Phenethyl Isothiocyanate Research Articles

Anti-rheumatic activity of Phenethyl isothiocyanate via inhibition of histone deacetylase-1

Rheumatoid Arthritis (RA) affects approximately 1% of the total world population. Despite incessant research and development of new therapeutic agents, management of RA is still a troublesome affair. Histone Deacetylase 1 (HDAC1) is an epigenetic regulator which play important role in pathogenesis of RA. In present study, we hypothesized that Phenethyl isothiocyanate (PEITC), a potent inhibitor of HDAC1, may ameliorate RA. Efficacy of PEITC was evaluated in Complete Freund's Adjuvant (CFA) induced arthritis model in rats. CFA (0.1 ml) was injected subplantarly in the left hind paw on day 0 to all the groups except normal control. The administration of test drug PEITC (10, 24 & 50 mg/kg) and standard drug Ibuprofen started simultaneously and was continued for 21 days. Paw edema, total arthritic index, mobility score, stair climbing ability, behavioral parameters, and bone erosion were evaluated. Further, radiographic studies, TNF-alpha as well as HDAC1 levels in synovial tissue homogenate and histological analysis were performed. Prophylactic treatment of PEITC attenuated paw edema, total arthritic index, mobility score, stair climbing ability, behavioral parameters, and bone erosion in dose dependent manner. Furthermore, there was significant decrease in TNF-alpha as well as HDAC1 levels in synovial tissue homogenate. Histological analysis revealed no cartilage damage, bone erosion, hyperplasia at synovial lining as well as infiltration of inflammatory cells in treatment group. Results of this study suggest potent anti-rheumatoid arthritis activity of Phenethyl isothiocyanate in CFA induced RA model in rats.

β-Phenethyl Isothiocyanate Induces Cell Death in Human Osteosarcoma through Altering Iron Metabolism, Disturbing the Redox Balance, and Activating the MAPK Signaling Pathway

Osteosarcoma is the most common primary malignancy of the skeleton in children and adults. The outcomes of people with osteosarcomas are unsatisfied. β-Phenethyl isothiocyanate (PEITC) exhibits chemoprevention and chemotherapeutic activities against many human cancers. The molecular mechanism underlying its action on osteosarcoma is still unknown. This study was aimed at investigating the effect of PEITC on human osteosarcoma both in vitro and in vivo. The results showed that PEITC reduced cell viability, inhibited proliferation, and caused G2/M cell cycle arrest in four human osteosarcoma cell lines (MNNG/HOS, U-2 OS, MG-63, and 143B). Then, we found that PEITC altered iron metabolism related to the processes of iron import, storage, and export, which resulted in increased labile iron. Expectedly, PEITC caused oxidative stress as a consequence of GSH depletion-inducing ROS generation and lipid peroxidation. Multiple cell death modalities, including ferroptosis, apoptosis, and autophagy, were triggered in human osteosarcoma cells. Three MAPKs (ERK, p38, and JNK) were all activated after PEITC treatment; however, they presented different responses among the four human osteosarcoma cell lines. ROS generation was proved to be the major cause of PEITC-induced decreased proliferative potential, altered iron metabolism, cell death, and activated MAPKs in human osteosarcoma cells. In addition, PEITC also significantly delayed tumor growth in a xenograft osteosarcoma mouse model with a 30 mg/kg administration dose. In conclusion, this study reveals that PEITC simultaneously triggers ferroptosis, apoptosis, and autophagy in human osteosarcoma cells by inducing oxidative stress.

Nutrientes e compostos bioativos na modulação epigenética associada à prevenção e combate ao câncer

