Apoptosis induction of 2′-hydroxycinnamaldehyde as a proteasome inhibitor is associated with ER stress and mitochondrial perturbation in cancer cells

2'-Hydroxycinnamaldehyde Alleviates Intestinal Inflammation by Attenuating Intestinal Mucosal Barrier Damage Via Directly Inhibiting STAT3

BACKGROUND

The currently available clinical therapeutic drugs for ulcerative colitis (UC) are considered inadequate owing to certain limitations. There have been reports on the anti-inflammatory effects of 2'-hydroxycinnamaldehyde (HCA). However, whether HCA can improve UC is still unclear. Here, we aimed to investigate the pharmacological effects of HCA on UC and its underlying molecular mechanisms.

METHODS

The pharmacological effects of HCA were comprehensively investigated in 2 experimental setups: mice with dextran sulfate sodium (DSS)-induced colitis and lipopolysaccharide (LPS)-treated fetal human colon (FHC) cells. Furthermore, the interaction between HCA and signal transducer and activator of transcription 3 (STAT3) was investigated using molecular docking. The FHC cells with STAT3 knockdown or overexpression and mice with intestinal epithelium-specific STAT3 deletion (STAT3ΔIEC) were used to evaluate whether STAT3 mediated the pharmacological effects of HCA.

RESULTS

2'-Hydroxycinnamaldehyde attenuated dysregulated expression of inflammatory cytokines in a dose-dependent manner while increasing the expression of tight junction proteins, reducing the apoptosis of intestinal epithelial cells, and effectively alleviating inflammation both in vivo and in vitro. 2'-Hydroxycinnamaldehyde bound directly to STAT3 and inhibited its activation. The modulation of STAT3 activation levels due to STAT3 knockdown or overexpression influenced the mitigating effects of HCA on colitis. Further analysis indicated that the remission effect of HCA was not observed in STAT3ΔIEC mice, indicating that STAT3 mediated the anti-inflammatory effects of HCA.

CONCLUSIONS

We present a novel finding that HCA reduces colitis severity by attenuating intestinal mucosal barrier damage via STAT3. This discovery holds promise as a potential new strategy to alleviate UC.

Evaluation of cinnamaldehyde derivatives as potential protective agents against oxidative-stress induced myotube atrophy using chemical, biological and computational analysis

Skeletal muscle atrophy, associated with increased morbidity, mortality and poor quality of life, is a metabolic disorder with no FDA approved drug. Oxidative stress is one of the key mediators of atrophy that influences various cell signaling molecules. The goal of this study is to identify potential antioxidant agents that could be used to treat atrophy. In this study in vitro and in situ screening of different cinnamaldehyde (CNA) derivatives for their antioxidant effects was done along with computational analysis to understand the relationship between their chemical structure and biological activity. Data show that 2-hydroxycinnamaldehyde (2HCNA) worked better than other CNA analogues at physiological pH, while 4-Fluoro-2-methoxycinnamaldehyde (4FoCNA) showed the maximum antioxidant activity under acidic conditions. However, these derivatives (2HCNA and 4FoCNA) were found to be toxic to the cultured myotubes (mature myofiber) under both physiological and pathophysiological conditions. Immunofluorescence, bright-field microscopic and biochemical studies conducted using live C2C12 cells showed that pre-incubation with other CNA analogues i.e. 2-methoxycinnamaldehyde (2MeCNA) and 2-benzyloxycinnamaldehyde (2BzCNA) not only maintained the normal morphology of myotubes but also protected them from H2O2-induced atrophy. These compounds (2MeCNA and 2BzCNA) showed higher stability and antioxidant potential, as indicated by computer simulation data analyzed by Density Functional Theory (DFT) based molecular modeling. Overall, the chemical, biological, and computational studies reveal the therapeutic potential of CNA analogues (BzCNA and MeCNA) against oxidative-stress induced muscle atrophy in C2C12 cells.

Self-amplified chain-shattering cinnamaldehyde-based poly(thioacetal) boosts cancer chemo-immunotherapy

The selective activation of stimuli-responsive polymers in the tumor microenvironment is a great concern to achieve intelligent cancer therapy, but most of them show inadequate response due to insufficient endogenous triggering agents. Herein, we rationally designed a reactive oxygen species (ROS)-responsive cinnamaldehyde (CA)-based poly(thioacetal), consisting of ROS-responsive thioacetal (TA) and ROS-generating agent CA, with self-amplified chain-shattering polymer degradation. The mechanism of self-amplified chain-shattering is that endogenous ROS as a triggering agent facilitates chain cleavage of TA with the release of CA, which in turn produces more ROS through mitochondrial dysfunction, resulting in an exponential polymer degradation cascade. The polymer can be further modified with anticancer drug doxorubicin (DOX) for cooperative amplification of oxidative stress and immunogenic cell death (ICD) of tumor cells, thereby boosting the effect of chemo-immunotherapy. The self-amplified chain-shattering polymer designed in this work holds great promise in developing stimuli-responsive polymers for efficient drug delivery. STATEMENT OF SIGNIFICANCE: This study presented an approach to utilize self-amplified chain-shattering cinnamaldehyde-based poly (thioacetal) as a drug delivery system to restrain tumor growth and boost chemo-immunotherapy. The endogenous ROS as a triggering agent initiates the chain cleavage with the release of CA, which in turn produces ROS through mitochondria dysfunction, resulting in an exponential polymer degradation cascade and rapid drug release.

Cinnamaldehyde induces autophagy-mediated cell death through ER stress and epigenetic modification in gastric cancer cells

Previous reports suggested that cinnamaldehyde (CA), the bioactive ingredient in Cinnamomum cassia, can suppress tumor growth, migratory, and invasive abilities. However, the role and molecular mechanisms of CA in GC are not completely understood. In the present study, we found that CA-induced ER stress and cell death via the PERK-CHOP axis and Ca²⁺ release in GC cells. Inhibition of ER stress using specific-siRNA blocked CA-induced cell death. Interestingly, CA treatment resulted in autophagic cell death by inducing Beclin-1, ATG5, and LC3B expression and by inhibiting p62 expression whereas autophagy inhibition suppressed CA-induced cell death. We showed that CA induces the inhibition of G9a and the activation of LC3B. Moreover, CA inhibited G9a binding on Beclin-1 and LC3B promoter. Overall, these results suggested that CA regulates the PERK-CHOP signaling, and G9a inhibition activates autophagic cell death via ER stress in GC cells.

