Novel chromone and xanthone derivatives: Synthesis and ROS/RNS scavenging activities

Development of chromone-thiazolidine-2,4-dione Knoevenagel conjugates as apoptosis inducing agents

Overexpression of Bcl-2 protein is a predominant hallmark of disturbed apoptotic pathway in most of the cancers. Herein, chromone-linked thiazolidinediones were designed and synthesized to target Bcl-2 for regulating anti-apoptotic proteins. The study on in vitro cancer cell lines revealed the presence of compounds 8a, 8k, 8l, and 8n, which were found to have good to moderate anti-proliferative activity (with an IC50 concentration less than 10 µM). Among them, 8l depicted the highest cytotoxicity on the A549 cell line with an IC50 of 6.1 ± 0.02 µM. Aberrantly, the compounds displayed less toxicity towards human embryonic kidney HEK cells underlining its selectivity. The DCFDA study revealed a gradual increase in the ROS generation of 8l, followed by its quantification by flow analysis. Similarly, the studies including DAPI, AO/EtBr and Annexin-V binding clearly elucidated the DNA damage, membrane integrity prospects, and insights for early and late apoptotic phases. Markedly, the Bcl-2-FITC anti-body study revealed that compound 8l reduced the expression of anti-apoptotic proteins by 79.1 % compared to the control at 9 µM concentration. In addition, the molecular docking study provided the impending scope of these hybrids, showing promising interaction with the Mcl-1 target (member of the Bcl-2 family) with comparable binding affinities.

Two new phenylbutenoids from the rhizomes of cassumunar ginger and their α-glucosidase inhibitory activity

An extract from the rhizomes of Cassumunar ginger (Zingiber purpureum Roscoe). was found to have significant α-glucosidase inhibitory activity with an IC50 value of 6.3 µg/mL. Two new phenylbutenoids, cassudimin A (1) and cassumunol N (2), and seven known compounds (3-9) were isolated. Their structures and relative configurations of two new compounds were elucidated based on spectra interpretation. Compounds 1-3, 6-9 showed more potent α-glucosidase inhibitory activity than a positive control, acarbose (IC50 = 168.0 µM). Dehydrozingerone (6) exhibited the most potent α-glucosidase inhibition with an IC50 value of 8.3 μM. Compounds 7 and 9 were found in Z. purpureum rhizomes for the first time.

Drug Discovery Based on Oxygen and Nitrogen (Non-)Heterocyclic Compounds Developed @LAQV-REQUIMTE/Aveiro

Artur Silva's research group has a long history in the field of medicinal chemistry. The development of new synthetic methods for oxygen (mostly polyphenols, e.g., 2- and 3-styrylchromones, xanthones, flavones) and nitrogen (e.g., pyrazoles, triazoles, acridones, 4-quinolones) heterocyclic compounds in order to be assessed as antioxidant, anti-inflammatory, antidiabetic, and anticancer agents has been the main core work of our research interests. Additionally, the synthesis of steroid-type compounds as anti-Alzheimer drugs as well as of several chromophores as important dyes for cellular imaging broadened our research scope. In this review article, we intend to provide an enlightened appraisal of all the bioactive compounds and their biological properties that were synthesized and studied by our research group in the last two decades.

Agarwood-The Fragrant Molecules of a Wounded Tree

Agarwood, popularly known as oudh or gaharu, is a fragrant resinous wood of high commercial value, traded worldwide and primarily used for its distinctive fragrance in incense, perfumes, and medicine. This fragrant wood is created when Aquilaria trees are wounded and infected by fungi, producing resin as a defense mechanism. The depletion of natural agarwood caused by overharvesting amidst increasing demand has caused this fragrant defensive resin of endangered Aquilaria to become a rare and valuable commodity. Given that instances of natural infection are quite low, artificial induction, including biological inoculation, is being conducted to induce agarwood formation. A long-term investigation could unravel insights contributing toward Aquilaria being sustainably cultivated. This review will look at the different methods of induction, including physical, chemical, and biological, and compare the production, yield, and quality of such treatments with naturally formed agarwood. Pharmaceutical properties and medicinal benefits of fragrance-associated compounds such as chromones and terpenoids are also discussed.

