Involvement of reactive oxygen species in capsaicinoid-induced apoptosis in transformed cells

Capsiate ameliorates secondary hyperparathyroidism by improving insulin sensitivity and inhibiting angiogenesis

Secondary hyperparathyroidism has a significant impact on the overall well-being of the body. Capsiates, known for their antioxidant and metabolic properties, have emerged as a promising alternative treatment for secondary hyperparathyroidism. This study aims to evaluate the effects and mechanisms of capsiates in the treatment of secondary hyperparathyroidism. To achieve our research objectives, we conducted a study on patients' serum and examined changes in metabolic markers using serum metabolomics. We induced secondary hyperparathyroidism in rat through dietary intervention and divided them into four groups. The first group, referred to as the Parathyroid Hormone (PTH) group, received a low-calcium and high-phosphate diet (0.2% calcium, 1.2% phosphorus). The second group served as the control group, receiving a standard phosphate and calcium diet (0.6% calcium, 0.6% phosphorus). The third group, called the capsiates group, consisted of rat from the control group treated with capsiates (intraperitoneal injection of 2 mg/kg capsiates for 2 weeks after 2 weeks of dietary intervention). The fourth group was the capsiates-treated PTH group. Subsequently, we conducted ribose nucleic acid (RNA) sequencing on parathyroid gland cells and evaluated serum thyroxine levels, oxidative stress, expression of proteins associated with vascular neogenesis, measurement of SOD, GSH and 3-nitrotyrosine, micro-CT and histological staining. The serum metabolomic data revealed a significant decrease in capsiate levels in the secondary hyperparathyroidism group. Administration of capsiates to PTH rat resulted in increased calcium levels compared to the PTH group. Additionally, the PTH + Capsiates group showed significantly lower levels of PTH and phosphate compared to the PTH group. The PTH group exhibited a notable increase in the quantity and size of mitochondria compared to the control group. Following capsiates administration to the PTH group, there was a significant reduction in the number of mitochondria and length of microvilli, but an increase in the size of mitochondria compared to the PTH group. Sequencing analysis revealed that vascular endothelial growth factor (VEGF) and Vascular Endothelial Growth Factor Receptor 1 (VEGFR1) play crucial roles in this process. Vascular-related variables and downstream signalling were significantly elevated in hyperthyroidism and were alleviated with capsaicin treatment. Finally, combining capsiates with the PTH group improved bone mineral density, Tb.N, BV.TV, Cs.Th, Tt.Ar, OPG, Ob.TV and Oc.TV, as well as the mineral apposition rate, but significantly decreased Tb.Sp and Receptor Activator for Nuclear Factor-κ B Ligand (RANKL) compared to the PTH group. The findings suggest that capsiates can improve secondary hyperparathyroidism and ameliorated osteoporosis outcomes by inhibiting angiogenesis and reducing oxidative stress.

Antioxidant potential and factors influencing the content of antioxidant compounds of pepper: A review with current knowledge

The use of natural food items as antioxidants has gained increasing popularity and attention in recent times supported by scientific studies validating the antioxidant properties of natural food items. Peppers (Capsicum spp.) are also important sources of antioxidants and several studies published during the last few decades identified and quantified various groups of phytochemicals with antioxidant capacities as well as indicated the influence of several pre- and postharvest factors on the antioxidant capacity of pepper. Therefore, this review summarizes the research findings on the antioxidant activity of pepper published to date and discusses their potential health benefits as well as the factors influencing the antioxidant activity in pepper. The major antioxidant compounds in pepper include capsaicinoids, capsinoids, vitamins, carotenoids, phenols, and flavonoids, and these antioxidants potentially modulate oxidative stress related to aging and diseases by targeting reactive oxygen and nitrogen species, lipid peroxidation products, as well as genes for transcription factors that regulate antioxidant response elements genes. The review also provides a systematic understanding of the factors that maintain or improve the antioxidant capacity of peppers and the application of these strategies offers options to pepper growers and spices industries for maximizing the antioxidant activity of peppers and their health benefits to consumers. In addition, the efficacy of pepper antioxidants, safety aspects, and formulations of novel products with pepper antioxidants have also been covered with future perspectives on potential innovative uses of pepper antioxidants in the future.