Os componentes presentes em alguns alimentos tem a capacidade de influenciar diretamente o processo saúde-doença por meio de mecanismos moleculares epigenéticos, reduzindo o risco de desenvolvimento de algumas doenças, sobretudo as Doenças Crônicas Não Transmissíveis (DCNTs), como o câncer. Nesse sentido, o presente estudo busca elucidar o papel de alguns nutrientes e compostos bioativos dos alimentos na modulação epigenética como forma de prevenção e combate ao câncer. Para tanto, foi realizada uma busca sistemática nas bases de dados LILACS, PubMed e BVS. Foram utilizados os descritores: Epigenômica, Compostos Fitoquímicos, Neoplasias e Nutrientes, todos selecionados de acordo com os Descritores em Ciências da Saúde e utilizados nos idiomas: Português e Inglês. Inicialmente foram encontradas 3177 publicações e após a aplicação dos critérios de inclusão e exclusão pré-definidos, restaram 9 publicações pertinentes para construção do trabalho. Verificou-se a partir da literatura selecionada, que alguns nutrientes e compostos bioativos, tais como a Curcumina do açafrão da terra, o Sulforafano e o Isotiocianato de Fenetil (PEITC) dos vegetais crucíferos, o Resveratrol (RES) das uvas vermelhas e do vinho, o β-caroteno dos vegetais alaranjados, a Vitamina C das frutas cítricas e alguns fitoquímicos, como a Quercetina e o Ácido cafeico, desempenham importante papel no combate ao câncer, pois, dentre outros benefícios, eles podem estimular epigenéticamente a expressão gênica de fatores preventivos, como também podem inibir a expressão de fatores ligados à metástase e progressão da patologia já instalada. Por fim, percebe-se que a influência que alguns alimentos tem sobre a expressão gênica representa uma importante ferramenta contra o câncer, sobretudo em relação à prevenção. No entanto, se faz necessário a realização de estudos mais detalhados em relação à doses e possíveis efeitos maléficos.

Phenethyl isothiocyanate synergistically induces apoptosis with Gefitinib in non-small cell lung cancer cells via endoplasmic reticulum stress-mediated degradation of Mcl-1.

Isothiocyanates (ITCs) are natural compounds abundant in cruciferous vegetables. Numerous studies have shown that ITCs exhibit anticancer activity by affecting multiple pathways including apoptosis and oxidative stress, and are expected to be developed into novel anticancer drugs. In our previous studies, we demonstrated that ITCs effectively inhibit the proliferation of non-small cell lung cancer (NSCLC) cells, also induce apoptosis and autophagy. In the present study, we found that phenethyl isothiocyanate (PEITC) had significant synergistic effects with epidermal growth factor receptor tyrosine kinase inhibitor Gefitinib in NSCLC cell lines NCI-H1299 and SK-MES-1; and the degradation of antiapoptotic factor myeloid cell leukemia 1 (Mcl-1) caused by PEITC treatment played key roles in the sensitivity of NSCLC cells to Gefitinib. We further illustrated that PEITC regulated the expression of Mcl-1 through protein kinase RNA-like endoplasmic reticulum kinase (PERK)-eukaryotic translation initiation factor 2α-CHOP-Noxa pathway by a posttranscriptional modulation. Pretreatment with endoplasmic reticulum stress (ER stress) inhibitor tauroursodeoxycholic acid and knockdown of PERK expression attenuated the degradation of Mcl-1 caused by PEITC. In in vivo study, nude mice bearing NCI-H1299 xenograft were administrated with PEITC (50 mg/kg, ip) and Gefitinib (50 mg/kg, ig) for 15 days, the PEITC-Gefitinib combination treatment resulted in a significant synergistic reduction in tumor growth, and significantly induced both ER stress and Mcl-1 degradation in tumor tissues. In conclusion, we explored the prospect of PEITC in improving the efficacy of targeted drug therapy and demonstrated the synergistic effects and underlined mechanisms of PEITC combined with Gefitinib in NSCLC cells treatment. This study provided useful information for developing novel therapy strategies by combination treatment of PEITC with targeted drugs.

PEITC triggers multiple forms of cell death by GSH-iron-ROS regulation in K7M2 murine osteosarcoma cells.