Antibacterial activities of plant-derived xanthones

The increasing threat to global health posed by antibiotic resistance remains a serious concern. This troublesome scenario has steered a need for the discovery and evaluation of novel antibacterial agents. Natural products are the main sources of antimicrobials used in clinical practice, serving as a rich reservoir for the discovery of new antibiotics. Pharmaceutical phenolics especially xanthones widely exist in the plant kingdom, and are important plant metabolites. They possess versatile biological activities, including antiviral, antibacterial, neurotrophic, and anticancer. In the present study, we focus on the antibacterial activities of phytoxanthones and summarize their structures and sources, categories and drug-likeness evaluations, and antibacterial activities. A total of 226 different plant xanthones are identified through the NETs screening, and most of them are distributed in Clusiaceae family. These phytoxanthones are divided into four groups according to the intrinsic structural properties, including the most common simple xanthones and the majority of biprenylated ones. Moreover, their physicochemical parameters are calculated and the structure-activity relationships are discussed as well. These results indicate that the biprenylated xanthone derivatives may be promising antibacterial candidates and that the natural products of plants may be a poorly understood repository for the discovery of novel antibacterial agents.

Advances in the site-selective C-5, C-3 and C-2 functionalization of chromones via sp2 C-H activation

In this work, site-selective C-H activation at C-5, C-3 and C-2 positions of chromones for the introduction of structural diversity to the chromone scaffold was studied. The keto group of the chromone moiety acts as the directing group for the selective functionalization of chromones at the C-5 position. Furthermore, the C-H functionalization at the electron-rich C-3 position of the chromone can be achieved using electrophilic coupling partners. The C-H functionalization at the C-2 position can be possible using nucleophilic coupling partners. The direct functionalization methods provide a better pathway for the generation of C-5, C-3 and C-2-substituted chromones with good atom economy than that of classical pre-functionalized reaction protocols.

An In Silico and an In Vitro Inhibition Analysis of Glycogen Phosphorylase by Flavonoids, Styrylchromones, and Pyrazoles

Glycogen phosphorylase (GP) is a key enzyme in the glycogenolysis pathway. GP inhibitors are currently under investigation as a new liver-targeted approach to managing type 2 diabetes mellitus (DM). The aim of the present study was to evaluate the inhibitory activity of a panel of 52 structurally related chromone derivatives; namely, flavonoids, 2-styrylchromones, 2-styrylchromone-related derivatives [2-(4-arylbuta-1,3-dien-1-yl)chromones], and 4- and 5-styrylpyrazoles against GP, using in silico and in vitro microanalysis screening systems. Several of the tested compounds showed a potent inhibitory effect. The structure–activity relationship study indicated that for 2-styrylchromones and 2-styrylchromone-related derivatives, the hydroxylations at the A and B rings, and in the flavonoid family, as well as the hydroxylation of the A ring, were determinants for the inhibitory activity. To support the in vitro experimental findings, molecular docking studies were performed, revealing clear hydrogen bonding patterns that favored the inhibitory effects of flavonoids, 2-styrylchromones, and 2-styrylchromone-related derivatives. Interestingly, the potency of the most active compounds increased almost four-fold when the concentration of glucose increased, presenting an IC₅₀ < 10 µM. This effect may reduce the risk of hypoglycemia, a commonly reported side effect of antidiabetic agents. This work contributes with important considerations and provides a better understanding of potential scaffolds for the study of novel GP inhibitors.

