Various 6-methoxytetrahydro-β-carboline derivatives, namely BEN (6-methoxy-1-phenyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole), ANI (6-methoxy-1-(4-methoxyphenyl)-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole), ACE (6-methoxy-1-methyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole) and VAN (2-methoxy-4-(6-methoxy-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indol-1-l)phenol), were prepared via the Maillard reaction using food flavours and 5-methoxytryptamine in aqueous medium and were investigated for their in vitro antioxidant and cytotoxicity properties. These derivatives were found to exhibit moderate antioxidant properties, based on a combination of DPPH, ABTS and FRAP assays. The results suggested that the Maillard reaction could be used to generate β-carboline antioxidants. It was beneficial that VAN showed the highest antioxidant activity but the least cytotoxic activities on non-tumourous cell lines of NIH/3T3, CCD18-Co and B98-5 using MTT assay. ACE, ANI and BEN showed mild toxicity at effective antioxidative concentrations derived from DPPH and ABTS assays. Furthermore, they are safer compared to 5-fluorouracil, cisplatin and betulinic acid on NIH/3T3, CCD18-Co and B98-5 cells. In conclusion, the antioxidant and cytotoxicity properties of 6-methoxytetrahydro-β-carbolines were demonstrated for the first time.
A selective reproducible high-performance liquid chromatographic assay for the simultaneous quantitative determination of the antimalarial compound artemether (ARM), dihydroartemisinin (DQHS) and artemisinin (QHS), as internal standard, is described. After extraction from plasma, ARM and DQHS were analysed using a Lichrocart/Lichrosphere 100 CN stainless-steel column and a mobile phase of acetonitrile-0.05 M acetic acid (15:85, v/v) adjusted to pH 5.0, and electrochemical detection in the reductive mode. The mean recovery of ARM and DQHS over a concentration range of 30-120 ng/ml was 81.6% and 93.4%, respectively. The within-day coefficients of variation were 0.89-7.01% for ARM and 3.45-8.11% for DQHS. The day-to-day coefficients of variation were 2.06-8.43% and 3.22-6.33%, respectively. The minimum detectable concentration for ARM and DQHS in plasma was 2.5 and 1.25 ng/ml for both compounds. The method was found to be suitable for use in clinical pharmacological studies.
Background: Kratom (Mitragyna speciosa Korth), a popular opioid-like plant holds its therapeutic potential in pain management and opioid dependence. However, there are growing concerns about the safety or potential toxicity risk of kratom after prolonged use. Aim of the study: The study aimed to assess the possible toxic effects of kratom decoction and its major alkaloids, mitragynine, and speciociliatine in comparison to morphine in an embryonic zebrafish model. Methods: The zebrafish embryos were exposed to kratom decoction (1,000-62.5 μg/ml), mitragynine, speciociliatine, and morphine (100-3.125 μg/ml) for 96 h post-fertilization (hpf). The toxicity parameters, namely mortality, hatching rate, heart rate, and morphological malformations were examined at 24, 48, 72, and 96 hpf, respectively. Results: Kratom decoction at a concentration range of ≥500 μg/ml caused 100% mortality of zebrafish embryos and decreased the hatching rate in a concentration-dependent manner. Meanwhile, mitragynine and speciociliatine exposure resulted in 100% mortality of zebrafish embryos at 100 μg/ml. Both alkaloids caused significant alterations in the morphological development of zebrafish embryos including hatching inhibition and spinal curvature (scoliosis) at the highest concentration. While exposure to morphine induced significant morphological malformations such as pericardial oedema, spinal curvature (lordosis), and yolk edema in zebrafish embryos. Conclusion: Our findings provide evidence for embryonic developmental toxicity of kratom decoction and its alkaloids both mitragynine and speciociliatine at the highest concentration, hence suggesting that kratom consumption may have potential teratogenicity risk during pregnancy and thereby warrants further investigations.
