The antioxidant butylated hydroxytoluene induces apoptosis in human U937 cells: the role of hydrogen peroxide and altered redox state

Pomegranate peel and peel extracts: chemistry and food features

The present review focuses on the nutritional, functional and anti-infective properties of pomegranate (Punica granatum L.) peel (PoP) and peel extract (PoPx) and on their applications as food additives, functional food ingredients or biologically active components in nutraceutical preparations. Due to their well-known ethnomedical relevance and chemical features, the biomolecules available in PoP and PoPx have been proposed, for instance, as substitutes of synthetic food additives, as nutraceuticals and chemopreventive agents. However, because of their astringency and anti-nutritional properties, PoP and PoPx are not yet considered as ingredients of choice in food systems. Indeed, considering the prospects related to both their health promoting activity and chemical features, the nutritional and nutraceutical potential of PoP and PoPx seems to be still underestimated. The present review meticulously covers the wide range of actual and possible applications (food preservatives, stabilizers, supplements, prebiotics and quality enhancers) of PoP and PoPx components in various food products. Given the overall properties of PoP and PoPx, further investigations in toxicological and sensory aspects of PoP and PoPx should be encouraged to fully exploit the health promoting and technical/economic potential of these waste materials as food supplements.

Neuroprotective effect by Dammishimgyu-herbal acupuncture against H2O2-induced apoptosis in human neuroblastoma, SH-SY5Y cells

BACKGROUND

The free radical is involved in neuronal cell death in human neurodegenerative disease. Dammishimgyu (DMSG)-herbal acupuncture has been used to treat neurological disorders in Korea. The present study was aimed to investigate the neuroprotective effect of DMSG-herbal acupuncture against H(2)O(2)-induced apoptosis in human neuroblastoma cell line, SH-SY5Y.

METHODS

The neuroprotective effect of DMSG-herbal acupuncture on H(2)O(2) induced apoptosis was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, 4,6-diamidino-2-phenylindole (DAPI) staining, reverse transcription-polymerase chain reaction (RT-PCR), western blots and nitrite assay.

RESULTS

In this study, 100 microM H(2)O(2)-treated cells decreased the cell viability with apoptotic features and increased the production of nitric oxide (NO). However, 0.1% DMSG treatment after exposure to 100 microM H(2)O(2) inhibited both H(2)O(2)-stimulated mRNA and protein expressions of BCL2-associated X protein (BAX) and caspase 3 apoptosis-related cysteine peptidase (CASP3). In addition, 0.1% DMSG treatment inhibited the increased NO production induced by H(2)O(2).

CONCLUSION

These results suggest that DMSG-herbal acupuncture shows protective effect against H(2)O(2)-induced neuronal damage.

Apoptotic effects of hydrogen peroxide and vitamin C on chicken embryonic fibroblasts: redox state and programmed cell death

The pro-apoptotic effects of hydrogen peroxide and the purported anti-apoptotic effects of Vitamin C on chicken embryonic fibroblasts were investigated. Hydrogen peroxide induced morphological changes in a dose dependent manner, and a myriad of autophagosomes were observed using transmission electron microscopy. Doxorubicin elicited alterations were not inhibited by co-incubation with Vitamin C except that mitochondrial structure was slightly improved. TUNEL assay, cytotoxicity analysis and flow cytometry revealed that the cytotoxicity, DNA fragmentation and apoptotic rates were dose dependent upon treatment with hydrogen peroxide. Calcium homeostasis was disrupted in a dose dependent manner, and cell cycle was blocked at G(2)/M checkpoint at low concentration and S/G(2) checkpoint at high concentration respectively upon treatment with hydrogen peroxide. The administration of Vitamin C only has a modest effect against doxorubicin induced apoptosis, calcium homeostasis disruption and cell cycle arrest. This research demonstrated that the elevation of reactive oxygen species is sufficient to induce the apoptosis of chicken embryonic fibroblasts, whereas the administration of Vitamin C does not necessarily have certain anti-apoptotic effects, especially when the stimulus is not directly linked with redox state.

Enhancement of allergic responses in vivo and in vitro by butylated hydroxytoluene

The effect of butylated hydroxytoluene (BHT), which is used widely as an antioxidant, on IgE-dependent allergic responses in vivo and in vitro was investigated. For in vivo study, passive cutaneous anaphylaxis (PCA) was elicited in rats by i.d. injection of anti-DNP IgE and 48 h later by i.v. injection of DNP-HSA. BHT was i.p. given immediately after anti-DNP IgE injection. For in vitro studies, the rat mast cell line RBL2H3 sensitized with monoclonal anti-dinitrophenol (DNP) IgE was challenged with the multivalent antigen DNP-human serum albumin (DNP-HSA) in the presence or absence of BHT. beta-Hexosaminidase and histamine released from RBL2H3 cells, as indicators of degranulation of the cells, the concentration of intracellular Ca2+, the level of phosphorylated-Akt, and global tyrosine phosphorylation as indicators of mast cell activation, were measured. The results showed that BHT given to anti-DNP IgE-sensitized rats augmented DNP-specific PCA in a dose-dependent manner. In the presence of BHT, IgE-induced releases of beta-hexosaminidase and histamine from RBL2H3 cells were increased. BHT also further elevated IgE-mediated increased concentrations of intracellular Ca2+ and the levels of phosphorylated-Akt, but did not affect global tyrosine phosphorylation, in RBL2H3 cells. Moreover, the PI3K inhibitor LY294002 inhibited IgE-dependent degranulation and its enhancement by BHT. These findings indicate that BHT may upregulate PCA by enhancing mast cell degranulation associated with enhancements of intracellular Ca2+ concentration and PI3K activation, suggesting that BHT might affect allergic diseases such as allergic rhinitis and asthma.

