Evaluating the Therapeutic Potential of Curcumin and Synthetic Derivatives: A Computational Approach to Anti-Obesity Treatments.

Natural compounds such as curcumin, a polyphenolic compound derived from the rhizome of turmeric, have gathered remarkable scientific interest due to their diverse metabolic benefits including anti-obesity potential. However, curcumin faces challenges stemming from its unfavorable pharmacokinetic profile. To address this issue, synthetic curcumin derivatives aimed at enhancing the biological efficacy of curcumin have previously been developed. In silico modelling techniques have gained significant recognition in screening synthetic compounds as drug candidates. Therefore, the primary objective of this study was to assess the pharmacokinetic and pharmacodynamic characteristics of three synthetic derivatives of curcumin. This evaluation was conducted in comparison to curcumin, with a specific emphasis on examining their impact on adipogenesis, inflammation, and lipid metabolism as potential therapeutic targets of obesity mechanisms. In this study, predictive toxicity screening confirmed the safety of curcumin, with the curcumin derivatives demonstrating a safe profile based on their LD50 values. The synthetic curcumin derivative 1A8 exhibited inactivity across all selected toxicity endpoints. Furthermore, these compounds were deemed viable candidate drugs as they adhered to Lipinski's rules and exhibited favorable metabolic profiles. Molecular docking studies revealed that both curcumin and its synthetic derivatives exhibited favorable binding scores, whilst molecular dynamic simulations showed stable binding with peroxisome proliferator-activated receptor gamma (PPARγ), csyclooxygenase-2 (COX2), and fatty acid synthase (FAS) proteins. The binding free energy calculations indicated that curcumin displayed potential as a strong regulator of PPARγ (-60.2 ± 0.4 kcal/mol) and FAS (-37.9 ± 0.3 kcal/mol), whereas 1A8 demonstrated robust binding affinity with COX2 (-64.9 ± 0.2 kcal/mol). In conclusion, the results from this study suggest that the three synthetic curcumin derivatives have similar molecular interactions to curcumin with selected biological targets. However, in vitro and in vivo experimental studies are recommended to validate these findings.

Wastewater-based SARS-CoV-2 airport surveillance: key trends at the Cape Town International Airport.

Monitoring of SARS-CoV-2 RNA in wastewater has revealed the role of mobility in the transmission of coronavirus disease (COVID-19), and the surveillance of airport wastewater in cities across the world has demonstrated how travel entry points can give an indication of trends in transmission. This study undertook wastewater surveillance at the Cape Town International Airport (CTIA) to assess the use of a WBE approach to provide supplementary information on the presence of COVID-19 at a key air travel entry point in South Africa. Grab wastewater samples (n = 55) were collected from the CTIA wastewater pump station and analysed using quantitative real-time polymerase chain reaction (qRT-PCR) method. The study found a correlation between the wastewater data and clinical cases reported in the City of Cape Town during various time periods and during the peak of a COVID-19 wave. Highly elevated viral loads in the wastewater were observed at times there was increased mobility through the airport. The study also revealed elevated viral load levels at the airport despite the stricter restrictions and through the lower restrictions. The study findings indicate wastewater surveillance and airports can provide supplementary information to airport authorities to assess the impacts of imposed travel restrictions.

Dual-Target Mycobacterium tuberculosis Inhibition: Insights into the Molecular Mechanism of Antifolate Drugs.

The escalating prevalence of drug-resistant strains of Mycobacterium tuberculosis has posed a significant challenge to global efforts in combating tuberculosis. To address this issue, innovative therapeutic strategies are required that target essential biochemical pathways while minimizing the potential for resistance development. The concept of dual targeting has gained prominence in drug discovery against resistance bacteria. Dual targeting recognizes the complexity of cellular processes and disrupts more than one vital pathway, simultaneously. By inhibiting more than one essential process required for bacterial growth and survival, the chances of developing resistance are substantially reduced. A previously reported study investigated the dual-targeting potential of a series of novel compounds against the folate pathway in Mycobacterium tuberculosis. Expanding on this study, we investigated the predictive pharmacokinetic profiling and the structural mechanism of inhibition of UCP1172, UCP1175, and UCP1063 on key enzymes, dihydrofolate reductase (DHFR) and 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione 5'-phosphate reductase (RV2671), involved in the folate pathway. Our findings indicate that the compounds demonstrate lipophilic physiochemical properties that promote gastrointestinal absorption, and may also inhibit the drug-metabolizing enzyme, cytochrome P450 3A4, thus enhancing their biological half-life. Furthermore, key catalytic residues (Serine, Threonine, and Aspartate), conserved in both enzymes, were found to participate in vital molecular interactions with UCP1172, which demonstrated the most favorable free binding energies to both DHFR and RV2671 (-41.63 kcal/mol, -48.04 kcal/mol, respectively). The presence of characteristic loop shifts, which are similar in both enzymes, also indicates a common inhibitory mechanism by UCP1172. This elucidation advances the understanding of UCP1172's dual inhibition mechanism against Mycobacterium tuberculosis.

