This is not a pipe - But how harmful is electronic cigarette smoke.

This issue of the Biomedical Journal tells us about the risks of electronic cigarette smoking, variations of SARS-CoV-2 and ACE2, and how COVID-19 affects the gastrointestinal system. Moreover, we learn that cancer immunotherapy seems to work well in elderly patients, how thyroid hormones regulate noncoding RNAs in a liver tumour context, and that G6PD is a double-edged sword of redox signalling. We also discover that Perilla leaf extract could inhibit SARS-CoV-2, that artificial neural networks can diagnose COVID-19 patients and predict vaccine epitopes on the Epstein-Barr Virus, and that men and women have differential inflammatory responses to physical effort. Finally, the surgical strategies for drug-resistant epilepsy, computer-supervised double-jaw surgery, dental pulp stem cell motility, and the restitution of the brain blood supply after atherosclerotic stroke are discussed.

Natural killer cells play an important role in virus infection control: Antiviral mechanism, subset expansion and clinical application.

With the global spread of coronavirus disease 2019 (COVID-19), the important role of natural killer (NK) cells in the control of various viral infections attracted more interest, via non-specific activation, such as antibody-dependent cell-mediated cytotoxicity (ADCC) and activating receptors, as well as specific activation, such as memory-like NK generation. In response to different viral infections, NK cells fight viruses in different ways, and different NK subsets proliferate. For instance, cytomegalovirus (CMV) induces NKG2C + CD57 + KIR+ NK cells to expand 3-6 months after hematopoietic stem cell transplantation (HSCT), but human immunodeficiency virus (HIV) induces KIR3DS1+/KIR3DL1 NK cells to expand in the acute phase of infection. However, the similarities and differences among these processes and their molecular mechanisms have not been fully discussed. In this article, we provide a summary and comparison of antiviral mechanisms, unique subset expansion and time periods in peripheral blood and tissues under different conditions of CMV, HIV, Epstein-Barr virus (EBV), COVID-19 and hepatitis B virus (HBV) infections. Accordingly, we also discuss current clinical NK-associated antiviral applications, including cell therapy and NK-related biological agents, and we state the progress and future prospects of NK cell antiviral treatment.

Associations between environmental factors and serological Epstein-Barr virus antibodies in patients with nasopharyngeal carcinoma in South China.

Epstein-Barr virus (EBV) reactivation, reflected by aberrantly increased levels of various serological antibodies, has been suggested to be an early indicator of nasopharyngeal carcinoma (NPC) onset and progression. We have previously suggested that certain lifestyle and dietary factors were associated with elevated serological levels of the antibody against various EBV antigens namely VCA, Zta, EBNA1, and oral EBV DNA loads among healthy population. It remains unclear whether these potential environmental factors would also influence EBV serological antibodies in NPC patients. We conducted an epidemiological study to evaluate the associations between such environmental factors and EBV antibody levels among 1701 NPC patients in South China. Pretreatment serums were collected and examined for VCA-IgA and EA-IgA by immunoenzymatic assays and antienzyme rate (AER) of EBV DNase-specific neutralizing antibody. We found that consumption of Canton-style herbal tea was significantly correlated with increased serological antibody levels of VCA-IgA and EA-IgA, with adjusted ORs of 1.35 (95% CI: 1.03-1.76) and 1.32 (95% CI: 1.01-1.73), respectively, in the weekly intake frequency stratum, while not related to AER of EBV DNase-specific neutralizing antibody. Smoking was found to be not only an apparent risk factor for higher antibody levels of AER in stage III-IV patients (OR = 1.60, 95% CI: 1.11-2.30), but also associated closely with NPC stage at diagnosis (OR = 2.17, 95% CI: 1.47-3.22), with dose-response effects. In conclusion, we found consumption of Canton-style herbal tea and cigarette smoking were in positive associations with elevated EBV antibodies in NPC patients, which may be of public health significance for the primary prevention of EBV-associated diseases especially NPC.