The Role of Bioactive Compounds from Dietary Spices in the Management of Metabolic Syndrome: An Overview

Metabolic syndrome (MetS) is a combination of physiologically dysregulated parameters that can include elevated fasting blood glucose, high blood pressure, central obesity, increased triglyceride levels, insulin resistance, diabetes, elevated low density lipoprotein levels, and reduced high density lipoprotein levels in the blood. Effective clinical management of MetS is critical as it is strongly associated with long lasting and fatal complications in patients. Alongside standard care of lifestyle changes and medication, dietary supplements derived from herbal resources could be an alternative therapeutic strategy that is safe, efficient, culturally acceptable, and has few side effects. Of the dietary supplements, spicy foods have always been considered a great source of functional bioactive compounds. Herbal therapy is broadly used in many countries as a treatment or as a preventive measure in the management of MetS risk factors, including blood glucose, blood pressure, and blood lipid levels. Herein, an attempt is made to evaluate the recent studies in the management of MetS with herbal alternatives, and to explore the possibility of their use as therapeutic treatments or supplements.

Aromatic monophenols from cinnamon bark act as proteasome inhibitors by upregulating ER stress, suppressing FoxM1 expression, and inducing apoptosis in prostate cancer cells

Cinnamon contains bioactive substances with diverse medicinal properties. We investigated the anticancer potential of abundant monophenols from cinnamon, namely, cinnamaldehyde, cinnamic acid, and eugenol, by hypothesizing that they possess proteasome inhibitory activities capable of suppressing cancer cell proliferation and inducing apoptosis. This hypothesis was tested by evaluating proteasome inhibitory activities of the compounds, and assessing downstream molecular and cellular events that are known to be impacted by proteasome inhibitors. The cinnamon compounds inhibited the catalytic activities of the proteasome in prostate cancer cells, but not in normal cells. Treatment with cinnamon compounds or the synthetic proteasome inhibitor MG132 upregulated p27 and IkBα proteins, and downregulated FoxM1 and angiogenic markers. These molecular events were associated with the decreased proliferation of prostate cancer cells. Treatment with cinnamon compounds or MG132 upregulated the expression of genes associated with endoplasmic reticulum (ER) stress/unfolded protein response (BIP, PERK, CHOP, and XBP1(S)). Furthermore, cinnamon compounds or MG132 upregulated the expression of genes required for the assembly of the caspase-8 activation platform in autophagosomes (LC3B, ATG5, p62, and Beclin1). The autophagy inhibitor, 3-methyladenine, blocked the compounds-mediated activation of caspase-8 and its downstream target caspase-3. In conclusion, proteasome inhibition by aromatic monophenols from cinnamon inhibits proliferation and leads to the death of prostate cancer cells by autophagy-dependent apoptosis.

Two Promising Anti-Cancer Compounds, 2-Hydroxycinnaldehyde and 2-Benzoyloxycinnamaldehyde: Where do we stand?

Natural bioactive compounds with anti-carcinogenic activity are gaining tremendous interest in the field of oncology. Cinnamon, an aromatic condiment commonly used in tropical regions, appeared incredibly promising as adjuvant for cancer therapy. Indeed, its whole or active parts (e.g., bark, leaf) exhibited significant anti-carcinogenic activity, which is mainly due to two cinnamaldehyde derivatives, namely 2-hydroxycinnaldehyde (HCA) and 2-benzoyloxycinnamaldehyde (BCA). In addition to their anti-cancer activity, HCA and BCA exert immunomodulatory, anti-platelets, and anti-inflammatory activities. Highly reactive α,ß-unsaturated carbonyl pharmacophore, called Michael acceptor, contribute to their therapeutic effects. The molecular mechanisms, underlying their anti-tumoral and anti-metastatic effects are miscellaneous, strongly suggesting that these compounds are multi-targeting compounds. Nevertheless, unravelling the exact molecular mechanisms of HCA and BCA remain a challenging matter which is necessary for optimal controlled-drug targeting delivery, safety, and efficiency. Eventually, their poor pharmacological properties (e.g., systemic bioavailability and solubility) represent a limitation, and depend both on their administration route (e.g., per os, intravenously) and the nature of the formulation (e.g., free, smart nano-). This concise review focused on the potential of HCA and BCA as adjuvants in Cancer. We described their medicinal effects as well as provide an update about their molecular mechanisms reported either in-vitro, ex-vivo, or in animal models.

Cinnamaldehyde and Doxorubicin Co-Loaded Graphene Oxide Wrapped Mesoporous Silica Nanoparticles for Enhanced MCF-7 Cell Apoptosis

Background

Combined chemotherapy is often affected by the different physicochemical properties of chemotherapeutic drugs, which should be improved by the reasonable design of co-loaded preparations.

Purpose

A kind of simple but practical graphene oxide (GO) wrapped mesoporous silica nanoparticles (MSN) modified with hyaluronic acid (MSN@GO-HA) were developed for the co-delivery of cinnamaldehyde (CA) and doxorubicin (DOX), in order to enhance their combined treatment on tumor cells and reduce their application defects.

Methods

The MSN_CA@GO_DOX-HA was constructed by MSN_CA (loading CA via physical diffusion) and GO_DOX-HA (modified with HA and loading DOX via π–π stacking) through the electrostatic adsorption, followed by the physicochemical characterization, serum stability and in vitro release study. Cytotoxicity on different cells was detected, followed by the tumor cell uptake tests. The intracellular reactive oxygen species (ROS) changes, mitochondrial functions and activities of caspase-3/-9 in MCF-7 cells were also evaluated, respectively.

Results

The MSN_CA@GO_DOX-HA nanoparticles kept stable in FBS solution and achieved pH-responsive release behavior, which was beneficial to increase the accumulation of CA and DOX in tumor cells to enhance the treatment. MSN_CA@GO_DOX-HA exerted higher cytotoxicity to MCF-7 human breast cancer cells than H9c2 cardiac myocyte cells, which were not only attributed to the active targeting to tumor cells by HA, but also related with the activation of intrinsic apoptotic pathway in MCF-7 cells induced by CA, which was mediated by the specific ROS signal amplification and the interference with mitochondrial function. Moreover, the efficacy of DOX was also enhanced by the above process.

Conclusion

The establishment of the MSN_CA@GO_DOX-HA nanoparticles played a role in promoting strengths and restricting shortcomings of CA and DOX, thereby exerting their function and achieving efficient treatment against cancer.

