumin: An Interesting Comparison between Single and Double Tryptophan Proteins

The progressive escalation in the applications of bile salts in diverse fields has triggered research on their interaction with various biological macromolecules, especially with proteins. A proper understanding of the interaction process of bile salts, particularly in the lower concentrations range, with the serum albumin seems important since the normal serum concentration of bile salts is approximately in the micromolar range. The current study deals with a comprehensive and comparative analysis of the interaction of submicellar concentrations of sodium deoxycholate (NaDC) with two homologous transport proteins: bovine serum albumin (BSA) and human serum albumin (HSA). HSA and BSA with one and two tryptophans, respectively, provide the opportunity for an interesting comparison of tryptophan fluorescence behavior on interaction with NaDC. The study suggests a sequential interaction of NaDC in three discrete stages with the two proteins. A detailed study using warfarin and ibuprofen as site markers provides information about the sites of interaction, which is further confirmed by inclusive molecular dynamics simulation analysis. Moreover, the comparison of the thermodynamics and stability of the NaDC-serum albumin complexes confirms the stronger interaction of NaDC with BSA as compared to that with HSA. The differential interaction between the bile salt and the two serum albumins is further established from the difference in the extent of decrease in the esterase-like activity assay of the proteins in the presence of NaDC. Therefore, the present study provides important insight into the effect of submicellar concentrations of NaDC on the structure, stability, and activity of the two homologous serum albumins and thus can contribute not only to the general understanding of the complex nature of serum albumin-bile salt interactions but also to the design of more effective pharmaceutical formulations in the field of drug delivery and biomedical research.

Understanding the basis of thermostability for enzyme "Nanoluc" towards designing industry-competent engineered variants

As a leading contender in the study of luminescence, nanoluciferase has recently attracted attention and proven effective in a wide variety of research areas. Although numerous attempts have been made to improve activity, there has yet to be a thorough exploration of further possibilities to improve thermostability. In this study, protein engineering in tandem with molecular dynamics simulation at various temperatures (300 K, 400 K, 450 K and 500 K) was used to improve our understanding of nanoluciferase dynamics and identification of factors that could significantly enhance the thermostability. Based on these, three novel mutations have been narrowed down, which were hypothesised to improve thermostability. Root mean square deviation and root mean square fluctuation studies confirmed higher stability of mutant at high temperature. Solvent-accessible surface area and protein unfolding studies revealed a decreased tendency of mutant to unfold at higher temperatures. Further free energy landscape and principal component analysis was adapted to get deeper insights into the thermodynamic and structural behavior of these proteins at elevated temperature. Thus, this study provides a deeper insight into the dynamic factors for thermostability and introduces a novel, enhanced nanoluciferase candidate with potential use in industry.Communicated by Ramaswamy H. Sarma.

Meta-analysis of transcriptome reveals key genes relating to oil quality in olive

BACKGROUND

Olive oil contains monounsaturated oleic acid up to 83% and phenolic compounds, making it an excellent source of fat. Due to its economic importance, the quantity and quality of olive oil should be improved in parallel with international standards. In this study, we analyzed the raw RNA-seq data with a meta-analysis approach to identify important genes and their metabolic pathways involved in olive oil quality.

RESULTS

A deep search of RNA-seq published data shed light on thirty-nine experiments associated with the olive transcriptome, four of these proved to be ideal for meta-analysis. Meta-analysis confirmed the genes identified in previous studies and released new genes, which were not identified before. According to the IDR index, the meta-analysis had good power to identify new differentially expressed genes. The key genes were investigated in the metabolic pathways and were grouped into four classes based on the biosynthetic cycle of fatty acids and factors that affect oil quality. Galactose metabolism, glycolysis pathway, pyruvate metabolism, fatty acid biosynthesis, glycerolipid metabolism, and terpenoid backbone biosynthesis were the main pathways in olive oil quality. In galactose metabolism, raffinose is a suitable source of carbon along with other available sources for carbon in fruit development. The results showed that the biosynthesis of acetyl-CoA in glycolysis and pyruvate metabolism is a stable pathway to begin the biosynthesis of fatty acids. Key genes in oleic acid production as an indicator of oil quality and critical genes that played an important role in production of triacylglycerols were identified in different developmental stages. In the minor compound, the terpenoid backbone biosynthesis was investigated and important enzymes were identified as an interconnected network that produces important precursors for the synthesis of a monoterpene, diterpene, triterpene, tetraterpene, and sesquiterpene biosynthesis.

