Essential oils and their nanoformulations for breast cancer therapy.

Breast Cancer (BC) is the most prevalent type of cancer in the world. Current treatments include surgery, radiation, and chemotherapy but often are associated with high toxicity to normal tissues, chemoresistance, and relapse. Thus, developing novel therapies which could combat these limitations is essential for effective treatment. In this context, phytochemicals are increasingly getting popular due to their safety profile, ability to efficiently target tumors, and circumvent limitations of existing treatments. Essential Oils (EOs) are mixtures of various phytochemicals which have shown potential anticancer activity in preclinical BC models. However, their clinical translation is limited by factors such as high volatility, low stability, and poor solubility. Nanotechnology has facilitated their encapsulation in a variety of nanostructures and proven to overcome these limitations. In this review, we have efficiently summarized the current knowledge on the anticancer effect of EOs and constituents in both in in vitro and in in vivo BC models. Further, we also provide a descriptive account on the potential of nanotechnology in enhancing the anti-BC activity of EOs and their constituents. The papers discussed in this review were selected using the keywords "antiproliferative Essential Oils in breast cancer," "anticancer activity of Essential Oil in breast cancer," and "cytotoxicity of Essential Oils in breast cancer" performed in PubMed and ScienceDirect databases.

Pinus mugo Essential Oil Impairs STAT3 Activation through Oxidative Stress and Induces Apoptosis in Prostate Cancer Cells.

Essential oils (EOs) and their components have been reported to possess anticancer properties and to increase the sensitivity of cancer cells to chemotherapy. The aim of this work was to select EOs able to downregulate STAT3 signaling using Western blot and RT-PCR analyses. The molecular mechanism of anti-STAT3 activity was evaluated through spectrophotometric and fluorometric analyses, and the biological effect of STAT3 inhibition was analyzed by flow cytometry and wound healing assay. Herein, Pinus mugo EO (PMEO) is identified as an inhibitor of constitutive STAT3 phosphorylation in human prostate cancer cells, DU145. The down-modulation of the STAT3 signaling cascade decreased the expression of anti-proliferative as well as anti-apoptotic genes and proteins, leading to the inhibition of cell migration and apoptotic cell death. PMEO treatment induced a rapid drop in glutathione (GSH) levels and an increase in reactive oxygen species (ROS) concentration, resulting in mild oxidative stress. Pretreatment of cells with N-acetyl-cysteine (NAC), a cell-permeable ROS scavenger, reverted the inhibitory action of PMEO on STAT3 phosphorylation. Moreover, combination therapy revealed that PMEO treatment displayed synergism with cisplatin in inducing the cytotoxic effect. Overall, our data highlight the importance of STAT3 signaling in PMEO cytotoxic activity, as well as the possibility of developing adjuvant therapy or sensitizing cancer cells to conventional chemotherapy.

Redox Sensitive Cysteine Residues as Crucial Regulators of Wild-Type and Mutant p53 Isoforms.

The wild-type protein p53 plays a key role in preventing the formation of neoplasms by controlling cell growth. However, in more than a half of all cancers, the TP53 gene has missense mutations that appear during tumorigenesis. In most cases, the mutated gene encodes a full-length protein with the substitution of a single amino acid, resulting in structural and functional changes and acquiring an oncogenic role. This dual role of the wild-type protein and the mutated isoforms is also evident in the regulation of the redox state of the cell, with antioxidant and prooxidant functions, respectively. In this review, we introduce a new concept of the p53 protein by discussing its sensitivity to the cellular redox state. In particular, we focus on the discussion of structural and functional changes following post-translational modifications of redox-sensitive cysteine residues, which are also responsible for interacting with zinc ions for proper structural folding. We will also discuss therapeutic opportunities using small molecules targeting cysteines capable of modifying the structure and function of the p53 mutant isoforms in view of possible anticancer therapies for patients possessing the mutation in the TP53 gene.

The anti-STAT1 polyphenol myricetin inhibits M1 microglia activation and counteracts neuronal death.