Concise Chemoenzymatic Total Synthesis and Identification of Cellular Targets of Cepafungin I

The natural product cepafungin I was recently reported to be one of the most potent covalent inhibitors of the 20S proteasome core particle through a series of in vitro activity assays. Here, we report a short chemoenzymatic total synthesis of cepafungin I featuring the use of a regioselective enzymatic oxidation to prepare a key hydroxylated amino acid building block in a scalable fashion. The strategy developed herein enabled access to a chemoproteomic probe, which in turn revealed the exceptional selectivity and potency of cepafungin I toward the β2 and β5 subunits of the proteasome. Further structure-activity relationship studies suggest the key role of the hydroxyl group in the macrocycle and the identity of the lipid tail in modulating the potency of this natural product family. This study lays the groundwork for further medicinal chemistry exploration to fully realize the anticancer potential of cepafungin I.

Rationally Designed Polymer Conjugate for Tumor-Specific Amplification of Oxidative Stress and Boosting Antitumor Immunity

The crosstalk between tumor and stroma cells is a central scenario in the tumor microenvironment (TME). While the predominant effect of tumor cells on immune cells is establishing an immunosuppressive context, tumor cell death at certain conditions will boost antitumor immunity. Herein, we report a rationally designed tumor specific enhanced oxidative stress polymer conjugate (TSEOP) for boosting antitumor immunity. The TSEOP is prepared by Passerini reaction between cinnamaldehyde (CA), 4-formylbenzeneboronic acid pinacol ester, and 5-isocyanopent-1-yne, followed by azide-alkyne click reaction with poly(l-glutamic acid)-graft-poly(ethylene glycol) monomethyl ether (PLG-g-mPEG). Under tumor stimuli condition, CA and quinone methide (QM) are quickly generated, which cooperatively induce strong oxidative stress, immunogenic tumor cell death (ICD), and activation of antigen presenting cells. In vivo studies show that the TSEOP treatment boosts tumor-specific antitumor immunity and eradicates both murine colorectal and breast tumors. This study should be inspirational for designing polymers as immunotherapeutics in cancer therapy.

A review of cinnamaldehyde and its derivatives as antibacterial agents

There is a continuing rise in the occurrence of multidrug-resistant bacterial infections. Antibiotic resistance to currently available antibiotics has become a global health issue leading to an urgent need for alternative antibacterial strategies. There has been a renewed interest in the development of antibacterial agents from natural sources, and trans-cinnamaldehyde is an example of a naturally occurring compound that has received significant attention in recent years. Trans-Cinnamaldehyde has been shown to possess substantial antimicrobial activity, as well as an array of other medicinal properties, and represents an intriguing hit compound from which a number of derivatives have been developed. In some cases, these derivatives have been shown to possess improved activity, not only compared to trans-cinnamaldehyde but also to commonly used antibiotics. Therefore, understanding the antibacterial mechanisms of action that these compounds elicit is imperative in order to facilitate their development and the development of new antibacterial agents that could exploit similar mechanistic approaches. The purpose of this review is to provide an overview of current knowledge on the antibacterial activity and mechanisms of action of cinnamaldehyde and its derivatives, and to highlight significant contributions made in this research area. It is hoped that the findings presented in this work will aid the future development of new antibacterial agents.

Regulating intracellular ROS signal by a dual pH/reducing-responsive nanogels system promotes tumor cell apoptosis

Purpose: The levels of reactive oxygen species (ROS) in tumor cells are much higher than that in normal cells, and rise rapidly under the influence of exogenous or endogenous inducing factors, eventually leading to the apoptosis of tumor cells. Therefore, this study prepared a dual pH/reducing-responsive poly (N-isopropylacrylamide-co-Cinnamaldehyde-co-D-α-tocopheryl polyethylene glycol 1000 succinate, PssNCT) nanogels, which employed two exogenous ROS inducers, cinnamaldehyde (CA) and D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS), to selectively induce apoptosis by regulating ROS levels in tumor cells. Methods: The PssNCT nanogels were prepared by the free radical precipitation polymerization under the crosslink between pH-sensitive hydrazone and reducing-sensitive disulfide bonds, followed by the physicochemical and morphological characteristics investigations. Plasma stability, dual pH/reducing responsive degradation and in vitro release were also assessed. In cell experiments, cytotoxicity in different cells were first detected. The intracellular ROS levels and mitochondrial functions of tumor cells were then evaluated. Moreover, the apoptosis and western-blot assays were employed to verify the association between ROS levels elevation and apoptosis in tumor cells. Results: The nanogels exhibited a round-like hollow structure with the diameter smaller than 200nm. The nanogels were stable in plasma, while showed rapid degradation in acidic and reducing environments, thus achieving significant release of CA and TPGS in these media. Furthermore, the sufficient amplification of ROS signals was induced by the synergistically function of CA and TPGS on mitochondria, which resulted in the opening of the mitochondrial apoptotic pathway and enhanced cytotoxicity on MCF-7 cells. However, nanogels barely affected L929 cells owing to their lower intracellular ROS basal levels. Conclusion: The specific ROS regulation method achieved by these nanogels could be explored to selectively kill tumor cells according to the difference of ROS signals in different kinds of cells.

Anti-cancer effects of cinnamon: Insights into its apoptosis effects

Cancer is known as a leading cause of death worldwide. In the last two decades, the incidence of cancer has been dramatically increased mostly due to lifestyle changes. The importance of this issue has attracted further attention to discover novel therapies to prevent and treat cancers. According to previous studies, drugs used to treat cancer have shown significant limitations. Therefore, the role of herbal medicines alone or in combination with chemotherapy drugs has been extensively studied in cancer treatment. Cinnamon is a natural component showing a wide range of pharmacological functions including anti-oxidant, anti-microbial and anti-cancer activities. Impaired apoptosis plays critical roles in the initiation and progression of cancer. Increasing evidence indicates that cinnamon, as a therapeutic agent, has anti-cancer effects via affecting numerous apoptosis-related pathways in cancer cells. Here, we highlighted anticancer properties of cinnamon, particularly through targeting apoptosis-related mechanisms.

