Norharmane as a potential chemical entity for development of anticancer drugs

Evaluation of the in vivo acute toxicity and in vitro genotoxicity and mutagenicity of synthetic β-carboline alkaloids with selective cytotoxic activity against ovarian and breast cancer cell lines

The aim of this study was to evaluate the in vitro cytotoxic, genotoxic, and mutagenic potential and to determine the in silico ADME parameters of two synthetic β-carboline alkaloids developed as prototypes of antitumor agents (NQBio-06 and NQBio-21). Additionally, acute toxicity of the compounds was evaluated in mice. The results from the MTT assay showed that NQBio-06 presented higher cytotoxicity in the ovarian cancer cell line TOV-21 G (IC50 = 2.5 µM, selectivity index = 23.7). NQBio-21 presented an IC50 of 6.9 µM and a selectivity index of 14.5 against MDA-MB-231 breast cancer cells. Comet assay results showed that NQBio-06 did not induce chromosomal breaks in vitro, but NQBio-21 was genotoxic with and without metabolic activation (S9 fraction). Micronucleus assay showed that both compounds were mutagenic. In addition, metabolic activation enhanced this effect in vitro. The in silico predictions showed that the compounds met the criteria set by Lipinski's rules, had strong prediction for intestinal absorption, and were possible substrates for P-glycoprotein. The in vivo results demonstrated that both the compounds exhibited low acute toxicity. These results suggest that the mechanisms underlying the cytotoxicity of NQBio-06 and NQBio-21 are related to DNA damage induction and that the use of S9 enhanced these effects. In vivo analysis showed signs of toxicity after a single administration of the compounds in mice. These findings highlight the potential of β-carboline compounds as sources for the development of new anticancer chemotherapeutic agents.

Nanosynthesis, phycochemical constituents, and pharmacological properties of cyanobacterium Oscillatoria sp

The Oscillatoria sp., a blue-green alga or cyanobacterium, consists of about 305 species distributed globally. Cyanobacteria are prokaryotes possessing several secondary metabolites that have industrial and biomedical applications. Particularly, the published reviews on Oscillatoria sp. have not recorded any pharmacology, or possible details, while the detailed chemical structures of the alga are reported in the literature. Hence, this study considers pertinent pharmacological activities of the plethora of bioactive components of Oscillatoria sp. Furthermore, the metallic nanoparticles produced with Oscillatoria sp. were documented for plausible antibacterial, antifungal, antioxidant, anticancer, and cytotoxic effects against several cultured human cell lines. The antimicrobial activities of solvent extracts of Oscillatoria sp. and the biotic activities of its derivatives, pyridine, acridine, fatty acids, and triazine were structurally described in detail. To understand the connotations with research gaps and provide some pertinent prospective suggestions for further research on cyanobacteria as potent sources of pharmaceutical utilities, attempts were documented. The compounds of Oscillatoria sp. are a potent source of secondary metabolites that inhibit the cancer cell lines, in vitro. It could be expected that by holistic exploitation, the natural Oscillatoria products, as the source of chemical varieties and comparatively more potent inhibitors, would be explored against pharmacological activities with the integument of SARs.

Insight to biotechnological utility of phycochemicals from cyanobacterium Anabaena sp.: An overview

Cyanobacteria (blue-green algae) are well-known for the ability to excrete extra-cellular products, as a variety of cyanochemicals (phycocompounds) of curio with several extensive therapeutic applications. Among these phycocompound, the cyanotoxins from certain water-bloom forming taxa are toxic to biota, including crocodiles. Failure of current non-renewable source compounds in producing sustainable and non-toxic therapeutics led the urgency of discovering products from natural sources. Particularly, compounds of the filamentous N2-fixing Anabaena sp. have effective antibacterial, antifungal, antioxidant, and anticancer properties. Today, such newer compounds are the potential targets for the possible novel chemical scaffolds, suitable for mainstream-drug development cascades. Bioactive compounds of Anabaena sp. such as, anatoxins, hassallidins and phycobiliproteins have proven their inherent antibacterial, antifungal, and antineoplastic activities, respectively. Herein, the available details of the biomass production and the inherent phyco-constituents namely, alkaloids, lipids, phenols, peptides, proteins, polysaccharides, terpenoids and cyanotoxins are considered, along with geographical distributions and morphological characteristics of the cyanobacterium. The acquisitions of cyanochemicals in recent years have newly addressed several pharmaceutical aliments, and the understanding of the associated molecular interactions of phycochemicals have been considered, for plausible use in drug developments in future.