Chromone a Privileged Scaffold in Drug Discovery: Developments on the Synthesis and Bioactivity

Chromones are the class of secondary metabolites broadly occurred in the plant kingdom in a noticeable quantity. This rigid bicyclic system has been categorized "as privileged scaffolds in compounds" in medicinal chemistry. The wide biological responses made them an important moiety in a drug discovery program. This review provides updates on the various methods of synthesis of chromones and biological applications in medicinal chemistry. Various synthetic strategies for the construction of chromones include readily available phenols, salicylic acid and its derivatives, ynones, chalcones, enaminones, chalcones and 2-hydroxyarylalkylketones as starting materials. Synthesis of chromones by using metal, metal free, nanomaterials and different catalysts are included. Details of diverse biological activities such as anti-cancer agents, antimicrobial agents, anti-viral property, anti-inflammatory agents, antioxidants, Monoamine Oxidase-B (MAO-B) Inhibitors, anti-Alzheimer's agents, anti-diabetic agent, antihistaminic potential, antiplatelet agents of chromone derivatives are diecussed.

1,7-Dihydroxy-3,4-Dimethoxyxanthone Inhibits Lipopolysaccharide-Induced Inflammation in RAW264.7 Macrophages by Suppressing TLR4/NF-κB Signaling Cascades

Securidaca inappendiculata Hassk. is a traditional Chinese anti-rheumatic herbal medicine native to southern China. In this study, we identified a possible TLR4 inhibitor from this plant. General effects of its xanthone-rich fraction (XRF) on inflammation in vitro were investigated by immunoblotting experiments performed on lipopolysaccharides (LPS)-treated RAW264.7 cells, and the possible ligand of TLR4 within was screened out by analyzing chemical composition differences of the XRF containing cell culture medium under different inflammatory circumstances. The interaction between ligand and TLR4 was validated by cellular thermal shift assay (CETSA) and molecular docking simulation, and TLR4/NF-κB pathway status was investigated by immunoprecipitation, ELISA, immunofluorescence, dual-luciferase reporter, and immunoblotting experiments. Treatment with XRF resulted in significant decrease in p-p65 and p-JNK, and the signal accounting for 1,7-dihydroxy-3,4-dimethoxyxanthone (XAN) at 12.5 min with mass of 289.29 was greatly decreased in XRF containing medium after LPS stimulus because of enhanced interaction with increased TLR4. CETSA and molecular docking simulation demonstrated that XAN could bind to TLR4 directly on a smooth region adjacent to its contact interface with MD-2. XAN treatment inhibited the dimerization of TLR4 and transcriptional activity of NF-κB in HEK293T cells and decreased p65 accumulation in nucleus and pro-inflammatory cytokines production in RAW264.7 cells receiving LPS treatment. Overall evidences suggest that XAN could be a selective TLR4 inhibitor with potent anti-inflammatory effects. Also, it indicated that xanthone derivatives could have promising clinical application in many immune-mediated inflammations by acting as TLR4 inhibitors.

New 3-O-substituted xanthone derivatives as promising acetylcholinesterase inhibitors

A new series of 3-O-substituted xanthone derivatives were synthesised and evaluated for their anti-cholinergic activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The results indicated that the xanthone derivatives possessed good AChE inhibitory activity with eleven of them (5, 8, 11, 17, 19, 21-23, 26-28) exhibited significant effects with the IC₅₀ values ranged 0.88 to 1.28 µM. The AChE enzyme kinetic study of 3-(4-phenylbutoxy)-9H-xanthen-9-one (23) and ethyl 2-((9-oxo-9H-xanthen-3-yl)oxy)acetate (28) showed a mixed inhibition mechanism. Molecular docking study showed that 23 binds to the active site of AChE and interacts via extensive π–π stacking with the indole and phenol side chains of Trp86 and Tyr337, besides the hydrogen bonding with the hydration site and π–π interaction with the phenol side chain of Y72. This study revealed that 3-O-alkoxyl substituted xanthone derivatives are potential lead structures, especially 23 and 28 which can be further developed into potent AChE inhibitors.

