An Indole-Chalcone Inhibits Multidrug-Resistant Cancer Cell Growth by Targeting Microtubules

Structure-Activity Relationship Study of (E)-3-(6-Fluoro-1H-indol-3-Yl)-2-methyl-1-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (FC116) Against Metastatic Colorectal Cancers Resistant to Oxaliplatin

Advanced metastatic colorectal cancer (mCRC) and the development of drug resistance to chemotherapy pose significant challenges in clinical settings. In previous studies, we have demonstrated the potent cytotoxic activity of (E)-3-(6-fluoro-1H-indol-3-yl)-2-methyl-1-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (FC116) and related 30 derivatives against mCRC by targeting microtubules. In this study, we aimed to evaluate the efficacy of the 31 compounds and explore the structure-activity relationship (SAR) against oxaliplatin-resistant mCRC. We found that most of the derivatives showed high sensitivity toward the oxaliplatin-resistant HCT-116/L cells. Particularly, FC116 exhibited a better GI50 value against the resistant mCRC cell line, HCT-116/L, compared to standard therapies. We also observed a safer therapeutic window for FC116 and a synergistic effect when it was used in combination with oxaliplatin. Mechanistically, FC116 induced the G2/M phase arrest by downregulating cyclin B1 expression through its interaction with microtubules in resistant colorectal cancer cells. Furthermore, in vivo experiments demonstrated that FC116 significantly suppressed tumor growth, achieving a 78% reduction at a dose of 3 mg/kg, which was superior to the 40% reduction achieved by oxaliplatin treatment. Overall, our findings suggest that the indole-chalcone compound FC116 represents a promising lead for chemotherapy in oxaliplatin-resistant mCRC.

Current scenario of chalcone hybrids with antibreast cancer therapeutic applications

Breast cancer, an epithelial malignant tumor that occurs in the terminal ducts of the breast, is the most common female malignancy. Currently, approximately 70%-80% of breast cancer with early-stage, nonmetastatic disorder is curable, but the emergency of drug resistance often leads to treatment failure. Moreover, advanced breast cancer with distant organ metastases is incurable with the available therapeutics, creating an urgent demand to explore novel antibreast cancer agents. Chalcones, the precursors for flavonoids and isoflavonoids, exhibit promising activity against various breast cancer hallmarks, inclusive of proliferation, angiogenesis, invasion, metastasis, inflammation, stemness, and regulation of cancer epigenetics, representing useful scaffolds for the discovery of novel antibreast cancer chemotherapeutic candidates. In particular, chalcone hybrids could act on two or more different biological targets simultaneously with more efficacy, lower toxicity, and less susceptibility to resistance. Accordingly, there is a huge scope for application of chalcone hybrids to tackle the present difficulties in breast cancer therapy. This review outlines the chalcone hybrids with antibreast cancer potential developed from 2018. The structure-activity relationships as well as mechanisms of action are also discussed to shed light on the development of more effective and multitargeted chalcone candidates.

Synthesis, and In-silico Studies of Indole-chalcone Derivatives Targeting Estrogen Receptor Alpha (ER-α) for Breast Cancer

BACKGROUND

Breast cancer is the prominent reason of death in women worldwide, and the cases are increasing day by day. There are many FDA-approved drugs for treating breast cancer. Due to drug resistance, and problems in selectivity, there is a need to develop more effective agents with few side effects. Indole derivatives have demonstrated significant pharmacological potential as anti-breast cancer agents. Further, chalcone derivatives incorporating heterocyclic scaffolds play a significant role in medicine. Indole-chalcone-based compounds offer the potential for improved biological activity and enhanced drug-like properties. It prompted us to explore the synthesis of Indole-Chalcone derivatives targeting estrogen receptor alpha (ER-α) to discover potent anti-breast cancer agents.

OBJECTIVES

To synthesize indole-chalcone derivatives and study their binding interactions for ER-α protein by molecular docking for breast cancer treatment.

METHODS

In this study, indole-chalcone derivatives have been synthesized using conventional heating. With the help of Schrodinger software, molecular interaction as well as ADME (Adsorption, Distribution, Metabolism, and Excretion) studies of the compounds were conducted.

RESULTS

Among all the synthesized compounds, four compounds (1, 2, 3, and 4) showed better docking scores (-10.24 kcal/mol, -10.15 kcal/mol, -9.40 kcal/mol, -9.29 kcal/mol, respectively) than the standard tamoxifen (-8.43 kcal/mol).

CONCLUSION

From In-silico studies, we can conclude that four compounds from the synthesized series fit into the active site of ER-α. ADME properties of synthesized derivatives were found in the acceptable range. In the future, these compounds can be further explored for biological activity.