Phenethyl isothiocyanate (PEITC) is an isothiocyanate that largely exists in cruciferous vegetables and exhibits chemopreventive and chemotherapeutic potential against various cancers. However, it is little known about the molecular mechanisms of its antitumor action against osteosarcoma, which is the second highest cause of cancer-related death in children and adolescents. In this study, we investigated the effects of PEITC on K7M2 murine osteosarcoma both in vitro and in vivo. We found that treatment with PEITC dose-dependently inhibited the viability of K7M2 murine osteosarcoma cells with an IC50 value of 33.49 μM at 24 h. PEITC (1, 15, 30 μM) dose-dependently inhibited the cell proliferation, caused G2/M cell cycle arrest, depleted glutathione (GSH), generated reactive oxygen species (ROS), altered iron metabolism, and triggered multiple forms of cell death, namely ferroptosis, apoptosis, and autophagy in K7M2 cells. We further revealed that PEITC treatment activated MAPK signaling pathway, and ROS generation was a major cause of PEITC-induced cell death. In a syngeneic orthotopic osteosarcoma mouse model, administration of PEITC (30, 60 mg/kg every day, ig, for 24 days) significantly inhibited the tumor growth, but higher dose of PEITC (90 mg/kg every day) compromised its anti-osteosarcoma effect. Histological examination showed that multiple cell death processes were initiated, iron metabolism was altered and MAPK signaling pathway was activated in the tumor tissues. In conclusion, we demonstrate that PEITC induces ferroptosis, autophagy, and apoptosis in K7M2 osteosarcoma cells by activating the ROS-related MAPK signaling pathway. PEITC has promising anti-osteosarcoma activity. This study sheds light on the redox signaling-based chemotherapeutics for cancers.

Combination of xanthohumol and phenethyl isothiocyanate inhibits NF-κB and activates Nrf2 in pancreatic cancer cells

Phytochemicals such as phenethyl isothiocyanate (PEITC), indole-3-carbinol (I3C), xanthohumol (XAN), and resveratrol (RES) have been shown to target signaling pathways that are involved in the proliferation and survival of different pancreatic cancer (PC) cell lines. While the activity of these compounds alone was extensively studied, their combinations were never assessed. Thus, the aim of this study was to evaluate and compare the effect of PEITC, I3C, XAN, and RES and their combinations on the expression and activation of NF-κB and Nrf2 in human PC cell line PANC-1. The combination of XAN and PEITC was more efficient than the single compounds in reducing the binding of NF-κB p65 subunits to DNA by 47–60% and expression of p65 gene by 28–48%. The combination of XAN and PEITC also enhanced the activation and expression of Nrf2 and subsequently the expression of GSTP, NQO1, and SOD genes which are controlled by this transcription factor. Modulation of the activity of NF-κB and Nrf2 by the combination of XAN and PEITC was found to lead to reduced proliferation of PANC-1 cells.These results suggest that the combination of XAN and PEITC might be considered as a novel strategy for the prophylaxis and/or treatment of PC.

Molecular Mechanisms of the Anti-Cancer Effects of Isothiocyanates from Cruciferous Vegetables in Bladder Cancer.

Bladder cancer (BC) is a representative of urological cancer with a high recurrence and metastasis potential. Currently, cisplatin-based chemotherapy and immune checkpoint inhibitors are used as standard therapy in patients with advanced/metastatic BC. However, these therapies often show severe adverse events, and prolongation of survival is unsatisfactory. Therefore, a treatment strategy using natural compounds is of great interest. In this review, we focused on the anti-cancer effects of isothiocyanates (ITCs) derived from cruciferous vegetables, which are widely cultivated and consumed in many regions worldwide. Specifically, we discuss the anti-cancer effects of four ITC compounds—allyl isothiocyanate, benzyl isothiocyanate, sulforaphane, and phenethyl isothiocyanate—in BC; the molecular mechanisms underlying their anti-cancer effects; current trends and future direction of ITC-based treatment strategies; and the carcinogenic potential of ITCs. We also discuss the advantages and limitations of each ITC in BC treatment, furthering the consideration of ITCs in treatment strategies and for improving the prognosis of patients with BC.

Phenethyl Isothiocyanate Suppresses Stemness in the Chemo- and Radio-Resistant Triple-Negative Breast Cancer Cell Line MDA-MB-231/IR Via Downregulation of Metadherin.