Cyclopia intermedia (Honeybush) Induces Uncoupling Protein 1 and Peroxisome Proliferator-Activated Receptor Alpha Expression in Obese Diabetic Female db/db Mice.

Previously, we reported that a crude polyphenol-enriched fraction of Cyclopia intermedia (CPEF), a plant consumed as the herbal tea, commonly known as honeybush, reduced lipid content in 3T3-L1 adipocytes and inhibited body weight gain in obese, diabetic female leptin receptor-deficient (db/db) mice. In the current study, the mechanisms underlying decreased body weight gain in db/db mice were further elucidated using western blot analysis and in silico approaches. CPEF induced uncoupling protein 1 (UCP1, 3.4-fold, p < 0.05) and peroxisome proliferator-activated receptor alpha (PPARα, 2.6-fold, p < 0.05) expression in brown adipose tissue. In the liver, CPEF induced PPARα expression (2.2-fold, p < 0.05), which was accompanied by a 31.9% decrease in fat droplets in Hematoxylin and Eosin (H&E)-stained liver sections (p < 0.001). Molecular docking analysis revealed that the CPEF compounds, hesperidin and neoponcirin, had the highest binding affinities for UCP1 and PPARα, respectively. This was validated with stabilising intermolecular interactions within the active sites of UCP1 and PPARα when complexed with these compounds. This study suggests that CPEF may exert its anti-obesity effects by promoting thermogenesis and fatty acid oxidation via inducing UCP1 and PPARα expression, and that hesperidin and neoponcirin may be responsible for these effects. Findings from this study could pave the way for designing target-specific anti-obesity therapeutics from C. intermedia.

Delineating the Spread and Prevalence of SARS-CoV-2 Omicron Sublineages (BA.1-BA.5) and Deltacron Using Wastewater in the Western Cape, South Africa.

This study was one of the first to detect Omicron sublineages BA.4 and BA.5 in wastewater from South Africa. Spearman rank correlation analysis confirmed a strong positive correlation between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral RNA in wastewater samples and clinical cases (r = 0.7749, P < .0001). SARS-CoV-2 viral load detected in wastewater, resulting from the Delta-driven third wave, was significantly higher than during the Omicron-driven fourth wave. Whole-genome sequencing confirmed presence of Omicron lineage defining mutations in wastewater with the first occurrence reported 23 November 2021 (BA.1 predominant). The variant spread rapidly, with prevalence of Omicron-positive wastewater samples rising to >80% by 10 January 2022 with BA.2 as the predominant sublineage by 10 March 2022, whilst on 18 April 2022 BA.4 and BA.5 were detected in selected wastewater sites. These findings demonstrate the value of wastewater-based epidemiology to monitor the spatiotemporal spread and potential origin of new Omicron sublineages.

Tracing Potential Covalent Inhibitors of an E3 Ubiquitin Ligase through Target-Focused Modelling.

The Nedd4-1 E3 Ubiquitin ligase has been implicated in multiple disease conditions due its overexpression. Although the enzyme may be targeted both covalently and non-covalently, minimal studies provide effective inhibitors against it. Recently, research has focused on covalent inhibitors based on their characteristic, highly-selective warheads and ability to prevent drug resistance. This prompted us to screen for new covalent inhibitors of Nedd4-1 using a combination of computational approaches. However, this task proved challenging due to the limited number of electrophilic moieties available in virtual libraries. Therefore, we opted to divide an existing covalent Nedd4-1 inhibitor into two parts: a non-covalent binding group and a pre-selected α, ß-unsaturated ester that forms the covalent linkage with the protein. A non-covalent pharmacophore model was built based on molecular interactions at the binding site. The pharmacophore was then subjected to virtual screening to identify structurally similar hit compounds. Multiple filtrations were implemented prior to selecting four hits, which were validated with a covalent conjugation and later assessed by molecular dynamic simulations. The results showed that, of the four hit molecules, Zinc00937975 exhibited advantageous molecular groups, allowing for favourable interactions with one of the characteristic cysteine residues. Predictive pharmacokinetic analysis further justified the compound as a potential lead molecule, prompting its recommendation for confirmatory biological evaluation. Our inhouse, refined, pharmacophore model approach serves as a robust method that will encourage screening for novel covalent inhibitors in drug discovery.