Design and Synthesis of Novel α-Methylchalcone Derivatives, Anti-Cervical Cancer Activity, and Reversal of Drug Resistance in HeLa/DDP Cells

In this study, a collection of newly developed α-methylchalcone derivatives were synthesized and assessed for their inhibitory potential against human cervical cancer cell lines (HeLa, SiHa, and C33A) as well as normal human cervical epithelial cells (H8). Notably, compound 3k exhibited substantial inhibitory effects on both HeLa and HeLa/DDP cells while demonstrating lower toxicity toward H8 cells. Furthermore, the compound 3k was found to induce apoptosis in both HeLa and HeLa/DDP cells while also inhibiting the G2/M phase, resulting in a decrease in the invasion and migration capabilities of these cells. When administered alongside cisplatin, 3k demonstrated a significant reduction in the resistance of HeLa/DDP cells to cisplatin, as evidenced by a decrease in the resistance index (RI) value from 7.90 to 2.10. Initial investigations into the underlying mechanism revealed that 3k did not impact the expression of P-gp but instead facilitated the accumulation of rhodamine 123 in HeLa/DDP cells. The results obtained from CADD docking analysis demonstrated that 3k exhibits stable binding to microtubule proteins and P-gp targets, forming hydrogen bonding interaction forces. Immunofluorescence analysis further revealed that 3k effectively decreased the fluorescence intensity of α and β microtubules in HeLa and HeLa/DDP cells, resulting in disruptions in cell morphology, reduction in cell numbers, nucleus coagulation, and cell rupture. Additionally, Western blot analysis indicated that 3k significantly reduced the levels of polymerized α and β microtubule proteins in both HeLa and HeLa/DDP cell lines while concurrently increasing the expression of dissociated α and β microtubule proteins. The aforementioned findings indicate a potential correlation between the inhibitory effects of 3k on HeLa and HeLa/DDP cells and its ability to inhibit tubulin and P-gp.

Indole derivatives targeting colchicine binding site as potential anticancer agents

Microtubules are appealing as intracellular targets for anticancer activity due to their importance in cell division. Three important binding sites are present on the tubulin protein: taxane, vinca, and colchicine binding sites (CBS). Many USFDA-approved drugs such as paclitaxel, ixabepilone, vinblastine, and combretastatin act by altering the dynamics of the microtubules. Additionally, a large number of compounds have been synthesized by medicinal chemists around the globe that target different tubulin binding sites. Although CBS inhibitors have proved their cytotoxic potential, no CBS-targeting drug had been able to reach the market. Several studies have reported design, synthesis, and biological evaluation of indole derivatives as potential anticancer agents. These compounds have been shown to inhibit cancer cell proliferation, induce apoptosis, and disrupt microtubule formation. Moreover, the binding affinity of these compounds to the CBS has been demonstrated using molecular docking studies and competitive binding assays. The present work has reviewed indole derivatives as potential colchicine-binding site inhibitors. The structure-activity relationship studies have revealed the crucial pharmacophoric features required for the potent and selective binding of indole derivatives to the CBS. The development of these compounds with improved efficacy and reduced toxicity could potentially lead to the development of novel and effective cancer therapies.

Fluoroindole chalcone analogues targeting the colchicine binding site of tubulin for colorectal oncotherapy

Colorectal cancer (CRC) is a common malignancy of the gastrointestinal tract with high morbidity and mortality. Our previous studies have demonstrated that indole-chalcone-based compounds targeting tubulin displayed potential cytotoxicity to CRC cells. Herein, three new series of derivatives were systematically designed and synthesized to explore their structure-activity relationship (SAR) against CRC based on prior research. Among them, a representative fluorine-containing analog (FC116) exerted superior efficacy on HCT116 (IC₅₀ = 4.52 nM) and CT26 (IC₅₀ = 18.69 nM) cell lines, and HCT116-xenograft mice with tumor growth inhibition rate of 65.96% (3 mg/kg). Of note, FC116 could also suppress the growth of organoid models (IC₅₀ = 1.8-2.5 nM) and showed adenoma number inhibition rate of 76.25% at the dose of 3 mg/kg in APC^min/+ mice. In terms of mechanism, FC116 could induce endoplasmic reticulum (ER) stress to produce excess reactive oxygen species (ROS), leading to mitochondrial damage to promote the apoptosis of CRC cells by targeting microtubules. Our results support that indole-chalcone compounds are promising tubulin inhibitors and highlight the potential of FC116 to combat CRC.