Breast cancer remains one of the leading causes of cancer-related deaths globally and the most prominent among females, yet with limited effective therapeutic options. Most of the current medications are challenged by various factors including low efficacy, incessant resistance, immune evasion and frequent recurrence of the disease. Further understanding of the prognosis and identification of plausible therapeutic channels thus requires multimodal approaches. In this review, epigenetics studies of several pathways to BC oncogenesis via the inducement of oncogenic changes on relevant markers have been overviewed. Similarly, the counter-epigenetic mechanisms to reverse such changes as effective therapeutic strategies were surveyed. The epigenetic oncogenesis occurs through several pathways, notably, DNMT-mediated hypermethylation of DNA, dysregulated expression for ERα, HER2/ERBB and PR, histone modification, overexpression of transcription factors including the CDK9-cyclin T1 complex and suppression of tumour suppressor genes. Scientifically, the regulatory reversal of the mechanisms constitutes effective epigenetic approaches for mitigating BC initiation, progression and metastasis. These were exhibited at various experimental levels by classical chemotherapeutic agents including some repurposable drugs, endocrine inhibitors, monoclonal antibodies and miRNAs, natural products, metal complexes and nanoparticles. Dozens of the potential candidates are currently in clinical trials while others are still at preclinical experimental stages showing promising anti-BC efficacy. The review presents a model for a wider understanding of epigenetic oncogenic pathways to BC and reveals plausible channels for reversing the unpleasant changes through epigenetic modifications. It advances the science of therapeutic designs for ameliorating the global burden of BC upon further translational studies.
Since the emergence of their primitive strains, the complexity surrounding their pathogenesis, constant genetic mutation and translation are contributing factors to the scarcity of a successful vaccine for coronaviruses till moment. Although, the recent announcement of vaccine breakthrough for COVID-19 renews the hope, however, there remains a major challenge of accessibility to urgently match the rapid global therapeutic demand for curtailing the pandemic, thereby creating an impetus for further search. The reassessment of results from a stream of experiments is of enormous importance in identifying bona fide lead-like candidates to fulfil this quest. This review comprehensively highlights the common pathomechanisms and pharmacological targets of HCoV-OC43, SARS-CoV-1, MERS-CoV and SARS-CoV-2, and potent therapeutic potentials from basic and clinical experimental investigations. The implicated targets for the prevention and treatment include the viral proteases (Mpro, PLpro, 3CLpro), viral structural proteins (S- and N-proteins), non-structural proteins (nsp 3, 8, 10, 14, 16), accessory protein (ns12.9), viroporins (3a, E, 8a), enzymes (RdRp, TMPRSS2, ADP-ribosyltransferase, MTase, 2'-O-MTase, TATase, furin, cathepsin, deamidated human triosephosphate isomerase), kinases (MAPK, ERK, PI3K, mTOR, AKT, Abl2), interleukin-6 receptor (IL-6R) and the human host receptor, ACE2. Notably among the 109 overviewed inhibitors include quercetin, eriodictyol, baicalin, luteolin, melatonin, resveratrol and berberine from natural products, GC373, NP164 and HR2P-M2 from peptides, 5F9, m336 and MERS-GD27 from specific human antibodies, imatinib, remdesivir, ivermectin, chloroquine, hydroxychloroquine, nafamostat, interferon-β and HCQ from repurposing libraries, some iron chelators and traditional medicines. This review represents a model for further translational studies for effective anti-CoV therapeutic designs.
The nsp3 macrodomain and nsp12 (RdRp) enzymes are strongly implicated in the virulent regulation of the host immune response and viral replication of SARS-CoV-2, making them plausible therapeutic targets for mitigating infectivity. Remdesivir remains the only FDA-approved small-molecule inhibitor of the nsp12 in clinical conditions while none has been approved yet for the nsp3 macrodomain. In this study, 69,067 natural compounds from the IBScreen database were screened for efficacious potentials with mechanistic multitarget-directed inhibitory pharmacology against the dual targets using in silico approaches. Standard and extra precision (SP and XP) Maestro glide docking analyses were employed to evaluate their inhibitory interactions against the enzymes. Four compounds, STOCK1N-45901, 03804, 83408, 08377 consistently showed high XP scores against the respective targets and interacted strongly with pharmacologically essential amino acid and RNA residues, in better terms than the standard, co-crystallized inhibitors, GS-441524 and remdesivir. Further assessments through the predictions of ADMET and mutagenicity distinguished STOCK1N-45901, a natural derivative of o-hydroxybenzoate as the most promising candidate. The ligand maintained a good conformational and thermodynamic stability in complex with the enzymes throughout the trajectories of 100 ns molecular dynamics, indicated by RMSD, RMSF and radius of gyration plots. Its binding free energy, MM-GBSA was recorded as -54.24 and -31.77 kcal/mol against the respective enzyme, while its structure-activity relationships confer high probabilities as active antiviral, anti-inflammatory, antiinfection, antitussive and peroxidase inhibitor. The IBScreen database natural product, STOCK1N-45901 (2,3,4,5,6-pentahydroxyhexyl o-hydroxybenzoate) is thus recommended as a potent inhibitor of dual nsp3 and nsp12 of SARS-CoV-2 for further study. Communicated by Ramaswamy H. Sarma.
