An update on antitumor activity of naturally occurring chalcones

Synthesis and In vitro evaluation of bichalcones as novel anti-toxoplasma agents

Toxoplasmosis is a zoonotic disease caused by Toxoplasma gondii, an apicomplexan parasite that infects approximately a third of the world's human population. This disease can cause serious complications during pregnancy and can be fatal in immunocompromised hosts. The current treatment options for toxoplasmosis face several limitations. Thus, to address the urgent medical need for the discovery of novel anti-toxoplasma potential drug candidates, our research focused on exploring a series of monomeric and dimeric chalcones, polyphenolic molecules belonging to the class of flavonoids. Chalcones 1aa-1bg and axially chiral A-A'-connected bichalcones 2aa-2bg were evaluated in vitro against the proliferation of the parasite in a cell-based assay. A comparison of the efficacy demonstrated that, in several cases, bichalcones exhibited increased bioactivity compared to their corresponding monomeric counterparts. Among these compounds, a bichalcone with a phenyl substituent and a methyl moiety 2ab showed the most potent and selective inhibitory activity in the nanomolar range. Both enantiomers of this bichalcone were synthesized using an axially chiral biphenol building block. The biaryl bond was forged using Suzuki cross-coupling in water under micellar catalysis conditions. Separation of the atropisomers of this biphenol building block was conducted by chiral HPLC on a preparative scale. The biological evaluation of the enantiomers revealed that the (R a)-enantiomer (R a)-2ab is the eutomer. These studies suggest that bichalcones may be important drug candidates for further in vivo evaluations for the discovery of anti-toxoplasma drugs.

Antitumor Effect of the Synthesized Chalcone Analogues on HeLa Cell Line

Chalcones represent a type of flavonoids which are located at vegetative and reproductive organs of plants and they can be metabolic progenitor molecules for several flavonoids and isoflavonoids. Many studies indicated that molecular structure of chalcone accountable for their anti-tumor, anti-inflammatory and anti-oxidant effects. The aim of our research was to investigate anti-tumor effect and mechanism of action of three synthesized chalcone analogues on HeLa cells. The anti-tumor effectiveness of chalcone analogues was compared to effects of the dehydrozingerone and cisplatin that were used as referent substances.

The viability of the treated cells was evaluated using MTT assay. Evaluation of cell death was determined by flow cytometry and cells were stained with Annexin V-FITC/7-AAD. The result of our research indicated that used chalcones have stronger antitumor effect relative to the dehydrozingerone and cisplatin.

The IC50 values of the chalcones ranged between 1.69-6.18 μM, with CH1 being more cytotoxic after 24 h of treatment, while CH3 being more cytotoxic after 48 h of treatment on HeLa cells. All investigated chalcones induced apoptosis in HeLa cells via mitochondrial pathway, which was detected expression Bax and Bcl- 2 proteins.

Our results provided evidence that chalcones induced apoptosis in HeLa cervical carcinoma through the intrinsic apoptotic pathway. These findings provide insights into the molecular mechanism of chalcones-induced cell death.

Novel Nitrogen-Based Chalcone Analogs Provoke Substantial Apoptosis in HER2-Positive Human Breast Cancer Cells via JNK and ERK1/ERK2 Signaling Pathways

Natural chalcones possess antitumor properties and play a role as inducers of apoptosis, antioxidants and cytotoxic compounds. We recently reported that novel nitrogen chalcone-based compounds, which were generated in our lab, have specific effects on triple-negative breast cancer cells. However, the outcome of these two new compounds on human epidermal growth factor receptor 2 (HER2)-positive breast cancer remains nascent. Thus, we herein investigated the effects of these compounds (DK-13 and DK-14) on two HER2-positive breast cancer cell lines, SKBR3 and ZR75. Our data revealed that these compounds inhibit cell proliferation, deregulate cell-cycle progression and significantly induce cell apoptosis in both cell lines. Furthermore, the two chalcone compounds cause a significant reduction in the cell invasion ability of SKBR3 and ZR75 cancer cells. In parallel, we found that DK-13 and DK-14 inhibit colony formation of both cell lines in comparison to their matched controls. On the other hand, we noticed that these two compounds can inhibit angiogenesis in the chorioallantoic membrane model. The molecular pathway analysis of chalcone compounds exposed cells revealed that these compounds inhibit the expression of both JNK1/2/3 and ERK1/2, the major plausible molecular pathways behind these events. Our findings implicate that DK-13 and DK-14 possess effective chemotherapeutic outcomes against HER2-positive breast cancer via the ERK1/2 and JNK1/2/3 signaling pathways.