CONCLUSIONS

The results of the current investigation can produce functional data related to the quality of olive oil and would be a useful step in reducing the time of cultivar screening by developing gene specific markers in olive breeding programs, releasing also new genes that could be applied in the genome editing approach.

Role of Gemini Surfactants with Variable Spacers and SiO2 Nanoparticles in ct-DNA Compaction and Applications toward In Vitro/In Vivo Gene Delivery

Compaction of calf thymus DNA (ct-DNA) by two cationic gemini surfactants, 12-4-12 and 12-8-12, in the absence and presence of negatively charged SiO₂ nanoparticles (NPs) (∼100 nm) has been explored using various techniques. 12-8-12 having a longer hydrophobic spacer induces a greater extent of ct-DNA compaction than 12-4-12, which becomes more efficient with SiO₂ NPs. While 50% ct-DNA compaction in the presence of SiO₂ NPs occurs at ∼77 nM of 12-8-12 and ∼130 nM of 12-4-12, but a conventional counterpart surfactant, DTAB, does it at its concentration as high as ∼7 μM. Time-resolved fluorescence anisotropy measurements show changes in the rotational dynamics of a fluorescent probe, DAPI, and helix segments in the condensed DNA. Fluorescence lifetime data and ethidium bromide exclusion assays reveal the binding sites of surfactants to ct-DNA. 12-8-12 with SiO₂ NPs has shown the highest cell viability (≥90%) and least cell death in the human embryonic kidney (HEK) 293 cell lines in contrast to the cell viability of ≤80% for DTAB. These results show that 12-8-12 with SiO₂ NPs has the highest time and dose-dependent cytotoxicity compared to 12-8-12 and 12-4-12 in the murine breast cancer 4T1 cell line. Fluorescence microscopy and flow cytometry are performed for in vitro cellular uptake of YOYO-1-labeled ct-DNA with surfactants and SiO₂ NPs using 4T1 cells after 3 and 6 h incubations. The in vivo tumor accumulation studies are carried out using a real-time in vivo imaging system after intravenous injection of the samples into 4T1 tumor-bearing mice. 12-8-12 with SiO₂ has delivered the highest amount of ct-DNA in cells and tumors in a time-dependent manner. Thus, the application of a gemini surfactant with a hydrophobic spacer and SiO₂ NPs in compacting and delivering ct-DNA to the tumor is proven, warranting its further exploration in nucleic acid therapy for cancer treatment.

Traditional Medicine Beliefs and Practices among Caregivers of Children under Five Years-The Child Health and Mortality Prevention Surveillance (CHAMPS), Western Kenya: A qualitative study

BACKGROUND

Approximately 80% of the population residing in sub-Saharan Africa relies on Traditional Medicine (TM). However, literature on factors motivating the use of TM for children under the age of five in these settings is limited. Such information can guide policy formulation for integration of TM into mainstream health care services. This study aimed to describe the motivation on use of TM among caregivers of children residing in rural and urban communities in western Kenya.

METHODS

The socio-behavioral sciences (SBS) arm of the Child Health and Mortality Prevention Surveillance (CHAMPS) program in western Kenya, conducted a cross-sectional qualitative study in Manyatta-an urban informal settlement located in Kisumu town and Karemo-a rural setting in Siaya County. We performed 29 in-depth interviews, 5 focus group discussions and 11 semi-structured interviews with community representatives (n = 53), health workers (n = 17), and community leaders (n = 18). All the participants were purposively sampled. We performed thematic analysis using both inductive and deductive approaches. Data management was completed on Nvivo 11.0 software (QSR International, Melbourne, Australia).