Combined treatment with 2'-hydroxycinnamaldehyde and temozolomide suppresses glioblastoma tumorspheres by decreasing stemness and invasiveness

INTRODUCTION

Glioblastoma (GBM) is the most common and aggressive human primary brain malignancy. The key properties of GBM, stemness and invasiveness, are known to be associated with a highly unfavorable prognosis. Notably, the process of epithelial-mesenchymal transition (EMT) is closely related to the progression of GBM. On the basis of reports that 2'-hydroxycinnamaldehyde (HCA) and its derivative, 2'-benzoyloxycinnamaldehyde (BCA), suppresses EMT in several human cancer cells, we sought to evaluate the therapeutic efficacy of HCA and BCA, alone and in combination with temozolomide (TMZ), on GBM tumorspheres (TSs).

METHODS

Two human GBM TSs were treated with HCA, BCA, or TMZ. Therapeutic effects were evaluated by measuring ATP levels, neurosphere formation, 3D-invasion in collagen matrix, and viability. Protein expression profiles after drug treatment were evaluated by western blotting. In vivo anticancer efficacy of drugs was examined in a mouse orthotopic xenograft model.

RESULTS

Combined treatment of GBM TSs with HCA or BCA and TMZ significantly reduced cell viability, stemness, and invasiveness. Expression levels of stemness-, invasiveness-, and mesenchymal transition-associated markers, Zeb1, N-cadherin, and β-catenin, were also substantially decreased by the combined treatment. The combined treatment also reduced tumor growth in a mouse orthotopic xenograft model.

CONCLUSION

Our findings suggest that HCA and BCA, combined with TMZ, are potential therapeutic agents in the treatment of GBM.

Acid-responsive nanoparticles as a novel oxidative stress-inducing anticancer therapeutic agent for colon cancer

Objective

Nanoparticles can efficiently carry and deliver anticancer agents to tumor sites. Mounting evidence indicates that many types of cancer cells, including colon cancer, have a weakly acidic microenvironment and increased levels of reactive oxygen species. The construction of nano drug delivery vehicles "activatable" in response to the tumor microenvironment is a new antitumor therapeutic strategy.

Methods

Cinnamaldehyde (CA) was designed to link directly with dextran to form a polymer through an acid cleavable acetal bond. Herein, a novel pH-sensitive drug delivery system was constructed with co-encapsulated 10-hydroxy camptothecin (HCPT). Dynamic light scattering (DLS) analysis, transmission electron microscopy (TEM) analysis, and release kinetics analysis of HCPT-CA-loaded nanoparticles (PCH) were conducted to investigate the physical and chemical properties. The cellular uptake signatures of the nanoparticles were observed by confocal microscopy and flow cytometry. Cell viability, cell scratch assay, apoptosis assay, and colony formation assay were performed to examine the potent antiproliferative and apoptotic effects of the PCH. The antitumor mechanism of the treatment with PCH was evaluated by Western blotting, flow cytometry, and TEM analysis. The pharmacokinetics of PCH were examined in healthy Sprague Dawley rats within 6 hours after sublingual vein injection. We lastly examined the biodistribution and the in vivo anticancer activity of PCH using the xenograft mouse models of HCT116 cells.

Results

Both HCPT and CA were quickly released by PCH in an acidic microenvironment. PCH not only induced cancer cell death through the generation of intracellular reactive oxygen species in vitro but also facilitated the drug uptake, effectively prolonged drug circulation, and increased accumulation of drug in tumor sites. More attractively, PCH exhibited excellent therapeutic performance and better in vivo systemic safety.

Conclusion

Overall, PCH not only utilized the tumor microenvironment to control drug release, improve drug pharmacokinetics, and passively target the drug to the tumor tissue, but also exerted a synergistic anticancer effect. The acid-responsive PCH has enormous potential as a novel anticancer therapeutic strategy.

2'-Hydroxycinnamaldehyde inhibits proliferation and induces apoptosis via signal transducer and activator of transcription 3 inactivation and reactive oxygen species generation

Inhibition of the signal transducer and activator of transcription 3 (STAT3) signaling pathway is a novel therapeutic strategy to treat human cancers with constitutively active STAT3. During the screening of natural products to find STAT3 inhibitors, we identified 2′‐hydroxycinnamaldehyde (HCA) as a STAT3 inhibitor, which was isolated from the stem bark of Cinnamomum cassia. In this study, we found that HCA inhibited constitutive and inducible STAT3 activation in STAT3‐activated DU145 prostate cancer cells. HCA selectively inhibited the STAT3 activity by direct binding to STAT3, which was confirmed by biochemical methods, including a pull‐down assay with biotin‐conjugated HCA, a drug affinity responsive target stability (DARTS) experiment and a cellular thermal shift assay (CETSA). HCA inhibited STAT3 phosphorylation at the tyrosine 705 residue, dimer formation, and nuclear translocation in DU145 cells, which led to a downregulation of STAT3 target genes. The downregulation of cell cycle progression and antiapoptosis‐related gene expression by HCA induced the accumulation of cells in the G0/G1 phase of the cell cycle and then induced apoptosis. We also found that reactive oxygen species (ROS) were involved in the HCA‐induced inhibition of STAT3 activation and cell proliferation because the suppressed p‐STAT3 level was rescued by glutathione or N‐acetyl‐L‐cysteine treatment, which are general ROS inhibitors. These results suggest that HCA could be a potent anticancer agent targeting STAT3‐activated tumor cells.

Cinnamaldehydes in Cancer Chemotherapy

Cinnamaldehyde and cinnamaldehyde-derived compounds are candidates for the development of anticancer drugs that have received extensive research attention. In this review, we summarize recent findings detailing the positive and negative aspects of cinnamaldehyde and its derivatives as potential anticancer drug candidates. Furthermore, we describe the in vivo pharmacokinetics and metabolism of cinnamaldehydes. The oxidative and antioxidative properties of cinnamaldehydes, which contribute to their potential in chemotherapy, have also been discussed. Moreover, the mechanism(s) by which cinnamaldehydes induce apoptosis in cancer cells have been explored. In addition, evidence of the regulatory effects of cinnamaldehydes on cancer cell invasion and metastasis has been described. Finally, the application of cinnamaldehydes in treating various types of cancer, including breast, prostate, and colon cancers, has been discussed in detail. The effects of cinnamaldehydes on leukemia, hepatocellular carcinoma, and oral cancer have been summarized briefly. Copyright © 2016 John Wiley & Sons, Ltd.