Chalcone Derivatives: Role in Anticancer Therapy

Chalcones (1,3-diaryl-2-propen-1-ones) are precursors for flavonoids and isoflavonoids, which are common simple chemical scaffolds found in many naturally occurring compounds. Many chalcone derivatives were also prepared due to their convenient synthesis. Chalcones as weandhetic analogues have attracted much interest due to their broad biological activities with clinical potentials against various diseases, particularly for antitumor activity. The chalcone family has demonstrated potential in vitro and in vivo activity against cancers via multiple mechanisms, including cell cycle disruption, autophagy regulation, apoptosis induction, and immunomodulatory and inflammatory mediators. It represents a promising strategy to develop chalcones as novel anticancer agents. In addition, the combination of chalcones and other therapies is expected to be an effective way to improve anticancer therapeutic efficacy. However, despite the encouraging results for their response to cancers observed in clinical studies, a full description of toxicity is required for their clinical use as safe drugs for the treatment of cancer. In this review, we will summarize the recent advances of the chalcone family as potential anticancer agents and the mechanisms of action. Besides, future applications and scope of the chalcone family toward the treatment and prevention of cancer are brought out.

Molecular Mechanisms of Antiproliferative Effects of Natural Chalcones

Simple Summary

Despite the important progress in cancer treatment in the past decades, the mortality rates in some types of cancer have not significantly decreased. Therefore, the search for novel anticancer drugs has become a topic of great interest. Chalcones, precursors of flavonoid synthesis in plants, have been documented as natural compounds with pleiotropic biological effects including antiproliferative/anticancer activity. This article focuses on the knowledge on molecular mechanisms of antiproliferative action of chalcones and draws attention to this group of natural compounds that may be of importance in the treatment of cancer disease.

Abstract

Although great progress has been made in the treatment of cancer, the search for new promising molecules with antitumor activity is still one of the greatest challenges in the fight against cancer due to the increasing number of new cases each year. Chalcones (1,3-diphenyl-2-propen-1-one), the precursors of flavonoid synthesis in higher plants, possess a wide spectrum of biological activities including antimicrobial, anti-inflammatory, antioxidant, and anticancer. A plethora of molecular mechanisms of action have been documented, including induction of apoptosis, autophagy, or other types of cell death, cell cycle changes, and modulation of several signaling pathways associated with cell survival or death. In addition, blockade of several steps of angiogenesis and proteasome inhibition has also been documented. This review summarizes the basic molecular mechanisms related to the antiproliferative effects of chalcones, focusing on research articles from the years January 2015–February 2021.

Secondary Metabolites, Antioxidant, and Antiproliferative Activities of Dioscorea bulbifera Leaf Collected from Endau Rompin, Johor, Malaysia

Breast cancer is among the most commonly diagnosed cancer and the leading cause of cancer-related death among women globally. Malaysia is a country that is rich in medicinal plant species. Hence, this research aims to explore the secondary metabolites, antioxidant, and antiproliferative activities of Dioscorea bulbifera leaf collected from Endau Rompin, Johor, Malaysia. Antioxidant activity was assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) assays, while the cytotoxicity of D. bulbifera on MDA-MB-231 and MCF-7 breast cancer cell lines was tested using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Cell cycle analysis and apoptosis were assessed using flow cytometry analysis. Phytochemical profiling was conducted using gas chromatography-mass spectrometry (GC-MS). Results showed that methanol extract had the highest antioxidant activity in DPPH, FRAP, and ABTS assays, followed by ethyl acetate and hexane extracts. D. bulbifera tested against MDA-MB-231 and MCF-7 cell lines showed a pronounced cytotoxic effect with IC₅₀ values of 8.96 μg/mL, 6.88 μg/mL, and 3.27 μg/mL in MCF-7 and 14.29 μg/mL, 11.86 μg/mL, and 7.23 μg/mL in MDA-MB-231, respectively. Cell cycle analysis also indicated that D. bulbifera prompted apoptosis at various stages, and a significant decrease in viable cells was detected within 24 h and substantially improved after 48 h and 72 h of treatment. Phytochemical profiling of methanol extract revealed the presence of 39 metabolites such as acetic acid, n-hexadecanoic acid, acetin, hexadecanoate, 7-tetradecenal, phytol, octadecanoic acid, cholesterol, palmitic acid, and linolenate. Hence, these findings concluded that D. bulbifera extract has promising anticancer and natural antioxidant agents. However, further study is needed to isolate the bioactive compounds and validate the effectiveness of this extract in the In in vivo model.

