Synthesis of Triazole Derivatives of Levoglucosenone As Promising Anticancer Agents: Effective Exploration of the Chemical Space through retro-aza-Michael//aza-Michael Isomerizations

An updated review on 1,2,3-/1,2,4-triazoles: synthesis and diverse range of biological potential

The synthesis of triazoles has attracted a lot of interest in the field of organic chemistry because of its versatile chemical characteristics and possible biological uses. This review offers an extensive overview of the different pathways used in the production of triazoles. A detailed analysis of recent research indicates that triazole compounds have a potential range of pharmacological activities, including the ability to inhibit enzymes, and have antibacterial, anticancer, and antifungal activities. The integration of computational and experimental methods provides a thorough understanding of the structure-activity connection, promoting sensible drug design and optimization. By including triazoles as essential components in drug discovery, researchers can further explore and innovate in the synthesis, biological assessment, and computational studies of triazoles as drugs, exploring the potential therapeutic significance of triazoles.

Photochemical reactions of biomass derived platform chemicals

Platform chemicals obtained from biomass will play an important role in chemical industry. Already existing compounds or not yet established chemicals are produced from this renewable feedstock. Using photochemical reactions as sustainable method for the conversion of matter furthermore permits to develop processes that are interesting from the ecological and economical point of view. Furans or levoglucosenone are thus obtained from carbohydrate containing biomass. Photochemical rearrangements, photooxygenation reactions or photocatalytic radical reactions can be carried out with such compounds. Also, sugars such pentoses or hexoses can be more easily transformed into heterocyclic target compounds when such photochemical reactions are used. Lignin is an important source for aromatic compounds such as vanillin. Photocycloaddition of these compounds with alkenes or the use light supported multicomponent reactions yield interesting target molecules. Dyes, surfactants or compounds possessing a high degree of molecular diversity and complexity have been synthesized with photochemical key steps. Alkenes as platform chemicals are also produced by fermentation processes, for example, with cyanobacteria using biological photosynthesis. Such alkenes as well as terpenes may further be transformed in photochemical reactions yielding, for example, precursors of jet fuels.

Camellia sinensis methanolic leaves extract: Phytochemical analysis and anticancer activity against human liver cancer cells

BACKGROUND

The study's primary goal is to ascertain whether there is a relationship between the processed green tea methanolic extract's (GTME) phytochemical components and its potential effectiveness against human liver cancer cells. The GTME's phytochemical composition was identified using gas chromatography-mass spectrometry, and the extract's capacity to lower cellular proliferation and cause apoptosis in HepG2 cancerous liver cell lines was checked.

RESULTS

The findings of the gas chromatography-mass chromatogram showed that GTME included bioactive antioxidants and anticancer substances. Additionally, utilizing the MTT, comet assay, and acridine assay, GTME revealed a selective cytotoxic impact with a significant IC50 value (27.3 µg/ml) on HepG2 cells without any harmful effects on WI-38 healthy cells. Also, compared to untreated cells, the extract-treated HepG2 cells had an upsurge in the proportion of cells that have undergone apoptosis and displayed a comet nucleus, which is a sign of DNA damage. In addition, HepG2 cells treated with GTME revealed a stop in the G1 phase and sub-G1 apoptotic cells (37.32%) in a flow cytometry analysis. Furthermore, reactive oxygen species were shown to be responsible for HepG2 apoptosis, and the tested extract significantly reduced their levels in the treated cells. Lastly, compared to untreated cells in treated HepG2 cells, GTME significantly changed protein expression levels linked with cell cycle arrest in the G1 phase and apoptosis.

CONCLUSION

These findings provided information about the processes through which the GTME inhibited the growth of HepG2. Therefore, it has potential as an effective natural therapy for the treatment of human liver cancer. However, to validate these findings, animal models must be used for in vivo studies.