Conjugating Prussian blue nanoparticles onto antigen-specific T cells as a combined nanoimmunotherapy.

AIM: To engineer a novel nanoimmunotherapy comprising Prussian blue nanoparticles (PBNPs) conjugated to antigen-specific cytotoxic T lymphocytes (CTL), which leverages PBNPs for their photothermal therapy (PTT) capabilities and Epstein-Barr virus (EBV) antigen-specific CTL for their ability to traffic to and destroy EBV antigen-expressing target cells. MATERIALS & METHODS: PBNPs and CTL were independently biofunctionalized. Subsequently, PBNPs were conjugated onto CTL using avidin-biotin interactions. The resultant cell-nanoparticle construct (CTL:PBNPs) were analyzed for their physical, phenotypic and functional properties. RESULTS: Both PBNPs and CTL maintained their intrinsic physical, phenotypic and functional properties within the CTL:PBNPs. CONCLUSION: This study highlights the potential of our CTL:PBNPs nanoimmunotherapy as a novel therapeutic for treating virus-associated malignancies such as EBV+ cancers.

The beneficial effects of vitamin D3 on reducing antibody titers against Epstein-Barr virus in multiple sclerosis patients.

Recently, the relationship between immunoreactivity to Epstein-Barr virus (EBV) and hypo-vitamin D in multiple sclerosis (MS) patients has been described. The aim of this study was to investigate whether vitamin D3 supplementation in MS patients could influence the immune response against latent EBV infection. Forty MS patients were recruited in this study. Twenty-seven patients were supplemented with 50,000 IU/week of vitamin D3 for 6 months and thirteen enrolled as controls. 25-Hydroxyvitamin D (25OHD) levels and IgG titers against EBNA1 and VCA were determined pre- and post-supplementation. All the patients were seropositive for EBV prior to vitamin D supplementation. In this cohort, 22.5% and 47.5% of the MS patients had deficient and insufficient levels of 25OHD, respectively. Our findings confirm that antibody titers against EBV in MS patients rise after the onset of the disease and indicate that vitamin D3 supplementation could limit augmentation of these titers in MS patients.

Effect of high dose vitamin C on Epstein-Barr viral infection.

Background Many natural compounds were tested for the ability to suppress viral replication. The present manuscript details an analysis of high dose vitamin C therapy on patients with EBV infection. Material and Methods The data were obtained from the patient history database at the Riordan Clinic. Among people in our database who were treated with intravenous vitamin C (7.5 g to 50 g infusions) between 1997 and 2006, 178 patients showed elevated levels of EBV EA IgG (range 25 to 211 AU) and 40 showed elevated levels of EBV VCA IgM (range 25 to 140 AU). Most of these patients had a diagnosis of chronic fatigue syndrome, with the rest being diagnosed as having mononucleosis, fatigue, or EBV infection. Results Our data provide evidence that high dose intravenous vitamin C therapy has a positive effect on disease duration and reduction of viral antibody levels. Plasma levels of ascorbic acid and vitamin D were correlated with levels of antibodies to EBV. We found an inverse correlation between EBV VCA IgM and vitamin C in plasma in patients with mononucleosis and CFS meaning that patients with high levels of vitamin C tended to have lower levels of antigens in the acute state of disease. In addition, a relation was found between vitamin D levels and EBV EA IgG with lower levels of EBV early antigen IgG for higher levels of vitamin D. Conclusions The clinical study of ascorbic acid and EBV infection showed the reduction in EBV EA IgG and EBV VCA IgM antibody levels over time during IVC therapy that is consistent with observations from the literature that millimolar levels of ascorbate hinder viral infection and replication in vitro.

Antibodies to Epstein-Barr virus and MRI disease activity in multiple sclerosis.