3-O-Methylquercetin from Achyrocline satureioides-cytotoxic activity against A375-derived human melanoma cell lines and its incorporation into cyclodextrins-hydrogels for topical administration

3-O-Methylquercetin (3OMQ), a natural 3-O-methylflavonoid, was isolated from Achyrocline satureioides and purified using the high-performance counter current chromatography (HPCCC) on a semi-preparative scale. High-purity 3OMQ (98%) was obtained with excellent recovery (81.8% (w/w)) and good yield (190 mg/100 g of plant). Isolated 3OMQ was evaluated against the A375 human amelanotic melanoma cancer cell line and A375-derived with different degrees of aggressiveness (A375-A7, A375-G10, and A375-PCDNA3). The results showed that 3OMQ reduced the cell viability of all strains, demonstrating time- and dose-dependent responses. 3OMQ was used to obtain hydrogels for the topical treatment of melanoma. Thus, 3OMQ was incorporated into hypromellose hydrogels with/without different cyclodextrins (CDs). The 3OMQ formulations showed permeation/retention in all skin layers, namely stratum corneum, epidermis, and dermis. A significant amount of 3OMQ was found in the replication site of the melanoma cells (epidermis and dermis). Altogether, these results demonstrate that 3OMQ can be isolated from Achyrocline satureioides by HPCCC on a semi-preparative scale and exhibit cytotoxic activity against melanoma cells. Its incorporation into an HPMC hydrogel containing HP-β-CD yielded a formulation with excellent technological and biopharmaceutical characteristics for evaluating the topical management of melanoma.

Effect of Calomelanone, a Dihydrochalcone Analogue, on Human Cancer Apoptosis/Regulated Cell Death in an In Vitro Model

Calomelanone, 2',6'-dihydroxy-4,4'-dimethoxydihydrochalcone, possesses anticancer activities. This study was conducted to investigate the cytotoxic effect of calomelanone, a dihydrochalcone analogue, on human cancer cells and its associated mechanisms. The cytotoxic effect of calomelanone was measured by MTT assay. Annexin V-FITC/propidium iodide and DiOC6 staining that employed flow cytometry were used to determine the mode of cell death and reduction of mitochondrial transmembrane potential (MTP), respectively. Caspase activities were measured using specific substrates and colorimetric analysis. The expression levels of Bcl-2 family proteins were determined by immunoblotting. Reactive oxygen species were also measured using 2',7'-dihydrodichlorofluorescein diacetate and dihydroethidium (fluorescence dyes). Calomelanone was found to be toxic towards various human cancer cells, including acute promyelocytic HL-60 and monocytic leukemic U937 cells, in a dose-dependent manner at 24 h and human hepatocellular HepG2 cells at 48 h. However, the proliferation of HepG2 cells increased at 24 h. Calomelanone was found to induce apoptosis in HL-60 and U937 at 24 h and HepG2 apoptosis at 48 h via the intrinsic pathway by inducing MTP disruption. This compound also induced caspase-3, caspase-8, and caspase-9 activities. Calomelanone upregulated proapoptotic Bax and Bak and downregulated antiapoptotic Bcl-xL proteins in HepG2 cells. Moreover, signaling was also associated with oxidative stress in HepG2 cells. Calomelanone induced autophagy at 24 h of treatment, which was evidenced by staining with monodansylcadaverine (MDC) to represent autophagic flux. This was associated with a decrease of Akt (survival pathway) and an upregulation of Atg5 (the marker of autophagy). Thus, calomelanone induced apoptosis/regulated cell death in HL-60, U937, and HepG2 cells. However, it also induced autophagy in HepG2 depending on duration, dose, and type of cells. Thus, calomelanone could be used as a potential anticancer agent for cancer treatment. Nevertheless, acute and chronic toxicity should be further investigated in animals before conducting investigations in human patients.