The anticancer mechanism of 2'-hydroxycinnamaldehyde in human head and neck cancer cells

Cinnamaldehyde has been shown to effectively induce apoptosis in a number of human cancer cells. In the present study, cinnamaldehyde derivative-induced apoptosis and its signaling pathways were assessed in p53-wild (SGT) and p53-mutant (YD-10B) human head and neck cancer cells. The cinnamaldehyde derivatives, 2'-hydroxycinnamaldehyde (HCA) and 2'-benzoyloxycinnamaldehyde (BCA), exhibited powerful anti-proliferative effects on SGT and YD-10B cells. The apoptotic effect induced by HCA or BCA was supported by caspase-3, -7, -9 and PARP activation, and confirmed by Annexin V-FITC/PI double staining. HCA induced the expression of p21 in both SGT and YD-10B cells. Furthermore, HCA induced the level of pro-apoptotic Bak1 expression while decreasing the level of anti-apoptotic Bcl-2 in both cell lines, suggesting that HCA induced the cell death pathway in a p53-independent manner. HCA also induced the expression of LC3B in SGT and YD-10B cells. Following pre-incubation with the autophagy inhibitor 3-MA, HCA-induced apoptosis was largely increased in SGT cells, while inhibited in YD-10B cells, suggesting that autophagy may actively contribute to HCA-induced apoptosis. Taken together, these observations suggest that HCA may be an effective therapeutic agent in the treatment of head and neck cancer regardless of p53 status.

Cinnamon: Mystic powers of a minute ingredient

Cinnamon, due to its exotic flavor and aroma, is a key ingredient in the kitchen of every household. From the beginning of its use in 2800 BC by our ancestors for various purposes such as anointment, embalming and various ailments, it has instigated the interest of many researchers. Recently many trials have explored the beneficial effects of cinnamon in Parkinsons, diabetes, blood, and brain. After extensive research on PubMed and Google scholar, data were collected regarding its antioxidant, anti-inflammatory, antilipemic, antidiabetic, antimicrobial, and anticancer effect. This systematic review underlines the surplus health benefits of this clandestine ingredient and the scope of further research in these clinical scenarios.

A Novel Cinnamon-Related Natural Product with Pim-1 Inhibitory Activity Inhibits Leukemia and Skin Cancer

The Pim-1 kinase regulates cell survival, proliferation, and differentiation and is overexpressed frequently in many malignancies, including leukemia and skin cancer. In this study, we used kinase profiling analysis to demonstrate that 2'-hydroxycinnamicaldehyde (2'-HCA), a compound found in cinnamon, specifically inhibits Pim-1 activity. Cocrystallography studies determined the hydrogen bonding pattern between 2'-HCA and Pim-1. Notably, 2'-HCA binding altered the apo kinase structure in a manner that shielded the ligand from solvent, thereby acting as a gatekeeper loop. Biologically, 2'-HCA inhibited the growth of human erythroleukemia or squamous epidermoid carcinoma cells by inducing apoptosis. The compound was also effective as a chemopreventive agent against EGF-mediated neoplastic transformation. Finally, 2'-HCA potently suppressed the growth of mouse xenografts representing human leukemia or skin cancer. Overall, our results offered preclinical proof of concept for 2'-HCA as a potent anticancer principle arising from direct targeting of the Pim-1 kinase.

Hydrogen peroxide-responsive anticancer hyperbranched polymer micelles for enhanced cell apoptosis

Hydrogen peroxide-responsive nanomicelles from hyperbranched polymers were developed for effective cancer therapy through enhanced apoptotic cell death.

EGR1-dependent PTEN upregulation by 2-benzoyloxycinnamaldehyde attenuates cell invasion and EMT in colon cancer

There has been little evidence to support EGR1 and PTEN function on the EMT of cancer cells. We tried to evaluate how these genes affect cancer cell invasion and EMT through investigating the molecular mechanism(s) of 2'-benzoyloxycinnamaldehyde (BCA). Matrigel invasion and wound healing assay, and in vivo mice model were used to evaluate the effect of BCA on colon cancer cell migration. The molecular mechanism(s) of BCA were evaluated by knock-down or overexpression of EGR1 and PTEN. BCA at 50 nM increased E-cadherin and EGR1 expression without cytotoxicity. Cell migration was inhibited significantly by BCA both in vitro and in vivo. Moreover, BCA inhibits Snail and Vimentin expression, as well as β-catenin nuclear accumulation. Suppression of EGR1 by siRNA attenuated the inhibition of matrigel invasion by BCA, indicating that EGR1 is responsible for BCA effect. PTEN was upregulated by BCA treatment or EGR1 overexpression. In addition, shPTEN transfection stimulated EMT and cell invasion in vitro. Our data suggest that BCA leads to a remarkable upregulation of EGR1 expression, and that EMT and invasion is decreased via EGR1-dependent PTEN activation. These data showed a critical role of EGR1-PTEN signaling pathway in the EMT of colon cancer, as well as metastasis.

Early growth response protein 1 upregulation and nuclear translocation by 2'-benzoyloxycinnamaldehyde induces prostate cancer cell death

2'-Benzoyloxycinnamaldehyde (BCA) induces apoptosis in human cancer cells through ROS generation. BCA upregulates proapoptotic genes such as activating transcription factor 3 (ATF3), NSAID-activated gene 1 protein (NAG-1), and growth arrest and DNA-damage-inducible protein alpha (GADD45A) in prostate cancer cells. These genes are known to be induced by transcription factor early growth response protein 1 (EGR1). BCA induces significant EGR1 upregulation, while EGR1 knockdown decreases the induction of these genes with concurrent alleviation of cell death by BCA. Antioxidant glutathione pretreatment with BCA removes EGR1 expression increase, suggesting that EGR1 upregulation is dependent on oxidative stress generated by BCA. In prostate cancer cells, EGR1 localizes in the cytoplasm; however, BCA remarkably upregulates EGR1 nuclear translocalization, suggesting its possible effect as a transcriptional activator. BCA induces transient upregulation of importin-7 (IPO7) which is critical for EGR1 nuclear translocation, and IPO7 knockdown led to a significant decrease in chemosensitivity to BCA. Taken together, our findings suggest that BCA induces prostate cancer cell death via EGR1 upregulation and nuclear translocalization, followed by activation of proapoptotic target genes.