A novel one-pot synthesis of flavones

In this paper, a one-pot facile route for the BiCl₃/RuCl₃-mediated synthesis of functionalized flavones is described, including: (i) intermolecular ortho-acylation of substituted phenols with cinnamoyl chlorides, and (ii) intramolecular cyclodehydrogenation of the resulting o-hydroxychalcones. The reaction conditions are discussed herein.

A one-pot facile route for the BiCl₃/RuCl₃-mediated synthesis of functionalized flavones is described, including: (i) ortho-acylation of phenols with cinnamoyl chlorides, and (ii) cyclodehydrogenation of the resulting o-hydroxychalcones.

An efficient approach for the synthesis of 1,2-dihydroxanthones enabled by one-pot Claisen condensation/cyclization reactions

A mild, efficient method for the synthesis of 1,2-dihydroxanthones by a one-pot reaction was developed under waste-induced relay catalysis.

Chalcones as Scavengers of HOCl and Inhibitors of Oxidative Burst: Structure-Activity Relationship Studies

AIMS

Evaluate the ability of chalcones to scavenge hypochlorous acid (HOCl) and modulate oxidative burst.

BACKGROUND

The chemistry of chalcones has long been a matter of interest to the scientific community due to the phenolic groups often present and to the various replaceable hydrogens that allow the formation of a broad number of derivatives. Due to this chemical diversity, several biological activities have been attributed to chalcones, namely anti-diabetic, anti-inflammatory and antioxidant.

OBJECTIVES

Evaluate the ability of a panel of 34 structurally related chalcones to scavenge HOCl and/or suppress its produc-tion through the inhibition of human neutrophils' oxidative burst, followed by the establishment of the respective structure-activity relationships.

METHODS

The ability of chalcones to scavenge HOCl was evaluated by fluorimetric detection of the inhibition of dihydro-rhodamine 123 oxidation. The ability of chalcones to inhibit neutrophils' oxidative burst was evaluated by chemiluminomet-ric detection of the inhibition of luminol oxidation.

RESULTS

It was observed that the ability to scavenge HOCl depends on the position and number of hydroxy groups on both aromatic rings. Chalcone 5b was the most active with an IC50 value of 1.0 ± 0.1 μM. The ability to inhibit neutrophils' oxi-dative burst depends on the presence of a 2'-hydroxy group on A-ring and on other substituents groups, e.g. methoxy, hy-droxy, nitro and/or chlorine atom(s) at C-2, C-3 and/or C-4 on B-ring, as in chalcones 2d, 2f, 2j, 2i, 4b, 2n and 1d, which were the most actives with IC50 values ranging from 0.61 ± 0.02 μM to 1.7 ± 0.2 μM.

CONCLUSION

The studied chalcones showed high activity at a low micromolar range, indicating their potential as antioxidant agents and to be used as a molecular structural scaffold for the design of new anti-inflammatory compounds.

2,4-Dihydroxyphenyl-benzo[d]thiazole (MHY553), a synthetic PPARα agonist, decreases age-associated inflammatory responses through PPARα activation and RS scavenging in the skin

We previously reported that 2,4-dihydroxyphenyl-benzo[d]thiazole (MHY553) is a PPARα agonist, which has been shown to inhibit tyrosinase activity in murine melanocyte and alleviate hepatic steatosis in aged rats. This study investigated the effects of MHY553 on the age-related occurrence of inflammatory responses via the molecular modulation of the nuclear factor-κB (NF-κB) signaling pathway in the skin of aged rats and skin fibroblast cells. Moreover, we investigated the antioxidant effect of MHY553 via in vitro assays of reactive oxygen species (ROS) and peroxynitrite (ONOO^-) scavenging activities. We also scrutinized the ability of MHY553 as a PPARα activator in aged rat skin and H₂O₂-induced Hs27 fibroblast cells. In vivo experiments were performed in young, aged, and MHY553-fed aged rats (3 mg or 5 mg∙kg ^-1∙day ^-1 for 4 weeks). MHY553 dose-dependently scavenged ROS and ONOO^-. Furthermore, we found that MHY553 suppressed the NF-κB transcription factor and downregulated mitogen-activated protein kinase (MAPK)/activator protein-1 (AP-1) signaling. MHY553 also inhibited the expression of pro-inflammatory cytokines including COX-2, iNOS, IL-1β, and IL-6. Our findings indicate the MHY553 scavenges ROS/reactive nitrogen species and inhibits inflammatory cytokines through PPARα activation in the skin. Thus, these results suggest that MHY553 may be of therapeutic interest for protecting skin from oxidative stress-induced damage and intrinsic aging.