A Systematic Review on Anti-diabetic Properties of Chalcones

The use of anti-diabetic drugs has been increasing worldwide and the evolution of therapeutics has been enormous. Still, the currently available anti-diabetic drugs do not present the desired efficacy and are generally associated with serious adverse effects. Thus, entirely new interventions, addressing the underlying etiopathogenesis of type 2 diabetes mellitus, are required. Chalcones, secondary metabolites of terrestrial plants and precursors of the flavonoids biosynthesis, have been used for a long time in traditional medicine due to their wide-range of biological activities, from which the anti-diabetic activity stands out. This review systematizes the information found in literature about the anti-diabetic properties of chalcones, in vitro and in vivo. Chalcones are able to exert these properties by acting in different therapeutic targets: Dipeptidyl Peptidase 4 (DPP-4); Glucose Transporter Type 4 (GLUT4), Sodium Glucose Cotransporter 2 (SGLT2), α-amylase, α-glucosidase, Aldose Reductase (ALR), Protein Tyrosine Phosphatase 1B (PTP1B), Peroxisome Proliferator-activated Receptor-gamma (PPARγ) and Adenosine Monophosphate (AMP)-activated Protein Kinase (AMPK). Chalcones are, undoubtedly, promising anti-diabetic agents, and some crucial structural features have already been established. From the Structure-Activity Relationships analysis, it can generally be stated that the presence of hydroxyl, prenyl and geranyl groups in their skeleton improves their activity for the evaluated anti-diabetic targets.

Roles of Histone Deacetylases and Inhibitors in Anticancer Therapy

Histones are the main structural proteins of eukaryotic chromatin. Histone acetylation/ deacetylation are the epigenetic mechanisms of the regulation of gene expression and are catalyzed by histone acetyltransferases (HAT) and histone deacetylases (HDAC). These epigenetic alterations of DNA structure influence the action of transcription factors which can induce or repress gene transcription. The HATs catalyze acetylation and the events related to gene transcription and are also responsible for transporting newly synthesized histones from the cytoplasm to the nucleus. The activity of HDACs is mainly involved in silencing gene expression and according to their specialized functions are divided into classes I, II, III and IV. The disturbance of the expression and mutations of HDAC genes causes the aberrant transcription of key genes regulating important cancer pathways such as cell proliferation, cell-cycle regulation and apoptosis. In view of their role in cancer pathways, HDACs are considered promising therapeutic targets and the development of HDAC inhibitors is a hot topic in the search for new anticancer drugs. The present review will focus on HDACs I, II and IV, the best known inhibitors and potential alternative inhibitors derived from natural and synthetic products which can be used to influence HDAC activity and the development of new cancer therapies.

Apoptosis and apoptotic body: disease message and therapeutic target potentials

Apoptosis is widely known as programmed cell death eliciting no inflammatory responses. The intricacy of apoptosis has been a focus of an array of researches, accumulating a wealth of knowledge which led to not only a better understanding of the fundamental process, but also potent therapies of diseases. The classic intrinsic and extrinsic signaling pathways of apoptosis, along with regulatory factors have been well delineated. Drugs and therapeutic measures designed based on current understanding of apoptosis have long been employed. Small-molecule apoptosis inducers have been clinically used for eliminating morbid cells and therefore treating diseases, such as cancer. Biologics with improved apoptotic efficacy and selectivity, such as recombinant proteins and antibodies, are being extensively researched and some have been approved by the FDA. Apoptosis also produces membrane-bound vesicles derived from disassembly of apoptotic cells, now known as apoptotic bodies (ApoBDs). These little sealed sacs containing information as well as substances from dying cells were previously regarded as garbage bags until they were discovered to be capable of delivering useful materials to healthy recipient cells (e.g., autoantigens). In this review, current understandings and knowledge of apoptosis were summarized and discussed with a focus on apoptosis-related therapeutic applications and ApoBDs.

A Potent Tyrosinase Inhibitor, (E)-3-(2,4-Dihydroxyphenyl)-1-(thiophen-2-yl)prop-2-en-1-one, with Anti-Melanogenesis Properties in α-MSH and IBMX-Induced B16F10 Melanoma Cells