Sweet pepper and its principle constituent capsiate: functional properties and health benefits

Capsiate is a non-pungent analogue of capsaicin. It belongs to the family of capsinoids which are esters of vanillyl alcohol with fatty acids while capsaicin belongs to the family of capsaicinoids that are amides of vanillylamine with a variety of branched-chain fatty acids. While capsaicin is extensively reported for plethora of pharmacological actions, capsiate remains much less explored. Extracted from various species of Capsicum plant, the molecule has also been chemically synthesized via a number of synthetic and enzymatic routes. Based on its action on transient receptor potential vanilloid subfamily member 1 receptors, recent research has focused on its potential roles in treatment of obesity, metabolic disorders, cancer, cardiovascular disorders and gastro-intestinal disorders. Its toxicity profile has been reported to be much safe. The molecule, however, faces the challenge of low aqueous solubility and stability. It has been commercialized for its use as a weight loss supplement. However, the therapeutic potential of the compound which is much beyond boosting metabolism remains unexplored hitherto. This comprehensive review summarizes the studies demonstrating the therapeutic potential of capsiate in various pathological conditions. Discussed also are potential future directions for formulation strategies to develop efficient, safe and cost-effective dosage forms of capsiate to explore its role in various disease conditions. The databases investigated include Cochrane library, Medline, Embase, Pubmed and in-house databases. The search terms were "capsiate," "capsinoids," "thermogenesis," and their combinations. The articles were screened for relevance by going through their abstract. All the articles pertaining to physicochemical, physiological, pharmacological and therapeutic effects of capsiate have been included in the manuscript.

González-de-Peredo A, Espada-Bellido E, Ferreiro-González M, Palma M, Garcés-Claver A, F. Barbero G. Content of Capsaicinoids and Capsiate in "Filius" Pepper Varieties as Affected by Ripening

Peppers are fruits with wide genetic variability and multiple ways of being consumed that hold a relevant position in the human diet. Nowadays, consumers are interested in new gastronomic experiences provided by pepper cultivars that present new shapes, colors, and flavors while preserving their bioactive compounds, such as their capsaicinoids and capsinoids. However, numerous changes take place during their development that may alter their biological properties. Therefore, this work evaluates the capsaicinoid and capsiate contents in two traditional varieties of ornamental peppers ("Filius Blue" and "Filius Green'") during fruit maturation. The aim is to determine the ideal harvesting moment depending on the farmer's objective (e.g., achieving a specific color, shape, or flavor; achieving the maximum concentrations of bioactive compounds). The capsaicinoid contents followed different patterns in the two varieties analyzed. The "Filius Blue" variety exhibited increasing concentrations of capsaicinoids up to the 41st day post-anthesis (dpa), from which point on this trend was reversed. The concentrations in the "Filius Green" variety increased and decreased several times, reaching maximum concentrations on the 69th dpa. Regarding capsiate contents, both varieties varied in the same way, reaching maximum concentrations on the 34th dpa and then decreasing.

Fecal peritonitis in aging rat model. Therapeutic response to different antibiotic strategies

PURPOSE

To evaluate the response of aging rats with sepsis to two different antibiotic regimens.

METHODS

The study was conducted with 30 aging rats (18 month-old) with autologous feces peritonitis. The animals were divided into three groups: Group 0 received no therapeutic intervention (control), while Group 1 received a single dose of 40 mg/kg meropenem and Group 2 received a single dose of 20 mg/kg moxifloxacin. The intervention in both Groups was made 6 hours after induction of peritonitis. The animals were followed up to 15 days for evaluating morbidity and mortality. The weights at baseline were similar in all groups.

RESULTS

At the end of follow-up, weight loss was significantly greater (p=0.0045) in Group 0 (non-intervention controls). Culture from a blood sample at the end of follow-up was positive in all the animals in Group 0, in two animals in Group 1 and in four animals in Group 2. Morbidity/mortality was significantly higher in Group 0 compared to both Groups 1 and 2 (p=0.003) but the scores were not significantly different between Groups 1 and 2 (p=0.6967).

CONCLUSION

Both antibiotic regimens rendered promising results for the treatment of fecal peritonitis.

IN-VITRO evidence for the protective properties of the main components of the Mediterranean diet against colorectal cancer: A systematic review

AIM

Epidemiological studies have shown that the incidence and mortality rates of colorectal cancer (CRC) vary over 10-fold worldwide where within Westernized societies lower rates are observed amongst populations living within the Mediterranean basin, suggesting a significant influence of environment and dietary style in CRC carcinogenesis. Interpretation of the data concerning the benefits of mediterranean (MD) diet is difficult in vivo because of the variability of alimentary regimens used, the differing compliance with dietary supplementation and because of the non-uniform duration of patient cohort observation. Therefore, the aim of this review is to evaluate the in-vitro effects on colorectal cancer cell lines.

METHODS

the literature concerning the in-vitro effects of 4 of the principal components symbolizing the MD such as olive oil (polyphenol), red chili (capsaicin), tomato (lycopene) and red grapes (resveratrol) have been systematically reviewed.

RESULTS

Several studies have demonstrated that polyphenols form olive oil, lycopene, resveratrol and capsaicin have multiple anticancer properties affecting several metabolic pathways involved in cancerogenesis, apoptosis, and metastasis in CRC cell lines.

CONCLUSION

This review summarizes some of the most recent data potentially supportive of the use of MD in CRC chemoprevention, analyzing the in vitro effects of individual components of the MD on CRC cell development, progression, metastasis and apoptosis.