Current Strategies in Development of New Chromone Derivatives with Diversified Pharmacological Activities: A Review

Chromone derivatives possess a spectrum of biological activities. Chromone has been recognized as a privileged structure for new drug invention and development. Substitution pattern of chromone scaffold determines different type of biological activities. The type, number and position of substituents connected to the chromone core play a vital role in determining pharmacological activities. In the present review, we have discussed new chromone derivatives as anticancer, anti-diabetic, antimicrobial, anti-inflammatory, antioxidant and as anti-Alzheimer agents. This review deals with the chromone derivatives prepared by combining chromone molecule with various natural and synthetic pharmacophores and pharmacological activities presented by them. The main aim is to highlight the diversified pharmacological activities exhibited by chromone hybrid molecules during the last eight to ten years.

Recent advances in the synthesis of xanthones and azaxanthones

A useful chemical toolbox for (aza)xanthones from 2012 to 2020 that covers the optimization of known procedures and novel methodologies.

Human health-related properties of chromones: an overview

Natural compounds occurring throughout the world are scientifically and practically valuable because of their unique and beneficial properties to control a wide range of disorders in the human body. Chromones are attracting increasing attention as novel therapeutic agents due to their effective bioactivities for human health. Accordingly, the present overview article was designed to scan the biological and pharmacological performance of chromones, including their anti-inflammatory, anticancer, anti-oxidant, and anti-microbial activities.

Vitexin protects against ischemia/reperfusion-induced brain endothelial permeability

Brain endothelial permeability plays a crucial role in blood-brain barrier (BBB), but the permeability enhancement in cerebral ischemia reperfusion (I/R). Vitexin has certain neuroprotective effects, but the effect brain endothelial permeability in I/R injury was unknown. In this study, the effects of Vitexin on endothelial permeability and the underlying mechanisms in human brain microvascular endothelial cells (HBMEc) I/R injury model were investigated. Cell viability, lactate dehydrogenase (LDH), inflammation and apoptosis were detected. The effects of Vitexin on BBB integrity tight junction, matrix metalloproteinases (MMP) were also investigated. The mechanism was confirmed by PI3K inhibitor and NOS inhibitor in normal or eNOS siRNA transfection HBMEc. Vitexin significantly reduced LDH, Caspase 3 level, alleviated inflammation, also could maintain BBB integrity, increased tight junction proteins expression and inhibited MMP. The mechanism is related to reduction of intracellular NO and ONOO^-, regulated eNOS, iNOS activity. Vitexin significantly preserved eNOS phosphorylation in response to the activated Akt. Moreover, combined with PI3K inhibitor or low dosage of NOS inhibitor, totally abolished Vitexin-induced eNOS phosphorylation, the protected effect was also attenuated, but still significantly between model cells. However, combined with high dosage NOS inhibitor which both inhibited the eNOS phosphorylation and iNOS, the protected effect of Vitexin was abrogated. In addition, eNOS silencing cells were used to further clarify the regulatory role of Vitexin on iNOS. Our findings showed that Vitexin could play a protective role in I/R-induced brain endothelial permeability by simultaneously increase eNOS phosphorylation and inhibit iNOS.