Resistance to chemotherapy and radiation therapy is considered a major therapeutic barrier in breast cancer. Cancer stem cells (CSCs) play a prominent role in chemo and radiotherapy resistance. The established chemo and radio-resistant triple-negative breast cancer (TNBC) cell line MDA-MB-231/IR displays greater CSC characteristics than the parental MDA-MB-231 cells. Escalating evidence demonstrates that metadherin (MTDH) is associated with a number of cancer signaling pathways as well as breast cancer therapy resistance, making it an attractive therapeutic target. Kaplan–Meier plot analysis revealed a correlation between higher levels of MTDH and shorter lifetimes in breast cancer and TNBC patients. Moreover, there was a positive correlation between the MTDH and CD44 expression levels in The Cancer Genome Atlas breast cancer database. We demonstrate that MTDH plays a pivotal role in the regulation of stemness in MDA-MB-231/IR cells. Knockdown of MTDH in MDA-MB-231/IR cells resulted in a reduction in the CSC population, aldehyde dehydrogenase activity, and major CSC markers, including β-catenin, CD44+, and Slug. In addition, MTDH knockdown increased reactive oxygen species (ROS) levels in MDA-MB-231/IR cells. We found that phenethyl isothiocyanate (PEITC), a well-known pro-oxidant phytochemical, suppressed stemness in MDA-MB-231/IR cells through ROS modulation via the downregulation of MTDH. Co-treatment of PEITC and N-Acetylcysteine (a ROS scavenger) caused alterations in PEITC induced cell death and CSC markers. Moreover, PEITC regulated MTDH expression at the post-transcriptional level, which was confirmed using cycloheximide, a protein synthesis inhibitor.

PEITC by regulating Aurora Kinase A reverses chemoresistance in breast cancer cells

Development of acquired chemoresistance renders a challenge in breast cancer therapy. Aurora kinases, a family of serine/threonine mitotic kinases play pivotal roles in the acquirement of chemoresistance. Aurora A is intricately associated with mitotic events and is overexpressed in different cancers including breast cancer. Amplification or overexpression Aurora A confers chemoresistance and are considered as a promising therapeutic target in cancers. Therefore, targeting Aurora A by natural means particularly by using Phenethyl isothiocyanate (PEITC), a natural isothiocyanate might be an effective strategy for reversing resistance towards chemotherapeutics. The present study investigated the modulatory role of PEITC on Aurora A and their downstream target proteins in breast adenocarcinoma cell line (MCF-7) and its paclitaxel-resistant counterpart; designated as MCF-7Pacli/R. Paclitaxel resistance was warranted by P-gp1, MRP1, Ki-67 overexpression, rhodamine 123 accumulations and upregulation of Aurora-A along with phospho-IκBα. Multidrug resistance was confirmed by MTT assay. Western blotting, RT-PCR analysis revealed overexpression of Aurora-A in MCF-7Pacli/R cells; which was eventually diminished by PEITC. PEITC by targeting Aurora A and their downstream proteins (phospho-p53, phospho-IκBα) acted as a resistance-modifying agent and ultimately led to paclitaxel- induced apoptosis. These findings demonstrated that PEITC reverses chemoresistance by regulating Aurora A and restores chemosensitivity towards paclitaxel.

Characterisation of naturally occurring isothiocyanates as glutathione reductase inhibitors

Glutathione reductase (GR), an essential antioxidant enzyme against oxidative stress, has become an attractive drug target for the development of anticancer and antimalarial drugs. In this regard, we evaluated the naturally occurring isothiocyanates as promising GR inhibitors and elucidated the mechanism of action. It was found that benzyl isothiocyanate (BITC) and phenethyl isothiocyanate (PEITC) inhibited yeast GR (yGR) and human GR (hGR) in a time- and concentration-dependent manner. The Ki and kinact of BITC against yGR were determined to be 259.87 µM and 0.0266 min−1, respectively. The GR inhibition occurred only in the presence of NADPH and persisted after extensive dialysis. The tandem mass spectrometric analysis revealed that Cys61 rather than Cys66 at the active site of yGR was mono-benzyl thiocarbamoylated by BITC. Inhibition of intracellular GR by BITC and PEITC in cultured cancer cells was also observed. BITC and PEITC were evaluated as competitive and irreversible inhibitors of GR.

Phenylethyl isothiocyanate induces oxidative damage of porcine kidney cells mediated by reactive oxygen species.