Photocatalytic Transformation of Biomass and Biomass Derived Compounds-Application to Organic Synthesis

Biomass and biomass-derived compounds have become an important alternative feedstock for chemical industry. They may replace fossil feedstocks such as mineral oil and related platform chemicals. These compounds may also be transformed conveniently into new innovative products for the medicinal or the agrochemical domain. The production of cosmetics or surfactants as well as materials for different applications are examples for other domains where new platform chemicals obtained from biomass can be used. Photochemical and especially photocatalytic reactions have recently been recognized as being important tools of organic chemistry as they make compounds or compound families available that cannot be or are difficultly synthesized with conventional methods of organic synthesis. The present review gives a short overview with selected examples on photocatalytic reactions of biopolymers, carbohydrates, fatty acids and some biomass-derived platform chemicals such as furans or levoglucosenone. In this article, the focus is on application to organic synthesis.

Synthesis of sugar enones and their use as powerful synthetic precursors of thiodisaccharides

Monosaccharide derivatives having a double bond conjugated to a carbonyl (sugar enones or enuloses) are relevant synthetic tools. They are also suitable starting materials, or versatile intermediates, for the synthesis of a wide variety of natural or synthetic compounds with a broad spectrum of biological and pharmacological activities. The preparation of enones is mainly focused on the search for more efficient and diastereoselective synthetic methodologies. The usefulness of enuloses relies on the diverse reaction possibilities offered by alkene and carbonyl double bonds, which are prone to undergo varied reactions such as halogenation, nitration, epoxidation, reduction, addition, etc. The addition of thiol groups that led to sulfur glycomimetics, such as thiooligosaccharides, is particularly relevant. Therefore, the synthesis of enuloses and the Michael addition of sulfur nucleophiles to give thiosugars or thiodisaccharides are discussed here. Chemical modifications of the conjugate addition products to afford biologically active compounds are also reported.

DNA binding studies of antifungal drug posaconazole using spectroscopic and molecular docking methods

The binding studies of DNA with small molecules have been an emerging field of research all the time since DNA as the genetic material is a major biological target for various drugs. Interpretation of small molecule-DNA binding helps in understanding their interactions with designing new drugs of greater medicinal activity. Posaconazole is an antifungal drug in the class of triazoles which are known to possess numerous pharmacological properties. In this work, the nature of the binding of posaconazole with calf-thymus DNA has been studied using spectroscopic techniques and molecular docking studies. A binding constant of the order of 10³ M^-1 was observed from UV-visible and fluorescence studies for the interaction between posaconazole and calf-thymus DNA. The fluorescence property of posaconazole was found to be quenched by calf-thymus DNA with a quenching constant of the order of 10³ M^-1. Competitive displacement of ethidium bromide and Hoechst 33258 by posaconazole using fluorescence technique suggested minor groove binding of posaconazole in calf-thymus DNA. Confirmation of the binding mode was further complemented by the viscosity measurement and DNA melting studies followed by KI quenching experiments. The studies on the effect of ionic strength on the binding suggested a possible role of electrostatic force in the interaction. Molecular docking studies reflected a crescent shape of the posaconazole within the minor groove of calf-thymus DNA validating the experimental findings showing the residues involved in the interaction.

Bioactive compounds, antibacterial and antioxidant activities of methanol extract of Tamarindus indica Linn