Chiral Derivatives of Xanthones with Antimicrobial Activity

According to the World Health Organization, the exacerbated use of antibiotics worldwide is increasing multi-resistant infections, especially in the last decade. Xanthones are a class of compounds receiving great interest in drug discovery and development that can be found as natural products or obtained by synthesis. Many derivatives of xanthones are chiral and associated with relevant biological activities, including antimicrobial. The aim of this review is to compile information about chiral derivatives of xanthones from natural sources and their synthesized examples with antimicrobial activity.

PIDA-mediated α-C–H functionalization of enaminones: the synthesis of thiocyano enaminones and chromones in water

Herein, an efficient, metal-free process for the α-C–H thiocyanation of enaminones was developed using PhI(OAc)₂ as an oxidant at room temperature in an aqueous medium.

A novel sulfonyl chromen-4-ones (CHW09) preferentially kills oral cancer cells showing apoptosis, oxidative stress, and DNA damage

Several functionalized chromones, the key components of naturally occurring oxygenated heterocycles, have anticancer effects but their sulfone compounds are rarely investigated. In this study, we installed a sulfonyl substituent to chromen-4-one skeleton and synthesized CHW09 to evaluate its antioral cancer effect in terms of cell viability, cell cycle, apoptosis, oxidative stress, and DNA damage. In cell viability assay, CHW09 preferentially kills two oral cancer cells (Ca9-22 and CAL 27), less affecting normal oral cells (HGF-1). Although CHW09 does not change the cell cycle distribution significantly, CHW09 induces apoptosis validated by flow cytometry for annexin V and by western blotting for cleaved poly(ADP-ribose) polymerase (PARP), and caspases 3/8/9. These apoptosis signaling expressions are partly decreased by apoptosis inhibitor (Z-VAD-FMK) or free radical scavenger (N-acetylcysteine). Furthermore, CHW09 induces oxidative stress validated by flow cytometry for the generations of reactive oxygen species (ROS) and mitochondrial superoxide (MitoSOX), and the suppression of mitochondrial membrane potential (MMP). CHW09 also induces DNA damage validated by flow cytometry for the increases of DNA double strand break marker γH2AX and oxidative DNA damage marker 8-oxo-2'-deoxyguanosine (8-oxodG). Therefore, our newly synthesized CHW09 induces apoptosis, oxidative stress, and DNA damage, which may lead to preferential killing of oral cancer cells compared with normal oral cells.

A comprehensive review on xanthone derivatives as α-glucosidase inhibitors

α-Glucosidase plays an important role in carbohydrate metabolism and is therefore an attractive therapeutic target for the treatment of diabetes, obesity and other related complications. In the last two decades, considerable interest has been given to natural and synthetic xanthone derivatives in this field of research. Herein, a comprehensive review of the literature on xanthones as inhibitors of α-glucosidase activity, their mechanism of action, experimental procedures and structure-activity relationships have been reviewed for more than 280 analogs. With this overview we intend to motivate and challenge researchers (e.g. chemistry, biology, pharmaceutical and medicinal areas) for the design of novel xanthones as multipotent drugs and exploit the properties of this class of compounds in the management of diabetic complications.

2,3-Diarylxanthones as Potential Inhibitors of Arachidonic Acid Metabolic Pathways

