Structure-Bioactivity Relationship Study of Xanthene Derivatives: A Brief Review

New Bis(pyrazolo[5,1-b]quinazolines) and Bis(9H-xanthenediones) Linked to Alkane Cores: One-Pot Synthesis, Antibacterial Screening, and SAR Study

Effective one-pot methods were used to synthesize some new alkane-linked bis(pyrazolo[5,1-b]quinazolines) and bis(9H-xanthenediones). The first series was produced, in 80-88 % yields, via the reaction of one equivalent of the appropriate bis(aldehydes) with two equivalents of 1H-pyrazole-3,5-diamine and dimedone in DMF at 150 °C for 5-6 h. The second series was prepared, in 82-89 % yields, via the reaction one equivalent of the appropriate bis(aldehydes) with four equivalents of dimedone in acetic acid at 120 °C for 4-5 h. The new products displayed a broad range of antibacterial activity against different bacterial strains. Generally, the antibacterial activity of the alkane-linked bis(pyrazolo[5,1-b]quinazoline) units is more than 2-fold their bis(9H-xanthenedione) analogues. The (p-tolylthio)methyl)-linked bis(pyrazolo[5,1-b]quinazolines) demonstrate the best antibacterial activity with MIC/MBC values up to 3.3/6.6 μM.

Nonoxidovanadium(IV) Complex-Catalyzed Synthesis of 2-Amino-3-cyano-4H-pyrans/4H-chromenes, Biscoumarins, and Xanthenes under Green Conditions

Reaction of [VIVO(acac)2] (Hacac = acetylacetone) with a Mannich base, N,N,N',N'-tetrakis(2-hydroxy-3,5-di-tert-butyl benzyl)-1,2-diaminoethane (H4L, I) in a 1:1 molar ratio in MeOH, leads to the formation of the nonoxidovanadium(IV) complex [VIVL] (1). Air stable complex 1 has been characterized using various spectroscopic techniques, DFT calculations, and single-crystal X-ray studies. 1 adopts distorted octahedral geometry where ligand coordinates through all coordination functionalities available. This complex has been used as a catalyst in the one-pot, three-component synthesis of 2-amino-3-cyano-4H-pyrans using 1,3-dicarbonyls (1,3-cyclohexanedione, dimedone, barbituric acid, and 4-hydroxycoumarin), malononitrile, and various substituted aromatic aldehydes in equimolar amounts employing ethanol as a green solvent. The catalytic reaction revealed that the multicomponent synthesis of 4H-pyrans and chromenes is greatly influenced by both types of 1,3-dicarbonyl compound employed and the nature of the substituent on the aromatic ring of the aldehyde. Synthesized catalyst has also been used in the synthesis of pharmacologically relevant oxygen-containing heterocycles, specifically, 1,8-dioxo-octahydro-1H-xanthenes and biscoumarins. The possible mechanism for the synthesized one-pot, multicomponent product has been proposed by isolating intermediate(s) generated during synthesis.

Cellular Red-Ox system in health and disease: The latest update

Cells are continually exposed to reactive oxygen species (ROS) generated during cellular metabolism. Apoptosis, necrosis, and autophagy are biological processes involving a feedback cycle that causes ROS molecules to induce oxidative stress. To adapt to ROS exposure, living cells develop various defense mechanisms to neutralize and use ROS as a signaling molecule. The cellular redox networks combine signaling pathways that regulate cell metabolism, energy, cell survival, and cell death. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) are essential antioxidant enzymes that are required for scavenging ROS in various cell compartments and response to stressful situations. Among the non-enzymatic defenses, vitamin C, glutathione (GSH), polyphenols, carotenoids, vitamin E, etc., are also essential. This review article describes how ROS are produced as byproducts of oxidation/reduction (redox) processes and how the antioxidants defense system is directly or indirectly engaged in scavenging ROS. In addition, we used computational methods to determine the comparative profile of binding energies of several antioxidants with antioxidant enzymes. The computational analysis demonstrates that antioxidants with a high affinity for antioxidant enzymes regulate their structures.

N-, O- and S-Heterocycles Synthesis in Deep Eutectic Solvents

The synthesis of heterocycles is a fundamental area of organic chemistry that offers enormous potential for the discovery of new products with important applications in our daily life such as pharmaceuticals, agrochemicals, flavors, dyes, and, more generally, engineered materials with innovative properties. As heterocyclic compounds find application across multiple industries and are prepared in very large quantities, the development of sustainable approaches for their synthesis has become a crucial objective for contemporary green chemistry committed to reducing the environmental impact of chemical processes. In this context, the present review focuses on the recent methodologies aimed at preparing N-, O- and S-heterocyclic compounds in Deep Eutectic Solvents, a new class of ionic solvents that are non-volatile, non-toxic, easy to prepare, easy to recycle, and can be obtained from renewable sources. Emphasis has been placed on those processes that prioritize the recycling of catalyst and solvent, as they offer the dual benefit of promoting synthetic efficiency while demonstrating environmental responsibility.