Tamarindus indica is one of the tropical medicinal plants that has been attributed curative potential of numerous diseases by many rural dwellers. This study was designed to evaluate the antioxidant, antibacterial activities and also to determine the various chemical constituents responsible for its pharmacological activities. The methanol extract of Tamarindus indica fruit pulp was analyzed by Gas Chromatography/Mass Spectrometer to determine the volatile compounds present. The antioxidant activities were performed using DPPH and FRAP method and the antibacterial activity was tested against some common pathogens by macro broth dilution method. The GCMS analysis shows the presence of 37 compounds, out of which 14 had their peak area percentages ≥ 1% and only two compounds had no reported pharmacological activities. Most of the bioactive compounds including 5-Hydroxymethylfurfural (31.06%)-3-O-Methyl-d-glucose (16.31%), 1,6-anhydro-β-D-Glucopyranose (9.95%), 5-methyl-Furancarboxaldehyde (3.2%), Triethylenediamine (1.17%), 1-(2-furanyl)-1-Propcanone (2.18%), Methyl 2-furoate (3.14%), Levoglucosenone (3.21%), methyl ester-Hepta-2,4-dienoic acid, (8.85%), 2,3-dihydro-3,5-dihydrox-4H-Pyran-4-one (3.4%), O-α-D-glucopyranosyl-(1.fwdarw.3)-β-D-fructofuranosyl-α-D-Glucopyranoside (2.18%), n-Hexadecanoic acid (1.38%), 2-Heptanol, acetate (1.29%), 5-[(5-methyl-2-fur-2-Furancarboxaldehyde (1.08%), 3-Methyl-2-furoic acid (1.05%) and cis-Vaccenic acid (2.85%)have been reported with different activities such as antibacterial, antifungal, antitubercular, anticancer, antioxidant and other prophylactic activities. The extract demonstrated inhibitory potential against all tested pathogen. However, Plesiomonas shigellosis ATCC 15903 and Bacillus pumillus ATCC 14884 are more sensitive with the MIC of 0.22 and 0.44 mg/ml respectively. The antioxidant activity was relatively low due to the low phenolic content of the extract. This shows that there is a strong correlation between antioxidant activities and phenolic content. GC–MS analysis revealed the presence of bioactive phytoconstituents with various biological activities and this justifies the rationale behind its usage as a curative therapy by many local dwellers.

Levoglucosenone: Bio-Based Platform for Drug Discovery

Levoglucosone (LGO) is a bio-privileged molecule that can be produced on scale from waste biomass. This chiral building block has been converted via well-established chemical processes into previously difficult-to-synthesize building blocks such as enantiopure butenolides, dihydropyrans, substituted cyclopropanes, deoxy-sugars and ribonolactones. LGO is an excellent starting material for the synthesis of biologically active compounds, including those which have anti-cancer, anti-microbial or anti-inflammatory activity. This review will cover the conversion of LGO to biologically active compounds as well as provide future research directions related to this platform molecule.

1,2,3-Triazole derivatives with anti-breast cancer potential

Abstract:

Breast cancer is one of the most prevalent malignant diseases and one of the main mortality causes among women across the world. Despite advances in chemotherapy, drug resistance remains major clinical concerns, creating an urgent need to explore novel anti-breast cancer drugs. 1,2,3-Triazole is a privileged moiety, and its derivatives could inhibit cancer cell proliferation, and induce the cell cycle arrest and apoptosis. Accordingly, 1,2,3-triazole derivatives possess profound activity against various cancers including breast cancer. This review summarizes the latest progresses related to the anti-breast cancer potential of 1,2,3-triazole derivatives, covering articles published from January 2017 to December 2021. The mechanisms of action and structure-activity relationships (SARs) are also discussed for further rational design of more effective candidates.

Recent advances in synthesis and anticancer potential of triazole containing scaffolds

Cancer is the most lethal disease that may be found anywhere on the globe. Approximately 10% of individuals die as a result of cancer of various types, with 19.3 million new cancer cases and 10 million deaths expected in 2020. More than 100 medications are commercially available for the treatment of cancer, but only a few candidates have high specificity, resulting in several side effects. The scientific community has spent the past decades focusing on drug discovery. Natural resources are used to isolate pharmaceutically active candidates, which are then synthesized in laboratories. More than 60% of all prescribed drugs are made from natural ingredients. Unique five-membered heteroaromatic center motifs with sulfur, oxygen and nitrogen atoms are found in heterocyclic compounds such as indazole, thiazole, triazole, triazole, and oxazole, and are used as a core scaffold in many medicinally important therapies. Triazole possesses a wide range of pharmacological activities including anticancer, antibacterial, antifungal, antibiotic antiviral, analgesic, anti-inflammatory, anti-HIV, antidiabetic, and antiprotozoal activities. Novel Triazole motifs with a variety of biological characteristics have been successfully synthesized using versatile synthetic methods. We intend here to facilitate the rational design and development of innovative triazole-based anti-cancer medicines with increased selectivity for various cancer cell lines by providing insight into various ligand-receptor interactions.