A Facile Synthesis and Molecular Characterization of Certain New Anti-Proliferative Indole-Based Chemical Entities

Cancer cells frequently develop drug resistance, which leads to chemotherapeutic treatment failure. Additionally, chemotherapies are hindered by their high toxicity. Therefore, the development of new chemotherapeutic drugs with improved clinical outcomes and low toxicity is a major priority. Several indole derivatives exhibit distinctive anti-cancer mechanisms which have been associated with various molecular targets. In this study, target compounds 4a-q were obtained through the reaction of substituted benzyl chloride with hydrazine hydrate, which produces benzyl hydrazine. Subsequently, the appropriate substituted benzyl hydrazine was allowed to react with 1H-indole-2-carboxylic acid or 5-methoxy-1H-indole-2-carboxylic acid using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide as a coupling agent. All compounds exhibited cytotoxicity in three cell lines, namely, MCF-7, A549, and HCT. Compound 4e exhibited the highest cytotoxicity, with an average IC50 of 2 µM. Moreover, a flow cytometry study revealed a significantly increased prevalence of Annexin-V and 7-AAD positive cell populations. Several derivatives of 4a-q showed moderate to high cytotoxicity against the tested cell lines, with compound 4e having the highest cytotoxicity, indicating that it may possess potential apoptosis-inducing capabilities.

Structure optimization of an F-indole-chalcone (FC116) on 4-methoxyphenyl group and therapeutic potential against colorectal cancers with low cytotoxicity

Advanced metastatic colorectal cancers (CRCs) are regarded as a challenge in clinical cancer therapy. Our previous studies have demonstrated that a representative fluoro-substituted indole-chalcone (FC116), was obtained to display highly potent activity against CRC using multiple in vitro and in vivo mouse models by targeting microtubules. However, several problems, such as low dose tolerance and highly toxic to the brain and colon, low solubility unsuitable for intravenous (i.v.) administration, are still existed and limit further development. Herein, we developed two series of FC116 derivatives on the 4-methoxyphenyl group by a structure-based design strategy. Among them, FC11619 with an amino terminus maintained the in vitro cytotoxicity against HCT-116 CRC in a low nanomolar range. This compound could induce G2/M phase arrest via regulating cyclin B1 expression, produce excess reactive oxygen species (ROS), and target tubulin in CRC cells. In vivo, FC11619 significantly suppressed tumor growth, achieving 65.3 and 73.4 % at doses of 5 and 10 mg/kg/d (i.v., 21 d), which were much better than 54.1% of Taxol at 7 mg/kg. In addition, this compound showed better in vivo tolerance compared to that of FC116 (only 3 mg/kg tolerance, intraperitoneal, i.p.), and no major organ-related toxicity, especially no apparent degenerated neurons, intestinal obstruction in clinical Taxol standard therapy. Taken together, the 4-amino-substitutedphenyl indole-chalcones represent lead compounds as chemotherapy of CRC for further drug development in this field.

Chalcones: Promising therapeutic agents targeting key players and signaling pathways regulating the hallmarks of cancer

The need for innovative anticancer treatments with high effectiveness and low toxicity is urgent due to the development of malignancies that are resistant to chemotherapeutic agents and the poor specificity of existing anticancer treatments. Chalcones are 1,3-diaryl-2-propen-1-ones, which are the precursors for flavonoids and isoflavonoids. Chalcones are readily available from a wide range of natural resources and consist of very basic chemical scaffolds. Because the ease with which the synthesis it allows for the production of several chalcone derivatives. Various in-vitro and in-vivo studies indicate that naturally occurring and synthetic chalcone derivatives exhibit promising biological activities against cancer hallmarks such as proliferation, angiogenesis, invasion, metastasis, inflammation, stemness, and regulation of cancer epigenetics. According to their structure and functional groups, chalcones derivatives and their hybrid compounds exert a broad range of biological activities through targeting key elements and signaling molecules relevant to cancer progression. This review will provide valuable insights into the latest updates of chalcone groups as anticancer agents and extensively discuss their underlying molecular mechanisms of action.

Natural and Synthetic Chalcones: Potential Impact on Breast Cancer

Chalcones are small molecules, naturally found in fruits and vegetables, and exhibit diverse pharmacological activities. They also possess anticancer activity against different tumors. They can be converted into numerous derivatives by modifying hydrogen moieties, enabling the exploration of their diverse anticancer potentials. The main aims are to provide valuable insights into the recent progress made in utilizing chalcones and their derivatives as agents against breast cancer while delivering their underlying molecular mechanisms of action. This review presents anticancer molecular mechanisms and signaling pathways modulated by chalcones. Furthermore, it helps in the understating of the precise mechanisms of action and specific molecular targets of chalcones and their synthetic derivatives for breast cancer treatment.