Microglia activation toward M1 pro-inflammatory phenotype represents one of the earliest events of neurological disorders. Therefore, reducing microglia activation should inhibit neuroinflammation, thereby delaying the progression of neurodegeneration. Recently, we pointed out the role of STAT1 signaling in hypoxia-induced M1 activation and proposed STAT1 as a suitable molecular target for the prevention and treatment of neurodegeneration. Myricetin (MYR) is a natural flavonoid that exhibits a specific anti-STAT1 activity correlated with its direct interaction with STAT1 protein itself. Herein, we investigated the anti-inflammatory effect of MYR and its ability to protect neurons from death in an in vitro model of neurotoxicity using the neuroblast-like SH-SY5Y cells that were exposed to conditioned media from hypoxia-activated microglia BV2 cells. We demonstrate that MYR pretreatment is able to switch off hypoxia-induced M1 microglia polarization through the inhibition of STAT1 signaling. The analysis of the molecular mechanism suggests that the direct interaction of MYR with STAT1 impairs its S-glutathionylation and phosphorylation. Moreover, treatment of SH-SY5Y cells with conditioned medium from hypoxia-activated microglia pretreated with MYR produced a significant reduction in neuronal viability. Our data indicate that MYR may represent a promising candidate for prevention and treatment of neuroinflammation in neurodegenerative disorders.

Redox Regulation of STAT1 and STAT3 Signaling.

STAT1 and STAT3 are nuclear transcription factors that regulate genes involved in cell cycle, cell survival and immune response. The cross-talk between these signaling pathways determines how cells integrate the environmental signals received ultimately translating them in transcriptional regulation of specific sets of genes. Despite being activated downstream of common cytokine and growth factors, STAT1 and STAT3 play essentially antagonistic roles and the disruption of their balance directs cells from survival to apoptotic cell death or from inflammatory to anti-inflammatory responses. Different mechanisms are proposed to explain this yin-yang relationship. Considering the redox aspect of STATs proteins, this review attempts to summarize the current knowledge of redox regulation of STAT1 and STAT3 signaling focusing the attention on the post-translational modifications that affect their activity.

Rehabilitation and Biomarkers of Stroke Recovery: Study Protocol for a Randomized Controlled Trial.

Background: Stroke is a leading cause of disability. Nonetheless, the care pathway for stroke rehabilitation takes partially into account the needs of chronic patients. This is due in part to the lack of evidence about the mechanisms of recovery after stroke, together with the poor knowledge of related and influencing factors. Here we report on the study protocol "Rehabilitation and Biomarkers of Stroke Recovery," which consists of 7 work-packages and mainly aim to investigate the effects of long-term neurorehabilitation on stroke patients and to define a related profile of (clinical-biological, imaging, neurophysiological, and genetic-molecular) biomarkers of long-term recovery after stroke. The work-package 1 will represent the main part of this protocol and aims to compare the long-term effects of intensive self-rehabilitation vs. usual (rehabilitation) care for stroke. Methods: We planned to include a total of 134 adult subacute stroke patients (no more than 3 months since onset) suffering from multidomain disability as a consequence of first-ever unilateral ischemic stroke. Eligible participants will be randomly assigned to one of the following groups: intensive self-rehabilitation (based on the principles of "Guided Self-Rehabilitation Contract") vs. usual care (routine practice). Treatment will last 1 year, and patients will be evaluated every 3 months according to their clinical presentation. The following outcomes will be considered in the main work-package: Fugl-Meyer assessment, Cognitive Oxford Screen Barthel Index, structural and functional neuroimaging, cortical excitability, and motor and somatosensory evoked potentials. Discussion: This trial will deal with the effects of an intensive self-management rehabilitation protocol and a related set of biomarkers. It will also investigate the role of training intensity on long-term recovery after stroke. In addition, it will define a set of biomarkers related to post-stroke recovery and neurorehabilitation outcome in order to detect patients with greater potential and define long-term individualized rehabilitation programs. Clinical Trial Registration: www.ClinicalTrials.gov, identifier: NCT04323501.

Immunoprecipitation methods to identify S-glutathionylation in target proteins.