Induction of tumor cell death through targeting tubulin and evoking dysregulation of cell cycle regulatory proteins by multifunctional cinnamaldehydes

Multifunctional trans-cinnamaldehyde (CA) and its analogs display anti-cancer properties, with 2-benzoyloxycinnamaldehyde (BCA) and 5-fluoro-2-hydroxycinnamaldehyde (FHCA) being identified as the ortho-substituted analogs that possess potent anti-tumor activities. In this study, BCA, FHCA and a novel analog 5-fluoro-2-benzoyloxycinnamaldehyde (FBCA), were demonstrated to decrease growth and colony formation of human colon-derived HCT 116 and mammary-derived MCF-7 carcinoma cells under non-adhesive conditions. The 2-benzoyloxy and 5-fluoro substituents rendered FBCA more potent than BCA and equipotent to FHCA. The cellular events by which these cinnamaldehydes caused G(2)/M phase arrest and halted proliferation of HCT 116 cells were thereby investigated. Lack of significant accumulation of mitosis marker phospho-histone H3 in cinnamaldehyde-treated cells indicated that the analogs arrested cells in G(2) phase. G(2) arrest was brought about partly by cinnamaldehyde-mediated depletion of cell cycle proteins involved in regulating G(2) to M transition and spindle assembly, namely cdk1, cdc25C, mad2, cdc20 and survivin. Cyclin B1 levels were found to be increased, which in the absence of active cdk1, would fail to drive cells into M phase. Concentrations of cinnamaldehydes that brought about dysregulation of levels of cell cycle proteins also caused tubulin aggregation, as evident from immunodetection of dose-dependent tubulin accumulation in the insoluble cell lysate fractions. In a cell-free system, reduced biotin-conjugated iodoacetamide (BIAM) labeling of tubulin protein pretreated with cinnamaldehydes was indicative of drug interaction with the sulfhydryl groups in tubulin. In conclusion, cinnamaldehydes treatment at proapoptotic concentrations caused tubulin aggregation and dysegulation of cell cycle regulatory proteins cdk1 and cdc25C that contributed at least in part to arresting cells at G(2) phase, resulting in apoptotic cell death characterized by emergence of cleaved forms of caspase 3 and poly (ADP-ribose) polymerase (PARP). Results presented in this study have thus provided further insights into the intricate network of cellular events by which cinnamaldehydes induce tumor cell death.

Shikonin induces immunogenic cell death in tumor cells and enhances dendritic cell-based cancer vaccine

Immunogenic cell death is characterized by damage-associated molecular patterns, which can enhance the maturation and antigen uptake of dendritic cells. Shikonin, an anti-inflammatory and antitumor phytochemical, was exploited here as an adjuvant for dendritic cell-based cancer vaccines via induction of immunogenic cell death. Shikonin can effectively activate both receptor- and mitochondria-mediated apoptosis and increase the expression of all five tested damage-associated molecular patterns in the resultant tumor cell lysates. The combination treatment with damage-associated molecular patterns and LPS activates dendritic cells to a high maturation status and enhances the priming of Th1/Th17 effector cells. Shikonin-tumor cell lysate-loaded mature dendritic cells exhibit a high level of CD86 and MHC class II and activate Th1 cells. The shikonin-tumor cell lysate-loaded dendritic cell vaccines result in a strong induction of cytotoxic activity of splenocytes against target tumor cells, a retardation in tumor growth, and an increase in the survival of test mice. The much enhanced immunogenicity and efficacy of the current cancer vaccine formulation, that is, the use of shikonin-treated tumor cells as cell lysates for the pulse of dendritic cells in culture, may suggest a new ex vivo approach for developing individualized, dendritic cells-based anticancer vaccines.

2'-Benzoyloxycinnamaldehyde-mediated DJ-1 upregulation protects MCF-7 cells from mitochondrial damage

2'-Benzoyloxycinnamaldehyde (BCA) is a promising antitumor agent which induces cancer cells apoptosis via reactive oxygen species (ROS) generation. BCA shows more effective antiproliferation in MDA-MB-435 than in MCF-7 breast cancer cells. DJ-1 has been known to protect cells against oxidative stress as an antioxidant because of its cysteine residues sensitive to oxidative stress. In the present study, we evaluated the mechanism of DJ-1 for cell protection from oxidative stress after BCA treatment in MCF-7 cell. BCA upregulates the expression of DJ-1 in MCF-7 cells. However, DJ-1 expression decreased continuously for 24 h after BCA treatment in MDA-MB-435 cells. DJ-1 knockdown sensitized MCF-7 cells to BCA, on the contrary, DJ-1 overexpression induced MDA-MB-435 cells less sensitive to BCA. Confocal microscopic observation showed that only in MCF-7 cells BCA increased the overlapped signal between mitochondria and DJ-1 protein. Mitochondrial membrane potential (MMP) was decreased in MDA-MB-435 cells by BCA, and DJ-1 overexpression inhibited BCA-induced MMP decrease in these cells. On the contrary, DJ-1 knockdown in MCF-7 induced MMP perturbation by BCA. These findings suggest that DJ-1 upregulation protects MCF-7 cells from BCA via inhibiting mitochondrial damage.

2-Hydroxycurcuminoid induces apoptosis of human tumor cells through the reactive oxygen species-mitochondria pathway

2-Hydroxycinnamaldehyde (HCA) and curcumin have been reported to have antitumor effects against various human tumor cells in vitro and in vivo by generation of ROS. Aldehyde-free HCA analogs were synthesized based on the structure of curcumin, which we have called 2-hydroxycurcuminoids. The hydroxyl group of curcuminoids enhances the ability to generate ROS. 2-Hydroxycurcuminoid (HCC-7) strongly inhibited the growth of SW620 colon tumor cells with a GI(50) value of 7μM, while the parent compounds, HCA and curcumin, displayed GI(50) values of 12 and 30μM, respectively. HCC-7 was found to induce apoptosis through the reactive oxygen species-mitochondria pathway and cell cycle arrest at G2/M phase.

Increased accumulation of hypoxia-inducible factor-1α with reduced transcriptional activity mediates the antitumor effect of triptolide

Background

Hypoxia-inducible factor-1α (HIF-1α), a critical transcription factor to reduced O₂ availability, has been demonstrated to be extensively involved in tumor survival, aggressive progression, drug resistance and angiogenesis. Thus it has been considered as a potential anticancer target. Triptolide is the main principle responsible for the biological activities of the Traditional Chinese Medicine tripterygium wilfordii Hook F. Triptolide possesses great chemotherapy potential for cancer with its broad-spectrum anticancer, antiangiogenesis, and drug-resistance circumvention activities. Numerous biological molecules inhibited by triptolide have been viewed as its possible targets. However, the anticancer action mechanisms of triptolide remains to be further investigated. Here we used human ovarian SKOV-3 cancer cells as a model to probe the effect of triptolide on HIF-1α.