This study examines the in vitro antioxidant activities of the methanol extract of Swietenia mahagoni seeds (SMCM seed extract). The extract was screened for possible antioxidant activities by free radical scavenging activity (DPPH), xanthine oxidase inhibition (XOI), hydrogen peroxide scavenging activity (HPSA) and ferric-reducing antioxidant power (FRAP) assays. The total phenolic and flavonoid contents were also determined. The extract exhibits antioxidant activity of 23.29% with an IC(50 )value of 2.3 mg/mL in the DPPH radical scavenging method, 47.2% in the XOI assay, 49.5% by the HPSA method, and 0.728 mmol/Fe(II)g in the FRAP method at the concentration tested. The amount of total phenolics and flavonoid contents was 70.83 mg gallic acid equivalent (GAE) and 2.5 +/- 0.15 mg of catechin equivalent per gram of dry extract, respectively. High Performance Thin Layer Chromatography (HPTLC) screening indicates the presence of phenolic compounds in the SMCM seed extract. The results indicate that the extract has both high free radical scavenging and xanthine oxidase inhibition activity. The antioxidant activity of SMCM seed extract is comparable with that of other Malaysian tropical fruits and herbal plants.
Antibiotic resistance (AR) remains one of the leading global health challenges, mostly implicated in disease-related deaths. The Enterobacteriaceae-producing metallo-β-lactamases (MBLs) are critically involved in AR pathogenesis through Zn-dependent catalytic destruction of β-lactam antibiotics, yet with limited successful clinical inhibitors. The efficacy of relevant broad-spectrum β-lactams including imipenem and meropenem are seriously challenged by their susceptibility to the Zn-dependent carbapenemase hydrolysis, as such, searching for alternatives remains imperative. In this study, computational molecular modelling and virtual screening methods were extensively applied to identify new putative Zn-sensitive broad-spectrum inhibitors of MBLs, specifically imipenemase-1 (IMP-1) from the IBScreen database. Three ligands, STOCK3S-30154, STOCK3S-30418 and STOCK3S-30514 selectively displayed stronger binding interactions with the enzymes compared to reference inhibitors, imipenem and meropenem. For instance, the ligands showed molecular docking scores of -9.450, -8.005 and -10.159 kcal/mol, and MM-GBSA values of -40.404, -31.902 and -33.680 kcal/mol respectively against the IMP-1. Whereas, imipenem and meropenem showed docking scores of -9.038 and -10.875 kcal/mol, and MM-GBSA of -31.184 and -32.330 kcal/mol respectively against the enzyme. The ligands demonstrated good thermodynamic stability and compactness in complexes with IMP-1 throughout the 100 ns molecular dynamics (MD) trajectories. Interestingly, their binding affinities and stabilities were significantly affected in contacts with the remodelled Zn-deficient IMP-1, indicating sensitivity to the carbapenemase active Zn site, however, with non-β-lactam scaffolds, tenable to resist catalytic hydrolysis. They displayed ideal drug-like ADMET properties, thus, representing putative Zn-sensitive non-β-lactam inhibitors of IMP-1 amenable for further experimental studies.
Serotonin (5-HT) antagonists and reuptake inhibitors (SARIs) are atypical antidepressants for managing major depressive disorder. They are oftentimes applied as adjuvants for ameliorating aftereffects of SSRI antidepressants including insomnia and sexual dysfunction. The few available candidates of this class including lorpiprazole and trazodone also display some daunting side effects, making a continuous search for improved alternatives essential. Natural β-carboline alkaloids (NβCs) are interestingly renowned with broad pharmacological spectrum against several neuropsychiatric disorders including depression. However, their potentials as SARIs remain underexplored. In this study, 982 NβCs retrieved from the Ambinter-Greenpharma (Amb) database were virtually screened for potent SARI alternatives using computational and biocheminformatics approaches: homology modelling of 5-HT1A receptor, Glide HTVS, SP and XP molecular docking, molecular dynamics (MD) simulation, ADMET and mutagenicity predictions. The homology receptor was validated as a good representative of human 5HT1A receptor using the RCSB structure validation and quality protocols. From the virtual screening against the 5-HT1A receptor, Amb ligands, Amb18709727 and Amb37857532 showed higher binding affinities by XP scores of -8.725 and -7.976 kcal/mol, and MMGBSA of -87.972 and -107.585 kcal/mol respectively compared to lorpiprazole, a reference SARI with XP score and MMGBSA of -6.512 and -62.788 kcal/mol respectively. They maintained ideal contacts with pharmacologically essential amino acid residues implicated in SARI mechanisms and expressed higher stability and compactness than lorpiprazole throughout the trajectories of 100 ns MD simulation. They also displayed interesting ADME, druggability, low toxicity and mutagenicity profiles, ideal for CNS drug prospects, thus, recommended as putative SARI candidates for further study.Communicated by Ramaswamy H. Sarma.