Solid-state emitting twisted π-conjugate as AIE-active DSE-gen: in vitro anticancer properties against FaDu and 4T1 with biocompatibility and bioimaging

Dual-state emissive fluorogens (DSE-gens) are currently defining their importance as a transpiring tool in biological and biomedical applications. This work focuses on designing and synthesizing indole-anthracene-based solid-state emitting twisted π-conjugates using a metal-free protocol to achieve AIE-active DSE-gens, expanding their scope in biological applications. Special effort has been made to introduce proficient and photo/thermostable DSE-gens that inhibit cancer but not normal cells. Here, the lead DSE-gen initially detects cancer and normal cells by bioimaging; however, it could also confirm and distinguish cancer cells from normal cells by its abated fluorescence signal after killing cancer cells. In contrast, the fluorescence signals for a normal cell remain unscathed. Surprisingly, these molecules displayed decent anticancer properties against FaDu and 4T1 but not MCF-7 cell lines. From a series of newly designed indole-based molecules, we report one single 2,3,4-trimethoxybenzene-linked DSE-gen (the lead), exhibiting high ROS generation, less haemolysis, and less cytotoxicity than doxorubicin (DOX) for normal cells, crucial parameters for a biocompatible in vitro anticancer probe. Thus, we present a potentially applicable anticancer drug, offering a bioactive material with bioimaging efficacy and a way to detect dead cancer cells selectively. The primary mechanism behind the identified outcomes is deciphered with the support of experimental (steady-state and time-resolved fluorescence, biological assays, cellular uptake) and molecular docking studies.

Novel dual inhibitor for targeting PIM1 and FGFR1 kinases inhibits colorectal cancer growth in vitro and patient-derived xenografts in vivo

Colorectal cancer (CRC) is the second most common cause of cancer-related death in the world. The pro-viral integration site for Moloney murine leukemia virus 1 (PIM1) is a proto-oncogene and belongs to the serine/threonine kinase family, which are involved in cell proliferation, migration, and apoptosis. Fibroblast growth factor receptor 1 (FGFR1) is a tyrosine kinase that has been implicated in cell proliferation, differentiation and migration. Small molecule HCI-48 is a derivative of chalcone, a class of compounds known to possess anti-tumor, anti-inflammatory and antibacterial effects. However, the underlying mechanism of chalcones against colorectal cancer remains unclear. This study reports that HCI-48 mainly targets PIM1 and FGFR1 kinases, thereby eliciting antitumor effects on colorectal cancer growth in vitro and in vivo. HCI-48 inhibited the activity of both PIM1 and FGFR1 kinases in an ATP-dependent manner, as revealed by computational docking models. Cell-based assays showed that HCI-48 inhibited cell proliferation in CRC cells (HCT-15, DLD1, HCT-116 and SW620), and induced cell cycle arrest in the G2/M phase through modulation of cyclin A2. HCI-48 also induced cellular apoptosis, as evidenced by an increase in the expression of apoptosis biomarkers such as cleaved PARP, cleaved caspase 3 and cleaved caspase 7. Moreover, HCI-48 attenuated the activation of downstream components of the PIM1 and FGFR1 signaling pathways. Using patient-derived xenograft (PDX) murine tumor models, we found that treatment with HCI-48 diminished the PDX tumor growth of implanted CRC tissue expressing high protein levels of PIM1 and FGFR1. This study suggests that the inhibitory effect of HCI-48 on colorectal tumor growth is mainly mediated through the dual-targeting of PIM1 and FGFR1 kinases. This work provides a theoretical basis for the future application of HCI-48 in the treatment of clinical CRC.

A novel anti-lung cancer agent inhibits proliferation and epithelial-mesenchymal transition

OBJECTIVE

To synthesize a novel chalcone-1,3,4-thiadiazole hybrid and investigate its anticancer effects against NCI-H460 cells.

METHODS

(E)-3-(4-bromophenyl)-1-(4-hydroxyphenyl)prop-2-en-1-one, 1,3-dibromopropane and 1,3,4-thiadiazole-2-thiol were used as chemical materials to synthesize compound ZW97. The NCI-H460 lung cancer cell line was selected to explore the antitumor effects of compound ZW97 in vitro and in vivo.

RESULTS

Compound ZW97 selectively inhibited cell proliferation against lung cancer cell lines NCI-H460, HCC-44 and NCI-H3122 with IC₅₀ values of 0.15 μM, 2.06 μM and 1.17 μM, respectively. ZW97 suppressed migration and the epithelial-mesenchymal transition process in NCI-H460 cells in a concentration-dependent manner. Based on the kinase activity results and docking analysis, compound ZW97 is a novel tyrosine-protein kinase Met (c-Met kinase) inhibitor. It also inhibited NCI-H460 cell growth in xenograft models without obvious toxicity to normal tissues.

CONCLUSIONS

Compound ZW97 is a potential c-Met inhibitor that might be a promising agent to treat lung cancer by inhibiting the epithelial-mesenchymal transition process.