S-glutathionylation is a reversible post-translational modification of proteins that generate a mixed disulfide between glutathione to thiolate anion of cysteine residues in target proteins. In the last ten years, S-glutathionylation has been extensively studied since it represents the cellular response to oxidative stress, in physiological as well as pathological conditions. This modification may be a protective mechanism from irreversible oxidative damage and, on the other hand, may modulate protein folding and function. Due to the importance of S-glutathionylation in cellular redox signaling, various methods have been developed to identify S-gluthationylated proteins. Herein, we describe two easy methods to recognized S-glutathionylation of a target protein after oxidative stress in cellular extracts based on different immunoprecipitation procedures. The immunoprecipitation assay allows the capture of one glutathionylated protein using a specific antibody that binds to the target protein. The presence of S-glutathionylation in the immunoprecipitated protein is identified using anti-glutathione antibody. The second type of approach is based on the detection of the glutathionylated protein with biotin/streptavidin technique. After different steps of protection of non-oxidized thiolic groups and reduction of S-glutathionylated groups, the newly-formed protein free-thiols are labeled with biotin-GSH. The modified protein can be isolate with streptavidin-beads and recognized using an antibody against target protein. •S-glutathionylation is a reversible post-translational modification of proteins that recently has been emerged as important signaling in the redox regulation of protein function.•Both methods to identify glutathionylated proteins are economic, easy and do not require particular equipment.•The setups of both methods guarantee high reproducibility.

Natural Sesquiterpene Lactones Enhance Chemosensitivity of Tumor Cells through Redox Regulation of STAT3 Signaling.

STAT3 is a nuclear transcription factor that regulates genes involved in cell cycle, cell survival, and immune response. Although STAT3 activation drives cells to physiological response, its deregulation is often associated with the development and progression of many solid and hematological tumors as well as with drug resistance. STAT3 is a redox-sensitive protein, and its activation state is related to intracellular GSH levels. Under oxidative conditions, STAT3 activity is regulated by S-glutathionylation, a reversible posttranslational modification of cysteine residues. Compounds able to suppress STAT3 activation and, on the other hand, to modulate intracellular redox homeostasis may potentially improve cancer treatment outcome. Nowadays, about 35% of commercial drugs are natural compounds that derive from plant extracts used in phytotherapy and traditional medicine. Sesquiterpene lactones are an interesting chemical group of plant-derived compounds often employed in traditional medicine against inflammation and cancer. This review focuses on sesquiterpene lactones able to downmodulate STAT3 signaling leading to an antitumor effect and correlates the anti-STAT3 activity with their ability to decrease GSH levels in cancer cells. These properties make them lead compounds for the development of a new therapeutic strategy for cancer treatment.

Tumor Dormancy and Interplay with Hypoxic Tumor Microenvironment.

The tumor microenvironment is a key factor in disease progression, local resistance, immune-escaping, and metastasis. The rapid proliferation of tumor cells and the aberrant structure of the blood vessels within tumors result in a marked heterogeneity in the perfusion of the tumor tissue with regions of hypoxia. Although most of the tumor cells die in these hypoxic conditions, a part of them can adapt and survive for many days or months in a dormant state. Dormant tumor cells are characterized by cell cycle arrest in G0/G1 phase as well as a low metabolism, and are refractive to common chemotherapy, giving rise to metastasis. Despite these features, the cells retain their ability to proliferate when conditions improve. An understanding of the regulatory machinery of tumor dormancy is essential for identifying early cancer biomarkers and could provide a rationale for the development of novel agents to target dormant tumor cell populations. In this review, we examine the current knowledge of the mechanisms allowing tumor dormancy and discuss the crucial role of the hypoxic microenvironment in this process.

Biopsychosocial model of resilience in young adults with multiple sclerosis (BPS-ARMS): an observational study protocol exploring psychological reactions early after diagnosis.

INTRODUCTION: Multiple sclerosis (MS), the most common neurological disease causing disability in young adults, is widely recognised as a major stress factor. Studies have shown that the first years after the diagnosis are distressing in terms of adjustment to the disease and that MS negatively affects patients' psychological well-being, quality of life (QoL) and social functioning. However, the links between disease-specific variables at diagnosis, resilience and psychological adjustment of patients with MS remain largely unexplored, especially in adolescents and young adults. This observational study aims to fill the gap of knowledge on biopsychosocial characteristics and resilience of young adults with MS to evaluate the relationship among these variables and to develop a biopsychosocial model of resilience. METHODS AND ANALYSIS: Biological and clinical characteristics of young adults newly diagnosed with MS will be investigated by collecting clinical information, performing neurological examinations, MRI and analysing cerebrospinal fluid and blood biomarkers (eg, measures of inflammation), body composition, gut microbiota and movement/perceptual markers. Psychosocial characteristics (eg, psychological distress, coping strategies), QoL, psychological well-being and resilience will be assessed by self-report questionnaires. Comparative statistics (ie, analysis of variance or unpaired samples t-test, correlation and regression analyses) will be applied to evaluate the relationship among biological, psychological and social factors. The results are expected to allow a comprehensive understanding of the determinants of resilience in young patients with MS and to inform resilience interventions, tailored to young patients' specific needs, aiming to reduce the risk of maladaptive reactions to the disease and to improve psychological well-being and QoL. ETHICS AND DISSEMINATION: The study has been approved by the Verona University Hospital Ethics Committee (approval number: 2029CESC). The findings will be disseminated through scientific publications in peer-reviewed journals, conference presentations, social media and specific websites. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov (NCT03825055).