Using Wastewater Surveillance to Compare COVID-19 Outbreaks during the Easter Holidays over a 2-Year Period in Cape Town, South Africa.

Wastewater surveillance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has shown to be an important approach to determine early outbreaks of infections. Wastewater-based epidemiology (WBE) is regarded as a complementary tool for monitoring SARS-CoV-2 trends in communities. In this study, the changes in the SARS-CoV-2 RNA levels in wastewater during Easter holidays in 2021 and 2022 in the City of Cape Town were monitored over nine weeks. Our findings showed a statistically significant difference in the SARS-CoV-2 RNA viral load between the study weeks over the Easter period in 2021 and 2022, except for study week 1 and 4. During the Easter week, 52% of the wastewater treatment plants moved from the lower (low viral RNA) category in 2021 to the higher (medium to very high viral RNA) categories in 2022. As a result, the median SARS-CoV-2 viral loads where higher during the Easter week in 2022 than Easter week in 2021 (p = 0.0052). Mixed-effects model showed an association between the SARS-CoV-2 RNA viral loads and Easter week over the Easter period in 2021 only (p < 0.01). The study highlights the potential of WBE to track outbreaks during the holiday period.

Molecular dynamic mechanism(s) of inhibition of bioactive antiviral phytochemical compounds targeting cytochrome P450 3A4 and P-glycoprotein.

P-glycoprotein (ABCB1) and cytochrome P450 3A4 (CYP3A4) metabolize almost all known human immunodeficiency virus' protease inhibitor drugs (PIs). Over induction of these proteins' activities has been linked to rapid metabolism of PIs which are then pumped out of the circulatory system, eventually leading to drug-resistance in HIV-positive patients. This study aims to determine, with the use of computational tools, the inhibitory potential of four phytochemical compounds (PCs) (epigallocatechin gallate (EGCG), kaempferol-7-glucoside (K7G), luteolin (LUT) and ellagic acid (EGA)) in inhibiting the activities of these drug-metabolizing proteins. The comparative analysis of the MM/GBSA results revealed that the binding affinity (ΔGbind) of EGCG and K7G for CYP3A4 and ABCB1 are higher than LUT and EGA and fall between the ΔGbind of the inhibitors of CYP3A4 and ABCB1 (Ritonavir (strong inhibitor) and Lopinavir (moderate inhibitor)). The structural analysis (RMSD, RMSF, RoG and protein-ligand interaction plots) also confirmed that EGCG and K7G showed similar inhibitory activities with the inhibitors. The study has shown that EGCG and K7G have inhibitory activities against the two proteins and assumes they could decrease intracellular efflux of PIs, consequently increasing the optimal concentration of PIs in the systemic circulation.Communicated by Ramaswamy H. Sarma.

Tracking the circulating SARS-CoV-2 variant of concern in South Africa using wastewater-based epidemiology.

This study uses wastewater-based epidemiology (WBE) to rapidly and, through targeted surveillance, track the geographical distribution of SARS-CoV-2 variants of concern (Alpha, Beta and Delta) within 24 wastewater treatment plants (WWTPs) in the Western Cape of South Africa. Information obtained was used to identify the circulating variant of concern (VOC) within a population and retrospectively trace when the predominant variant was introduced. Genotyping analysis of SARS-CoV-2 showed that 50% of wastewater samples harbored signature mutations linked to the Beta variant before the third wave, with the Delta variant absent within the population. Over time, the prevalence of the beta variant decreased steadily. The onset of the third wave resulted in the Delta variant becoming the predominant variant, with a 100% prevalence supporting the theory that the Delta variant was driving the third wave. In silico molecular docking analysis showed that the signature mutations of the Delta variant increased binding to host proteins, suggesting a possible molecular mechanism that increased viral infectivity of the Delta variant.