Capsaicin inhibits the adipogenic differentiation of bone marrow mesenchymal stem cells by regulating cell proliferation, apoptosis, oxidative and nitrosative stress

Suppression of the maturation of pre-adipocytes into adipocytes and inhibition of the differentiation of mesenchymal stem cells into adipocytes by capsaicin.

The potential antitumor effects of capsaicin

Capsaicin, one of the major pungent ingredients found in red peppers, has been recently demonstrated to induce apoptosis in many types of malignant cell lines including colon adenocarcinoma, pancreatic cancer, hepatocellular carcinoma, prostate cancer, breast cancer, and many others. The mechanism whereby capsaicin induces apoptosis in cancer cells is not completely elucidated but involves intracellular calcium increase, reactive oxygen species generation, disruption of mitochondrial membrane transition potential, and activation of transcription factors such as NFkappaB and STATS. Recently, a role for the AMP-dependent kinase (AMPK) and autophagy pathways in capsaicin-triggered cell death has been proposed. In addition, capsaicin shows antitumor activity in vivo by reducing the growth of many tumors induced in mice. In this chapter, we report the last advances performed in the antitumor activity of capsaicin and review the main signaling pathways involved.

Antitumor activity of capsaicin on human colon cancer cells in vitro and colo 205 tumor xenografts in vivo

Capsaicin was reported to inhibit cancer cell growth. The aim of this study was to evaluate the antitumor potential of capsaicin by studying antitumor activity in vitro as well as in vivo. The in vitro studies are to examine the effects of capsaicin on human colon cancer colo 205 cells after exposure to capsaicin. The results showed that capsaicin induced cytotoxic effects in a time- and dose-dependent manner and increased reactive oxygen species (ROS) and Ca(2+) but decreased the level of mitochondrial membrane potential (ΔΨ(m)) in colo 205 cells. Data from Western blotting analysis indicated that the levels of Fas, cytochrome c, and caspases were increased, leading to cell apoptosis. Capsaicin decreased the levels of anti-apoptotic proteins such as Bcl-2 and increased the levels of pro-apoptotic proteins such as Bax. Capsaicin-induced apoptosis in colo 205 cells was also done through the activations of caspase-8, -9 and -3. In vivo studies in immunodeficient nu/nu mice bearing colo 205 tumor xenografts showed that capsaicin effectively inhibited tumor growth. The potent in vitro and in vivo antitumor activities of capsaicin suggest that capsaicin might be developed for the treatment of human colon cancer.

Novel loss-of-function putative aminotransferase alleles cause biosynthesis of capsinoids, nonpungent capsaicinoid analogues, in mildly pungent chili peppers (Capsicum chinense)

Capsinoids are a group of nonpungent capsaicinoid analogues produced in Capsicum fruits. They have similar bioactivities to capsaicinoids such as suppression of fat accumulation and antioxidant activity. They are more palatable ingredients in dietary supplements than capsaicinoids because of their low pungency. Previous studies on nonpungent Capsicum annuum cultivars showed that capsinoid biosynthesis is caused by loss-of-function putative aminotransferase (p-amt) alleles. This study showed that three mildly pungent cultivars of Capsicum chinense (Zavory Hot, Aji Dulce strain 2, and Belize Sweet) contain high levels of capsinoid. It was shown that these cultivars have novel p-amt alleles, which contain mutations that differ from those of C. annuum. Sequence analysis of p-amt in Belize Sweet revealed that a 5 bp insertion (TGGGC) results in a frameshift mutation. A transposable element (Tcc) was found in the p-amt of Zavory Hot and Aji Dulce strain 2. Tcc has features similar to those of the hAT transposon family. This was inserted in the fifth intron of Zavory Hot and in third intron of Aji Dulce strain 2. The p-amt alleles harboring Tcc cannot produce an active p-AMT. These mildly pungent cultivars will provide a new natural source of capsinoids.

Recent advances in the study on capsaicinoids and capsinoids

Chili peppers are the major source of nature capsaicinoids, which consist of capsaicin, dihydrocapsaicin, nordihydrocapsaicin, homodihydrocapsaicin, and homocapsaicin, etc. Capsaicinoids are found to exert multiple pharmacological and physiological effects including the activities of analgesia, anticancer, anti-inflammation, antioxidant and anti-obesity. Therefore, capsaicinoids may have the potential value in clinic for pain relief, cancer prevention and weight loss. In addition, capsaicinoids also display the benefits on cardiovascular and gastrointestinal system. It has been shown that capsaicinoids are potential agonists of capsaicin receptor or transient receptor potential vanilloid subfamily member 1 (TRPV1). They could exert the effects not only through the receptor-dependent pathway but also through the receptor-independent one. CH-19 Sweet peppers are the source of nature capsinoids, which share similar structure with capsaicinoids and consist of capsiate, dihydrocapsiate, and nordihydrocapsiate, etc, Comparing with capsaicinoids, capsinoids are less pungent and easily broken down in the normal aqueous conditions. So far, it has been found that capsinoids possess the biological properties of antitumor, antioxidant and anti-obesity. Since capsinoids are less toxic than capsaicinoids, therefore, capsinoids may have the advantages over capsaicinoids in clinical applications such as cancer prevention and weight loss.