Target-based anticancer indole derivatives and insight into structure‒activity relationship: A mechanistic review update (2018‒2021)

Cancer, which is the uncontrolled growth of cells, is the second leading cause of death after heart disease. Targeting drugs, especially to specific genes and proteins involved in growth and survival of cancer cells, is the prime need of research world-wide. Indole moiety, which is a combination of aromatic-heterocyclic compounds, is a constructive scaffold for the development of novel leads. Owing to its bioavailability, high unique chemical properties and significant pharmacological behaviours, indole is considered as the most inquisitive scaffold for anticancer drug research. This is illustrated by the fact that the U.S. Food and Drug Administration (FDA) has recently approved several indole-based anticancer agents such as panobinostat, alectinib, sunitinib, osimertinib, anlotinib and nintedanib for clinical use. Furthermore, hundreds of studies on the synthesis and activity of the indole ring have been published in the last three years. Taking into account the facts stated above, we have presented the most recent advances in medicinal chemistry of indole derivatives, encompassing hot articles published between 2018 and 2021 in anticancer drug research. The recent advances made towards the synthesis of promising indole-based anticancer compounds that may act via various targets such as topoisomerase, tubulin, apoptosis, aromatase, kinases, etc., have been discussed. This review also summarizes some of the recent efficient green chemical synthesis for indole rings using various catalysts for the period during 2018–2021. The review also covers the synthesis, structure‒activity relationship, and mechanism by which these leads have demonstrated improved and promising anticancer activity. Indole molecules under clinical and preclinical stages are classified into groups based on their cancer targets and presented in tabular form, along with their mechanism of action. The goal of this review article is to point the way for medicinal chemists to design and develop effective indole-based anticancer agents.

Structure modification and biological evaluation of indole-chalcone derivatives as anti-tumor agents through dual targeting tubulin and TrxR

Microtubule target agents (MTAs) are widely-used clinical anti-cancer drugs for decades, but the acquired drug resistance severely restricted their application. Thioredoxin reductases (TrxR) was reported to be overexpressed in most tumors and closely related to high risk of cancer recurrence and drug resistance, making it a potential target for anticancer drug discovery. Multi-target-directed ligands (MTDLs) by a single molecule provide a logical and alternative approach to drug combinations. In this work, based on the structure-activity relationships obtained in our previous study, some structure modifications were performed. On one hand, the retained skeleton structure of MTAs endowed its tubulin polymerization inhibition activity, on the other hand, the selenium-containing structure and α,β-unsaturated ketone moiety endowed the TrxR inhibition activity. As results, the newly obtained compounds exhibited superior anti-proliferative activities towards various human cancer cells and drug-resistance cells, and displayed high selectivity towards various human normal cells. The mechanism study revealed that the dual effect of cell cycle arrest triggered by targeting tubulin and the abnormal accumulation of ROS caused by TrxR inhibition eventually lead to cell apoptosis. Notably, compared with the MTA agents CA-4P, and the TrxR inhibitor Ethaselen, the optimized compound 14c, which served as dual-targeting inhibitor of tubulin and TrxR, exerted greatly improved in vivo anti-tumor activity. In summary, 14c deserved further consideration for cancer therapy.

Natural Indole Alkaloids from Marine Fungi: Chemical Diversity and Biological Activities

The indole scaffold is one of the most important heterocyclic ring systems for pharmaceutical development, and serves as an active moiety in several clinical drugs. Fungi derived from marine origin are more liable to produce novel indole-containing natural products due to their extreme living environments. The indole alkaloids from marine fungi have drawn considerable attention for their unique chemical structures and significant biological activities. This review attempts to provide a summary of the structural diversity of marine fungal indole alkaloids including prenylated indoles, diketopiperazine indoles, bisindoles or trisindoles, quinazoline-containing indoles, indole-diterpenoids, and other indoles, as well as their known biological activities, mainly focusing on cytotoxic, kinase inhibitory, antiinflammatory, antimicrobial, anti-insecticidal, and brine shrimp lethal effects. A total of 306 indole alkaloids from marine fungi have been summarized, covering the references published from 1995 to early 2021, expecting to be beneficial for drug discovery in the future.

A review on synthetic chalcone derivatives as tubulin polymerisation inhibitors

Microtubules play an important role in the process of cell mitosis and can form a spindle in the mitotic prophase of the cell, which can pull chromosomes to the ends of the cell and then divide into two daughter cells to complete the process of mitosis. Tubulin inhibitors suppress cell proliferation by inhibiting microtubule dynamics and disrupting microtubule homeostasis. Thereby inducing a cell cycle arrest at the G2/M phase and interfering with the mitotic process. It has been found that a variety of chalcone derivatives can bind to microtubule proteins and disrupt the dynamic balance of microtubules, inhibit the proliferation of tumour cells, and exert anti-tumour effects. Consequently, a great number of studies have been conducted on chalcone derivatives targeting microtubule proteins. In this review, synthetic or natural chalcone microtubule inhibitors in recent years are described, along with their structure-activity relationship (SAR) for anticancer activity.