Antineoplastic activity of products derived from cellulose-containing materials: levoglucosenone and structurally-related derivatives as new alternatives for breast cancer treatment

Breast cancer is the leading cause of cancer death among women worldwide. For this reason, the development of new therapies is still essential. In this work we have analyzed the antitumor potential of levoglucosenone, a chiral building block derived from the pyrolysis of cellulose-containing materials such as soybean hulls, and three structurally related analogues. Employing human and murine mammary cancer models, we have evaluated the effect of our compounds on cell viability through MTS assay, apoptosis induction by acridine orange/ethidium bromide staining and/or flow cytometry and the loss of mitochondrial potential by tetramethylrhodamine methyl ester staining. Autophagy and senescence induction were also evaluated by Western blot and β-galactosidase activity respectively. Secreted metalloproteases activity was determined by quantitative zymography. Migratory capacity was assessed by wound healing assays while invasive potential was analyzed using Matrigel-coated transwell chambers. In vivo studies were also performed to evaluate subcutaneous tumor growth and experimental lung colonization. All compounds impaired in vitro proliferation with IC₅₀ values in a range of low micromolar. Apoptosis was identified as the main mechanism responsible for the reduction of monolayer cell content induced by the compounds without detecting modulations of autophagy or senescence processes. Two of the four compounds (levoglucosenone and its brominated variant) were able to modulate in vitro events associated with tumor progression, such as migratory potential, invasiveness, and proteases secretion. Furthermore, tumor volume and metastatic spread were significantly reduced in vivo after the treatment these two compounds. Here, we could obtain from soybean hulls, a material with almost no commercial value, a variety of chemical compounds useful for breast cancer treatment.

A critical review on the use of DP4+ in the structural elucidation of natural products: the good, the bad and the ugly. A practical guide

Covering: 2015 up to the end of 2020Even in the golden age of NMR, the number of natural products being incorrectly assigned is becoming larger every day. The use of quantum NMR calculations coupled with sophisticated data analysis provides ideal complementary tools to facilitate the elucidation process in challenging cases. Among the current computational methodologies to perform this task, the DP4+ probability is a popular and widely used method. This updated version of Goodman's DP4 synergistically combines NMR calculations at higher levels of theory with the Bayesian analysis of both scaled and unscaled data. Since its publication in late 2015, the use of DP4+ to solve controversial natural products has substantially grown, with several predictions being confirmed by total synthesis. To date, the structures of more than 200 natural products were determined with the aid of DP4+. However, all that glitters is not gold. Besides its intrinsic limitations, on many occasions it has been improperly used with potentially important consequences on the quality of the assignment. Herein we present a critical revision on how the scientific community has been using DP4+, exploring the strengths of the method and how to obtain optimal results from it. We also analyze the weaknesses of DP4+, and the paths to by-pass them to maximize the confidence in the structural elucidation.

Highlight on the Mechanism of Linear Polyamidoamine Degradation in Water

This paper aims at elucidating the degradation mechanism of linear polyamidoamines (PAAs) in water. PAAs are synthesized by the aza-Michael polyaddition of prim-monoamines or bis-sec-amines with bisacrylamides. Many PAAs are water-soluble and have potential for biotechnological applications and as flame-retardants. PAAs have long been known to degrade in water at pH ≥ 7, but their degradation mechanism has never been explored in detail. Filling this gap was necessary to assess the suitability of PAAs for the above applications. To this aim, a small library of nine PAAs was expressly synthesized and their degradation mechanism in aqueous solution studied by 1H-NMR in different conditions of pH and temperature. The main degradation mechanism was in all cases the retro-aza-Michael reaction triggered by dilution but, in some cases, hints were detected of concurrent hydrolytic degradation. Most PAAs were stable at pH 4.0; all degraded at pH 7.0 and 9.0. Initially, the degradation rate was faster at pH 9.0 than at pH 7.0, but the percent degradation after 97 days was mostly lower. In most cases, at pH 7.0 the degradation followed first order kinetics. The degradation rates mainly depended on the basicity of the amine monomers. More basic amines acted as better leaving groups.