In this study, we designed and synthesized eight thiophene chalcone derivatives (1a–h) as tyrosinase inhibitors and evaluated their mushroom tyrosinase inhibitory activities. Of these eight compounds, (E)-3-(2,4-dihydroxyphenyl)-1-(thiophen-2-yl)prop-2-en-1-one (1c) showed strong competitive inhibition activity against mushroom tyrosinase with IC₅₀ values of 0.013 μM for tyrosine hydroxylase and 0.93 μM for dopa oxidase. In addition, we used enzyme kinetics study and docking program to further evaluate the inhibitory mechanism of 1c toward tyrosinase. As an underlying mechanism of 1c mediated anti-melanogenic effect, we investigated the inhibitory activity against melanin contents and cellular tyrosinase in B16F10 melanoma cells. As the results, the enzyme kinetics and docking results supports that 1c highly interacts with tyrosinase residues in the tyrosinase active site and it can directly inhibit tyrosinase as competitive inhibitor. In addition, 1c exhibited dose-dependent inhibitory effects in melanin contents and intracellular tyrosinase on α-MSH and IBMX-induced B16F10 cells. Overall, our results suggested that 1c might be considered potent tyrosinase inhibitor for use in the development of therapeutic agents for diseases associated with hyperpigment disorders.

From Carbamate to Chalcone: Consecutive Anionic Fries Rearrangement, Anionic Si → C Alkyl Rearrangement, and Claisen-Schmidt Condensation

A highly efficient one-pot procedure was developed for the synthesis of various 2'-hydroxychalcones from phenyl diethylcarbamate, featuring consecutive Snieckus-Fries rearrangement, anionic Si → C alkyl rearrangement, and Claisen-Schmidt condensation in a single operation. The applicability of this protocol was demonstrated by the highly efficient synthesis of the anti-inflammatory natural product lonchocarpin. The mechanism insight is also provided.

Hemi-Synthesis and Anti-Oomycete Activity of Analogues of Isocordoin

An efficient synthesis of a series of 4′-oxyalkyl-isocordoin analogues (2–8) is reported for the first time. Their structures were confirmed by ¹H-NMR, ¹³C-NMR, and HRMS. Their anti-oomycete activity was evaluated by mycelium and spores inhibition assay against two selected pathogenic oomycetes strains: Saprolegnia parasitica and Saprolegnia australis. The entire series of isocordoin derivatives (except compound 7) showed high inhibitory activity against these oomycete strains. Among them, compound 2 exhibited strong activity, with minimum inhibitory concentration (MIC) and minimum oomyceticidal concentration (MOC) values of 50 µg/mL and 75 µg/mL, respectively. The results showed that 4′-oxyalkylated analogues of isocordoin could be potential anti-oomycete agents.

In vitro and in vivo anticancer studies of 2'-hydroxy chalcone derivatives exhibit apoptosis in colon cancer cells by HDAC inhibition and cell cycle arrest

Considering the therapeutic values of bioflavonoids in colon cancer treatment, six 2ʹ-hydroxy chalcones (C1-C6) were synthesized, characterized and screened for in vitro cytotoxicity on human colon carcinoma (HCT116) and African green monkey kidney epithelial cells (Vero). Only C5 showed selective cytotoxicity against HCT116 cells. Other potent cytotoxic compounds were C1, C2 and C3. Further screening included enzyme inhibition studies on histone deacetylase (HDAC) enzyme where C1 showed lowest IC₅₀ value (105.03 µM). Based on cytotoxicity data C1, C2 and C3 were selected for further in vitro mechanistic studies, namely apoptotic studies (Acridine orange/Ethidium bromide (AO/EB) and Annexin V), cell cycle analysis using propidium iodide (PI) stain and in vivo anticancer efficacy in 1,2-dimethyl hydrazine (DMH) induced colorectal carcinoma in Wistar rats. The compounds induced apoptosis in more than 30 % cells in AO/EB and Annexin V staining. They also showed cell cycle arrest in G₂/M phase with PI staining. They showed a significant reduction in aberrant crypt foci formation and adenocarcinoma count along with a significant (p<0.05) reduction in TNF-α levels as compared to DMH control at 100 mg/kg dose. Thus, it can be concluded that the synthesized 2ʹ-hydroxychalcones were effective against colon adenocarcinoma in in vitro and in vivo studies.