Viral diseases are prominent among the widely spread infections threatening human well-being. Real-life clinical successes of the few available therapeutics are challenged by pathogenic resistance and suboptimal delivery to target sites. Nanotechnology has aided the design of functionalised and non-functionalised Au and Ag nanobiomaterials through physical, chemical and biological (green synthesis) methods with improved antiviral efficacy and delivery. In this review, innovative designs as well as interesting antiviral activities of the nanotechnology-inclined biomaterials of Au and Ag, reported in the last 5 years were critically overviewed against several viral diseases affecting man. These include influenza, respiratory syncytial, adenovirus, severe acute respiratory syndromes (SARS), rotavirus, norovirus, measles, chikungunya, HIV, herpes simplex virus, dengue, polio, enterovirus and rift valley fever virus. Notably identified among the nanotechnologically designed promising antiviral agents include AuNP-M2e peptide vaccine, AgNP of cinnamon bark extract and AgNP of oseltamivir for influenza, PVP coated AgNP for RSV, PVP-AgNPs for SARS-CoV-2, AuNRs of a peptide pregnancy-induce d hypertension and AuNP nanocarriers of antigen for MERS-CoV and SARS-CoV respectively. Others are AgNPs of collagen and Bacillus subtilis for rotavirus, AgNPs labelled Ag30-SiO 2 for murine norovirus in water, AuNPs of Allium sativum and AgNPs of ribavirin for measles, AgNPs of Citrus limetta and Andrographis Paniculata for Chikungunya, AuNPs of efavirenz and stavudine, and AgNPs-curcumin for HIV, NPAuG3-S8 for HSV, AgNPs of Moringa oleifera and Bruguiera cylindrica for dengue while AgNPs of polyethyleneimine and siRNA analogues displayed potency against enterovirus. The highlighted candidates are recommended for further translational studies towards antiviral therapeutic designs.
The human serotonin transporters (hSERTs) are neurotransmitter sodium symporters of the aminergic G protein-coupled receptors, regulating the synaptic serotonin and neuropharmacological processes related to neuropsychiatric disorders, notably, depression. Selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine and (S)-citalopram are competitive inhibitors of hSERTs and are commonly the first-line medications for major depressive disorder (MDD). However, treatment-resistance and unpleasant aftereffects constitute their clinical drawbacks. Interestingly, vilazodone emerged with polypharmacological (competitive and allosteric) inhibitions on hSERTs, amenable to improved efficacy. However, its application usually warrants adjuvant/combination therapy, another subject of critical adverse events. Thus, the discovery of alternatives with polypharmacological potentials (one-drug-multiple-target) and improved safety remains essential. In this study, carbazole analogues from chemical libraries were explored using docking and molecular dynamics (MD) simulation. Selectively, two IBScreen ligands, STOCK3S-30866 and STOCK1N-37454 predictively bound to the active pockets and expanded boundaries (extracellular vestibules) of the hSERTs more potently than vilazodone and (S)-citalopram. For instance, the two ligands showed docking scores of -9.52 and -9.59 kcal/mol and MM-GBSA scores of -92.96 and -65.66 kcal/mol respectively compared to vilazodone's respective scores of -7.828 and -59.27 against the central active site of the hSERT (PDB 7LWD). Similarly, the two ligands also docked to the allosteric pocket (PDB 5I73) with scores of -8.15 and -8.40 kcal/mol and MM-GBSA of -96.14 and -68.46 kcal/mol whereas (S)-citalopram has -6.90 and -69.39 kcal/mol respectively. The ligands also conferred conformational stability on the receptors during 100 ns MD simulations and displayed interesting ADMET profiles, representing promising hSERT modulators for MDD upon experimental validation.Communicated by Ramaswamy H. Sarma.