Levoglucosenone and Its Pseudoenantiomer iso-Levoglucosenone as Scaffolds for Drug Discovery and Development

The bioderived platform molecule levoglucosenone (LGO, 1) and its readily prepared pseudoenantiomer (iso-LGO, 2) have each been subjected to α-iodination reactions with the product halides then being engaged in palladium-catalyzed Ullmann cross-coupling reactions with various bromonitropyridines. The corresponding α-pyridinylated derivatives such as 11 and 24, respectively, are produced as a result. Biological screening of such products reveals that certain of them display potent and selective antimicrobial and/or cytotoxic properties. In contrast, the azaindoles obtained by reductive cyclization of compounds such as 11 and 12 are essentially inactive in these respects. Preliminary mode-of-action studies are reported.

Design, synthesis and evaluation of novel levoglucosenone derivatives as promising anticancer agents

A series of levoglucosenone-derived 1,2,3-triazoles and isoxazoles featuring a flexible spacer between the heteroaromatic and anhydropyranose cores have been designed and synthesized following an hetero Michael // 1,3-dipolar cycloaddition path. The use of a design of experiments approach allowed the optimization of the oxa-Michael reaction with propargyl alcohol as nucleophile, a key step for the synthesis of the target compounds. All of the compounds were tested for their anticancer activity on MDA-MB-231 cells, featuring mutant p53. The results highlighted the importance of the introduction of the flexible spacer as well as the higher activity of oxa-Michael isoxazole-derivatives. The most prominent compounds also showed anti-proliferative activities against lung and colon cancer cell lines. The compounds showed enhanced cytotoxic effects in the presence of mutant p53, determined both by endogenous mutant p53 knock down (R280K) and by reintroducing p53 R280K in cells lacking p53 expression.

Aziridination and aza-Wharton Reactions of Levoglucosenone

Efficient conditions have been developed for the diastereoselective aziridination of the biomass pyrolysis product (−)-levoglucosenone, via the reaction of primary aliphatic amines with 3-iodolevoglucosenone. In contrast to the reactions of aliphatic amines, the use of 4-methoxyaniline resulted in an aza-Michael-initiated dimerisation reaction, and 1,3-diphenylurea gave a 2-imidazolidinone. The aziridine products were transformed using the aza-Wharton reaction, affording novel sulfonamide and amine-substituted 6,8-dioxabicyclo[3.2.1]oct-3-enes with potential as sp3-rich chiral scaffolds.

Highly N2-selective allylation of NH-1,2,3-triazoles with allenamides mediated by N-iodosuccinimide

We report a new protocol to synthesize N²-allyl-substituted 1,2,3-triazoles via NIS mediated allylation of allenamides with NH-1,2,3-triazoles.

Carbonic anhydrase inhibition with a series of novel benzenesulfonamide-triazole conjugates

We report the synthesis and characterisation of a novel series of triazole benzenesulfonamide derivatives, which incorporate the general pharmacophore associated with carbonic anhydrase (CA, EC 4.2.1.1) inhibitors. The synthesised compounds were tested in vitro against four human carbonic anhydrase (hCA, EC 4.2.1.1) isozymes, hCA I, hCA II, hCA IV and hCA IX. The obtained results showed that the tumour-associated hCA IX was the most sensitive to inhibition with the synthesised derivatives, with the triazolo-pyridine benzenesulfonamides 14, 16 and 17 being the most effective inhibitors. Some selected compounds were chosen for a single dose anti-proliferative activity testing against a panel of 57 human tumour cell lines and show some anti-proliferative activity ex vivo.