In response to an inflammatory stimulus, arachidonic acid (AA), the main polyunsaturated fatty acid present in the phospholipid layer of cell membranes, is released and metabolized to a series of eicosanoids. These bioactive lipid mediators of inflammation arise physiologically through the action of the enzymes 5-lipoxygenase (5-LOX) and cyclooxygenases (constitutive COX-1 and inducible COX-2). It is believed that dual inhibition of 5-LOX and COXs may have a higher beneficial impact in the treatment of inflammatory disorders rather than the inhibition of each enzyme. With this demand for new dual-acting anti-inflammatory agents, a range of 2,3-diarylxanthones were tested through their ability to interact in the AA metabolism. In vitro anti-inflammatory activity was evaluated through the inhibition of 5-LOX-catalyzed leukotriene B₄ (LTB₄) formation in human neutrophils and inhibition of COX-1- and COX-2-catalyzed prostaglandin E₂ (PGE₂) formation in human whole blood. The results showed that some of the studied arylxanthones were able to prevent LTB₄ production in human neutrophils, in a concentration-dependent manner. The xanthone with a 2-catechol was the most active one (IC₅₀ ∼ 9 μM). The more effective arylxanthones in preventing COX-1-catalyzed PGE₂ production presented IC₅₀ values from 1 to 7 μM, exhibiting a structural feature with at least one non-substituted aryl group. All the studied arylxanthones were ineffective to prevent the formation of PGE₂ catalyzed by COX-2, up to the maximum concentration of 100 μM. The ability of the tested 2,3-diarylxanthones to interact with both 5-LOX and COX-1 pathways constitutes an important step in the research of novel dual-acting anti-inflammatory drugs.

HSP27 inhibitor attenuates radiation-induced pulmonary inflammation

Radiation therapy has been used to treat over 70% of thoracic cancer; however, the method usually causes radiation pneumonitis. In the current study, we investigated the radioprotective effects of HSP27 inhibitor (J2) on radiation-induced lung inflammation in comparison to amifostine. In gross and histological findings, J2 treatment significantly inhibited immune cell infiltration in lung tissue, revealing anti-inflammatory potential of J2. Normal lung volume, evaluated by micro-CT analysis, in J2-treated mice was higher compared to that in irradiated mice. J2-treated mice reversed radiation-induced respiratory distress. However, amifostine did not show significant radioprotective effects in comparison to that of J2. In HSP27 transgenic mice, we observed increased immune cells recruitment and decreased volume of normal lung compared to wild type mice. Increased ROS production and oxidative stress after IR were down-regulated by J2 treatment, demonstrating antioxidant property of J2. The entire data of this study collectively showed that J2 may be an effective therapeutic agent for radiation-induced lung injury.

Synthesis of xanthone derivatives and studies on the inhibition against cancer cells growth and synergistic combinations of them

34 Xanthones were synthesized by microwave assisted technique. Their in vitro inhibition activities against five cell lines growth were evaluated. The SAR has been thoroughly discussed. 7-Bromo-1,3-dihydroxy-9H-xanthen-9-one (3-1) was confirmed as the most active agent against MDA-MB-231 cell line growth with an IC₅₀ of 0.46 ± 0.03 μM. Combination of 3-1 and 5,6-dimethylxanthone-4-acetic acid (DMXAA) showed the best synergistic effect. Apoptosis analysis indicated different contributions of early/late apoptosis and necrosis to cell death for both monomers and the combination. Western Blot implied that the combination regulated p53/MDM2 to a better healthy state. Furthermore, 3-1 and DMXAA arrested more cells on G2/M phase; while the combination arrested more cells on S phase. All the evidences support that the 3-1/DMXAA combination is a better anti-cancer therapy.

Arylxanthones and arylacridones: a synthetic overview

Arylxanthones and arylacridones although not yet found in nature are becoming an important group of heterocyclic compounds due to their promising biological activities. Their central cores, xanthone and acridone, are recognized as interesting motifs for drug development mainly to be used in antitumour chemotherapy. The synthesis of this type of compounds is still scarce but several successful examples were recently published and a large variety of arylated xanthone and acridone derivatives were prepared. A systematic survey of the literature dedicated to their synthesis will be presented and discussed in this review.

A catalyst-free approach to 3-thiocyanato-4H-chromen-4-ones

A facile and efficient approach to 3-thiocyanato-4H-chromen-4-ones from enaminones and KSCN was realized at room temperature. In addition, one-pot synthesis of 3-thiocyanatochromenones from 2-hydroxylacetophenones was also developed.