The nsp3 macrodomain is implicated in the viral replication, pathogenesis and host immune responses through the removal of ADP-ribosylation sites during infections of coronaviruses including the SARS-CoV-2. It has ever been modulated by macromolecules including the ADP-ribose until Ni and co-workers recently reported its inhibition and plasticity enhancement unprecedentedly by remdesivir metabolite, GS-441524, creating an opportunity for investigating other biodiverse small molecules such as β-Carboline (βC) alkaloids. In this study, 1497 βC analogues from the HiT2LEAD chemical database were screened, using computational approaches of Glide XP docking, molecular dynamics simulation and pk-CSM ADMET predictions. Selectively, βC ligands, 129, 584, 1303 and 1323 demonstrated higher binding affinities to the receptor, indicated by XP docking scores of -10.72, -10.01, -9.63 and -9.48 kcal/mol respectively than remdesivir and GS-441524 with -4.68 and -9.41 kcal/mol respectively. Consistently, their binding free energies were -36.07, -23.77, -24.07 and -17.76 kcal/mol respectively, while remdesivir and GS-441524 showed -21.22 and -24.20 kcal/mol respectively. Interestingly, the selected βC ligands displayed better stability and flexibility for enhancing the plasticity of the receptor than GS-441524, especially 129 and 1303. Their predicted ADMET parameters favour druggability and low expressions for toxicity. Thus, they are recommended as promising adjuvant/standalone anti-SARS-CoV-2 candidates for further study.Key words: SARS-CoV-2, nsp3 macrodomain, ADP-ribose, β-carboline, bioinformatics, drug design.
The seeds of Swietenia mahagoni have been applied in folk medicine for the treatment of hypertension, diabetes, malaria, amoebiasis, cough, chest pain, and intestinal parasitism. Here we are the first to report on the toxicity of the Swietenia mahagoni crude methanolic (SMCM) seed extract.
This study aims to evaluate the in vitro angiotensin-converting enzyme (ACE) inhibition activity of different extracts of Orthosiphon stamineus (OS) leaves and their main flavonoids, namely rosmarinic acid (RA), sinensetin (SIN), eupatorin (EUP) and 3'-hydroxy-5,6,7,4'-tetramethoxyflavone (TMF). Furthermore, to identify possible mechanisms of action based on structure-activity relationships and molecular docking. The in vitro ACE inhibition activity relied on determining hippuric acid (HA) formation from ACE-specific substrate (hippuryl-histidyl-leucine (HHL)) by the action of ACE enzyme. A High Performance Liquid Chromatography method combined with UV detection was developed and validated for measurement the concentration of produced HA. The chelation ability of OS extract and its reference compounds was evaluated by tetramethylmurexide reagent. Furthermore, molecular docking study was performed by LeadIT-FlexX: BioSolveIT's LeadIT program. OS ethanolic extract (OS-E) exhibited highest inhibition and lowest IC50 value (45.77 ± 1.17 µg/mL) against ACE compared to the other extracts. Among the tested reference compounds, EUP with IC50 15.35 ± 4.49 µg/mL had highest inhibition against ACE and binding ability with Zn (II) (56.03% ± 1.26%) compared to RA, TMF and SIN. Molecular docking studies also confirmed that flavonoids inhibit ACE via interaction with the zinc ion and this interaction is stabilized by other interactions with amino acids in the active site. In this study, we have demonstrated that changes in flavonoids active core affect their capacity to inhibit ACE. Moreover, we showed that ACE inhibition activity of flavonoids compounds is directly related to their ability to bind with zinc ion in the active site of ACE enzyme. It was also revealed that OS extract contained high amount of flavonoids other than RA, TMF, SIN and EUP. As such, application of OS extract is useful as inhibitors of ACE.
Mitragyna speciosa is reported to be beneficial for the management of chronic pain and opioid withdrawal in the evolving opioid epidemic. Data on the blood-brain barrier (BBB) transport of mitragynine and 7-hydroxymitragynine, the active compounds of the plant, are still lacking and inconclusive. Here, we present for the first time the rate and the extent of mitragynine and 7-hydroxymitragynine transport across the BBB, with an investigation of their post-BBB intra-brain distribution. We utilized an in vitro BBB model to study the rate of BBB permeation of the compounds and their interaction with efflux transporter P-glycoprotein (P-gp). Mitragynine showed higher apical-to-basolateral (A-B, i.e. blood-to-brain side) permeability than 7-hydroxymitragynine. 7-Hydroxymitragynine showed a tendency to efflux, with efflux ratio (B-A/A-B) of 1.39. Both were found to inhibit the P-gp and are also subject to efflux by the P-gp. Assessment of the extent of BBB transport in vivo in rats from unbound brain to plasma concentration ratios (Kp,uu,brain ) revealed extensive efflux of both compounds, with less than 10 percent of unbound mitragynine and 7-hydroxymitragynine in plasma crossing the BBB. By contrast, the extent of intra-brain distribution was significantly different, with mitragynine having 18-fold higher brain tissue uptake in brain slice assay compared with 7-hydroxymitragynine. Mitragynine showed a moderate capacity to accumulate inside brain parenchymal cells, while 7-hydroxymitragynine showed restricted cellular barrier transport. The presented findings from this systematic investigation of brain pharmacokinetics of mitragynine and 7-hydroxymitragynine are essential for design and interpretation of in vivo experiments aiming to establish exposure-response relationship.