Capsaicin induces apoptosis through ubiquitin-proteasome system dysfunction

Capsaicin is an active component of red pepper having an antiproliferative effect in a variety of cancer cells, which recent evidence suggests due to its ability to induce apoptosis. However, the molecular mechanisms through which capsaicin induces apoptosis are not well understood. Here we demonstrate that capsaicin-induced apoptosis is mediated via the inhibition cellular proteasome function. Treatment of capsaicin to mouse neuro 2a cells results in the inhibition of proteasome activity in a dose- and time-dependent manner that seems to correlate with its effect on cell death. The effect of capsaicin on cellular proteasome function is indirect and probably mediated via the generation of oxidative stress. Exposure of capsaicin also causes increased accumulation of ubiquitinated proteins as wells as various target substrates of proteasome like p53 and Bax and p27. Like many other classical proteasome inhibitors, capsaicin also triggers the intrinsic pathway of apoptosis involving mitochondria and induces neurite outgrowth. Our results strongly support for the use of capsaicin as an anticancer drug.

Newly mutated putative-aminotransferase in nonpungent pepper (Capsicum annuum) results in biosynthesis of capsinoids, capsaicinoid analogues

Capsinoids make up a group of nonpungent capsaicinoid analogues produced in Capsicum fruits. They have bioactivities similar to those of capsaicinoids such as suppression of fat accumulation and antioxidant activity. Because of their low pungency, they are more palatable ingredients in dietary supplements than capsaicinoids. We recently reported that capsinoid biosynthesis is caused by nonsense mutation in a putative aminotransferase gene (p-AMT) in a nonpungent cultivar CH-19 Sweet. Here we report on the screening of nonpungent germplasm that revealed a nonpungent cultivar Himo, which contains high levels of capsinoids. We have shown that Himo has a recessive allele of p-amt, which contains a mutation different from that of CH-19 Sweet. Sequence analysis of p-amt in Himo revealed that a single-nucleotide substitution results in one amino acid substitution from cysteine to arginine in the pyridoxal 5-phosphate binding domain. Genetic analysis using a cleaved amplified polymorphic sequence marker confirmed that the p-AMT genotype was precisely cosegregated with capsinoid biosynthesis and nonpungency. Himo will provide a new natural source of capsinoids.

Protective effect of capsinoid on lipid peroxidation in rat tissues induced by Fe-NTA

The activity of a single IP administration (15 or 30 mg/Kg body weight) of vanillyl nonanoate, a simplified analog of capsiate, on ferric nitrilotriacetate (Fe-NTA)-mediated oxidative damage was investigated. A sub-lethal dose of Fe-NTA (15 mg Fe/Kg body weight) was administered IP to rats; animals were sacrificed, and kidney and plasma were collected 1 h after injection. In response to the Fe-NTA administration, a reduction of the levels of total lipids, total unsaturated fatty acids and cholesterol was observed, accompanied by a rise in the concentrations of malondialdehyde (MDA), conjugated dienes fatty acids hydroperoxides and 7-ketocholesterol in plasma and kidney 1 h after administration. A pre-treatment with synthetic capsiate (SCPT) showed remarkable protective effect on the reduction of the levels of total lipids, total unsaturated fatty acids and cholesterol, and the cellular antioxidant vitamin E, inhibiting the increase of MDA, conjugated dienes fatty acids hydroperoxides and 7-ketocholesterol in the plasma and kidney. The protective effect of SCPT and two analogues (vanillyl alcohol and vanillin) during the linoleic acid and cholesterol oxidation was investigated in in vitro systems, providing evidence of definite structure-activity relationships.

Assessment of capsiconinoid composition, nonpungent capsaicinoid analogues, in capsicum cultivars

Capsiconinoid is a group of nonpungent capsaicinoid analogues produced in Capsicum fruits, which we recently identified. Capsiconinoids have agonist activity for transient receptor potential vanilloid type 1 (TRPV1), which is reported to be a receptor for capsaicin. It is, therefore, important to screen cultivars containing high levels of capsiconinoid for their use as a vegetable or dietary supplement. This study describes the quantitative analysis of capsiconinoid content in fruits of 35 Capsicum cultivars: 18 cultivars of C. annuum, 7 of C. baccatum, 5 of C. chinense, 4 of C. frutescens, and 1 of C. pubescens. Using high-performance liquid chromatography (HPLC), we found that 10 cultivars contained capsiconinoids. Capsiconinoid Baccatum (CCB) (C. baccatum var. praetermissum) showed the highest capsiconinoid content (3314 microg/g DW) and Charapita (C. chinense) had the second highest content. The other 8 cultivars had much lower capsiconinoid content than these two cultivars (<300 microg/g DW). Time-course analysis during fruit development clarified that capsiconinoid content in CCB fruits increased until 30 days after flowering (DAF) and then decreased rapidly until 40 DAF.