BACKGROUND: Previous reports indicate an association between Epstein-Barr virus (EBV) antibody levels and multiple sclerosis (MS) disease activity, but the results have been conflicting. OBJECTIVES: The objective of this paper is to study if EBV antibody levels reflect MRI disease activity in MS and examine the potential for EBV antibody levels as biomarkers for treatment response. METHODS: A total of 87 MS patients were followed for two years prior to and during interferon beta (IFNB) treatment, with MRI examinations and serum measurement of IgM and IgG antibodies to viral capsid antigen (VCA), EBV nuclear antigen 1 (EBNA-1) and early antigen (EA). Associations between EBV antibody levels and MRI activity were assessed by a logistic regression model. RESULTS: Higher anti-EBNA-1 IgG levels were associated with increased MRI activity, OR = 2.95 (95% CI 1.07-8.10; p = 0.036) for combined unique activity (CUA; the sum of T1Gd+ lesions and new or enlarging T2 lesions). Although most patients were anti-VCA IgM negative, there was an inverse association, OR = 0.32 (95% CI 0.12-0.84; p = 0.021) with CUA during IFNB treatment. CONCLUSIONS: This study supports an association between anti-EBNA-1 IgG levels and MS disease activity. We also found an inverse association with anti-VCA IgM levels during IFNB treatment not previously described, indicating anti-VCA IgM as a possible biomarker for IFNB treatment response.

A yeast-based assay identifies drugs that interfere with immune evasion of the Epstein-Barr virus.

Epstein-Barr virus (EBV) is tightly associated with certain human cancers, but there is as yet no specific treatment against EBV-related diseases. The EBV-encoded EBNA1 protein is essential to maintain viral episomes and for viral persistence. As such, EBNA1 is expressed in all EBV-infected cells, and is highly antigenic. All infected individuals, including individuals with cancer, have CD8(+) T cells directed towards EBNA1 epitopes, yet the immune system fails to detect and destroy cells harboring the virus. EBV immune evasion depends on the capacity of the Gly-Ala repeat (GAr) domain of EBNA1 to inhibit the translation of its own mRNA in cis, thereby limiting the production of EBNA1-derived antigenic peptides presented by the major histocompatibility complex (MHC) class I pathway. Here we establish a yeast-based assay for monitoring GAr-dependent inhibition of translation. Using this assay we identify doxorubicin (DXR) as a compound that specifically interferes with the GAr effect on translation in yeast. DXR targets the topoisomerase-II-DNA complexes and thereby causes genomic damage. We show, however, that the genotoxic effect of DXR and various analogs thereof is uncoupled from the effect on GAr-mediated translation control. This is further supported by the observation that etoposide and teniposide, representing another class of topoisomerase-II-DNA targeting drugs, have no effect on GAr-mediated translation control. DXR and active analogs stimulate, in a GAr-dependent manner, EBNA1 expression in mammalian cells and overcome GAr-dependent restriction of MHC class I antigen presentation. These results validate our approach as an effective high-throughput screening assay to identify drugs that interfere with EBV immune evasion and, thus, constitute candidates for treating EBV-related diseases, in particular EBV-associated cancers.

Marital distress prospectively predicts poorer cellular immune function.

OBJECTIVE: Distressed marriages enhance risk for a variety of health problems. Immune dysregulation is one potential mechanism; cross-sectional studies have demonstrated that marital distress is linked to maladaptive immune alterations. The current study filled an important gap in the literature by examining the ability of marital distress to prospectively predict immune alterations over a two-year period. METHOD: Participants were 90 couples (N=180 individuals; Mage=25.67) married less than a year at the time of their first study visit. Both members of a couple completed a baseline assessment of marital quality and provided blood samples at baseline and two years later. 63 couples (N=123 individuals) completed the follow-up assessment. RESULTS: Spouses in more distressed marriages had larger declines in cellular immune function over time than spouses in less distressed marriages. Furthermore, the results were highly consistent across two different indices, proliferative responses to two mitogens, concanavalin A (Con A) and phytohemagglutinin (PHA). CONCLUSIONS: Marital distress has a variety of negative health consequences. The current study provided important evidence that marital distress has longer-term immune consequences. Accordingly, the present results provide a glimpse into the pathways through which marital distress may impact health over time.