Current Status and De Novo Synthesis of Anti-Tumor Alkaloids in Nicotiana

Alkaloids are the most diversified nitrogen-containing secondary metabolites, having antioxidant and antimicrobial properties, and are extensively used in pharmaceuticals to treat different types of cancer. Nicotiana serves as a reservoir of anti-cancer alkaloids and is also used as a model plant for the de novo synthesis of various anti-cancer molecules through genetic engineering. Up to 4% of the total dry weight of Nicotiana was found to be composed of alkaloids, where nicotine, nornicotine, anatabine, and anabasine are reported as the dominant alkaloids. Additionally, among the alkaloids present in Nicotiana, β-carboline (Harmane and Norharmane) and Kynurenines are found to show anti-tumor effects, especially in the cases of colon and breast cancers. Creating new or shunting of existing biosynthesis pathways in different species of Nicotiana resulted in de novo or increased synthesis of different anti-tumor molecules or their derivatives or precursors including Taxadiane (~22.5 µg/g), Artemisinin (~120 μg/g), Parthenolide (~2.05 ng/g), Costunolide (~60 ng/g), Etoposide (~1 mg/g), Crocin (~400 µg/g), Catharanthine (~60 ng/g), Tabersonine (~10 ng/g), Strictosidine (~0.23 mg/g), etc. Enriching the precursor pool, especially Dimethylallyl Diphosphate (DMAPP), down-regulating other bi-product pathways, compartmentalization or metabolic shunting, or organelle-specific reconstitution of the precursor pool, might trigger the enhanced accumulation of the targeted anti-cancer alkaloid in Nicotiana.

Antiviral activities of plant-derived indole and β-carboline alkaloids against human and avian influenza viruses

The persistent evolution of drug-resistant influenza strains represents a global concern. The innovation of new treatment approaches through drug screening strategies and investigating the antiviral potential of bioactive natural-based chemicals may address the issue. Herein, we screened the anti-influenza efficacy of some biologically active indole and β-carboline (βC) indole alkaloids against two different influenza A viruses (IAV) with varied host range ranges; seasonal influenza A/Egypt/NRC098/2019(H1N1) and avian influenza A/chicken/Egypt/N12640A/2016(H5N1). All compounds were first assessed for their half-maximal cytotoxic concentration (CC₅₀) in MDCK cells and half-maximal inhibitory concentrations (IC₅₀) against influenza A/H5N1. Intriguingly, Strychnine sulfate, Harmalol, Harmane, and Harmaline showed robust anti-H5N1 activities with IC₅₀ values of 11.85, 0.02, 0.023, and 3.42 µg/ml, respectively, as compared to zanamivir and amantadine as control drugs (IC₅₀ = 0.079 µg/ml and 17.59 µg/ml, respectively). The efficacy of the predefined phytochemicals was further confirmed against influenza A/H1N1 and they displayed potent anti-H1N1 activities compared to reference drugs. Based on SI values, the highly promising compounds were then evaluated for antiviral efficacy through plaque reduction assay and consistently they revealed high viral inhibition percentages at non-toxic concentrations. By studying the modes of antiviral action, Harmane and Harmalol could suppress viral infection via interfering mainly with the viral replication of the influenza A/H5N1 virus, whilst Harmaline exhibited a viricidal effect against the influenza A/H5N1 virus. Whereas, Strychnine sulfate elucidated its anti-influenza potency by interfering with viral adsorption into MDCK cells. Consistently, chemoinformatic studies showed that all studied phytochemicals illustrated HB formations with essential peptide cleft through the NH of indole moiety. Among active alkaloids, harmalol displayed the best lipophilicity metrics including ligand efficiency (LE) and ligand lipophilic efficiency (LLE) for both viruses. Compounds geometry and their ability to participate in HB formation are very crucial.