RESULTS

Our findings reveal that some caregivers prefer TM to treat some childhood diseases. Use of TM was informed by illness beliefs about etiology of disease. We observed an appreciation from the study participants that malaria can effectively be treated by Conventional Medicine (CM) while TM was preferred to treat measles and diseases believed to be associated with supernatural etiology such as witchcraft, evil spirit or breaching cultural taboos. TM was also used in instances where CM failed to provide a diagnosis or when CM was 'slow'. TM in such cases was used as a last resort.

CONCLUSION

We observed varied beliefs that motivate caregivers' choice of TM use among children in western Kenya. It is therefore crucial to consider perceptions and socio-cultural beliefs about illnesses when formulating interventions that are geared towards child health.

How do surfactants unfold and refold proteins?

Although the anionic surfactant sodium dodecyl sulfate, SDS, has been used for more than half a century as a versatile and efficient protein denaturant for protein separation and size estimation, there is still controversy about its mode of interaction with proteins. The term "rod-like" structures for the complexes that form between SDS and protein, originally introduced by Tanford, is not sufficiently descriptive and does not distinguish between the two current vying models, namely protein-decorated micelles a.k.a. the core-shell model (in which denatured protein covers the surface of micelles) versus beads-on-a-string model (where unfolded proteins are surrounded by surfactant micelles). Thanks to a combination of structural, kinetic and computational work particularly within the last 5-10 years, it is now possible to rule decisively in favor of the core-shell model. This is supported unambiguously by a combination of calorimetric and small-angle X-ray scattering (SAXS) techniques and confirmed by increasingly sophisticated molecular dynamics simulations. Depending on the SDS:protein ratio and the protein molecular mass, the formed structures can range from multiple partly unfolded protein molecules surrounding a single shared micelle to a single polypeptide chain decorating multiple micelles. We also have much new insight into how this species forms. It is preceded by the binding of small numbers of SDS molecules which subsequently grow by accretion. Time-resolved SAXS analysis reveals an asymmetric attack by SDS micelles followed by distribution of the increasingly unfolded protein around the micelle. The compactness of the protein chain continues to evolve at higher SDS concentrations according to single-molecule studies, though the protein remains completely denatured on the tertiary structural level. SDS denaturation can be reversed by addition of nonionic surfactants that absorb SDS forming mixed micelles, leaving the protein free to refold. Refolding can occur in parallel tracks if only a fraction of the protein is initially stripped of SDS. SDS unfolding is nearly always reversible unless carried out at low pH, where charge neutralization can lead to superclusters of protein-surfactant complexes. With the general mechanism of SDS denaturation now firmly established, it largely remains to explore how other ionic surfactants (including biosurfactants) may diverge from this path.

Cationic gemini surfactant properties, its potential as a promising bioapplication candidate, and strategies for improving its biocompatibility: A review

Gemini surfactants consist of two cationic monomers of a surfactant linked together with a spacer. The specific structure of a cationic gemini surfactant is the reason for both its high surface activity and its ability to decrease the surface tension of water. The high surface activity and unique structure of gemini surfactants result in outstanding properties, including antibacterial and antifungal activity, anticorrosion properties, unique aggregation behaviour, the ability to form various structures reversibly in response to environmental conditions, and interactions with biomacromolecules such as DNA and proteins. These properties can be tailored by selecting the optimal structure of a gemini surfactant in terms of the nature and length of its alkyl substituents, spacer, and head group. Additionally, regarding their properties, comparison with their monomeric counterparts demonstrates that gemini surfactants have higher performance efficacy at lower concentrations. Hence, less material is needed, and the toxicity is lower. However, there are some limitations regarding their biocompatibility that have led researchers to develop amino acid-based and sugar-based gemini surfactants. Owing to their remarkable properties, cationic gemini surfactants are promising candidates for bioapplications such as drug delivery systems, gene carriers, and biomaterial surface modification.