A Nitrocarbazole as a New Microtubule-Targeting Agent in Breast Cancer Treatment

Breast cancer is still considered a high-incidence disease, and numerous are the research efforts for the development of new useful and effective therapies. Among anticancer drugs, carbazole compounds are largely studied for their anticancer properties and their ability to interfere with specific targets, such as microtubule components. The latter are involved in vital cellular functions, and the perturbation of their dynamics leads to cell cycle arrest and subsequent apoptosis. In this context, we report the anticancer activity of a series of carbazole analogues 1–8. Among them, 2-nitrocarbazole 1 exhibited the best cytotoxic profile, showing good anticancer activity against two breast cancer cell lines, namely MCF-7 and MDA-MB-231, with IC50 values of 7 ± 1.0 and 11.6 ± 0.8 μM, respectively. Furthermore, compound 1 did not interfere with the growth of the normal cell line MCF-10A, contrarily to Ellipticine, a well-known carbazole derivative used as a reference molecule. Finally, in vitro immunofluorescence analysis and in silico studies allowed us to demonstrate the ability of compound 1 to interfere with tubulin organization, similarly to vinblastine: a feature that results in triggering MCF-7 cell death by apoptosis, as demonstrated using a TUNEL assay.

Therapeutic potential of indole alkaloids in respiratory diseases: A comprehensive review

BACKGROUND

Indole alkaloids are very promising for potential therapeutic purposes and appear to be particularly effective against respiratory diseases. Several experimental studies have been performed, both in vivo and in vitro, to evaluate the effectiveness of indole alkaloids for the management of respiratory disorders, including asthma, emphysema, tuberculosis, cancer, and pulmonary fibrosis.

PURPOSE

The fundamental objective of this review was to summarize the in-depth therapeutic potential of indole alkaloids against various respiratory disorders.

STUDY DESIGN

In addition to describing the therapeutic potential, this review also evaluates the toxicity of these alkaloids, which have been utilized for therapeutic benefits but have demonstrated toxic consequences. Some indole alkaloids, including scholaricine, 19-epischolaricine, vallesamine, and picrinine, which are derived from the plant Alstonia scholaris, have shown toxic effects in non-rodent models.

METHODS

This review also discusses clinical studies exploring the therapeutic efficacy of indole alkaloids, which have confirmed the promising benefits observed in vivo and in vitro.

RESULTS

The indole alkaloidal compounds have shown efficacy in subjects with respiratory diseases.

CONCLUSION

The available data established both preclinical and clinical studies confirm the potential of indole alkaloids to treat the respiratory disorders.

Anticancer potential of indole derivatives: an update

The heterocyclic indole is one of the most prevalent pharmacophores in nature. It has been a highly privileged scaffold for designing targeted and anticancer therapeutics. Countless fused heterocyclic templates have been developed with diverse physicochemical and biological properties. Due to their versatile ethanobotanical and pharmacological values, indole and its derivatives seek high demand in the chemical and healthcare sectors. Extensive anticancer research has been conducted in this decade to evaluate their efficacy for diverse malignancies. The chapter explores the anticancer activity of natural and synthetic indole derivatives expressed through targeting different biological receptors and enzymes.

Chalcone Derivatives and their Activities against Drug-resistant Cancers: An Overview

Drug resistance, including multidrug resistance resulting from different defensive mechanisms in cancer cells, is the leading cause of the failure of the cancer therapy, posing an urgent need to develop more effective anticancer agents. Chalcones, widely distributed in nature, could act on diverse enzymes and receptors in cancer cells. Accordingly, chalcone derivatives possess potent activity against various cancers, including drug-resistant, even multidrug-resistant cancer. This review outlines the recent development of chalcone derivatives with potential activity against drug-resistant cancers covering articles published between 2010 and 2020 so as to facilitate further rational design of more effective candidates.

Indole Alkaloids, Synthetic Dimers and Hybrids with Potential In Vivo Anticancer Activity

Indole, a heterocyclic organic compound, is one of the most promising heterocycles found in natural and synthetic sources since its derivatives possess fascinating structural diversity and various therapeutic properties. Indole alkaloids, synthetic dimers and hybrids could act on diverse targets in cancer cells, and consequently, possess potential antiproliferative effects on various cancers both in vitro and in vivo. Vinblastine, midostaurin, and anlotinib as the representative of indole alkaloids, synthetic dimers and hybrids respectively, have already been clinically applied to treat many types of cancers, demonstrating indole alkaloids, synthetic dimers and hybrids are useful scaffolds for the development of novel anticancer agents. Covering articles published between 2010 and 2020, this review emphasizes the recent development of indole alkaloids, synthetic dimers and hybrids with potential in vivo therapeutic application for cancers.

