The cytotoxic effect of Bowman–Birk isoinhibitors,IBB1 and IBBD2, from soybean (Glycine max) on HT29 human colorectal cancer cells is related to their intrinsic ability to inhibit serine proteases

Bowman–Birk inhibitors (BBI) from soybean and related proteins are naturally occurring protease inhibitors with potential health‐promoting properties within the gastrointestinal tract. In this work, we have investigated the effects of soybean BBI proteins on HT29 colon adenocarcinoma cells, compared with non‐malignant colonic fibroblast CCD‐18Co cells. Two major soybean isoinhibitors, IBB1 and IBBD2, showing considerable amino acid sequence divergence within their inhibitory domains, were purified in order to examine their functional properties, including their individual effects on the proliferation of HT29 colon cancer cells. IBB1 inhibited both trypsin and chymotrypsin whereas IBBD2 inhibited trypsin only. Despite showing significant differences in their enzyme inhibitory properties, the median inhibitory concentration values determined for IBB1 and IBBD2 on HT29 cell growth were not significantly different (39.9±2.3 and 48.3±3.5 μM, respectively). The cell cycle distribution pattern of HT29 colon cancer cells was affected by BBI treatment in a dose‐dependent manner, with cells becoming blocked in the G0–G1 phase. Chemically inactive soybean BBI had a weak but non‐significant effect on the proliferation of HT29 cells. The anti‐proliferative properties of BBI isoinhibitors from soybean reveal that both trypsin‐ and chymotrypsin‐like proteases involved in carcinogenesis should be considered as potential targets of BBI‐like proteins.     

Dicaffeoylquinic acids in Yerba mate (Ilex paraguariensis St. Hilaire) inhibit NF-κB nucleus translocation in macrophages and induce apoptosis by activating caspases-8 and -3 in human colon cancer cells

Scope : The biological functions of caffeoylquinic acid (CQA) derivatives from various plant sources have been partially elucidated. The objectives were to isolate and purify diCQAs from Yerba mate tea leaves and assess their anti‐inflammatory and anti‐cancer capabilities in vitro and explore their mechanism of action. Methods and results : Methanol extracts of dried mate leaves were resolved by flash chromatography and further purified resulting in two fractions one containing 3,4‐ and 3,5‐diCQAs and the other 4,5‐diCQA with NMR‐confirmed structures. Both fractions inhibited LPS‐induced RAW 264.7 macrophage inflammation by suppressing nitric oxide/inducible nitric oxide and prostaglandin E₂/cyclooxygenase‐2 pathways through inhibiting nucleus translocation of Nuclear factor κB subunits, p50 and p65. The diCQA fractions inhibited Human colon cancer cells CRL‐2577 (RKO) and HT‐29 cell proliferation by inducing apoptosis in a time‐ and concentration‐dependent manner, but did not affect the protein levels of p21, p27, p53, and Bax:Bcl‐2 ratio in RKO cells. In HT‐29 cells, however, the diCQA fractions increased Bax:Bcl‐2 ratio. The diCQA fractions increased the activation of caspase‐8 leading to cleavage of caspase‐3 in both RKO and HT‐29 colon cancer cells. Conclusion : The results suggest that diCQAs in Yerba mate could be potential anti‐cancer agents and could mitigate other diseases also associated with inflammation.     

Vitamin B6 suppresses serine protease inhibitor 3 expression in the colon of rats and in TNF-α-stimulated HT-29 cells

Scope: Previous reports in the areas of animal studies and, recently epidemiology, have linked anti‐tumorigenic and anti‐inflammatory effects to dietary vitamin B6. This study investigated the molecular mechanism of these effects of vitamin B6. Methods and results: DNA microarray analysis was used to obtain information on changes in colon gene expression from vitamin B6 (pyridoxine) repletion in vitamin B6‐deficient rats. Pyridoxine supplementation down‐regulated the inflammatory molecule, serine protease inhibitor clade A member 3 (SPI‐3) mRNA expression in the colon. This study also showed that tumor necrosis factor α (TNF‐α) induced SPI‐3 mRNA expression in HT‐29 human colon cancer cells, and vitamin B6 (pyridoxal hydrochloride) pretreatment of HT‐29 cells inhibited TNF ‐induced mRNA expression of SPI‐3. Vitamin B6 inhibited TNF‐α‐induced NF‐κB activation via suppression of IκBα degradation in HT‐29 cells. HT‐29 cells stably expressing epitope‐tagged ubiquitin were generated and vitamin B6 pretreatment was shown to inhibit ubiquitination of the IkB protein in response to TNF‐α‐i. Conclusion: Vitamin B6 suppressed SPI‐3 expression in the colon of rats and in TNF‐α‐stimulated HT‐29 cells. Further, this study showed a possible role of vitamin B6 in the regulation of protein ubiquitination.     