Applications of Lysozyme, an Innate Immune Defense Factor, as an Alternative Antibiotic

Lysozyme is a ~14 kDa protein present in many mucosal secretions (tears, saliva, and mucus) and tissues of animals and plants, and plays an important role in the innate immunity, providing protection against bacteria, viruses, and fungi. Three main different types of lysozymes are known: the c-type (chicken or conventional type), the g-type (goose type), and the i-type (invertebrate type). It has long been the subject of several applications due to its antimicrobial properties. The problem of antibiotic resistance has stimulated the search for new molecules or new applications of known compounds. The use of lysozyme as an alternative antibiotic is the subject of this review, which covers the results published over the past two decades. This review is focused on the applications of lysozyme in medicine, (the treatment of infectious diseases, wound healing, and anti-biofilm), veterinary, feed, food preservation, and crop protection. It is available from a wide range of sources, in addition to the well-known chicken egg white, and its synergism with other compounds, endowed with antimicrobial activity, are also summarized. An overview of the modified lysozyme applications is provided in the form of tables.

Development of Oxadiazole-Sulfonamide-Based Compounds as Potential Antibacterial Agents

In this work, substituted 1,2,4-oxadiazoles (OX1-OX27) were screened against five bacterial strains, identified to be OX7 and OX11 as growth inhibitors with minimum inhibitory concentration (MIC) values of 31.25 and 15.75 μg/mL, respectively. The growth inhibitory property of OX7 and OX11 was further validated by disk diffusion, growth curve, and time kill curve assays. Both disrupted biofilm formation with 92-100% reduction examined by the XTT assay were further visualized by scanning electron microscopy analysis. These compounds in combination with ciprofloxacin also exhibit synergy against Escherichia coli cells. With insignificant cytotoxic behavior on HEK293 cells, human red blood cells, and Galleria mellonella larvae, OX11 was tested against 28 multidrug resistant environmental isolates of bacteria and showed inhibition of Kluyvera georgiana and Citrobacter werkmanii strains with 32 and 16 μg/mL MIC values, respectively. The synergistic behavior of OX11 with ampicillin showed many fold reductions in MIC values against K. georgiana and Klebsiella pneumoniae multidrug resistant strains. Further, transmission electron microscopy analysis of OX11-treated E. coli cells showed a significantly damaged cell wall, which resulted in the loss of integrity and cytosolic oozing. OX11 showed significant changes in the secondary structure of human serum albumin (HSA) in the presence of OX11, enhancing HSA stability. Overall, the study provided a suitable core for further synthetic alterations and development as an antibacterial agent.

Preparation of a Gemini Surfactant from Mixed Fatty Acid and its Use in Cosmetics

Among the surfactants, dimeric surfactants represent a niche group with multifunctional properties. In this work a modified gemini surfactant was synthesized using symmetrical fatty acids. Due to the spacers used to combine the two symmetrical monomers, the synthesized gemini surfactant is cationic. The structure of the compound was confirmed with 1H-NMR. The most advantageous property of the gemini surfactant is that it has a lower surface tension, i. e. less than 35 mNm–1 at 25°C, compared to monomeric surfactants. The surface tension was determined with a Kyowa tensiometer. The CMC (critical micelle formation concentration) was calculated according to the pyrene method and detected by UV spectroscopy at 25°C. The very low CMC is another market advantage of the gemini surfactant. Hydrophobicity and hydrophilicity of the synthesized compound were checked by the emulsification method. The ability of the synthesized gemini surfactant to wet and foam and the emulsification index at different pH values were tested. Based on the results, the gemini surfactant was used in formulations for hair and skin care. Conditioners and creams were prepared with the synthesized compound and the properties were analyzed at different concentrations of the gemini surfactant in the respective formulation.

Comparative binding analysis of noscapine and piperine with tRNA: A structural perturbation and energetic study

In this study, we have exploring the binding mechanisms of the two anticancer alkaloid noscapine (NOS) and piperine (PIP) with tRNA using different spectroscopy and computational method. Absorbance and emission spectra revealed that both the drugs show strong binding with tRNA, where NOS intercalate between the base pairs of tRNA and PIP binds in the groove of tRNA. Competitive binding study and steady state anisotropy further confirms the intercalative mode of binding between NOS and tRNA and groove binding in PIP-tRNA complex. The observed thermodynamic parameters suggested that NOS-tRNA complex formation is endothermic and entropy driven, however it was exothermic, and enthalpy driven in case of PIP-tRNA complex. CD and time resolved fluorescence studies show the structural perturbations and conformational change in tRNA structure with NOS as well as PIP. Molecular docking studies are comparable with experimental results and further confirmed that the hydrophobic interactions involved in the NOS-tRNA binding, whereas hydrogen binding and van der Waals interactions play important role in the PIP-tRNA complex formation. This study can be useful to understand the potential binding and resultant tRNA damage by alkaloids and deigned new target specific anticancer drug.