Spatial and Temporal Trends of SARS-CoV-2 RNA from Wastewater Treatment Plants over 6 Weeks in Cape Town, South Africa.

Recent scientific trends have revealed that the collection and analysis of data on the occurrence and fate of SARS-CoV-2 in wastewater may serve as an early warning system for COVID-19. In South Africa, the first COVID-19 epicenter emerged in the Western Cape Province. The City of Cape Town, located in the Western Cape Province, has approximately 4 million inhabitants. This study reports on the monitoring of SARS-CoV-2 RNA in the wastewater of the City of Cape Town's wastewater treatment plants (WWTPs) during the peak of the epidemic. During this period, the highest overall median viral RNA signal was observed in week 1 (9200 RNA copies/mL) and declined to 127 copies/mL in week 6. The overall decrease in the amount of detected viral SARS-CoV-2 RNA over the 6-week study period was associated with a declining number of newly identified COVID-19 cases in the city. The SARS-CoV-2 early warning system has now been established to detect future waves of COVID-19.

Druggability and drug-likeness concepts in drug design: are biomodelling and predictive tools having their say?

The drug discovery process typically involves target identification and design of suitable drug molecules against these targets. Despite decades of experimental investigations in the drug discovery domain, about 96% overall failure rate has been recorded in drug development due to the "undruggability" of various identified disease targets, in addition to other challenges. Likewise, the high attrition rate of drug candidates in the drug discovery process has also become an enormous challenge for the pharmaceutical industry. To alleviate this negative outlook, new trends in drug discovery have emerged. By drifting away from experimental research methods, computational tools and big data are becoming valuable in the prediction of biological target druggability and the drug-likeness of potential therapeutic agents. These tools have proven to be useful in saving time and reducing research costs. As with any emerging technique, however, controversial opinions have been presented regarding the validation of predictive computational tools. To address the challenges associated with these varying opinions, this review attempts to highlight the principles of druggability and drug-likeness and their recent advancements in the drug discovery field. Herein, we present the different computational tools and their reliability of predictive analysis in the drug discovery domain. We believe that this report would serve as a comprehensive guide towards computational-oriented drug discovery research. Graphical abstract Highlights of methods for assessing the druggability of biological targets.

Human Rhinovirus Inhibition Through Capsid "Canyon" Perturbation: Structural Insights into The Role of a Novel Benzothiophene Derivative.

The challenge in targeting human rhinoviruses (HRV) over the years has been attributed to the wide variety in HRV serotypes. Nonetheless, the search for therapeutic agents against HRV continues unabated. These efforts have been augmented by the recent discovery of the novel benzothiophene derivative shown to inhibit HRV viral replication. Bound to subtype HRV-B14, the compound showed similar inhibitory activity as Pleconaril, a known capsid inhibitor. However, the molecular and structural basis of this inhibition remains unclear. In this in silico report, residue interaction network analysis revealed that the binding of the benzothiophene derivative into the "canyon" region of the active site of HRV-B14 distorts its initially extensively networked and compact residue profile. This was characterized by fewer inter-residue hydrogen bonds, reduced van der Waals interactions, and increased residue flexibility. Interestingly, however, the binding of this benzothiophene derivative decreased the flexibility of the north-south wall around the canyon region possibly impeding the "breathing motion" of HRV-B14, hence its inhibition. Atomistic insights also revealed the cruciality of Tyr152 toward inhibitor binding at HRV-B14. This was justified by the amino acid's high intermolecular interaction with both inhibitors. Findings provide important structural insights in the inhibitory activity the novel benzothiophene derivative, and reaffirm its promising potential as an alternative capsid inhibitor toward common cold therapy upon further experimental validation.

The Dual-Targeting Activity of the Metabolite Substrate of Para-amino Salicyclic Acid in the Mycobacterial Folate Pathway: Atomistic and Structural Perspectives.