Combining dasatinib with dexamethasone long-term leads to maintenance of antiviral and antileukemia specific cytotoxic T cell responses in vitro.

Maintaining graft versus leukemia (GvL) and antivirus responses of cytotoxic T cells (CTLs) while suppressing graft-versus-host disease (GvHD) remains a challenge after allogeneic bone marrow transplantation. Clinical observations indicate that combining glucocorticoids with multi-tyrosine-kinase inhibitors could be a successful therapeutic approach. We and others have shown that the BCR-ABL/SRC kinase inhibitor dasatinib may enhance or suppress T cells in vitro. In this report, we evaluated combination effects of dasatinib and dexamethasone on CD3⁺ and virus-specific CD8⁺ T cells directly ex vivo and on antigen-specific leukemia-reactive and alloreactive CD8⁺ T cell clones. Functional outcomes assessed included cytokine production (IL-2, IFN-γ, TNF-α), degranulation (CD107a/b), activation (CD69 upregulation), proliferation, apoptosis and necrosis induction, and signal transduction. Overall, helper CD4⁺ T cells were more sensitive to inhibitory effects of the drug combination than cytotoxic CD8⁺ T cells and were more naive than memory T cell subsets. Of note, synergistic inhibitory effects occurred in different memory but not in naive T cell subsets. The drug combination inhibited virus-specific CD8⁺ T cell proliferation, but left cytokine production and degranulation unaltered, which may be due to the viral memory subset composition. Dasatinib rather hampered IFN-γ secretion and cytotoxic activity of human leukocyte antigen (HLA)-reactive CTLs, whereas effector functions of leukemia-reactive CTLs were maintained or enhanced when applied long term. Our data suggest that dasatinib might modulate GvL- differently than GvHD-promoting CTLs and provide a rationale to explore the drug combination further to treat GvHD while preserving GvL and antiviral CTL responses.

Herpesvirus infections and allergic sensitization in children of families with anthroposophic and non-anthroposophic lifestyle - the ALADDIN birth cohort.

BACKGROUND: Growing up in families with an anthroposophic lifestyle has been associated with reduced risk of allergic disease in children. The aim of this report was to assess whether children with this lifestyle are infected earlier with Epstein-Barr virus (EBV), which has been associated with reduced risk of allergic disease, and three other herpesviruses potentially involved in allergy development, namely Human herpesvirus 6 (HHV6), Human herpesvirus 7 (HHV7) and cytomegalovirus (CMV). METHODS: Within the ALADDIN (Assessment of Lifestyle and Allergic Disease During Infancy), birth cohort study 157 children were categorized according to lifestyle into anthroposophic and non-anthroposophic. IgG-levels for EBV, HHV6, HHV7 and CMV were determined in plasma samples collected at ages 12 and 24 months and from parents. IgE levels against seven common allergens were analyzed at 24 months. RESULTS: No significant differences in seroprevalence of EBV, HHV7 or CMV were detected at any age between the two lifestyle groups. The seroprevalence of HHV6 was significantly lower in the anthroposophic group at 24 months of age (74.6% vs. 87.5%, p-value 0.048). Further, no significant associations between allergic sensitization and seropositivity to any of the viruses were detected; however, an interaction effect of lifestyle could not be ruled out. CONCLUSIONS: Our results indicate that there is no strong influence of exposure to the anthroposophic lifestyle on the time for infection with EBV, HHV6, HHV7 or CMV. These infections can therefore not be assumed to be important factors in the allergy-protective effect of this lifestyle.

Cytokine secretion and latent herpes virus reactivation with 28 days of horizontal hypokinesia.