Synergistic antimicrobial activity of N-methyl substituted pyrrolidinium-based ionic liquids and melittin against Gram-positive and Gram-negative bacteria

In pharmaceutical industry, the prodrug approaches and drug-drug conjugates are being now vastly used to optimize the efficacy of the drugs for multipurpose. The combination or conjugation of antimicrobials agents with natural antimicrobials may lead to better synergistic antimicrobial activity. Currently, many publications show the potential of ionic liquids (ILs) as novel antimicrobials and even as active pharmaceutical ingredients. The current study showed the synthesis of novel pyrrolidinium-based ILs (C_x, x = 4, 6, 8, 10, 12) and their antibacterial activity alone and in combination with antimicrobial peptide, melittin (MEL), against clinically relevant microorganism, E. coli and S. aureus. The cytotoxicity of synthesized ILs was administered on HEK 293 cell line using MTT assay. The obtained results showed the dependency of antibacterial activity of ILs on alkyl chain length (C4 < C6 < C8 < C10 < C12). The remarkable improvement in the antibacterial efficiency of MEL was seen with ILs; however, antibacterial effect is more pronounced with IL having large alkyl chain length (C₈, C₁₀, and C₁₂) at their minimal concentration with MEL to disrupt the cell membrane. In addition, the binding study and haemocompatibility results showed favourable biocompatibility and stability which could potentially improve its utility for the biomedical field. KEY POINTS: • The combination of melittin and pyrrolidinium-based ILs showed improved antibacterial activity against E. coli and S. aureus which may be used for developing new antibacterial agents. • Moreover, the cytotoxicity and haemocompatibility results showed excellent biocompatibility of the combinations on human cell line and human serum albumin, respectively, which could potentially improve its utility for the biomedical field.

Investigating the biomolecular interactions between model proteins and glycine betaine surfactant with reference to the stabilization of emulsions and antimicrobial properties

Binding effect and interaction of 2-pentadecanoyloxymethyl)trimethylammonium bromide (DMGM-14) with bovine serum albumin (BSA) and hen egg white lysozyme (HEWL) were systematically investigated by the fluorescence spectroscopy, circular dichroism (CD) spectroscopy, isothermal titration calorimetry (ITC), surface tension analysis, and molecular docking studies. The emulsion properties and particle size distribution of surfactant/protein complexes containing sunflower oil were studied using static light scattering and confocal laser scanning microscopy (CLSM). The fluorescence spectroscopy and ITC analysis confirmed the complexes formation of DMGM-14 with BSA and HEWL which was also verified by surface tension measurements. CD results explained the conformational changes in BSA and HEWL upon DMGM-14 complexation. Molecular docking study provides insight into the binding of DMGM-14 into the specific sites of BSA and HEWL. Besides, the studies drew a detailed picture on the emulsification properties of DMGM-14 with BSA and HEWL. In addition, the in vitro experiment revealed a broad antibacterial spectrum of DMGM-14 and DMGM-14/HEWL complex including activity against Gram-positive and Gram-negative bacteria. In conclusion, the present study revealed that the interaction between DMGM-14 with BSA and HEWL is important for the pharmaceutical, biological, and food products.