Results

Triptolide was observed to inhibit the proliferation of SKOV-3 cells, and meanwhile, to enhance the accumulation of HIF-1α protein in SKOV-3, A549 and DU145 cells under different conditions. Triptolide did not change the kinetics or nuclear localization of HIF-1α protein or the 26 S proteasome activity in SKOV-3 cells. However, triptolide was found to increase the levels of HIF-1α mRNA. Unexpectedly, the HIF-1α protein induced by triptolide appeared to lose its transcriptional activity, as evidenced by the decreased mRNA levels of its target genes including VEGF, BNIP3 and CAIX. The results were further strengthened by the lowered secretion of VEGF protein, the reduced sprout outgrowth from the rat aorta rings and the inhibitory expression of the hypoxia responsive element-driven luciferase reporter gene. Moreover, the silencing of HIF-1α partially prevented the cytotoxicity and apoptosis triggered by triptolide.

Conclusions

The potent induction of HIF-1α protein involved in its cytotoxicity, together with the suppression of HIF-1 transcriptional activity, indicates the great therapeutic potential of triptolide as an anticancer drug. Meanwhile, our data further stress the possibility that HIF-1α functions in an unresolved nature or condition.

Transport and metabolism of the antitumour drug candidate 2'-benzoyloxycinnamaldehyde in Caco-2 cells

The transport and metabolism of the antitumour drug candidate 2'-benzoyloxycinnamaldehyde (BCA) was characterized in Caco-2 cells. BCA disappeared rapidly from the donor side without being transported to the receiver side during its absorptive transport across Caco-2 cells. Its metabolites 2'-hydroxycinnamaldehyde (HCA) and o-coumaric acid (OCA) were formed in both the donor and the receiver sides. HCA, in a separate study, also disappeared rapidly from the donor side, mostly being converted to its oxidative metabolite OCA during its absorptive transport across Caco-2 cells. OCA was transported rapidly in the absorptive direction across Caco-2 cells with a P(app) of 25.4 +/- 1.0 x 10(-6) cm s(-1) (mean +/- standard deviation (SD), n = 3). OCA was fully recovered from both the donor and the receiver side throughout the time-course of this study. Formation of HCA from BCA was inhibited almost completely by bis(p-nitrophenyl)phosphate (BNPP), a selective inhibitor of carboxylesterases (CES), and phenylmethylsulfonyl fluoride (PMSF), a broad specificity inhibitor of esterases in Caco-2 cells, suggesting that this hydrolytic biotransformation was likely mediated predominantly by CES. Conversion of HCA to OCA was inhibited significantly by isovanillin, a selective inhibitor of aldehyde oxidase (AO). Inhibitors for xanthine oxidase (XO) and aldehyde dehydrogenase (ALDH), which are known to be involved in the oxidation of aldehydes to carboxylic acids, did not have a significant effect on the biotransformation of HCA to OCA in Caco-2 cells. In summary, the present work demonstrates that BCA is hydrolysed rapidly to HCA, followed by subsequent oxidation to OCA, in Caco-2 cells. The results provide a mechanistic understanding of the poor absorption and low bioavailability of BCA after oral administration.

2'-Benzoyloxycinnamaldehyde inhibits tumor growth in H-ras12V transgenic mice via downregulation of metallothionein

Cinnamaldehydes have been reported to induce apoptosis in human carcinomas through the generation of reactive oxygen species (ROS). 2'-benzoyloxycinnamaldehyde (BCA) has been reported to inhibit tumor formation in H-ras12V transgenic mice. To see the antitumor effects of BCA, BCA was administrated intraperitoneally (50 mg/kg) to H-ras12V transgenic mice for 3 wk, and it was found that the hepatic tumor volume and the total number of tumors were decreased in BCA-treated mice as compared to control H-ras12V transgenic mice. To identify possible target genes responsible for BCA antitumor effects in H-ras12V transgenic mice, cDNA microarray analyses were performed comparing gene expression between BCA treated and control transgenic mice. We found that 42 genes were downregulated, and 40 genes were upregulated in the BCA-treated transgenic mice. The downregulated genes included several genes involved in ROS regulation and immune response (aconitase, metallothionein-1, metallothionein-2, and purine nucleoside phosphorylase). The expression of ROS-related genes, metallothionein 1 and metallothionein 2, was decreased more than twofold with BCA treatment (P < 0.001). It was confirmed by RT-PCR and immunohistochemical analyses. The inhibition of tumor formation and growth in H-ras12V transgenic mice by BCA was mediated through inhibition of the expression of the ROS scavengers metallothionein 1 and metallothionein 2.

Cinnamaldehydes inhibit thioredoxin reductase and induce Nrf2: potential candidates for cancer therapy and chemoprevention

Trans-cinnamaldehyde (CA) and its analogs 2-hydroxycinnamaldehyde and 2-benzoyloxycinnamaldehyde have been reported to possess antitumor activity. CA is also a known Nrf2 activator. In this study, a series of ortho-substituted cinnamaldehyde analogs was synthesized and screened for antiproliferative and thioredoxin reductase (TrxR)-inhibitory activities. Whereas CA was weakly cytotoxic and TrxR inhibiting, hydroxy and benzoyloxy substitutions resulted in analogs with enhanced antiproliferative activity paralleling increased potency in TrxR inactivation. A novel analog, 5-fluoro-2-hydroxycinnamaldehyde, was identified as exhibiting the strongest antitumor effect (GI(50) 1.6 microM in HCT 116 cells) and TrxR inhibition (IC(50) 7 microM, 1 h incubation with recombinant TrxR). CA and its 2-hydroxy- and 2-benzoyloxy-substituted analogs possessed dual TrxR-inhibitory and Nrf2-inducing effects, both attributed to an active Michael acceptor pharmacophore. At lethal concentrations, TrxR-inhibitory potencies correlated with the compounds' antiproliferative activities. The penultimate C-terminal selenocysteine residue was shown to be a possible target. Conversely, at sublethal concentrations, these agents induced an adaptive antioxidant response through Nrf2-mediated upregulation of phase II enzymes, including TrxR induction. We conclude from the results obtained that TrxR inactivation contributes at least partly to cinnamaldehyde cytotoxicity. These Michael acceptor molecules can potentially be exploited for use in different concentrations in chemotherapeutic and chemopreventive strategies.