STAT1 drives M1 microglia activation and neuroinflammation under hypoxia.

Microglia are resident immune cells that act as the first active defence in the central nervous system. These cells constantly monitor the tissue microenvironment and rapidly react in response to hypoxia, infection and injuries. Hypoxia in the brain has been detected in several neurodegenerative disorders such as Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease and Huntington's disease. Hypoxic conditions activate microglia cells towards M1 phenotype resulting in oxidative stress and the release of pro-inflammatory cytokines. Recently, we have demonstrated that oxidative stress induces S-glutathionylation of the STAT1 and hyper-activates its signaling in microglia BV2 cells pointing out the importance of this transcription factor in neuroinflammation. In this paper we analyse the cellular mechanisms that drive M1 microglia activation in BV2 cells in response to hypoxia correlating it to STAT1 activation. The analysis of the molecular mechanism of STAT1 signaling reveals that hypoxia generates oxidative stress and induces both phosphorylation and S-glutathionylation of STAT1 that are responsible of its aberrant activation. The silencing of STAT1 protein expression counteracts hypoxia-M1 microglia phenotype suggesting the strong link between hypoxia-STAT1 and STAT1-microglia activation.

S-glutathionylation exerts opposing roles in the regulation of STAT1 and STAT3 signaling in reactive microglia.

STAT1 and STAT3 are two transcription factors involved in a lot of cellular functions such as immune response, proliferation, apoptosis, and cell survival. A number of literature evidences described a yin-yang relationship between activation of STAT1 and STAT3 in neurodegenerative disorders where STAT1 exerts a pro-apoptotic effect whereas STAT3 shows neuroprotective properties through the inhibition of apoptosis. Although the role of oxidative-stress in the pathogenesis of neurodegeneration is clearly described, its influence in the regulation of these pathways is poorly understood. Herein, we demonstrate that H2O2 rapidly induces phosphorylation of STAT1 whereas it is not able to influence phosphorylation of STAT3 in mouse microglia BV2 cells. The analysis of the molecular mechanism of STATs signaling reveals that H2O2 induces S-glutathionylation of both STAT1 and STAT3. The same post-translational event exerts an opposing role in the regulation of STAT1 and STAT3 signaling. These data not only confirm redox sensibility of STAT3 signaling but also reveal for the first time that STAT1 is susceptible to redox regulation. A deep study of the molecular mechanism of STAT1 redox regulation, identifies Cys324 and Cys492 as the main targets of S-glutathionylation and confirms that S-glutathionylation does not impair JAK2 mediated STAT1 tyrosine phosphorylation. These results demonstrate that both phosphorylation and glutathionylation contribute to activation of STAT1 during oxidative stress and underline that the same post-translation event exerts an opposing role in the regulation of STAT1 and STAT3 signaling in microglia cells.

Metastatic Breast Cancer Cells Enter Into Dormant State and Express Cancer Stem Cells Phenotype Under Chronic Hypoxia.

Tumor dormancy is a poorly understood stage in cancer progression characterized by mitotic cycle arrest in G0/G1 phase and low metabolism. The cells survive in a quiescent state and wait for appropriate environmental conditions to begin proliferation again giving rise to metastasis. Despite their key role in cancer development and metastasis, the knowledge about their biology and origin is still very limited due to the poorness of established in vitro models that faithfully recapitulated tumor dormancy. Using at least three cycles of 1% O2 hypoxia and reoxygenation, we establish and characterize the hypoxia-resistant human breast cancer cell line chMDA-MB-231 that can stably survive under 1% O2 condition by entering into dormant state characterized by arrest in G0/G1 phase and low metabolism. This dormant state is reversible since once replaced in normoxia the cells recover the proliferation rate in 2 weeks. We show that chronic hypoxia induces autophagy that may be the survival mechanism of chMDA-MB-231 cells. Furthermore, the data in this work demonstrate that cycling hypoxic/reoxygenation stress selects MDA-MB-231 population that presents the cancer stem-like phenotype characterized by CD24- /CD44+ /ESA+ expression and spheroid forming capacity. We believe that our study presents a promising approach to select dormant breast cancer cells with stem-like phenotype using the hypoxia/reoxygenation regimen that may represent an area with profound implications for therapeutic developments in oncology. J. Cell. Biochem. 118: 3237-3248, 2017. © 2017 Wiley Periodicals, Inc.