Comparative in vitro cytotoxicity and binding investigation of artemisinin and its biogenetic precursors with ctDNA

Artemisinin (ART) and its biogenetic precursors artemisinic acid (AA) and dihydroartemisinic acid (DHAA) are important traditional medicinal herb compounds with tumor growth inhibition properties. Herein, we have studied the cytotoxicity of ART, AA, and DHAA on different cancer cell lines (H1299, A431, and HCT 116) and investigated in detail their binding mechanisms with ctDNA by using spectroscopy, cyclic voltammetry, and computational methods. The UV absorbance, cyclic voltammetry, DNA helix melting, competition binding, and circular dichroism studies suggested that the complex formation of ART-ctDNA and AA-ctDNA occurs through groove binding. However, in the case of DHAA-ctDNA interaction, electrostatic interaction plays a major role. The thermodynamic parameters, viz., ΔG 0, ΔH 0, and ΔS 0 were calculated, which showed the involvement of hydrogen bonds and van der Waals interactions for drug-ctDNA interaction. FTIR and molecular docking results suggested that ART, AA, and DHAA were bound to the A-T rich region in the minor groove of ctDNA.

Interaction of selected biomolecules and metabolites with amyloidogenic proteins

The current manuscript reports docking and molecular interaction analyses of three FDA approved acetylcholinesterase inhibitors, nitrogenous bases and nucleotides with amyloidogenic proteins like hen egg white lysozyme (HEWL) and amyloid β peptide. After prediction of aggregation-prone regions in hen egg-white lysozyme and amyloid β peptide, grid boxes were defined for docking purposes covering these regions. We analyzed vital interactions and binding modes of molecules that dock near aggregation-prone regions of these proteins with acceptable statistics. The data hints toward the possibility that these molecules may bind to aggregation-prone regions and prevent amyloid/aggregation formation. We have also compared the binding energy and interactions of these molecules with certain other natural molecules viz. Curcumin, Coumarin and Resveratrol that have been previously reported to show anti-amyloidogenic activity as positive controls.Communicated by Ramaswamy H. Sarma.

Esterase activity and interaction of human hemoglobin with diclofenac sodium: A spectroscopic and molecular docking study

To get an idea about the pharmacokinetics and pharmacodynamics, it is important to study the drug-protein interaction. Therefore, herein, we studied the interaction of diclofenac sodium (DIC) with human hemoglobin. The binding study of nonsteroidal antiinflammatory drug, DIC with human hemoglobin (HHB) was done by utilizing fluorescence, UV-visible, time-resolved fluorescence and far-UV circular dichroism spectroscopy (CD). Various thermodynamic parameters such as enthalpy change (ΔH), entropy change (ΔS), and Gibbs free energy change (ΔG) were also calculated. CD results showed that DIC induces secondary structure change in HHB. Fluorescence resonance energy transfer was also performed. Additionally, it was also observed that DIC inhibits the esterase-like enzymatic activity of HHB via competitive inhibition.

Structural alteration of myoglobin with two homologous cationic surfactants and effect of β-cyclodextrin: multifaceted insight and molecular docking study

Structural alteration and regeneration of myoglobin.

Ionic Liquid Green Assembly-Mediated Migration of Piperine from Calf-Thymus DNA: A New Possibility of the Tunable Drug Delivery System

Biocompatible surface-active ionic liquid (SAIL) was used first to study the deintercalation process of a well-known natural compound piperine (PIP) as an anticancer drug, obtained from PIP-calf thymus DNA (ctDNA) complex under controlled experimental conditions. In this study, we have been exploring the interaction of PIP in SAIL (1-butyl-3-methylimidazolium octyl sulfate ionic liquid ([C₄mim][C₈OSO₃])), ctDNA, and deintercalation of PIP from the PIP-ctDNA complex through SAIL micelle using various spectroscopic techniques. Absorption, emission, and lifetime decay measurements provide strong evidence of the relocation of PIP molecules from ctDNA to SAIL micelle. Fluorescence quenching and steady-state fluorescence anisotropy were employed to examine the exact location of PIP in different media. Moreover, the surface tension technique was also employed to confirm the release of PIP molecules from the PIP-ctDNA complex in the presence of SAIL. Circular dichroism analysis suggested that SAIL micelle does not perturb the ctDNA structure, which supported the fact that SAIL micelle can be used as a safe vehicle for PIP. Overall, the study highlighted a novel strategy for deintercalation of drug using SAIL because the release of the drug can be controlled over a period by varying the concentration and composition of the SAIL.