INTRODUCTION: Hypokinesia is associated with spaceflight and prolonged illnesses and may lead to secondary immune deficiency. METHODS: The distribution of immunocytes in whole blood, mitogen-induced cytokine secretion in vitro, Epstein-Barr virus (EBV) reactivation, and plasma cortisol levels were studied in 13 healthy volunteers subjected to a horizontal bed rest (BR) regime for 28 d. Samples were collected before the study, weekly during BR, and then 3-5 d after the regime ended. Additionally, subjects were treated with hydrocortisone on the 1st and 27th d of BR to simulate the hypercortisolemia that occurs during stress. RESULTS: The factors of 28-d BR regime accompanied by acute hypercortisolemia significantly decreased the relative and absolute number of total lymphocytes, CD3+ T-cells, T-helper subset, and monocytes, but increased the percentage of the CD8+ T-cells, and NK cells at the 4th wk compared with the baseline. A significant decrease in mitogen-activated secretion of IL-2, IFN-gamma, TNF-beta, IL-6, and IL-10 was registered at the same interval. Also, secretion of IL-2 and IFN-gamma declined at the 2nd week of the BR regime. Secretion of IL-4 was significantly higher at the 2nd and 3rd weeks compared with the baseline. A significant increase in the shedding of EBV DNA in saliva was observed as early as the 3rd wk of BR. CONCLUSIONS: Stress factors associated with BR significantly alter immune responsiveness in vitro and in vivo. Changes in the cytokine secretion and cytokine imbalance precede latent EBV reactivation. PHA/LPS-activated cytokine secretion in whole blood can be used as a test system for predicting latent virus activation.

Bran extracts from pigmented rice seeds inhibit tumor promotion in lymphoblastoid B cells by phorbol ester.

Using flow cytometry, we quantitatively evaluated anti-tumor-promoting activity of rice bran extracts by measuring inhibition of Epstein-Barr virus early-antigen activation (EBV-EA) induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). This assay measures anti-tumor-promoting activity and cytotoxicity of target substances using the same batch of cells. Using this short-term procedure, we have determined the anti-tumor-promoting activity of 70% ethanol-water extracts of bran (outer layer) from seeds of five pigmented rice cultivars: Jumlalocal-1, DZ 78, Elwee, LK1-3-6-12-1-1, and LK1A-2-12-1-1. The results show that, compared to an extract from the non-pigmented white cooking rice variety Chuchung, the extracts from the pigmented varieties strongly inhibited phorbol ester-induced tumor promotion in marmoset lymphoblastoid cells B95-8 in vitro. These findings may facilitate development and use of new health-promoting rice varieties.

Stress and depression-induced immune dysfunction: implications for the development and progression of cancer.

The persistent activation of the hypothalamic-pituitary-adrenal axis and the sympathetic-adrenal-medullary axes in chronic stress response and in depression impairs the immune response and contributes to the development and progression of some types of cancer. This overview presents results from experimental animal models, human studies, and clinical evidence that various cellular and molecular immunological parameters are compromised in chronic stress and depression. At the cellular level, stressed and depressed patients had overall leukocytosis, high concentrations of circulating neutrophils, reduced mitogen-stimulated lymphocyte proliferation and neutrophil phagocytosis. At the molecular level, high levels of serum basal cortisol, acute phase proteins, specific antibodies against herpes simplex virus type 1 and Epstein Barr virus, plasma concentration of interleukins IL-1, IL-6, and TNF-alpha, and a shift in the balance of Th1 and Th2 immune response were observed. Both stress and depression were associated with the decreased cytotoxic T-cell and natural killer cell activities affecting the processes of the immune surveillance of tumours, and the events that modulate the development and the accumulation of somatic mutations and genomic instability. DNA damage, growth and angiogenic factors, proteases, matrix metalloproteinases, and reactive oxygen species were also related to the chronic stress response and depression. Behavioural strategies, psychological, and psychopharmacotherapeutic interventions that enhance effective coping and reduce affective distress showed beneficial effects in cancer patients. A better understanding of the bidirectional communication between the neuroendocrine and immune systems could contribute to novel clinical and treatment strategies in oncology.