Denbinobin inhibits nuclear factor-kappaB and induces apoptosis via reactive oxygen species generation in human leukemic cells

Denbinobin, a 1,4-phenanthrenequinone firstly isolated from the stems of Dendrobium moniliforme (Shi-Hu in Chinese medicine), has been reported to exhibit anti-tumoral and anti-inflammatory activities through mechanism(s) not yet fully understood. Because of the critical role of the transcription factor NF-kappaB and of ROS-induced activation of stress regulated kinases in tumorigenesis, we have investigated the effect of denbinobin on these pathways. We found that denbinobin is a potent inhibitor of TNFalpha and PMA-induced NF-kappaB activation, and that it can block the phosphorylation and degradation of IkappaBalpha by inhibiting TAK1 activity, an event lying upstream of IKK activation. Moreover, treatment with denbinobin not only elicited apoptotic signalling, including mitochondrial membrane dysfunction, activation of caspases and cleavage of poly(ADP-ribose) polymerase, but also induced intracellular reactive oxygen species (ROS) generation and sustained activation of the mitogen-activated kinases (MAPKs) ERK1+2, p38 and JNK 1+2. The apoptotic effects of denbinobin could be prevented by pre-treatment with the intracellular ROS scavenger N-acetyl-l-cysteine, but not by pharmacological inhibition of MAPKs, suggesting that intracellular ROS generation underlies denbinobin-induced apoptosis, and that this effect takes place in an MAPKs-independent pathway. To define the structural elements critical for these activities, a series of phenanthrenequinones with different substituents in the phenanthrene- and/or in the quinone ring were prepared and assayed for NF-kappaB inhibition and ROS production. In this way, the major structure-activity relationships and the structural elements critical for the activity of denbinobin could be established.

Protective effect of vanilloids against tert-butyl hydroperoxide-induced oxidative stress in vero cells culture

This study investigated the effect of synthetic capsiate, a simplified analogue of capsiate, and vanillyl alcohol on the oxidative stress induced by tert-butyl hydroperoxide (TBH) in a line of fibroblasts derived from monkey kidney (Vero cells). In response to the TBH-mediated oxidative stress, a reduction of the levels of total unsaturated fatty acids and cholesterol was observed, and a rise in the concentrations of conjugated dienes fatty acids hydroperoxides and 7-ketocholesterol. Pretreatment with both synthetic capsiate and vanillyl alcohol preserved Vero cells from oxidative damage and showed a remarkable protective effect on the reduction of the levels of total unsaturated fatty acids and cholesterol, inhibiting the increase of MDA, conjugated dienes fatty acids hydroperoxides, and 7-ketocholesterol. Both compounds were effective against peroxidation of cell membrane lipids induced by TBH, with synthetic capsiate essentially acting as a pro-drug of vanillyl alcohol, its hydrophilic hydrolytic derivative.

Isolation of coniferyl esters from Capsicum baccatum L., and their enzymatic preparation and agonist activity for TRPV1

Coniferyl esters--capsiconiate and dihydrocapsiconiate--were isolated from the fruits of the pepper, Capsicum baccatum L. var. praetermissum. Their structures were determined by spectroscopic methods to be coniferyl (E)-8-methyl-6-nonenoate (capsiconiate) and coniferyl 8-methylnonanoate (dihydrocapsiconiate). This finding was further confirmed by the lipase-catalyzed condensation of coniferyl alcohol with its corresponding fatty acid derivative. The agonist activity of the esters for transient receptor potential vanilloid 1 (TRPV1) was evaluated by conducting an analysis of the intracellular calcium concentrations in TRPV1-expressing HEK293 cells. The EC50 values of capsiconiate and dihydrocapsiconiate were 3.2 and 4.2 microM, respectively.

Induction of apoptosis in prostate tumor PC-3 cells and inhibition of xenograft prostate tumor growth by the vanilloid capsaicin

Capsaicin, the pungent ingredient of hot chilli pepper, has been recently shown to induce apoptosis in several cell lines through a not well known mechanism. Here, we investigated the role of the vanilloid capsaicin in the death regulation of the human cancer androgen-resistant cell line PC-3. Capsaicin inhibited the growth of PC-3 with an IC(50) of 20 microM cells and induced cell apoptosis, as assessed by flow cytometry and nuclei staining with DAPI. Capsaicin induced apoptosis in prostate cells by a mechanism involving reactive oxygen species generation, dissipation of the mitochondrial inner transmembrane potential (DeltaPsi(m)) and activation of caspase 3. Capsaicin-induced apoptosis was not reduced by the antagonist capsazepine in a dose range from 0.1 microM to 20 microM, suggesting a receptor-independent mechanism. To study the in vivo effects of capsaicinoids, PC-3 cells were grown as xenografts in nude mice. Subcutaneous injection of either capsaicin or capsazepine (5 mg/kg body weight) in nude mice suppressed PC-3 tumor growth in all tumors investigated and induced apoptosis of tumor cells. Our data show a role for capsaicin against androgen-independent prostate cancer cells in vitro and in vivo and suggest that capsaicin is a promising anti-tumor agent in hormone-refractory prostate cancer, which shows resistance to many chemotherapeutic agents.