Mild oxidative stress induces S-glutathionylation of STAT3 and enhances chemosensitivity of tumoural cells to chemotherapeutic drugs.

STAT3 is a transcription factor constitutively activated in a variety of cancers that has a critical role in the inhibition of apoptosis and induction of chemoresistance. Inhibition of the STAT3 signaling pathway suppresses cell survival signals and leads to apoptosis in cancer cells, suggesting that direct inhibition of STAT3 function is a viable therapeutic approach. Herein, we identify the naturally occurring sesquiterpene lactone cynaropicrin as a potent inhibitor of both IL-6-inducible and constitutive STAT3 activation (IC50=12 µM). Cynaropicrin, which contains an α-ß-unsaturated carbonyl moiety and acts as potent Michael reaction acceptor, induces a rapid drop in intracellular glutathione (GSH) concentration, thereby triggering S-glutathionylation of STAT3. Furthermore, glutathione ethylene ester, the cell permeable form of GSH, reverts the inhibitory action of cynaropicrin on STAT3 tyrosine phosphorylation. These findings suggest that this sesquiterpene lactone is able to induce redox-dependent post-translational modification of cysteine residues of STAT3 protein to regulate its function. STAT3 inhibition led to the suppression of two anti-apoptotic genes, Bcl-2 and survivin, in DU145 cells that constitutively express active STAT3. This event may be responsible for the decline in cell viability after cynaropicrin treatment. As revealed by PI/annexin-V staining, PARP cleavage, and DNA ladder formation, cynaropicrin cytotoxicity is mediated by apoptosis. Finally, cynaropicrin displayed a slight to strong synergism with two well-established chemotherapeutic drugs, cisplatin and docetaxel. Taken together our studies suggest that cynaropicrin suppresses the STAT3 pathway, leading to the down-regulation of STAT3-dependent gene expression and chemosensitization of tumour cells to chemotherapy.

Synthesis and biological evaluation of new N-alkylcarbazole derivatives as STAT3 inhibitors: preliminary study.

The signalling pathway of Janus tyrosine Kinases-Signal Transducers and Activators of Transcription (JAK-STAT) is activated by a number of cytokines, hormones (GH, erythropoietin and prolactin), and growth factors. JAK-STAT signalling is involved in regulation of cell proliferation, differentiation and apoptosis. These activities are due to different members of JAK-STAT family consisting of: JAK1, JAK2, JAK3, Tyk2 and STAT1, STAT2, STAT3, STAT4, STAT5a, STAT5b, STAT6. Recent studies suggest a key role for STAT family proteins, in particular for STAT3, in selectively inducing and maintaining a pro-carcinogenic inflammatory microenvironment, that promote tumour cells transformation. Moreover, a striking correlation between cancer development/progression and STAT3 persistent activation exists, probably due to STAT3 promoting of the pro-oncogenic inflammatory pathways, like NF-kB, IL-6 and JAK family kinases. Recent study demonstrated that carbazoles can inhibit STAT3 mediated transcription. From these evidences, STAT3 represents a therapeutic target, so we have synthesized a new set of N-alkylcarbazole derivatives substituted in positions 2, 4 and 6, to evaluate their activity on STAT3. Some of these compounds showed an interesting activity as STAT3 selective inhibitors; in particular, compounds 9a 9b and 9c revealed to inhibit the STAT3 activation for the 50%, 90% and 95%, respectively.

Pro-apoptotic activity of α-bisabolol in preclinical models of primary human acute leukemia cells.