Study of the antibacterial and antifungal activities of synthetic benzyl bromides, ketones, and corresponding chalcone derivatives

Several applications of chalcones and their derivatives encouraged researchers to increase their synthesis as an alternative for the treatment of pathogenic bacterial and fungal infections. In the present study, chalcone derivatives were synthesized through cross aldol condensation reaction between 4-(N,N-dimethylamino)benzaldehyde and multiarm aromatic ketones. The multiarm aromatic ketones were synthesized through nucleophilic substitution reaction between 4-hydroxy acetophenone and benzyl bromides. The benzyl bromides, multiarm aromatic ketones, and corresponding chalcone derivatives were evaluated for their activities against eleven clinical pathogenic Gram-positive, Gram-negative bacteria, and three pathogenic fungi by the disk diffusion method. The minimum inhibitory concentration was determined by the microbroth dilution technique. The results of the present study demonstrated that benzyl bromide derivatives have strong antibacterial and antifungal properties as compared to synthetic chalcone derivatives and ketones. Benzyl bromides (1a and 1c) showed high ester activity against Gram-positive bacteria and fungi but moderate activity against Gram-negative bacteria. Therefore, these compounds may be considered as good antibacterial and antifungal drug discovery. However, substituted ketones (2a–b) as well as chalcone derivatives (3a–c) showed no activity against all the tested strains except for ketone (2c), which showed moderate activity against Candida albicans.

The UPR inducer DPP23 inhibits the metastatic potential of MDA-MB-231 human breast cancer cells by targeting the Akt-IKK-NF-κB-MMP-9 axis

(E)-3-(3,5-dimethoxyphenyl)-1-(2-methoxyphenyl)prop-2-en-1-one (DPP23) is a synthetic polyphenol derivative that selectively induces apoptosis in cancer cells through the unfolded protein response pathway. In the present study, we evaluated the effect of DPP23 on tumour invasion and metastasis. Here, we show that DPP23 inhibited tumour necrosis factor alpha (TNFα)-induced motility, F-actin formation, and the invasive capability of MDA-MB-231 cells. DPP23 inhibited NF-κB-dependent MMP-9 expression at the transcriptional level. Akt is involved in the activation of IKK, an upstream regulator of NF-κB. DPP23 inhibited IKK and Akt, and knockdown of Akt2 significantly inhibited TNFα-induced IKK phosphorylation. We found that DPP23 bound to the catalytic domain of Akt2, as revealed by an in silico molecular docking analysis. These results suggest that DPP23 prevents TNFα-induced invasion of highly metastatic MDA-MB-231 breast cancer cells by inhibiting Akt–IKK–NF-κB axis-mediated MMP-9 gene expression. In addition, DPP23 attenuated experimental liver metastasis in a syngenic intrasplenic transplantation model using 4T1 mouse mammary carcinoma cells. Collectively, these results suggest that DPP23 could be used as a potential platform for the prevention of invasion and metastasis of early-stage breast cancer or as an adjuvant for chemo/radiotherapy.

Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand-Induced Apoptosis in Prostate Cancer Cells after Treatment with Xanthohumol-A Natural Compound Present in Humulus lupulus L

TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) is an endogenous ligand, which plays role in immune surveillance and anti-tumor immunity. It has ability to selectively kill tumor cells showing no toxicity to normal cells. We tested the apoptotic and cytotoxic activities of xanthohumol, a prenylated chalcone found in Humulus lupulus on androgen-sensitive human prostate adenocarcinoma cells (LNCaP) in combination with TRAIL. Cytotoxicity was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide tetrazolium reduction assay (MTT) and lactate dehydrogenase assay (LDH). The expression of death receptors (DR4/TRAIL-R1 and DR5/TRAIL-R2) and apoptosis were detected using flow cytometry. We examined mitochondrial membrane potential (ΔΨm) by DePsipher reagent using fluorescence microscopy. The intracellular expression of proteins was evaluated by Western blotting. Our study showed that xanthohumol enhanced cytotoxic and apoptotic effects of TRAIL. The tested compounds activated caspases-3, -8, -9, Bid, and increased the expression of Bax. They also decreased expression of Bcl-xL and decreased mitochondrial membrane potential, while the expression of death receptors was not changed. The findings suggest that xanthohumol is a compound of potential use in chemoprevention of prostate cancer due to its sensitization of cancer cells to TRAIL-mediated apoptosis.