Involvement of AMPK signaling cascade in capsaicin-induced apoptosis of HT-29 colon cancer cells

Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is activated during ATP-depleting metabolic states, such as hypoxia, heat shock, oxidative stress, and exercise. As a highly conserved heterotrimeric kinase that functions as a major metabolic switch to maintain energy homeostasis, AMPK has been shown to exert as an intrinsic regulator of mammalian cell cycle. Moreover, AMPK cascade has emerged as an important pathway implicated in cancer control. In this article, we have investigated the effects of capsaicin on apoptosis in relation to AMPK activation in colon cancer cell. Capsaicin-induced apoptosis was revealed by the presence of nucleobodies in the capsaicin-treated HT-29 colon cancer cells. Concomitantly, the activation of AMPK and the increased expression of the inactive form of acetyl-CoA carboxylase (ACC) were detected in capsaicin-treated colon cancer cells. We showed that both capsaicin and 5'-aminoimidazole-4-carboxamide-1-beta-D-ribonucleoside (AICAR), an AMPK activator possess the AMPK-activating capacity as well as apoptosis-inducing properties. Evidence of the association between AMPK activation and the increased apoptosis in HT-29 colon cancer cells by capsaicin treatment, and further findings of the correlation of the activated AMPK and the elevated apoptosis by cotreatment of AICAR and capsaicin support AMPK as an important component of apoptosis, as well as a possible target of cancer control.

Effects of capsaicin on induction of apoptosis and inhibition of adipogenesis in 3T3-L1 cells

Currently, at the beginning of the 21st century, obesity has become the leading metabolic disease in the world. It is a serious health problem in industrialized countries. Previous research has suggested that decreased preadipocyte differentiation and proliferation and decreased lipogenesis are mechanisms to reduce obesity. In the present study, the effects of capsaicin on the induction of apoptosis and inhibition of lipid accumulation in 3T3-L1 preadipocytes and adipocytes were investigated. The results demonstrated that capsaicin decreased cell population growth of 3T3-L1 preadipocytes, assessed with the MTT assay. Flow cytometric analysis of 3T3-L1 preadipocytes exposed to capsaicin showed that apoptotic cells increased in a time- and dose-dependent manner. Treatment with capsaicin decreased the number of normal cells and increased the number of early apoptotic and late apoptotic cells in a dose-dependent manner. The treatment of cells with capsaicin caused the loss of mitochondria membrane potential (delta psi m). The induction of apoptosis in 3T3-L1 preadipocytes by capsaicin was mediated through the activation of caspase-3, Bax, and Bak, and then through the cleavage of PARP and the down-regulation of Bcl-2. Moreover, capsaicin significantly decreased the amount of intracellular triglycerides and glycerol-3-phosphate dehydrogenase (GPDH) activity in 3T3-L1 adipocytes. Capsaicin also inhibited the expression of PPARgamma, C/EBPalpha, and leptin, but induced up-regulation of adiponectin at the protein level. These results demonstrate that capsaicin efficiently induces apoptosis and inhibits adipogenesis in 3T3-L1 preadipocytes and adipocytes.

Capsaicin induced apoptosis of B16-F10 melanoma cells through down-regulation of Bcl-2

Capsaicin (8-methyl-N-vanillyl-6-nonenamide), a pungent ingredient of hot chili peppers, has been reported to possess substantial anticarcinogenic and antimutagenic activities. In the present study, we investigated the effect of capsaicin on induction of apoptosis in highly metastatic B16-F10 murine melanoma cells. Capsaicin inhibited growth of B16-F10 cells in a concentration-dependent manner. Proapoptotic effect of capsaicin was evidenced by nuclear condensation, internucleosomal DNA fragmentation, in situ terminal nick-end labeling of fragmented DNA (TUNEL), and an increased sub G1 fraction. Treatment of B16-F10 cells with capsaicin caused release of mitochondrial cytochrome c, activation of caspase-3, and cleavage of poly (ADP-ribose) polymerase in a dose-dependent manner. Furthermore, Bcl-2 expression in the B16-F10 cells was slightly down-regulated by capsaicin treatment. In contrast, there were no alterations in the levels of Bax in capsaicin-treated cells. Collectively, these findings indicate that capsaicin-induces apoptosis of B16-F10 melanoma cells via down-regulation the Bcl-2.