Probing the Intercalation of Noscapine from Sodium Dodecyl Sulfate Micelles to Calf Thymus Deoxyribose Nucleic Acid: A Mechanistic Approach

Noscapine (NOS) is efficient in inhibiting cellular proliferation and induces apoptosis in nonsmall cell, lung, breast, lymphatic, and prostate cancers. The micelle-assisted drug delivery is a well-known phenomenon; however, the proper mechanism is still unclear. Therefore, in the present study, we have shown a mechanistic approach for the delivery of NOS from sodium dodecyl sulfate (SDS) micelles to calf thymus deoxyribose nucleic acid (ctDNA) base-pairs using various spectroscopic techniques. The absorption and emission spectroscopy results revealed that NOS interacts with the SDS micelle and resides in its hydrophobic core. Further, the intercalation of NOS from SDS micelles to ctDNA was also shown by these techniques. The anisotropy and quenching results further confirmed the relocation of NOS from SDS micelles to ctDNA. The CD analysis suggested that SDS micelles do not perturb the structure of ctDNA, which supported that SDS micelles can be used as a safe delivery vehicle for NOS. This work may be helpful for the invention of advanced micelle-based vehicles for the delivery of an anticancer drug to their specific target site.

Synthesis of Novel Benzimidazolium Gemini Surfactants and Evaluation of Their Anti-Candida Activity

Owing to the rise in antimicrobial and chemotherapeutic drug resistance, there is a desperate need to formulate newer as well as more effective agents. With this perspective, here we outline the synthesis of two novel gemini surfactants with different substitutions at the nitrogen atom of the benzimidazolium ring. Both the compounds induced significant reductions in Candida growth in various yeast strains. The reduction in Candida growth seemed likely through the reduction in ergosterol biosynthesis: a sterol constituent of yeast cell membranes. Different concentrations of both compounds were used to determine the cellular ergosterol content which indicates an important disordering of the ergosterol biosynthetic pathway. Cytotoxic studies were carried out using HEK 293 (human embryonic-kidney cells) and Galleria mellonella larvae (an in vivo model of antimicrobial studies). Administration of both the compounds to G. mellonella larvae diseased by the yeast Candida albicans resulted in increased survival indicating their in vivo activity.

Lysozyme-luteolin binding: molecular insights into the complexation process and the inhibitory effects of luteolin towards protein modification

In the proposed work, the complexation of bioactive flavonoid luteolin with hen egg white lysozyme (HEWL) along with its inhibitory influence on HEWL modification has been explored with the help of multi-spectroscopic and computational methods. The binding affinity has been observed to be moderate in nature (in the order of 10⁴ M^-1) and the static quenching mechanism was found to be involved in the fluorescence quenching process. The binding constant (K_b) shows a progressive increase with the increase in temperature from (4.075 ± 0.046 × 10⁴ M^-1) at 293 K to (6.962 ± 0.024 × 10⁴ M^-1) at 313 K under experimental conditions. Spectroscopic measurements along with molecular docking calculations suggest that Trp62 is involved in the binding site of luteolin within the geometry of HEWL. The positive changes in enthalpy (ΔH = +19.99 ± 0.65 kJ mol^-1) as well as entropy (ΔS = +156.28 ± 2.00 J K^-1 mol^-1) are indicative of the presence of hydrophobic forces that stabilize the HEWL-luteolin complex. The micro-environment around the Trp residues showed an increase in hydrophobicity as indicated by synchronous fluorescence (SFS), three dimensional fluorescence (3D) and red edge excitation (REES) studies. The % α-helix of HEWL showed a marked reduction upon binding with luteolin as indicated by circular dichroism (CD) and Fourier-transform infrared spectroscopy (FTIR) studies. Moreover, luteolin is situated at a distance of 4.275 ± 0.004 nm from the binding site as indicated by FRET theory, and the rate of energy transfer k_ET (0.063 ± 0.004 ns^-1) has been observed to be faster than the donor decay rate (1/τ_D = 0.606 ns^-1), which is indicative of the non-radiative energy transfer during complexation. Leaving aside the binding study, luteolin showed promising inhibitory effects towards the d-ribose mediated glycation of HEWL as well as towards HEWL fibrillation as studied by fluorescence emission and imaging studies. Excellent correlation with the experimental observations as well as precise location and dynamics of luteolin within the binding site has been obtained from molecular docking and molecular dynamics simulation studies.