Therapeutic targeting of folate biosynthetic pathway has recently been explored as a viable strategy in the treatment of tuberculosis. The bioactive metabolite substrate of Para-amino salicyclic acid (PAS-M) reportedly dual-targets dihydrofolate reductase (DHFR) and flavin-dependent thymidylate synthase (FDTS), two essential enzymes in folate biosynthetic pathway. However, the molecular mechanisms and structural dynamics of this dual inhibitory activity of the PAS-M remain elusive. Molecular dynamics simulations revealed that binding of PAS-M towards DHFR is characterized by a recurrence of strong conventional hydrogen bond interactions between a peculiar DHFR binding site residue (Asp27) and the 2-amino-decahydropteridin-4-ol group of PAS-M. Similarly, the binding of PAS-M towards FDTS also involved consistent strong conventional hydrogen bond interactions between some specific residues (Tyr101, Arg172, Thr4, Gln103, Arg87 and Gln106) and, the 2-amino-decahydropteridin-4-ol group, thus establishing the cruciality of the group. Structural dynamics of the bound complexes of both enzymes revealed that, upon binding, PAS-M is anchored at the entrance of hydrophobic pockets by strong hydrogen bond interactions while the rest of the structure gains access to deeper hydrophobic residues to engage in favorable interactions. Further analysis of atomistic changes of both enzymes showed increased C-α atom deviations as well as an increase C-α atoms radius of gyration consistent with structural disorientations. These conformational changes possibly interfered with the biological functions of the enzymes and hence their inhibition as experimentally reported. Structural Insights provided could open up a novel paradigm of structure-based design of multi-targeting inhibitors of biological targets in the folate biosynthetic pathway toward tuberculosis therapy.

Delving into the Characteristic Features of "Menace" Mycobacterium tuberculosis Homologs: A Structural Dynamics and Proteomics Perspectives.

The global increase in the morbidity/mortality rate of Mycobacterial infections, predominantly renascent tuberculosis, leprosy, and Buruli ulcers have become worrisome over the years. More challenging is the incidence of resistance mediated by mutant Mycobacterium strains against front-line antitubercular drugs. Homologous to all Mycobacteria species is the GlcNAc-6-phosphate deacetylase (NagA) which catalyzes essential amino sugars synthesis required for cell wall architecture, hence, metamorphosing into an important pharmacological target for curtailing virulence and drug-resistance. This study used integrated bioinformatics methods, MD simulations, and DynaMut and PolyPhen2 to; explore unique features, monitor dynamics, and analyze the functional impact of non-synonymous single-nucleotide polymorphisms of the six NagA of most ruinous Mycobacterium species; tuberculosis (Mtb), smegmatis (MS), marinum (MM), ulcerans, africanum, and microti respectively. This approach is essential for multi-targeting and could result in the identification of potential polypharmacological antitubercular compounds. Comparative sequential analyses revealed ≤ 50% of the overall structure, including the catalytic Asp267 and reactive Cys131, remained conserved. Interestingly, MS-NagA and MM-NagA possess unique hydrophobic isoleucine (Ile) residues at their active sites in contrast to leucine (Leu) found in other variants. More so, unique to the active sites of the NagA is a 'subunit loop' that covers the active site; probably crucial in binding (entry and exit) mechanisms of targeted NagA inhibitors. Relatively, nsSNP mutations exerted a destabilizing effect on the native NagA conformation. Structural and dynamical insights provided, basically pin-pointed the "Achilles' heel" explorable for the rational drug design of target-specific 'NagA' inhibitors potent against a wide range of mycobacterial diseases.

The pharmacokinetic properties of HIV-1 protease inhibitors: A computational perspective on herbal phytochemicals.

Acquired Immune Deficiency Syndrome is the most severe phase of Human Immunodeficiency Virus (HIV) infection. Recent studies have seen an effort to isolate phytochemicals from plants to repress HIV, but less studies have focused on the effects of these phytochemicals on the activities of enzymes/transporters involved in the metabolism of these drugs, which is one of the aims of this study and, to examine the antiviral activity of these compounds against HIV-1 protease enzyme using computational tools. Centre of Awareness-Food Supplement (COA®-FS) herbal medicine, has been said to have potential anti-HIV features. SWISSTARGETPREDICTION and SWISSADME servers were used for determination of the enzymes/transporters involved in the metabolism of these protease inhibitor drugs, (PIs) (Atazanavir, Lopinavir, Darunavir, Saquinavir) and the effects of the selected phytochemicals on the enzymes/transporters involved in the metabolism of these PIs. Using Computational tools, potential structural inhibitory activities of these phytochemicals were explored. Two sub-families of Cytochrome P450 enzymes (CYP3A4 and CYP2C19) and Permeability glycoprotein (P-gp) were predicted to be involved in metabolism of the PIs. Six phytochemicals (Geranin, Apigenin, Fisetin, Luteolin, Phthalic acid and Gallic acid) were predicted to be inhibitors of CYP3A4 and, may slowdown elimination of PIs thereby maintain optimal PIs concentrations. Free binding energy analysis for antiviral activities identified four phytochemicals with favourable binding landscapes with HIV-1 protease enzyme. Epigallocatechin gallate and Kaempferol-7-glucoside exhibited pronounced structural evidence as potential HIV-1 protease enzyme inhibitors. This study acts as a steppingstone toward the use of natural products against diseases that are plagued with adverse drug-interactions.