A novel class of xanthene dyes with chemically linked UV absorber molecule and their photophysical properties

In this paper, we prepared a new class of chemically linked UV absorber XU2 & XU3, and their photophysical, chemical properties and substrate durability were investigated. Spectroscopic behavior at various solvent and pH levels for this dye solution has been evaluated. Successfully designed an open ring form of xanthene moiety, linked a UV absorber to it, and made XU2 & XU3 that have shown good absorbance and emission band maxima at all solvents and pH mediums. Further, the found UV-Vis absorbance band maxima (λ_max), PL emission maxima (λ_em), molar extinction coefficient (ε_max) and Stokes shifts (ΔνST) when compared to commercially available dye 1. The synthesised XU2 & XU3 have shown brilliant results from exposed UV light at irradiation processing time, due to the light energy passes through the molecule by keto-enol tautomerisation between phenolic hydrogen and carbonyl carbon like a six-member ring. So it can be acted as radioless behaviour in the visible region, and it can relax the energy without any assistance. Hence, the UV absorber has protected the compound like a UV Resistance.

Oxidation of BINOLs by Hypervalent Iodine Reagents: Facile Synthesis of Xanthenes and Lactones

Xanthene derivatives have broad applications in medicines, fluorescent probes, dyes, food additives, etc. Therefore, much attention was focused on developing the synthetic methods to prepare these compounds. Binaphthyl‐based xanthene derivatives were prepared through the oxidation of BINOLs promoted by the hypervalent iodine reagent iodosylbenzene (PhIO). Nine‐membered lactones were obtained through a similar oxidative reaction when iodoxybenzene (PhIO₂) was used. Additionally, one‐pot reactions of BINOLs, PhIO and nucleophiles such as alcohols and amines were also investigated to provide alkoxylated products and amides in good to excellent yields.

A series of xanthenes inhibiting Rad6 function and Rad6-Rad18 interaction in the PCNA ubiquitination cascade

Ubiquitination of proliferating cell nuclear antigen (PCNA) triggers pathways of DNA damage tolerance, including mutagenic translesion DNA synthesis, and comprises a cascade of reactions involving the E1 ubiquitin-activating enzyme Uba1, the E2 ubiquitin-conjugating enzyme Rad6, and the E3 ubiquitin ligase Rad18. We report here the discovery of a series of xanthenes that inhibit PCNA ubiquitination, Rad6∼ubiquitin thioester formation, and the Rad6–Rad18 interaction. Structure-activity relationship experiments across multiple assays reveal chemical and structural features important for different activities along the pathway to PCNA ubiquitination. The compounds that inhibit these processes are all a subset of the xanthen-3-ones we tested. These small molecules thus represent first-in-class probes of Rad6 function and the association of Rad6 and Rad18, the latter being a new inhibitory activity discovered for a small molecule, in the PCNA ubiquitination cascade and potential therapeutic agents to contain cancer progression.

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Alpha-based HTS for PCNA ubiquitination modulators

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Target-based characterization of hits

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A series of xanthenes that inhibit Rad6 functions and Rad6–Rad18 interaction

One-Pot Green Synthesis of Acridine Alkaloid Derivatives and Screening of in vitro Anti-cancer Activity Against Cdc25b and SHP1

AIM

To develop anti-cancer active pharmaceutical intermediates.

BACKGROUND

Acridone derivatives possess a wide range of pharmacological activities: 1) they intercalate DNA and 2) form a covalent bond with DNA.

OBJECTIVE

To screen in vitro anti-cancer activity against Cdc25b and SHP1 of new acridone derivatives and preliminary study on the structure-activity relationship.

MATERIALS AND METHODS

The synthesis of new acridone derivatives and in vitro evaluation of their anti-cancer activity on Cdc25b and SHP1 was achieved. Natural products that contain acridine structures, such as cystodytin A and acronycine, are isolated from certain marine (tunicates & ascidians, sponges, sea anemones) and plant (bark of Australian scrub ash tree) species. Herein, we report the efficient one-pot green synthesis of twelve novel 3,4-dihydro-1 (2H) acridone derivatives, using montmorillonite K10 as the catalyst and iron/citric acid in water. Also, their inhibitory activity against Cdc25B and SHP1 is examined, in which specific derivatives show enhanced inhibitory activity compared to others.

RESULTS AND DISCUSSION

Twelve new acridone derivatives were prepared, starting from 2-nitrobenzaldehyde derivatives and 1, 3-cyclohexanedione derivatives, which exhibited substantial anti-cancer activity against Cdc25b and SHP1 cells.

CONCLUSION

Preliminary studies on the structure-activity relationship have shown the influence of the structural parameters and, in particular, the nature of the substituent on aromatic ring structure and cyclohexanone. Other: Further study on the structure-activity relationship is required.