IPP51, a chalcone acting as a microtubule inhibitor with in vivo antitumor activity against bladder carcinoma

We previously identified 1-(2,4-dimethoxyphenyl)-3-(1-methylindolyl) propenone (IPP51), a new chalcone derivative that is capable of inducing prometaphase arrest and subsequent apoptosis of bladder cancer cells. Here, we demonstrate that IPP51 selectively inhibits proliferation of tumor-derived cells versus normal non-tumor cells. IPP51 interfered with spindle formation and mitotic chromosome alignment. Accumulation of cyclin B1 and mitotic checkpoint proteins Bub1 and BubR1 on chromosomes in IPP51 treated cells indicated the activation of spindle-assembly checkpoint, which is consistent with the mitotic arrest. The antimitotic actions of other chalcones are often associated with microtubule disruption. Indeed, IPP51 inhibited tubulin polymerization in an in vitro assay with purified tubulin. In cells, IPP51 induced an increase in soluble tubulin. Furthermore, IPP51 inhibited in vitro capillary-like tube formation by endothelial cells, indicating that it has anti-angiogenic activity. Molecular docking showed that the indol group of IPP51 can be accommodated in the colchicine binding site of tubulin. This characteristic was confirmed by an in vitro competition assay demonstrating that IPP51 can compete for colchicine binding to soluble tubulin. Finally, in a human bladder xenograft mouse model, IPP51 inhibited tumor growth without signs of toxicity. Altogether, these findings suggest that IPP51 is an attractive new microtubule-targeting agent with potential chemotherapeutic value.

Mulberry leaf polysaccharides modulate murine bone-marrow-derived dendritic cell maturation

Various components of mulberry leaves, such as iminosugars, flavonoids and polysaccharides, have been reported to exert anti-diabetic activity. The purpose of our present study was to examine the modulating effect of mulberry leaf polysaccharides (MLPs) on murine bone-marrow-derived dendritic cells (BMDCs). The ultrastructure, phenotype and functional maturation of BMDCs were studied using transmission electron microscopy (TEM), flow cytometry (FCM), and tested for phagocytosis, acid phosphatase (ACP) activity using an enzyme linked immunosorbent assay (ELISA). Our results demonstrated that MLPs could markedly induce BMDC maturation by up-regulating the expression of membrane phenotypic markers, such as CD80, CD86, CD83,CD40, and MHC II, down-regulating phagocytosis and ACP activity, and by enhancing the production of interleukin 12 (IL-12) and tumor necrosis factor α (TNF-α) secreted by BMDCs. We therefore concluded that MLPs can positively modulate BMDCs.

Chalcone Scaffold in Anticancer Armamentarium: A Molecular Insight

Cancer is an inevitable matter of concern in the medicinal chemistry era. Chalcone is the well exploited scaffold in the anticancer domain. The molecular mechanism of chalcone at cellular level was explored in past decades. This mini review provides the most recent updates on anticancer potential of chalcones.

Enhanced cytotoxicity of prenylated chalcone against tumour cells via disruption of the p53-MDM2 interaction

AIM

Chalcones are naturally occurring compounds with recognized anticancer activity. It was recently shown that the O-prenyl derivative (2) of 2'-hydroxy-3,4,4',5,6'-pentamethoxychalcone (1) had a remarkably increased cytotoxicity against human tumour cells compared to its precursor. With this study, we aimed to investigate the molecular mechanism underlying the improved tumour cytotoxicity of prenylchalcone 2.

MAIN METHODS

The impact of chalcones 1 and 2 on p53-MDM2 interaction was investigated using yeast growth-inhibitory and p53 transactivation assays. Their tumour growth-inhibitory effects were assessed on human colon adenocarcinoma HCT116 cell lines with wild-type p53 and its p53-null derivative, followed by analysis of cell cycle and apoptosis. In tumour cells, the activation of a mitochondrial pathway was checked by analysis of reactive oxygen species generation, Bax mitochondrial translocation and cytochrome c release. Additionally, the up-regulation of p53 transcriptional activity was investigated through Western blot analysis of p53 target expression levels, and the disruption of the p53-MDM2 interaction was confirmed by co-immunoprecipitation.

KEY FINDINGS

The potent cell tumour growth-inhibitory activity of prenylchalcone 2 was associated with the activation of a p53 pathway involving cell cycle arrest and a mitochondria-dependent apoptosis. Furthermore, a correlation between the distinct cytotoxicity of chalcones 1 and 2 and their ability to disrupt the p53-MDM2 interaction was established.

SIGNIFICANCE

This work shows that prenylation is a determinant factor for the enhancement of chalcones tumour cytotoxicity by improving their ability to disrupt the p53-MDM2 interaction. Prenylchalcone 2 represents a starting basis for the design of new p53-MDM2 interaction inhibitors with improved antitumor properties.