Navigating Research Toward the Re-emerging Nipah Virus- A New Piece to the Puzzle.

BACKGROUND: The recent Nipah virus (NiV) outbreak in India has caused a state of chaos, with potential to become the next international pandemic. There is still a great deal to learn about NiV for the development of a potent treatment against it. The NiV non-structural proteins play important roles in the lifecycle of the virus, with the RNA-dependent RNA-polymerase (RdRp) being a vital component in viral replication. In this study, we not only provide a comprehensive overview of all the literature concerning NiV, we also propose a model of the NiV RdRp and screen for potential inhibitors of the viral enzyme. METHODS: In this study, computational tools were utilized in the design of a NiV RdRp homology model. The active site of RdRp was then identified and potential inhibitors of the protein were discovered with the use of pharmacophore-based screening. RESULTS: Ramachandran plot analysis revealed a favourable model. Upon binding of nucleoside analog, 4'- Azidocytidine, active site residues Trp1714 and Ser1713 took part in stabilizing hydrogen bonds, while Thr1716, Ser1478, Ser1476 and Glu1465 contributed to hydrophobic interactions. Pharmacophore based screening yielded 18 hits, of which ZINC00085930 demonstrated the most optimal binding energy (-8.1 kcal/mol), validating its use for further analysis as an inhibitor of NiV. CONCLUSION: In this study we provide a critical guide, elucidating on the in silico requirements of the drug design and discovery process against NiV. This material lays a foundation for future research into the design and development of drugs that inhibit NiV.

The Perplexity of Synergistic Duality: Inter-molecular Mechanisms of Communication in BCR-ABL1.

BACKGROUND: Aberrant and proliferative expression of the oncogene BCR-ABL in bone marrow cells is one of the prime causes of Chronic Myeloid Leukemia (CML). It has been established that the tyrosine kinase domain of the BCR-ABL protein is a potential therapeutic target for the treatment of CML. Although the first and second line inhibitors against the enzyme are available, recent studies have indicated that monotherapeutic resistance has become a great challenge. OBJECTIVE: In recent studies, the dual inhibition of BCR-ABL by Nilotinib and Asciminib has been shown to overcome drug resistance. This prompted us to investigate the dynamics behind this novel drug combination. METHODS: By the utilization of a wide range of computational tools, we defined and compared BCR-ABL's structural and dynamic characteristics when bound as a dual inhibitor system. RESULTS: Conformational ensemble analysis presented a sustained inactive protein, as the activation loop, inclusive of the characteristic Tyr257, remained in an open position due to the unassailable binding of Asciminib at the allosteric site. Nilotinib also indicated stronger binding at the catalytic site in the presence of Asciminib, thus exposing new avenues in treating Nilotinib-resistance. This was in accordance with intermolecular hydrogen bond interactions with key binding site residues GLU399, Asn259 and Thr252. CONCLUSION: The investigations carried out in this study gave rise to new possibilities in the treatment of resistance in CML, as well as assisting in the design of novel and selective inhibitors as dual anti-cancer drugs.

Grafted hyaluronic acid N-acetyl-l-methionine for targeting of LAT1 receptor: In-silico, synthesis and microscale thermophoresis studies.