Amine oxidases in apoptosis and cancer

Amine oxidases, the major enzymes of biogenic amines metabolism, are considered to be biological regulators, especially for cell growth and differentiation. A primary involvement of amine oxidases in cancer growth inhibition and progression, especially by means of aldehydes, H(2)O(2) and other reactive oxygen species, the amine oxidase-mediated products of biogenic amines oxidation, has been demonstrated. Amine oxidases are involved in cancer growth inhibition because of the higher content in tumour cells of biogenic amines in comparison to normal cells. The cytotoxic effect can be explained by a damage to cell membranes and/or nuclei or, indirectly, through modulation of membrane permeability transition and therefore apoptosis. The oxidation products of biogenic amines appears to be also carcinogenic, while acrolein, produced from the oxidation of spermine and spermidine, should be a key compound both carcinogenic and cytotoxic. The cancer inhibition/promotion effect of amine oxidases could be explained by taking into consideration the full pattern of the enzyme content of the cell. The balance of amine oxidases and antioxidant enzymes appear to be a crucial point for cancer inhibition or progression. A long lasting imbalance of these enzymes appears to be carcinogenic, while, for a short time, amine oxidases are cytotoxic for cancer cells.

Differential effects of catalase on apoptosis induction in human promonocytic cells. Relationships with heat-shock protein expression

The administration of the H(2)O(2)-specific scavenger catalase attenuated the generation of apoptosis by the antitumor drugs etoposide, camptothecin, doxorubicin, and cisplatin in U-937 human promonocytic cells. By contrast, the antioxidant potentiated the generation of apoptosis by the inducers of the stress response, heat shock and cadmium, in this and other myeloid cell types. Catalase also increased the heat shock-provoked stimulation of caspase-3 and -9 activities, as well as the release of cytochrome c from mitochondria to the cytosol. The potentiation of cell death by catalase correlated with its capacity to inhibit the stress response, as demonstrated by the suppression of 70- or 27-kDa heat-shock protein expression and the inhibition of heat-shock transcription factor 1 binding activity. Conversely, the toxicity of catalase plus heat shock was attenuated when the cells were preconditioned with a soft heating, which elevated the 70-kDa heat-shock protein levels. By contrast with catalase, the antioxidants superoxide dismutase and probucol did not inhibit heat-shock protein expression or affect apoptosis in U-937 cells. Finally, it was observed that the antitumor drugs did not activate the stress response in U-937 cells and that catalase failed to inhibit HSP expression and to potentiate apoptosis in heat shock-treated RPMI 8866 lymphoblastic cells. Taken together, these results provide the first demonstration of a proapoptotic action of catalase, suggest that H(2)O(2) is a critical regulator of both apoptosis and the stress response, and corroborate the antiapoptotic action of heat-shock proteins in myeloid cells.

Induction and mechanism of apoptotic cell death by propofol in HL-60 cells

BACKGROUND

Apoptosis (programmed cell death) occurs in various physiological and pathological conditions, exhibits a characteristic mechanism of intracellular sequential reaction and may be involved in determining clinical outcome. The antioxidant activity of propofol (2,6-diisopropylphenol) together with the stimulating effect of protein kinase C suggests that propofol might have the potential to modulate apoptosis. Thus, it is of both clinical interest and biomedical importance to investigate and clarify the effect and mechanism of propofol upon the intracellular reactions underlying apoptotic cell death.

METHODS

The effect of propofol on apoptosis was investigated using cultured human promyelocytic leukemia HL-60 cells. This well-characterized cell line is useful for the study of apoptosis because the various biochemical steps occurring during apoptosis have been well documented.

RESULTS

Treatment of HL-60 cells with propofol resulted in growth inhibition with the formation of apoptotic bodies in a concentration-dependent manner. DNA fragmentation and ladder formation was also observed in a concentration-dependent manner. Propofol treatment resulted in activation of caspase-3, -6, -8 and -9, thereby suggesting that cell surface death receptor activation of the caspase cascade mediates propofol-induced apoptosis with consequent formation of the cleaved product of Bid (a pro-apoptotic Bcl-2 family member protein) and activation of the mitochondrial pathway with cytosolic release of cytochrome c.

CONCLUSION

Propofol may induce apoptosis, which is dependent on the mechanism that activates both the cell surface death receptor pathway and the mitochondrial pathway.

Mechanistic aspects of the induction of apoptosis by lauryl gallate in the murine B-cell lymphoma line Wehi 231

The effect of lauryl gallate (antioxidant E-312) has been studied on the mouse B-cell lymphoma line Wehi 231. This compound is able to inhibit protein tyrosine kinases (PTKs) in whole cells and in crude extracts with a better efficiency than other well-known PTK inhibitors such as herbimycin or genistein. Initial events triggered upon the incubation of cells with lauryl gallate in phosphate-buffered saline (up to 1 h) include the inhibition of tyrosine phosphorylation, discharge of the mitochondrial transmembrane potential, and induction of mRNA for Bcl-2. Long-term cultures in complete medium supplemented with fetal calf serum (up to 24 h) in the presence of this compound exhibit clear apoptotic features such as increase in phosphatidylserine in the cell surface, decrease in the functionality of mitochondria, cytochrome c release to the cytosol, activation of caspases, hypodiploidy, and oligonucleosomal breakdown of DNA. Comparison between Wehi cells overexpressing Bcl-2 (Wehi-bcl-2) with Wehi-neo cells shows a delay in the manifestations of the apoptotic signs, indicating that Bcl-2 has a partial protective effect on the apoptosis induced by lauryl gallate. The proapoptotic effect of lauryl gallate is not dependent on DNA or protein synthesis, is not blocked by the chelation of calcium, and is not reverted by N-acetylcysteine.