Development of Novel Triazolo-Thiadiazoles from Heterogeneous "Green" Catalysis as Protein Tyrosine Phosphatase 1B Inhibitors

Condensed-bicyclic triazolo-thiadiazoles were synthesized via an efficient "green" catalyst strategy and identified as effective inhibitors of PTP1B in vitro. The lead compound, 6-(2-benzylphenyl)-3-phenyl-[1,2,4]triazolo[3][1,3,4]thiadiazole (BPTT) was most effective against human hepatoma cells, inhibits cell invasion, and decreases neovasculature in HUVEC and also tumor volume in EAT mouse models. This report describes an experimentally unidentified class of condensed-bicyclic triazolo-thiadiazoles targeting PTP1B and its analogs could be the therapeutic drug-seeds.

Inhibitory Effect of 3-(4-Hydroxyphenyl)-1-(thiophen-2-yl) prop-2-en-1-one, a Chalcone Derivative on MCP-1 Expression in Macrophages via Inhibition of ROS and Akt Signaling

Chalcones (1,3-diaryl-2-propen-1-ones), a subfamily of flavonoid, are widely known to possess potent anti-inflammatory and anti-oxidant properties. In this study, we investigated the effect of 3-(4-Hydroxyphenyl)-1-(thio3-(4-Hydroxyphenyl phen-2-yl)prop-2-en-1-one (TI-I-175), a synthetic chalcone derivative, on endotoxin-induced expression of monocyte chemoattractant protein-1 (MCP-1), one of the key chemokines that regulates migration and infiltration of immune cells, and its potential mechanisms. TII-175 potently inhibited MCP-1 mRNA expression stimulated by lipopolysaccharide (LPS) in RAW 264.7 macrophages without significant effect on cell viability. Treatment of cells with TI-I-175 markedly prevented LPS-induced transcriptional activation of activator protein-1 (AP-1) as measured by luciferase reporter assay, while nuclear factor-κB (NF-κB) activity was not inhibited by TI-I-175, implying that TI-I-175 suppressed MCP-1 expression probably via regulation of AP-1. In addition, TI-I-175 treatment significantly inhibited LPS-induced Akt phosphorylation and led to a significant decrease in reactive oxygen species (ROS) production by LPS, which act as up-stream signaling events required for AP-1 activation in RAW 264.7 macrophages. Taken together, these results indicate that TI-I-175 suppresses MCP-1 gene expression in LPS-stimulated RAW 264.7 macrophages via suppression of ROS production and Akt activation.

Isolation, Characterization, Crystal Structure Elucidation, and Anticancer Study of Dimethyl Cardamonin, Isolated from Syzygium campanulatum Korth

Syzygium campanulatum Korth is an equatorial, evergreen, aboriginal shrub of Malaysia. Conventionally it has been used as a stomachic. However, in the currently conducted study dimethyl cardamonin or 2′,4′-dihydroxy-6′-methoxy-3′,5′-dimethylchalcone (DMC) was isolated from S. campanulatum Korth, leaf extract. The structural characterization of DMC was carried out by making use of various techniques including UV, IR, NMR spectral followed by LC-MS, and X-ray crystallographic techniques. For determining the purity of compound, highly effective techniques including TLC, HPLC, and melting point were used. The cytotoxicity of DMC and three different extracts of S. campanulatum was evaluated against human colon cancer cell line (HT-29) by three different assays. DMC and ethanolic extract revealed potent and dose-dependent cytotoxic activity on the cancer cell line with IC₅₀ 12.6 and 90.1 µg/mL, respectively. Quite astonishingly to our knowledge, this is the very first report on S. campanulatum as being a rich source (3.5%) of DMC, X-ray crystallography, and anticancer activity on human colon cancer cells.

A new synthetic 2'-hydroxy-2,4,6-trimethoxy-5',6'-naphthochalcone induces G2/M cell cycle arrest and apoptosis by disrupting the microtubular network of human colon cancer cells

Methoxylated chalcones exert antitumor activities. In the present study, we characterized the cytotoxicity of methylated chalcone derivatives against human colon cancer cells. We synthesized a group of methoxychalcones and explored the molecular mechanisms underlying inhibition of tumor growth by these materials. A new synthetic methoxychalcone, 2'-hydroxy-2,4,6-trimethoxy-5',6'-naphthochalcone (named HMNC-74), most effectively inhibited the clonogenicity of SW620 colon cancer cells. Mechanistically, HMNC-74 triggered cell cycle arrest at G2/M phase, followed by an increase in apoptotic cell death. Our results indicate that the cytotoxicity of the novel compound HMNC-74 involves the disruption of microtubular networks.