Identification and characterization of molecular targets of natural products by mass spectrometry

Natural products, and their derivatives and mimics, have contributed to the development of important therapeutics to combat diseases such as infections and cancers over the past decades. The value of natural products to modern drug discovery is still considerable. However, its development is hampered by a lack of a mechanistic understanding of their molecular action, as opposed to the emerging molecule-targeted therapeutics that are tailored to a specific protein target(s). Recent advances in the mass spectrometry-based proteomic approaches have the potential to offer unprecedented insights into the molecular action of natural products. Chemical proteomics is established as an invaluable tool for the identification of protein targets of natural products. Small-molecule affinity selection combined with mass spectrometry is a successful strategy to "fish" cellular targets from the entire proteome. Mass spectrometry-based profiling of protein expression is also routinely employed to elucidate molecular pathways involved in the therapeutic and possible toxicological responses upon treatment with natural products. In addition, mass spectrometry is increasingly utilized to probe structural aspects of natural products-protein interactions. Limited proteolysis, photoaffinity labeling, and hydrogen/deuterium exchange in conjunction with mass spectrometry are sensitive and high-throughput strategies that provide low-resolution structural information of non-covalent natural product-protein complexes. In this review, we provide an overview on the applications of mass spectrometry-based techniques in the identification and characterization of natural product-protein interactions, and we describe how these applications might revolutionize natural product-based drug discovery.

Redox-directed cancer therapeutics: molecular mechanisms and opportunities

Redox dysregulation originating from metabolic alterations and dependence on mitogenic and survival signaling through reactive oxygen species represents a specific vulnerability of malignant cells that can be selectively targeted by redox chemotherapeutics. This review will present an update on drug discovery, target identification, and mechanisms of action of experimental redox chemotherapeutics with a focus on pro- and antioxidant redox modulators now in advanced phases of preclinal and clinical development. Recent research indicates that numerous oncogenes and tumor suppressor genes exert their functions in part through redox mechanisms amenable to pharmacological intervention by redox chemotherapeutics. The pleiotropic action of many redox chemotherapeutics that involves simultaneous modulation of multiple redox sensitive targets can overcome cancer cell drug resistance originating from redundancy of oncogenic signaling and rapid mutation.Moreover, some redox chemotherapeutics may function according to the concept of synthetic lethality (i.e., drug cytotoxicity is confined to cancer cells that display loss of function mutations in tumor suppressor genes or upregulation of oncogene expression). The impressive number of ongoing clinical trials that examine therapeutic performance of novel redox drugs in cancer patients demonstrates that redox chemotherapy has made the crucial transition from bench to bedside.

Structure-activity analysis of 2'-modified cinnamaldehyde analogues as potential anticancer agents

The natural product 2'-hydroxycinnamaldehyde (HCA) and its analogue, 2'-benzoyloxycinnamaldehyde (BCA), have been previously shown to have antiproliferative and proapoptotic effects in vitro and inhibit tumor growth in vivo. In this study, we use structure-activity analysis to define structural features that are important for the activity of cinnamaldehyde analogues. Our results emphasize an important role for both the propenal group as well as the modification at the 2'-position. Further studies were aimed to characterize the mechanism of action of BCA. Exposure to BCA induced cell death via caspase-dependent and -independent pathways. Cell death was not due to autophagy or necrosis as a result of energy depletion or induction of reactive oxygen species. Our findings have important implications for future drug design and highlight the importance of defining molecular drug targets for this promising class of potential anticancer agents.

The thioxotriazole copper(II) complex A0 induces endoplasmic reticulum stress and paraptotic death in human cancer cells

The copper(II) complex A0 induces a type of non-apoptotic cell death also known as paraptosis. Paraptosis involves extensive endoplasmic reticulum vacuolization in the absence of caspase activation. A wide panel of human cancer cell lines was used to demonstrate differences in cytotoxicity by the paraptosis-inducing drug A0 and the metal-based pro-apoptotic drug cisplatin. Gene expression profiling of the human fibrosarcoma HT1080 cells showed that, while cisplatin induced p53 targets, A0 up-regulated genes involved in the unfolded protein response (UPR) and response to heavy metals. The cytotoxic effects of A0 were associated with inhibition of the ubiquitin-proteasome system and accumulation of ubiquitinylated proteins, in a manner dependent on protein synthesis. Cycloheximide inhibited the accumulation of ubiquitinylated proteins and hampered A0-induced cell death process. The occurrence of the UPR during A0-induced death process was shown by the increased abundance of spliced XBP1 mRNA, transient eIF2alpha phosphorylation, and a series of downstream events, including attenuation of global protein synthesis and increased expression of ATF4, CHOP, BIP, and GADD34. Mouse embryonic fibroblasts expressing a mutant eIF2alpha, which could not be phosphorylated, were more resistant to A0 than wild type cells, pointing to a pro-death role of eIF2alpha phosphorylation. A0 may thus represent the prototypical member of a new class of compounds that cause paraptotic cell death via mechanisms involving eIF2alpha phosphorylation and the UPR.

Plasma pharmacokinetics and metabolism of the antitumour drug candidate 2'-benzoyloxycinnamaldehyde in rats

The pharmacokinetics and metabolism of 2'-benzoyloxycinnamaldehyde (BCA) was characterized in male Sprague-Dawley rats as part of the preclinical evaluations for developing this compound as an antitumour agent. BCA was not detected in the plasma following either intravenous or oral dose, whereas its putative metabolites 2'-hydroxycinnamaldehyde (HCA) and o-coumaric acid were present at considerable levels. In separate pharmacokinetics studies, HCA exhibited a high systemic clearance and a large volume of distribution, whereas both pharmacokinetic parameters were much lower for o-coumaric acid. The terminal half-life of both metabolites was approximately 2 h. BCA was converted rapidly to HCA in rat serum, liver microsomes and cytosol in vitro; HCA was subsequently converted to o-coumaric acid in a quantitative manner only in the liver cytosol. In addition, the formation of o-coumaric acid was inhibited significantly by menadione, a specific inhibitor for aldehyde oxidase. Taken collectively, the results suggest that the rapid systemic clearance of HCA is likely due mainly to hepatic clearance occurring from aldehyde oxidase-catalysed biotransformation to o- coumaric acid. In conclusion, the present work demonstrates that the anticancer drug candidate BCA is highly likely to work as its active metabolite HCA in the body.