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.

The Newly Synthetized Chalcone L1 Is Involved in the Cell Growth Inhibition, Induction of Apoptosis and Suppression of Epithelial-to-Mesenchymal Transition of HeLa Cells

Over the past decades, natural products have emerged as promising agents with multiple biological activities. Many studies suggest the antioxidant, antiangiogenic, antiproliferative and anticancer effects of chalcones and their derivatives. Based on these findings, we decided to evaluate the effects of the newly synthetized chalcone L1 in a human cervical carcinoma cell (HeLa) model. Presented results were obtained by western blot and flow cytometric analyses, live cell imaging and antimigratory potential of L1 in HeLa cells was demonstrated by scratch assay. In the present study, we proved the role of L1 as an effective agent with antiproliferative activity supported by G2/M cell cycle arrest and apoptosis. Moreover, we proved that L1 is involved in modulating Transforming Growth Factor-β1 (TGF-β) signal transduction through Smad proteins and it also modulates other signalling pathways including Akt, JNK, p38 MAPK, and Erk1/2. The involvement of L1 in epithelial-to-mesenchymal transition was demonstrated by the regulation of N-cadherin, E-cadherin, and MMP-9 levels. Here, we also evaluated the effect of conditioned medium from BJ-5ta human foreskin fibroblasts in HeLa cell cultures with subsequent L1 treatment. Taken together, these data suggest the potential role of newly synthesized chalcone L1 as an anticancer-tumour microenvironment modulating agent.

Synthesis, biological evaluation, and molecular docking analysis of phenstatin based indole linked chalcones as anticancer agents and tubulin polymerization inhibitors

A library of new phenstatin based indole linked chalcone compounds (9a-z and 9aa-ad) were designed and synthesized. Of these, compound 9a with 1-methyl, 2- and 3-methoxy substituents in the aromatic ring was efficacious against the human oral cancer cell line SCC-29B, spheroids, and in a mouse xenograft model of oral cancer AW13516. Compound 9a exhibited anti-cancer activity through disrupting cellular integrity and affecting glucose metabolism-which is a hallmark of cancer. The cellular architecture was affected by inhibition of tubulin polymerization as observed by an immunofluorescence assay on 9a-treated SCC-29B cells. An in vitro tubulin polymerization kinetics assay provided evidence of direct interaction of 9a with tubulin. This physical interaction between tubulin and compound 9a was further confirmed by Surface Plasmon Resonance (SPR) analysis. Molecular docking experiments and validations revealed that compound 9a interacts and binds at the colchicine binding site of tubulin and at active sites of key enzymes in the glucose metabolism pathway. Based on in silico modeling, biophysical interactions, and pre-clinical observations, 9a consisting of phenstatin based indole-chalcone scaffolds, can be considered as an attractive tubulin polymerization inhibitor candidate for developing anti-cancer therapeutics.

Chalcone hybrids as potential anticancer agents: Current development, mechanism of action, and structure-activity relationship

The continuous emergency of drug-resistant cancers and the low specificity of anticancer agents have been the major challenges in the control and treatment of cancer, making an urgent need to develop novel anticancer agents with high efficacy. Chalcones, precursors of flavonoids and isoflavonoids, exhibit structural heterogeneity and can act on various drug targets. Chalcones which demonstrated potential in vitro and in vivo activity against both drug-susceptible and drug-resistant cancers, are useful templates for the development of novel anticancer agents. Hybridization of chalcone moiety with other anticancer pharmacophores could provide the hybrids which have the potential to overcome drug resistance and improve the specificity, so it represents a promising strategy to develop novel anticancer agents. This review emphasizes the development, the mechanisms of action as well as structure-activity relationships of chalcone hybrids with potential therapeutic application for many cancers in recent 10 years.

Current scenario of indole derivatives with potential anti-drug-resistant cancer activity

Cancer chemotherapy is frequently hampered by drug resistance, so the resistance to anticancer agents represents one of the major obstacles for the effective cancer treatment. Indole derivatives have the potential to act on diverse targets in cancer cells and exhibit promising activity against drug-resistant cancers. Moreover, some indole-containing compounds such as Semaxanib, Sunitinib, Vinorelbine, and Vinblastine have already been applied in clinics for various kinds of cancer even drug-resistant cancer therapy. Thus, indole derivatives are one of significant resources for the development of novel anti-drug-resistant cancer agents. This review focuses on the recent development of indole derivatives with potential therapeutic application for drug-resistant cancers, and the mechanisms of action, the critical aspects of design as well as structure-activity relationships, covering articles published from 2010 to 2020.