The aim of this study is to confirm the toxic effect of phenylethyl isothiocyanate (PEITC) on porcine kidney cells (PK-15) and explore the effect of oxidative damage mediated by reactive oxygen species (ROS) induced by PEITC in PK-15 cells. Porcine kidney cell line (PK-15) was treated with PEITC (2, 5, and 10 µM) for 24 hours, and the oxidative damage mediated by PEITC through ROS was investigated. The survival rate of PK-15 cells decreased in a dose-dependent manner after the treatment of PEITC in a dose-dependent manner. A high concentration of PEITC (10 µM) can change cell morphology, increase the content of malondialdehyde, ROS, and lactate dehydrogenase, and decrease the activity of SOD, CAT, GSH-PX, and GSH. PEITC has a toxic effect on PK-15 cells by inducing oxidative stress in PK-15 cells through the generation of ROS.

Abstract A110: Isothiocyanate-containing hybrid androgen receptor (AR) antagonist downregulates AR and induces ferroptosis in GSH–deficient prostate cancer cells

Abstract Androgen receptor (AR) over-expression, mutation and the emergence of AR splice variants (AR-Vs) promote disease-driving AR signaling in castration-resistant prostate cancer (CRPC). In addition to the sustained AR activation, apoptosis evasion adds extra hurdle for treating hormone refractory prostate cancer (PCa). To overcome these challenges, we firstly designed isothiocyanate (ITC)-containing hybrid AR antagonist (ITC-ARi) and then rationally combined ITC-ARi with glutathione (GSH) biosynthesis inhibitor buthionine sulphoximine (BSO) to efficiently downregulate AR/AR-V and induce ferroptosis in enzalutamide (Enz)-resistant PCa cells. Naturally occurring ITCs (e.g., sulforaphane and phenylethyl isothiocyanate) display pleotropic anti-PCa activities. A representative ITC-ARi 2-63 is designed by incorporating ITC into an AR ligand scaffold. The sulfhydryl reactivity of ITC is transiently masked as N-acetyl cysteine (NAC) conjugate that gradually releases parental free ITC in aqueous solution. 2-63 antagonizes AR transactivation, downregulates AR/AR-V7, and upregulates cellular stress markers Hsp70 and heme oxygenase-1 (HO-1), indicating the disruption of heat shock proteins (Hsps) and the activation of Nrf2 pathway. Because the anticancer effects of ITC/ITC-NAC conjugate are attenuated by GSH-participated conjugation or thiol exchange, we rationally combined 2-63 with BSO for enhanced anti-PCa activities. 2-63 and BSO synergistically reduce viability of multiple PCa cell lines (VCaP, C4-2 and 22Rv-1), and the noncancerous prostatic RWPE-1 cell is much less affected. Because 2-63 plus BSO does not upregulate typical apoptosis markers, we investigated alternative cell death mechanism in combinatorial treatment. Drug combination-caused cell viability loss is effectively rescued by iron chelator deferoxamine (DFO), antioxidants α-tocopherol (α-Toc) and ferrostatin-1 (Fer-1), or the inhibitor of HO-1 Zinc (II) protoporphyrin IX (ZnPP). Both Fer-1 and α-Toc are potent radical scavengers blocking lipid hydroperoxide generation, and ZnPP suppresses HO-1-catalyzed upregulation of intracellular Fe2+. The reverse of growth suppression by DFO, antioxidants and ZnPP supports the induction of ferroptosis, a regulated non-apoptotic cell death caused by reactive oxygen species (ROS)- and iron-dependent lipid peroxidation. 2-63 and BSO also more efficiently downregulate AR/AR-V than 2-63 alone in Enz-resistant PCa cells. Interestingly, ferroptosis-preventing DFO and Fer-1 do not rescue AR/AR-V7 and are unable to suppress the upregulation of Hsp70 and HO-1. Our results suggest that the synergism of 2-63 and BSO occurs through increasing drug accessibility to cellular targets, expanding availability of iron and potentially affecting glutathione peroxidase 4 (GPX4) activity, the most important cellular defense to eliminate lipid hydroperoxide. Combining ITC-ARi and GSH-depleting agents could be a new concept leading to effective CRPC treatment. Citation Format: Zhihui Qin, Liping Xu, Siyu Ou. Isothiocyanate-containing hybrid androgen receptor (AR) antagonist downregulates AR and induces ferroptosis in GSH–deficient prostate cancer cells [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr A110. doi:10.1158/1535-7163.TARG-19-A110

NRF2-Independent Regulation of Intestinal Constitutive Androstane Receptor by the Pro-Oxidants Cadmium and Isothiocyanate in hUGT1 Mice.