Interactions of carbon quantum dots from roasted fish with digestive protease and dopamine

The carbon quantum dots from roasted fish interacted with digestive protease and dopamine.

Distinctive Performance of Gemini Surfactant in the Preparation of Hierarchically Porous Carbons via High-Internal-Phase Emulsion Template

The superior capability of gemini surfactant (GS) in the preparation of hierarchically porous carbons via high-internal-phase emulsion (HIPE) template followed by pyrolysis was confirmed in this work. Polymerized HIPEs (polyHIPEs) of phenol-formaldehyde resin were prepared by cross-linking the continuous phase of HIPEs stabilized by GS. Nonionic surfactant and cationic surfactant were also selected to stabilize HIPE for comparison. From scanning electron microscope observations, polyHIPEs with open-cell pore architectures were obtained with GS as emulsifier (polyHIPEs-GS) and the derived carbon foams (carboHIPEs-GS) well retained the original pore architectures, whereas polyHIPEs obtained using contrastive surfactants showed closed-cell porous structures and notable differences were observed for the derived carboHIPEs. Nitrogen adsorption/desorption measurements indicated that polyHIPEs-GS and carboHIPEs-GS both exhibited hierarchically porous architectures with much higher surface areas (SA) than those of the corresponding contrast samples. Mercury intrusion porosimetry results indicated that carboHIPEs-GS possessed higher SA and higher porosity than that of the contrast samples. The open-cell pore architecture and high SA are favorable to many applications, like energy storage. carboHIPE-GS expectably showed a higher capacitance than that of contrast samples when used as the electrode material of supercapacitor.

Interaction of promethazine and adiphenine to human hemoglobin: A comparative spectroscopic and computational analysis

The binding nature of amphiphilic drugs viz. promethazine hydrochloride (PMT) and adiphenine hydrochloride (ADP), with human hemoglobin (Hb) was unraveled by fluorescence, absorbance, time resolved fluorescence, fluorescence resonance energy transfer (FRET) and circular dichroism (CD) spectral techniques in combination with molecular docking and molecular dynamic simulation methods. The steady state fluorescence spectra indicated that both PMT and ADP quenches the fluorescence of Hb through static quenching mechanism which was further confirmed by time resolved fluorescence spectra. The UV-Vis spectroscopy suggested ground state complex formation. The activation energy (E_a) was observed more in the case of Hb-ADP than Hb-PMT interaction system. The FRET result indicates the high probability of energy transfer from β Trp37 residue of Hb to the PMT (r=2.02nm) and ADP (r=2.33nm). The thermodynamic data reveal that binding of PMT with Hb are exothermic in nature involving hydrogen bonding and van der Waal interaction whereas in the case of ADP hydrophobic forces play the major role and binding process is endothermic in nature. The CD results show that both PMT and ADP, induced secondary structural changes of Hb and unfold the protein by losing a large helical content while the effect is more pronounced with ADP. Additionally, we also utilized computational approaches for deep insight into the binding of these drugs with Hb and the results are well matched with our experimental results.

Physicochemical Evaluation of Micellar Solution and Lyotropic Phases Formed by Self-Assembled Aggregates of Morpholinium Geminis

The micellar solution and the lyotropic liquid crystalline phases formed by gemini surfactants containing morpholinium headgroups are investigated for their self-aggregation and physicochemical properties in water. These gemini surfactants demonstrated good surface activity because they are able to undergo micellization at lower concentration and form nanosized micellar aggregates in dilute aqueous solution. The binary mixture of the morpholinium gemini surfactant-water system is investigated over a wide range of concentrations. The micellar solution of the morpholinium gemini surfactants demonstrated Newtonian fluidlike behavior between 10 and 50 wt % as the observed viscosities were independent of the applied shear rate. At higher concentration, morpholinium geminis formed self-assembled lyotropic phases in water. These liquid crystalline phases were characterized by small-angle X-ray scattering and polarized optical microscopy techniques.