Differential activation of signal transducer and activator of transcription 6 in B cells from allergic children and their non-allergic siblings.

BACKGROUND: The germline (GL) epsilon promoter is regulated by IL-4 and is essential for class switching to IgE. IL-4-induced gene expression is largely mediated through activation of latent transcription factor STAT6 (signal transducer and activator of transcription 6). OBJECTIVE: We investigated whether increased levels of IgE in allergic individuals may be associated with alteration in the level or activation of STAT6 and subsequent increase in GL epsilon promoter activity. METHODS: Electrophoretic mobility shift assay and Western blotting assays were used to investigate the level of expression and activation of STAT6 in Epstein-Barr virus (EBV)-transformed B cell lines from children with birch pollen allergy and their non-allergic siblings. The activity of the GL epsilon promoter was tested in a transient transfection assay. RESULTS: STAT6 was expressed at the same level in all B cell lines tested. In two out of five sibling pairs STAT6 was activated by IL-4 more efficiently in the allergic individuals but in the three other pairs the opposite was found. In transient transfections, no difference in IL-4-induced GL epsilon promoter function was detected, although basal promoter activity varied between allergic and healthy siblings in two out of five pairs. CONCLUSIONS: We demonstrate for the first time that upon IL-4 signalling STAT6 transcription factor activation differs in B cells from different individuals. Although we did not find any association between STAT6 activation and allergy, we do not exclude a possibility that stronger activation of this transcription factor is associated with an expression of allergic phenotype.

Epstein-Barr virus (EBV) reactivation in allogeneic stem-cell transplantation: relationship between viral load, EBV-specific T-cell reconstitution and rituximab therapy.

BACKGROUND: Monitoring of Epstein-Barr virus (EBV) reactivation after allogeneic hematopoietic stem-cell transplantation markedly improved with quantitative real-time polymerase chain reaction amplification of EBV DNA and visualization of EBV-specific CD8+ T cells with peptide-human leukocyte antigen (HLA) class I tetramers. We decided to combine these methods to evaluate posttransplant EBV reactivation and rituximab therapy. METHODS: We followed 56 patients treated with an HLA-genoidentical sibling (n=32), an HLA-matched unrelated donor (MUD, n=19), or an unrelated cord-blood transplant (n=5). EBV DNA was quantified in plasma and in peripheral blood mononuclear cells (PBMC). Patient CD8+ T cells were stained with a panel of eight tetramers. RESULTS: EBV DNA was detected in half of the patients, mainly in the MUD group (17/19). In 19 patients, viral DNA was detected only in the cellular compartment. All patients who controlled reactivation without rituximab and despite a viral load of greater than 500 genome equivalents (gEq)/150,000 PBMC mounted an EBV-specific CD8+ T-cell response in greater than 1.4% of CD3+CD8+ T cells. Plasmatic EBV genome was found in nine patients preceded by a high cellular viral load. Three of these patients controlled the reactivation before or without the introduction of rituximab, and they all developed a significant and increasing EBV-specific T-cell response. Patients with EBV-specific T cells at the onset of reactivation controlled viral reactivation without rituximab. CONCLUSION: This study emphasizes the benefit of an early and close monitoring of EBV reactivation and CD8+-specific immune responses to initiate rituximab only when necessary and before the immune response becomes overwhelmed by the viral burden.

Potential anti-tumor promoting activity of lupane-type triterpenoids from the stem bark of Glochidion zeylanicum and Phyllanthus flexuosus.