Role of Indole Scaffolds as Pharmacophores in the Development of Anti-Lung Cancer Agents

Lung cancer is the leading cause of death in men and women worldwide, affecting millions of people. Between the two types of lung cancers, non-small cell lung cancer (NSCLC) is more common than small cell lung cancer (SCLC). Besides surgery and radiotherapy, chemotherapy is the most important method of treatment for lung cancer. Indole scaffold is considered one of the most privileged scaffolds in heterocyclic chemistry. Indole may serve as an effective probe for the development of new drug candidates against challenging diseases, including lung cancer. In this review, we will focus on discussing the existing indole based pharmacophores in the clinical and pre-clinical stages of development against lung cancer, along with the synthesis of some of the selected anti-lung cancer drugs. Moreover, the basic mechanism of action underlying indole based anti-lung cancer treatment, such as protein kinase inhibition, histone deacetylase inhibition, DNA topoisomerase inhibition, and tubulin inhibition will also be discussed.

Antiproliferative Effect of Acridine Chalcone Is Mediated by Induction of Oxidative Stress

Chalcones are naturally occurring phytochemicals with diverse biological activities including antioxidant, antiproliferative, and anticancer effects. Some studies indicate that the antiproliferative effect of chalcones may be associated with their pro-oxidant effect. In the present study, we evaluated contribution of oxidative stress in the antiproliferative effect of acridine chalcone 1C ((2 E)-3-(acridin-9-yl)-1-(2,6-dimethoxyphenyl)prop-2-en-1-one) in human colorectal HCT116 cells. We demonstrated that chalcone 1C induced oxidative stress via increased reactive oxygen/nitrogen species (ROS/RNS) and superoxide production with a simultaneous weak adaptive activation of the cellular antioxidant defence mechanism. Furthermore, we also showed chalcone-induced mitochondrial dysfunction, DNA damage, and apoptosis induction. Moreover, activation of mitogen activated phosphokinase (MAPK) signalling pathway in 1C-treated cancer cells was also observed. On the other hand, co-treatment of cells with strong antioxidant, N-acetyl cysteine (NAC), significantly attenuated all of the above-mentioned effects of chalcone 1C, that is, decreased oxidant production, prevent mitochondrial dysfunction, DNA damage, and induction of apoptosis, as well as partially preventing the activation of MAPK signalling. Taken together, we documented the role of ROS in the antiproliferative/pro-apoptotic effects of acridine chalcone 1C. Moreover, these data suggest that this chalcone may be useful as a promising anti-cancer agent for treating colon cancer.

Discovery of 1,2,4-triazine-based derivatives as novel neddylation inhibitors and anticancer activity studies against gastric cancer MGC-803 cells

Neddylation modification is often over-expressed in a variety of human tumor cells. Therefore, targeting neddylation pathway may represent a potential approach to the treatment of human tumors. Herein, we describe the discovery of a hit scaffold from our in-house library and further structure-based optimizations. In this work, compound V11 could block the neddylation and inhibit the activity of NAE (with an EC₅₀ value of 3.56 µM), and a dose-dependent reduction of the Ubc12-NEDD8 conjugations was also observed. Molecular docking results suggest compound V11 could bind tightly to NAE via hydrogen bonds and hydrophobic interactions. Compound V11 showed the best antiproliferative ability with an IC₅₀ value of 8.22 μM against gastric cancer MGC-803 cells. Further anticancer activity studies suggested that compound V11 inhibited MGC-803 cell growth, caused a cell cycle arrestment at G2/M phase and induced apoptosis via extrinsic and intrinsic apoptosis pathways. All the findings suggest that 1,2,4-triazine scaffold might provide a novel scaffold for the further development of neddylation inhibitors and compound V11 might be a potential neddylation inhibitor with anticancer activity.

Synthesis and evaluation of novel α-substituted chalcones with potent anti-cancer activities and ability to overcome multidrug resistance

A series of forty α-substituted chalcones were synthesized and screened for their antiproliferative activities against HCT116 (colorectal) and HCC1954 (breast) cancer cell lines. Compounds 5a and 5e were found to be the most potent compounds with GI₅₀ values of 0.63 µM and 0.725 µM in HCC1954 cell line and 0.69 µM and 1.59 µM in HCT116 cell line, respectively. Both compounds induced a G2/M cell cycle arrest and caused apoptotic cell death in HCT116 cells as shown by the induction of PARP cleavage. The compounds also stabilized p53 in a dose-dependent manner in HCT116 cells following 24-hour treatment. Furthermore, both 5a and 5e were able to overcome multidrug resistance in two MDR-1 overexpressing multidrug resistant cell lines.