Molecular dynamics simulation, synthesis and topoisomerase inhibitory actions of vanillin derivatives: a systematic computational structural integument

A series of 4-hydroxy-3-methoxy benzaldehyde (vanillin) derivatives (3a-3r) was designed for the principle of Schiff base condensation with several individual sulfanilamide analogues. The inhibitory potencies of the designed compounds were evaluated through molecular docking simulation studies against the targets, breast cancer-topo isomerase-IIα and estrogen receptor-α; and the top scoring poses with higher binding energy were selected to assess the mode of binding and stability of each complex through molecular dynamics simulations. Compounds that remained stable in the active sites of the both target receptors through a number of strong H-bonds and hydrophobic contacts were selected. Based on the computational results, these selected compounds, 3b, 3e and 3f were synthesized and were followed up for structural elucidation attempts, by FT/ATR, ¹H NMR and ¹³C NMR. From the experimental in vitro studies on 3b, 3e and 3f, the following remarkable activities against breast cancer cell line were done; IC₅₀ values of 3b, 3e and 3f were noted, 6.7, 4.3 and 11 ng/mL, respectively. These newly synthesized compounds may be used as novel inhibitors of nuclear receptors with potential therapeutic applications in control of cancer.Communicated by Ramaswamy H. Sarma.

A review on synthetic strategy, molecular pharmacology of indazole derivatives, and their future perspective

With different nitrogen-containing heterocyclic moieties, Indazoles earn one of the places among the top investigated molecules in medicinal research. Indazole, an important fused aromatic heterocyclic system containing benzene and pyrazole ring with a chemical formula of C₇ H₆ N₂ , is also called benzopyrazole. Indazoles consist of three tautomeric forms in which 1H-tautomers (indazoles) and 2H-tautomers (isoindazoles) exist in all phases. The tautomerism in indazoles greatly influences synthesis, reactivity, physical and even the biological properties of indazoles. The thermodynamic internal energy calculation of these tautomers points view 1H-indazole as the predominant and stable form over 2H-indazole. The natural source of indazole is limited and exists in alkaloidal nature (i.e., nigellidine, nigeglanine, nigellicine, etc.) found from Nigella plants. Some of the FDA-approved drugs like Axitinib, Entrectinib, Niraparib, Benzydamine, and Granisetron are being used to treat renal cell cancer, non-small cell lung cancer (NSCLC), epithelial ovarian cancer, chronic inflammation, chemotherapy-induced nausea, vomiting, and many more uses. Besides all these advantages regarding its biological activity, the main issue about indazoles is the less abundance in plant sources, and their synthetic derivatives also often face problems with low yield. In this review article, we discuss its chemistry, tautomerism along with their effects, different schematics for the synthesis of indazole derivatives, and their different biological activities.

The recent development of thymol derivative as a promising pharmacological scaffold

Thymol (a phenol ring bearing active phytoconstituent) is a privileged scaffold, which is diversified in natural sources. This scaffold acts as an obligatory template for scheming and arriving at designing some newer drug-molecules with potential biological activities. In the pharmacological perspective, the promising active sites of the scaffold are the positions C-1, C-4, and C-6 of thymol that would be accountable for developing potent drug candidates. This review aims to explore the various synthetic routes and the structural-activity relationship of thymol scaffold with suitable active pharmacophore sites.

β-Carboline-based molecular hybrids as anticancer agents: a brief sketch

Cancer is a huge burden on the healthcare system and is foremost cause of mortality across the globe. Among various therapeutic strategies, chemotherapy plays an enormous role in overcoming the challenges of treating cancer, especially in late stage detection. However, limitations such as extreme side/adverse effects and drug resistance associated with available drugs have impelled the development of novel chemotherapeutic agents. In this regard, we have reviewed the development of β-carboline-based chemotherapeutic agents reported in last five years. The review mainly emphasizes on the molecular hybrids of β-carbolines with various pharmacophores, their synthetic strategies, and in vitro anticancer evaluation. In addition, the mechanisms of action, in silico studies, structural influence on the potency and selectivity among diverse cancer cell lines have been critically presented. The review updates readers on the diverse molecular hybrids prepared and the governing structural features of high potential molecules that can help in the future development of novel cytotoxic agents.

Role of hormone receptors and HER2 as prospective molecular markers for breast cancer: An update

This review provides an updated account on the current methods, principles and mechanism of action of therapies for the detection of molecular markers of therapeutic importance in the prognosis of breast cancer progression and recurrence, which includes estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor2 (HER2). Indeed, hormone-receptors namely, ER, PR, proto-oncogene HER2 are the basic molecular markers that are recognized and established prognostic factors and predictors of response, for therapeutic practice. These markers can be detected by using immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH), which are established, faster and cost effective detection methods. These molecular markers along with clinicopathological prognostic parameters give the best prediction of the prognosis of cancer recurrence and progress. Finally, hormone receptors and HER2 as molecular markers are of prime therapeutic importance and have the capability to take part in future drug development techniques.