Environmental toxicants such as heavy metals from contaminated water or soil and isothiocyanates (ITC) from dietary sources act as pro-oxidants by directly generating reactive oxygen species (ROS) or through depleting cellular antioxidants such as glutathione. Toxicants can alter drug metabolism, and it was reported that CYP2B10 and UGT1A1 are induced by phenethyl isothiocyanate (PEITC) through the constitutive androstane receptor (CAR). The possibility that nuclear factor erythroid 2-related factor 2 (NRF2), the master regulator of the antioxidant response, could coactivate CAR was investigated in neonatal hUGT1/Nrf2 -/- mice. Neonatal mice were treated with PEITC or cadmium (Cd2+) by oral gavage for 2 days. Both PEITC and Cd2+ induced UGT1A1 RNA and protein in intestinal tissues in both hUGT1/Nrf2 +/- and hUGT1/Nrf2 -/- neonates, indicating NRF2-independent regulation of UGT1A1. Increases in CYP2B10 RNA in intestinal tissues were observed following PEITC or Cd2+ exposure. Activation of intestinal CAR by Cd2+ exposure was directly assessed by nuclear fractionation and Western blot analyses at 0.5, 1, 2, and 4 hours after treatment in hUGT1 neonates and after 48 hours in hUGT1/Nrf2 +/- and hUGT1/Nrf2 -/- neonates. CAR localized to the nucleus independently of NRF2 48 hours after exposure. Substantial CAR localization to the nucleus occurred at the 2- and 4-hour time points, coinciding with a decrease in phosphorylation of cytoplasmic extracellular signal-regulated kinases 1 and 2 and a nuclear increase in P38/p-P38 content. This suggests that a novel oxidative stress-MAPK-CAR axis exists with phenotypic consequences. SIGNIFICANCE STATEMENT: Pro-oxidant toxicants can alter drug metabolism through activation of CAR, independent of the NRF2-KEAP1 signaling pathway. Changes in proteins associated with drug metabolism and linked to increases in intestinal maturation are mediated through an oxidative stress-MAPK-CAR axis.

Comparison of the inhibitory potential of benzyl isothiocyanate and phenethyl isothiocyanate on Shiga toxin-producing and enterotoxigenic Escherichia coli

The aim of this study was to investigate the inhibitory effects of benzyl isothiocyanate (BITC) and phenethyl isothiocyanate (PEITC) against Shiga toxin-producing Escherichia coli (STEC) and enterotoxigenic E. coli (ETEC). Compared with that of PEITC, the antibacterial effect of BITC was more obvious. The minimal inhibitory concentration (MIC) of BITC was 60 and 160 μmol/L for STEC and ETEC, while that of PEITC was 400 μmol/L for both strains. Scanning electron microscopy (SEM) images indicated that treatment with BITC severely affected the cell integrity and led to partly sunken. Incubation of STEC and ETEC with BITC and PEITC for 1 and 4 h decreased total ATP level, while increased extracellular ATP level. Virulence genes were downregulated in dose-dependent fashion upon treatment with subinhibitory concentration of BITC and PEITC, as determined by real-time quantitative polymerase chain reaction (RT-qPCR). The expressions of stx2, eaeA and ehxA, was significantly lower in STEC treated with 1/4 MIC of PEITC than that of BITC. The inhibitory effects of BITC and PEITC on virulence genes were more obvious in STEC than ETEC. These results suggest that BITC and PEITC affect the strains growth, biological structure and expression of virulence genes of both strains.