BACKGROUND: We previously demonstrated that the plant-derived agent α-bisabolol enters cells via lipid rafts, binds to the pro-apoptotic Bcl-2 family protein BID, and may induce apoptosis. Here we studied the activity of α-bisabolol in acute leukemia cells. METHODS: We tested ex vivo blasts from 42 acute leukemias (14 Philadelphia-negative and 14 Philadelphia-positive B acute lymphoid leukemias, Ph-/Ph+B-ALL; 14 acute myeloid leukemias, AML) for their sensitivity to α-bisabolol in 24-hour dose-response assays. Concentrations and time were chosen based on CD34+, CD33+my and normal peripheral blood cell sensitivity to increasing α-bisabolol concentrations for up to 120 hours. RESULTS: A clustering analysis of the sensitivity over 24 hours identified three clusters. Cluster 1 (14 ± 5 µM α-bisabolol IC50) included mainly Ph-B-ALL cells. AML cells were split into cluster 2 and 3 (45 ± 7 and 65 ± 5 µM IC50). Ph+B-ALL cells were scattered, but mainly grouped into cluster 2. All leukemias, including 3 imatinib-resistant cases, were eventually responsive, but a subset of B-ALL cells was fairly sensitive to low α-bisabolol concentrations. α-bisabolol acted as a pro-apoptotic agent via a direct damage to mitochondrial integrity, which was responsible for the decrease in NADH-supported state 3 respiration and the disruption of the mitochondrial membrane potential. CONCLUSION: Our study provides the first evidence that α-bisabolol is a pro-apoptotic agent for primary human acute leukemia cells.

Dual modulation of nitric oxide production in the heart during ischaemia/reperfusion injury and inflammation.

Nitric oxide (NO) homeostasis maintained by neuronal/endothelial nitric oxide (NO) synthase (n/eNOS) contributes to regulate cardiac function under physiological conditions. At the early stages of ischaemia, NO homeostasis is disturbed due to Ca2+-dependent e/nNOS activation. In endothelial cells, successive drop in NO concentration may occur due to both uncoupling of eNOS and/or successive inhibition of nNOS catalytic activity mediated by arachidonic acid-induced tyrosine phosphorylation of this enzyme. The reduced NO bioavailability triggers nuclear factor (NF)-kB activation followed by the induction of inducible NOS (iNOS) expression. In cardiomyocytes ischaemia also triggers the induction of iNOS expression during reperfusion. The massive amounts of NO which are subsequently produced following iNOS induction may exert on cardiomyocytes and the other cell types of cells of the heart, such as endothelial and smooth muscle cells, macrophages and neutrophils, opposing effects, either beneficial or toxic. The balance between these two double-faced actions may contribute to the final clinical outcomes, determining the degree of functional adaptation of the heart to ischaemia/reperfusion injury. In the light of this new vision on the critical role played by the cross-talk between n/eNOS and iNOS as well as the non enzymatic NO production by nitrite, we have reason to believe that new pharmacological measurements or experimental interventions, such as ischaemic preconditioning, aimed at counteracting the drop in NO levels beyond the normal range of NO homeostasis during early reperfusion can represent an efficient strategy to reduce the extent of functional impairment and cardiac damage in the heart exposed to ischaemia/reperfusion injury.

Alpha-bisabolol: unexpected plant-derived weapon in the struggle against tumour survival?

Despite enormous scientific and economic effort tumour still is one of the most terrible pathologies among human population all over the world. Products derived from the plant kingdom have often offered an opportunity to counteract or alleviate this illness. Here, we summarize the short story of the study of an extraordinary effect of one plant compound towards transformed cells derived from highly malignant tumours. Alpha-bisabolol, a sesquiterpene widely present in plants, selectively kills transformed cells by apoptosis without affecting the viability of normal cells. One of its intracellular targets seems to be situated on mitochondria and is possibly identified as the permeability transition pore, as judged from rapid mitochondrial membrane potential dissipation induced by alpha-bisabolol and the failure to kill cells in the presence of cyclosporine A. Preferential adsorption of alpha-bisabolol into lipid rafts, rich in tumour cells, may explain the selective action of this compounds towards tumour cells. Furthermore, Surface Plasmon Resonance analysis indicates that alpha-bisabolol directly interacts with Bid protein, a member of the Bcl2 family deeply involved in apoptosis, suggesting a possibility that Bid, or similar protein(s), may be involved in a putative intracellular transport system of alpha-bisabolol from plasma membrane to mitochondria. Experiments with animals indicate that alpha-bisabolol is not toxic and is accumulated, through blood flow, in every tissues examined. Further animal studies to test its effect are currently under way.