β-carbolines norharman and harman in vegetable oils in China

The beta-carbolines norharman and harman, two heterocyclic aromatic amines with potential mutagenicity, have been determined in vegetable oils. Identification and analysis were carried out by ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometry (UPLC-MS/MS). In 88 samples analysed, the concentrations of norharman and harman were < LOD to 336.22 ng/g and < LOD to 505.14 ng/g, respectively. A high variability of norharman and harman levels among different oil types was observed. Sesame-, flaxseed-, sunflower seed-, peanut- and rapeseed oils were most contaminated. Both β-carbolines were most likely formed during roasting of the oilseeds. Oil consumption, especially of oils obtained after roasting of the seeds, was a major dietary source of the β-carbolines norharman and harman. Under existing oil risk factors, this investigation contributes to the unprecedented and essential information for dietary assessments associated with oil consumption.

Biogenic silver nanoparticle synthesis with cyanobacterium Chroococcus minutus isolated from Baliharachandi sea-mouth, Odisha, and in vitro antibacterial activity

The burden from microbial diseases has to be addressed in an increasing pace due to multidrug resistance, causing clinical annoyance, globally. Indeed, employing eco-friendly approaches by green syntheses of nanoparticles with metals/metalloids as antibacterial compounds would be continual and cost-effective. Herein, the synthesis of silver nanoparticles (AgNPs) by aqueous extracts of the cyanobacterium Chroococcus minutus (strain, CRLSUM10), collected from the meeting point of sea and river, East coast of India, are presented; both reducing and stabilizing mediators of the synthesized AgNPs were ascertained, by characteriztion by UV–visible spectrophotometry, XRD, FTIR, SEM and SEM-EDX. Furthermore, synthesized AgNPs had a remarkable antibacterial activity at the lowest dose, 100 mg against pathogenic strains of E. coli and S. pyogenes, rendering those as novel antibacterial agents against ‘upper respiratory tract infection’.

Molecular dynamics and computational study of Mannich-based coumarin derivatives: potent tyrosine kinase inhibitor

The manifestation of bacterial UTI (Urinary Tract Infection) has been predominantly endemic, globally; eventually, the development of new UTI antibacterial agent(s) remains the call of the day. Herein, two series of Mannich-based 4-hydroxy coumarin derivatives, 7a-m and 8a-m were designed by suitable heterocyclic amines condensed with aldehydes. The synthesised molecules were interpreted by ¹H-NMR and ¹³C-NMR spectral analyses with in vitro antibacterial studies. The compound, 4-hydroxy-3-((4-hydroxy-3-methoxyphenyl)(morpholino)methyl)-2H-chromen-2-one 8l was the significant derivative against pathogenic bacteria Staphylococcus aureus and Escherichia coli with MIC values 12.50 and 25 µM, respectively. Computational assessments with the Lipinski's rule of five, ADMET properties and molecular docking studies revealed that analogues, 7f, 7l, 8d, 8j and 8k could be potent druggable molecules with significant binding affinity towards bacterial tyrosine kinase, as target. To understand the mode of binding and intrinsic stabilities of potent receptor-ligand complexes, each system was subjected molecular dynamics simulations for 100 ns. Inter-molecular contact analysis and intrinsic hydrogen-bond stability portrayed the analogues 8l form a number of non-bonded contacts with the receptor tyrosine kinase being mostly dominated by electrostatic and hydrophobic contacts. The results from the present structure-based designing approach might be a valuable tool towards identification of a new antibacterial drug candidate(s) against UTI in near future.Abbreviations4-HC4-hydroxy coumarinADMETabsorption, distribution, metabolism, excretion, toxicityDCE1,2-dichloroethaneDCMdichloromethaneDMSOdimethyl sulfoxideMDmolecular dynamicsMICminimum inhibitory concentrationNMRnuclear magnetic resonanceNPTisothermal isobaric ensemblesNVTcanonical ensemblesPCAprincipal component analysisPDBprotein data bankRgradius gyrationRMSFroot-mean-square fluctuationsRSMDroot-mean-square deviationUTIurinary Tract InfectionCommunicated by Ramaswamy H. Sarma.