Four known lupane-type triterpenoids, glochidonol (1), glochidiol (2), lup-20(29)-ene-1beta,3beta-diol (3) and glochidone (3) were isolated from the stem bark of Glochidion zeylanicum. Previously, lupeol (5), lup-20(29)-ene-3beta,24-diol (6) and betulin (7) were isolated from the stem bark of Phyllanthus flexuosus. This study reports the assays of these lupane-type triterpenoids: all isolates 1-7 and synthetic analogues, glochidonyl acetate (1a), lup-20(29)-ene-1,3-dione (1b) and lup-20(29)-ene 3beta,24-diacetate (6a) were tested for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol 13-acetate (TPA). Among them, the effects of compounds 2 (IC50 = 290 mol ratio/32 pmol TPA) and 3 (IC50 = 300) were stronger than the others. In addition, compound 2 exhibited a strong inhibitory effect on mouse skin tumor promotion in an in vivo mouse two-stage carcinogenesis test.

Two new anti-tumor promoting serratane-type triterpenoids from the stem bark of Picea jezoensis var. jezoensis.

Two new serratane-type triterpenoids, 1 and 2, were isolated from the stem bark of Picea jezoensis Carr. var. jezoensis (Pinaceae). Their structures were determined to be 3beta-methoxyserrat-13-en-21beta-ol (1) and 13beta, l4beta-epoxy-3beta-methoxyserratan-21beta-ol (2) on the basis of spectroscopic methods and partial syntheses. Compounds 1 and 2 and their acetates were screened as potential anti-tumor promoters by using the in vitro short-term 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced Epstein-Barr virus early antigen (EBV-EA) activation assay. IC50 value evaluation showed that compound 1 was more effective than others. In addition, compounds 1 and 2 were examined for anti-tumor promoting activities in a two-stage carcinogenesis assay of mouse skin tumors induced by 7,12-dimethylbenz[a]anthracene (DMBA) as an initiator and TPA as a promoter. Compounds 1 and 2 exhibited significant anti-tumor promoting effects on mouse skin carcinogenesis.

Chemopreventive effect of resveratrol, sesamol, sesame oil and sunflower oil in the Epstein-Barr virus early antigen activation assay and the mouse skin two-stage carcinogenesis.

Resveratrol, sesamol, sesame oil and sunflower oil are known natural dietary components with intrinsic cancer chemopreventive potentials. As a part of our study of dietary constituents as potential cancer chemopreventive agents, we have assessed the anti-cancer potentials of these products in the promotion stage of cancer development employing the in vitro Epstein-Barr virus early antigen activation assay induced by the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA). Further, we studied the activities of these compounds in the brine shrimp cytotoxicity assay as well as on the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging bioassay with a view to comparing some of the mechanisms of their anti-cancer activity. Finally, we compared the observed chemoprotective capabilities of the four products in the in vivo 7,12 dimethylbenz(a)anthracene initiated and TPA-promoted mouse skin two-stage carcinogenesis protocols. All the products tested showed a profound inhibitory effect on the Epstein-Barr virus early antigen induction using Raji cells. Comparatively, sesame oil was the most potent followed by sesamol and then resveratrol. Only sesamol and resveratrol showed a remarkable cytotoxic activity in the brine shrimp lethality assays as well as profound free radical scavenging activity in the DPPH bioassay. In both test systems, sesamol exhibited a more remarkable activity than resveratrol while sesame oil and sunflower oil did not exhibit any appreciable activity even at the highest concentrations tested (4000 microg ml(-1) ). In our in vivo assay at a 50-fold molar ratio to TPA, sesamol offered 50% reduction in mouse skin papillomas at 20 weeks after promotion with TPA. Under an identical molar ratio to TPA, resveratrol offered a 60% reduction in the papillomas in mouse at 20 weeks. Thus sesamol seems to be an almost equally potent chemopreventive agent. Sesame oil and sunflower oil offered 20 and 40% protection, respectively, in the mouse skin tumor model. The anti-oxidant capabilities of these compounds could not solely explain the observed anti-cancer characteristics. Resveratrol is present in grapes. Sesamol, a constituent of sesame oil and sunflower oil are regularly consumed dietary natural products. The observed chemopreventive effect of these products particularly warrants more attention since they already exist in the population with no known adverse effects.