Neutral amino acids can be delivered into cells through the l-type amino acid transporter-1 (LAT1), which is a sodium independent transporter. The LAT1 protein is expressed in different tissues, including kidney, blood brain barrier and intestinal wall hence LAT1 can be used as a target in diseases associated with its overexpression. In-silico interactions between different ligands, including methionine (Met), N-acetyl-l-methionine (AcMet), hyaluronic acid (HA), grafted hyaluronic-acid l-methionine (HA-ADH-Met) and a novel grafted hyaluronic acid-N-acetyl-l-methionine (HA-ADH-AcMet), which are at the active site of the LAT1 transporter, were studied and the binding energies calculated. The HA-ADH-AcMet complex demonstrated binding energy and solvation energy of -74.84 and 81.46 kcal/mol, respectively, thus validating its potential to be synthesized. The structural conformation of the HA-ADH-AcMet was confirmed using 1H NMR, FTIR, DSC and PXRD. Microscale thermophoresis was employed to study the binding affinity between the different ligands and LAT1. The binding affinity was expressed in terms of a dissociation constant (Kd), where that of HA-ADH-AcMet was found to be 408 nM which was considered the strongest among the different ligands tested. HA-ADH-AcMet can be used as a targeting moiety for development of medicines to treat different diseases and processes that express LAT1 protein.

Discovery of novel natural flavonoids as potent antiviral candidates against hepatitis C virus NS5B polymerase.

The non-structural 5B (NS5B) polymerase of hepatitis C virus (HCV) is an attractive target for antiviral intervention. Quercetagetin (Que) is a natural flavonoid, which has been exhibited to have anti-HCV property through inhibition of RNA binding to NS5B. The last few decades have witnessed a growing interest in the extraction of natural flavonoids with a plethora of different biological activities. Considering the high therapeutic potential of Que, the aim of this study is to explore wide structure entities with potent activity using Que as a prototype. A virtual screen protocol involving docking and molecular dynamics has been performed to examine the potency of forty-three natural flavonoids which recently extracted from plants for inhibition of NS5B. During two screening stages, two compounds 24 and 41 were identified to have more favorable binding affinity to NS5B as compared to Que. The comparative analysis showed that there is a significant difference in the binding free energy of Que and 41 (ΔΔGbind = -11.17 kcal/mol). It was revealed that van der Waals (vdW) interaction drives the binding process of both 24 and 41 and plays an important role in increasing their activities relative to Que. PHE162 serves as a crucial residue in both the NS5B-24 and NS5B-41 systems, contributing the most vdW energy by π-π interaction, suggesting that aromatic interactions are critical for the binding of 24 and 41 to NS5B. Moreover, hydrogen bond analysis indicates that the hydrogen bonds formed by LYS98, THR137, ASP164 and ARG168, can play important roles in the increased binding affinity of 41 to NS5B relative to Que. The findings of this study will provide useful structure-activity relationship (SAR) guidelines for the design of novel inhibitors with improved/enhanced therapeutic activities in the treatment of hepatitis C.

Domperidone nanocrystals with boosted oral bioavailability: fabrication, evaluation and molecular insight into the polymer-domperidone nanocrystal interaction.

The aim of this study was to employ experimental and molecular modelling approaches to use molecular level interactions to rationalise the selection of suitable polymers for use in the production of stable domperidone (DOMP) nanocrystals with enhanced bioavailability. A low-energy antisolvent precipitation method was used for the preparation and screening of polymers for stable nanocrystals of DOMP. Ethyl cellulose was found to be very efficient in producing stable DOMP nanocrystals with particle size of 130 ± 3 nm. Moreover, the combination of hydroxypropyl methylcellulose and polyvinyl alcohol was also shown to be better in producing DOMP nanocrystals with smaller particle size (200 ± 3.5 nm). DOMP nanosuspension stored at 2-8 °C and at room temperature (25 °C) exhibited better stability compared to the samples stored at 40 °C. Crystallinity of the unprocessed and processed DOMP was monitored by differential scanning calorimetry and powder X-ray diffraction. DOMP nanocrystals gave enhanced dissolution rate compared to the unprocessed drug substance. DOMP nanocrystals at a dose of 10 mg/kg in rats showed enhanced bioavailability compared to the raw drug substance and marketed formulation. A significant increase in plasma concentration of 2.6 µg/mL with a significant decrease in time (1 h) to reach maximum plasma concentration was observed for DOMP nanocrystals compared to the raw DOMP. Molecular modelling studies provided underpinning knowledge at the molecular level of the DOMP-polymer nanocrystal interactions and substantiated the experimental studies. This included an understanding of the impact of polymers on the size of nanocrystals and their associated stability characteristics.