Increased Mortality, Delayed Hatching, Development Aberrations and Reduced Activity in Brown Trout (Salmo trutta) Exposed to Phenethyl Isothiocyanate

Plants of the order Brassicaceae have evolved a chemical defence against herbivory: the glucosinolate-myrosinase system. Mechanical damage to plant tissues, such as grazing, initiates the production of phenethyl isothiocyanate (PEITC), a compound toxic to invertebrates. Mechanical damage caused during biofumigation and the harvesting and washing of watercress presents routes for PEITC release into waterbodies, such as the chalk stream spawning sites of brown trout (Salmo trutta). This laboratory study exposed developing S. trutta embryos to PEITC at concentrations of 0.01, 0.1 and 1 μg/L. S. trutta exposed to 1 μg/L PEITC during embryonic development resulted in 100% mortality after four dose days. Exposure to 0.1 μg/L PEITC resulted in an approximate fourfold increase in mortality relative to the controls, while exposure to 0.01 μg/L PEITC had a negligible effect on embryo mortality. Embryos exposed to 0.1 μg/L PEITC showed a significant delay in hatching and produced alevins with significantly shorter total lengths, lighter body weights and an approximate threefold increase in spinal deformities relative to those exposed to the controls and 0.01 μg/L PEITC. The results of a motor activity assay demonstrate that alevins exposed to PEITC showed a significant decrease in swimming activity compared with control animals during periods of illumination. The increased mortality, teratogenic effects and impaired behaviour in S. trutta following embryonic exposure to relatively low concentrations of PEITC highlight a need to accurately quantify and monitor environmental levels of PEITC.

Role of Phytochemicals in Cancer Prevention.

The use of synthetic, natural, or biological agents to minimize the occurrence of cancer in healthy individuals is defined as cancer chemoprevention. Chemopreventive agents inhibit the development of cancer either by impeding DNA damage, which leads to malignancy or by reversing or blocking the division of premalignant cells with DNA damage. The benefit of this approach has been demonstrated in clinical trials of breast, prostate, and colon cancer. The continuous increase in cancer cases, failure of conventional chemotherapies to control cancer, and excessive toxicity of chemotherapies clearly demand an alternative approach. The first trial to show benefit of chemoprevention was undertaken in breast cancer patients with the use of tamoxifen, which demonstrated a significant decrease in invasive breast cancer. The success of using chemopreventive agents for protecting the high risk populations from cancer indicates that the strategy is rational and promising. Dietary components such as capsaicin, cucurbitacin B, isoflavones, catechins, lycopenes, benzyl isothiocyanate, phenethyl isothiocyanate, and piperlongumine have demonstrated inhibitory effects on cancer cells indicating that they may serve as chemopreventive agents. In this review, we have addressed the mechanism of chemopreventive and anticancer effects of several natural agents.

Glucosinolate-Degradation Products as Co-Adjuvant Therapy on Prostate Cancer in Vitro.

Glucosinolate-degradation products (GS-degradation products) are believed to be responsible for the anticancer effects of cruciferous vegetables. Furthermore, they could improve the efficacy and reduce side-effects of chemotherapy. The aim of the present study was to determine the cytotoxic effects of GS-degradation products on androgen-insensitive human prostate cancer (AIPC) PC-3 and DU 145 cells and investigate their ability to sensitize such cells to chemotherapeutic drug Docetaxel (DOCE). Cells were cultured under growing concentrations of allyl-isothiocyanate (AITC), sulforaphane (SFN), 4-pentenyl-isothiocyanate (4PI), iberin (IB), indole-3-carbinol (I3C), or phenethyl-isothiocyanate (PEITC) in absence or presence of DOCE. The anti-tumor effects of these compounds were analyzed using the trypan blue exclusion, apoptosis, invasion and RT-qPCR assays and confocal microscopy. We observed that AITC, SFN, IB, and/or PEITC induced a dose- and time-dependent cytotoxic effect on PC-3 and DU 145 cells, which was mediated, at least, by apoptosis and cell cycle arrest. Likewise, we showed that these GS-degradation products sensitized both cell lines to DOCE by synergic mechanisms. Taken together, our results indicate that GS-degradation products can be promising compounds as co-adjuvant therapy in prostate cancer.