Capsaicin, a spicy component of hot pepper, induces apoptosis by activation of the peroxisome proliferator-activated receptor gamma in HT-29 human colon cancer cells

Capsaicin (N-vanillyl-8-methyl-alpha-nonenamide), a spicy component of hot pepper, is a homovanillic acid derivative that preferentially induces certain cancer cells to undergo apoptosis and has a putative role in cancer chemoprevention. Peroxisome proliferator-activated receptor gamma(PPARgamma), a member of the nuclear receptor superfamily, is a ligand-dependent transcription factor. PAPRgamma activation results in growth arrest and/or apoptosis in a variety of cancer cells. In the present study, we investigated the potential of capsaicin to induce apoptotic cell death in human colon cancer cells and the association of PPARgamma in the capsaicin action. Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. PPARgamma and vanilloid receptor type 1 (VR-1) expressions at the protein or mRNA levels were detected by western blot analysis and reverse transcription-polymerase chain reaction. Apoptotic cell death was determined by DNA fragmentation and quantified by enzyme-linked immunosorbent assay. HT-29 human colon cancer cells expressed PPARgamma and VR-1. Treatment with capsaicin or the PPARgamma ligand troglitazone induced apoptotic cell death in a dose-dependent manner in HT-29 human colon cancer cells. Capsaicin-induced cell death was completely blocked by bisphenol A diglycidyl ether, a specific PPARgamma antagonist. Capsazepine, a specific antagonist for vanilloid receptor, did not inhibit capsaicin-induced apoptosis. Our data suggest that capsaicin-induced apoptotic cell death in HT-29 human colon cancer cells could be associated with the PPARgamma pathway without the involvement of the vanilloid receptor. Capsaicin may have a beneficial effect for the treatment of colon cancer.

Antitumor Effects of Two Novel Naturally Occurring Terpene Quinones Isolated from the Mediterranean Ascidian Aplidium conicum

The ascidian Aplidium conicum collected along Sardinia coasts (Italy) contained two novel prenylated benzoquinones, designated thiaplidiaquinone A (1) and thiaplidiaquinone B (2). These compounds showed an unprecedented tetracyclic structure. We have studied the pro-apototic mechanisms of both prenylated benzoquinones in the Jurkat cell line that is derived from a human T lymphoma, and we show that both compounds induce a strong production of intracellular reactive oxygen species (ROS) in this cell line. Moreover, kinetic experiments, comparing the timing of ROS induction with the collapse of the mitochondria potential (DeltaPsi(m)), clearly showed that ROS preceded the disruption of the mitochondrial potential, and the later one paralleled the appearance of apoptotic cells. Thus, thiaplidiaquinones A and B can enter into the cells and induce cell death by apoptosis.

Involvement of peroxynitrite in capsaicin-induced apoptosis of C6 glioma cells

Capsaicin induces apoptosis in some types of cells, but its mechanism remains obscure. In this study, peroxynitrite, a powerful oxidant generated from the reaction of superoxide and nitric oxide (NO) in biological system, was demonstrated to be responsible for capsaicin-mediated apoptosis in C6 glioma cells. Capsaicin-induced apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, and also identified by Annexin V staining and comet assay. Capsazepine and ruthenium red, the vanilloid receptor 1 (VR1/TPRV1) antagonists, did not inhibit capsaicin-induced apoptosis. Exposure to capsaicin not only promoted the generation of superoxide and iNOS, but also markedly suppressed the expression of SODs. Nitrite and nitrate, the NO metabolites accumulated in the medium, and the nitrotyrosine was also increased in proteins of C6 glioma cells exposed to capsaicin. Pretreatment of cells with 4 microM ebselen (a peroxynitrite scavenger) showed effective inhibitory effect on the capsaicin-induced apoptosis. These results suggest that peroxynitrite can act as a potential mediator in the capsaicin-induced apoptosis in C6 glioma cells.

On the antioxidant mechanisms of Bcl-2: a retrospective of NF-kappaB signaling and oxidative stress

Antioxidant and prooxidant signaling pathways are emanating as major players in, and regulators of, cell death and apoptosis. Redox conception of the critical role of oxidative stress in determining cell fate is being established-a foundation that craves deeper than the basic understanding of physiochemical interactions to extend beyond that into the realms of deciphering the molecular codes implicated with apoptosis. The proto-oncogene Bcl-2 is no stranger being a major player and decoder in controlling apoptosis, ostensibly via the regulation of redox equilibrium and disequilibrium. One of those potential mechanisms exhibited by Bcl-2 is its ability to counteract the detrimental effects of cell damage caused by free radicals, thereby gaining its well-known property of being an antioxidant. But the question is: what are the molecular mechanisms involved with the antioxidant role of Bcl-2 in the face of cell damage and apoptosis? Currently, a stance is being upheld in that the Bcl-2 antioxidant efficacy should be weighed against its ability to manipulate transcriptional control, through the regulation of specific transcription factors. NF-kappaB is no doubt one of the best candidates when it comes to the arena of oxidative stress, inflammation, and apoptosis. Therein, current themes in the burgeoning antioxidant role of Bcl-2 are exposed within the context of transcriptional control of NF-kappaB, thereby holding potential avenues for alleviating therapeutic approaches in the regulation of apoptosis.

Involvement of NADPH oxidase-mediated generation of reactive oxygen species in the apototic cell death by capsaicin in HepG2 human hepatoma cells

Although capsaicin (8-methyl-N-vanillyl-6-nonenamide), a pungent ingredient in a variety of red peppers of the genus Capsicum, has been shown to induce apoptotic cell death in many cancer cells, the exact mechanism of this action of capsaicin is not completely understood. In this study, we investigated the possible mediation of the NADPH oxidase-modulated production of reactive oxygen species (ROS) in the apoptotic mechanism of capsaicin in HepG2 human hepatoblastoma cells. Capsaicin induced apoptotic cell death in a time- and dose-dependent manner. Capsaicin at the concentration of inducing apoptosis also markedly increased the level of ROS. The capsaicin-induced generation of ROS and apoptosis was significantly suppressed by treatment with antioxidants, DPPD and tocopherol. In addition, inhibitors of NADPH oxidase, diphenylene iodonium, apocynin and neopterine, profoundly blocked the capsaicin-induced ROS generation and apoptosis. The expression of Rac1N17, a dominant negative mutant of Rac1, also significantly inhibited the capsaicin-induced apoptosis. Activation of nuclear factor-kappaB, a transcription factor essentially involved in ROS-induced apoptosis, was also observed by treatment with capsaicin. Collectively, these results suggest that the NADPH oxidase-mediated generation of ROS may be essentially involved in the mechanism of capsaicin-induced apoptosis in HepG2 cells. These results further suggest that capsaicin may be a valuable agent for the therapeutic intervention of human hepatomas.

Mechanism of cell death induced by an antioxidant extract of Cratoxylum cochinchinense (YCT) in Jurkat T cells: the role of reactive oxygen species and calcium

YCT is a semipurified extract from Cratoxylum cochinchinense that has antioxidant properties and contains mostly mangiferin. We show here that YCT is selectively toxic to certain cell types and investigate the mechanisms of this toxicity in Jurkat T cells. By flow cytometric analyses, we show that YCT causes intense oxidative stress and a rise in cytosolic Ca(2+). This is followed by a rise in mitochondrial Ca(2+), release of cytochrome c, collapse of Deltapsi(m), a fall in ATP levels, and eventually cell death. The mechanism(s) of intense oxidative stress may involve a plasma membrane redox system, as cell death is inhibited by potassium ferricyanide. Cell death has some features of apoptosis (propidium iodide staining, externalization of phosphatidylserine, limited caspase-3 and -9 activities), but there was no internucleosomal DNA fragmentation.

Cell cycle- and protein kinase C-specific effects of resiniferatoxin and resiniferonol 9,13,14-ortho-phenylacetate in intestinal epithelial cells

We have previously reported that protein kinase C (PKC) signaling can trigger hallmark events of cell cycle withdrawal in intestinal epithelial cells, including downregulation of cyclin D1, induction of p21(Waf1/Cip1), and activation of the growth suppressor function of pocket proteins. In the current study, we compared the cell cycle- and PKC-specific effects of the vanilloid resiniferatoxin (RTX), its parent diterpene resiniferonol 9,13,14-ortho-phenylacetate (ROPA), and the PKC agonist PMA in the IEC-18 non-transformed intestinal crypt cell line. ROPA and PMA were found to produce strikingly similar alterations in cell cycle progression and PKC activity in IEC-18 cells, although PMA was approximately 1000-fold more potent in producing these effects. Both agents induced a transient PKC-dependent blockade in G1---> S progression associated with transient downregulation of cyclin D1 and induction of p21(Waf1/Cip1). In contrast, RTX produced a prolonged PKC-independent cell cycle arrest in G(0)/G(1) phase which was maintained for longer than 24h. This arrest was vanilloid receptor-independent and associated with prolonged downregulation of cyclin D1 mRNA and protein, with little effect on levels of p21(Waf1/Cip1). Combined exposure to RTX and ROPA produced a sustained and complete cell cycle blockade in IEC-18 cells, associated with depletion of cyclin D1 and sustained enhancement of p21(Waf1/Cip1) levels. PMA, ROPA, RTX and the RTX/ROPA combination were capable of activating ERK1/2 signaling in IEC-18 cells, albeit with different kinetics. In contrast, only PMA and ROPA activated JNK1/2 and p38 in this system. Notably, some preparations of commercially obtained RTX produced effects indistinguishable from those of the RTX/ROPA combination, suggesting that certain batches of the compound may contain significant amounts of ROPA (or another PKC agonist activity). Together, these data demonstrate that structurally related compounds can produce similar cell cycle-specific effects but through distinct mechanisms. In addition, they add to a growing body of evidence that vanilloids can have antiproliferative effects in a variety of cell types.