Various modes of action of dietary phytochemicals, sulforaphane and phenethyl isothiocyanate, on pathogenic bacteria

Isothiocyanates (ITCs) derived from cruciferous plants reveal antibacterial activity, although detailed mechanism is not fully elucidated. Recently it has been reported that ITCs induce the stringent response in Escherichia coli strains. The aim of this work was to determine whether two isothiocyanates, sulforaphane (SFN) and phenethyl isothiocyanate (PEITC), similarly as in E. coli induce stringent response in Bacillus subtilis, model Gram(+) bacterium, and test their potency against a panel of clinical isolates belonging to Gram(+) or Gram(−) groups. Minimal inhibitory concentrations were determined as well as effect of ITCs on membranes integrity, synthesis of DNA, RNA and stringent response alarmones was assessed. SFN and PEITC are effective against B. subtilis and bacterial isolates, namely E. coli, K. pneumonia, S. aureus, S. epidermidis and E. faecalis. Interestingly, in B. subtilis and E. faecalis the inhibition of growth and nucleic acids synthesis is independent of ppGpp accumulation. In bacteria, which do not induce the stringent response in the presence of ITCs, membrane integrity disruption is observed. Thus, ITCs are effective against different pathogenic bacteria and act by at least two mechanisms depending on bacteria species.

Comparison of Pregnane X Receptor Antagonists for Enhancing the Antitumor Effect of Cisplatin.

Cisplatin is a platinum compound capable of inducing apoptosis of cancer cells. However, cancer cells can become cisplatin-resistant. A recent study showed that a pregnane X receptor (PXR) antagonist, leflunomide, can enhance the antitumor activity of cisplatin and overcome such resistance. This study determined whether PXR antagonists ketoconazole and phenethyl isothiocyanate (PEITC) enhance the antitumor activity of platinum compounds and by which mechanism(s) of action. Caspase-3 activity, intracellular platinum level, and expression of ATP-binding cassette subfamily C member 2 (ABCC2; previously named multidrug resistance-associated protein 2) were assessed in HepG2 human hepatocellular carcinoma cells exposed to carboplatin or cisplatin with and without PXR antagonist. In combination with platinum compounds, PEITC increased the intracellular platinum level, while ketoconazole induced higher caspase-3 activity. Additionally, PEITC suppressed ABCC2 protein expression. These results suggested that ketoconazole and PEITC enhance the antitumor activity of platinum compounds by different and complex mechanisms.

Phenethyl isothiocyanate induces IPEC-J2 cells cytotoxicity and apoptosis via S-G2/M phase arrest and mitochondria-mediated Bax/Bcl-2 pathway

Phenethyl isothiocyanate (PEITC) is one of the glucosinolates (GLs) present in cruciferous vegetables. Although there are many reports of livestock and poultry poisoning caused by plants containing GLs, the actual dosage that causes poisoning and the characteristics of GLs and their metabolites are unclear. Herein, we investigated the inhibitory effects of PEITC on IPEC-J2 cells and examined the mechanisms of PEITC-induced apoptosis via the mitochondrial pathway. Cell viability was determined by the MTT assay, and the levels of reactive oxygen species, mitochondrial membrane potential (∆Ψ), intracellular Ca2+ concentration, and cell apoptosis were detected by flow cytometry. IPEC-J2 cells were collected to assess the activities of superoxide dismutase, catalase, and glutathione peroxidase, as well as the contents of glutathione, malondialdehyde, H2O2, ATP, and lactate dehydrogenase, using biochemical methods. The levels of cytochrome c, Bax, Bcl-2, caspase-3, caspase-9, poly (ADP-ribose) polymerase (PARP)-1, p53, CDC25C, and cyclin A2 were analyzed by western blotting. We found that PEITC effectively inhibited the growth of IPEC-J2 cells, causing apoptosis. PEITC suppressed the level of mitochondrial membrane potential; released cytochrome c from the mitochondria to the cytoplasm; reduced ATP levels; inhibited Bcl-2 expression; increased Bax expression; and activated caspase-9, caspase-3, and PARP-1, leading to apoptosis. PEITC also induced G2/M and S phase arrest by affecting cell cycle-associated proteins such as p53, CDC25C, and cyclin A2. We conclude that PEITC causes oxidative stress, cell cycle arrest, and apoptosis in IPEC-J2 cells via a mitochondrial-dependent Bax/Bcl-2 pathway.