Anti‐inflammatory and anticancer activities of water‐soluble peptide extracts of buffalo and cow milk Cheddar cheeses

This article aimed to assess the anti‐inflammatory and anticancer potential of water‐soluble peptide (WSP) extracts from buffalo and cow milk Cheddar cheeses. Anti‐inflammatory activity was evaluated on the basis of nitric oxide (NO) production in lipopolysaccharide‐stimulated macrophage (RAW‐264.7) cells. A cell viability assay, cell cycle arrest and apoptosis were performed to explore anticancer activity in a colon cancer model (HT‐29). The WSP extracts of both Cheddar cheeses effectively inhibited NO production in activated macrophages. Maximum growth inhibition was observed in the HT‐29 cells at concentrations of 400 and 500 μg/mL. A significant increase in cell population at G₀/G₁ phase of the cell cycle was observed. Moreover, the WSP extracts also induced extensive apoptosis in colon cancer cells.     

Contribution of different molecular weight fractions to anticancer effect of sweet potato protein hydrolysates by six proteases on HT‐29 colon cancer cells

The contribution of different molecular weight fractions to anticancer effect of sweet potato protein hydrolysates (SPPH) by six proteases on HT‐29 colon cancer cells was investigated. SPPH prepared by six proteases showed certain antiproliferation effect on HT‐29 cells. Compared with other five proteases, SPPH by Alcalase exhibited the highest antiproliferation effect with the lowest IC₅₀ value of 119.72 μg mL^?1. SPPH by Alcalase was further separated into four fractions (>10, 5–10, 3–5 and <3 kDa), and <3 kDa fractions showed the strongest antiproliferation effect, which was 43.87% at 100 μg mL^?1 (P < 0.05). The <3 kDa fractions could cause G2/M cell cycle arrest with increased p21 expression and induce apoptosis via decreasing Bcl‐2 expression, increasing Bax expression and inducing caspase‐3 activation in HT‐29 cells. In addition, <3 kDa fractions could significantly inhibit cell migration of HT‐29 cells. Thus, SPPH might be potentially used as a natural supplement in functional foods.     

Cranberry extract and quercetin modulate the expression of cyclooxygenase‐2 (COX‐2) and IκBα in human colon cancer cells

BACKGROUND: Cranberry (Vaccinium marcocarpon) fruit and quercetin, a major flavonoid found in cranberries, are likely contributors to chemoprevention, and their anti‐inflammatory activities may play a potential role in colon cancer prevention. The aim of this study was to examine the effect of cranberry extract and quercetin on basal expression of cyclooxygenase‐2 (COX‐2) and IκBα as well as the effect on phorbol 12‐myristate 13‐acetate (PMA)‐induced COX‐2 expression in colon cancer cells. RESULTS: HT‐29 human colon adenocarcinoma cells were treated with various concentrations of cranberry extract or quercetin and/or PMA, and the protein expression of COX‐2 and IκBα was determined. The results indicated that cranberry extract and quercetin decreased COX‐2 expression and suppressed degradation of IκBα in unstimulated cells. In PMA‐stimulated cells, cranberry extract was also able to decrease COX‐2 expression and suppress degradation of IκBα. CONCLUSION: The results suggest that a possible mechanism involved in the anti‐cancer activity of cranberry and quercetin is partly mediated through its anti‐inflammatory action. These findings indicate that cranberry and quercetin may reduce the risk of colon cancer possibly by suppressing inflammatory responses. Copyright © 2008 Society of Chemical Industry     

Hydroxytyrosol inhibits the proliferation of human colon adenocarcinoma cells through inhibition of ERK1/2 and cyclin D1

Extra virgin olive oil is rich in phenolic compounds which are believed to exert beneficial effects against many pathological processes, including the development of colon cancer. We show that one of the major polyphenolic constituents of extra virgin olive oil, hydroxytyrosol (HT), exerts strong antiproliferative effects against human colon adenocarcinoma cells via its ability to induce a cell cycle block in G2/M. These antiproliferative effects were preceded by a strong inhibition of extracellular signal‐regulated kinase (ERK)1/2 phosphorylation and a downstream reduction of cyclin D1 expression, rather than by inhibition of p38 activity and cyclooxygenase‐2 (COX‐2) expression. These findings are of particular relevance due to the high colonic concentration of HT compared to the other olive oil polyphenols and may help explain the inverse link between colon cancer and olive oil consumption.     

Antiproliferative effects of prenylflavonoids from hops on human colon cancer cell lines

In recent years, interest in hop‐derived constituents, especially for prenylflavonoids has grown, as they have a wide range of biological properties including antioxidant, anticarcinogenic and antimicrobial activities. Two main hop prenylflavonoids, xanthohumol and isoxanthohumol, and hop extract enriched in prenylflavonoids, were tested for their antiproliferative activities on colon cancer cell lines, HT‐29 and SW620, and a noncancerous cell line, IEC‐6. It was confirmed that both xanthohumol and isoxanthohumol inhibited cell proliferation, even at micromolar concentrations. For cell line HT‐29, the IC₅₀ was 1.2 ± 0.9 and 16.9 ± 0.9 µmol dm^?3 for xanthohumol and isoxanthohumol, respectively. Similar values were obtained for SW620 cells (2.5 ± 0.2 and 37.3 ± 3.2 µmol dm^–3). None of the pure prenylflavonoids that were tested affected the proliferation of the noncancerous cell line, IEC‐6. The effect of the hop extract containing xanthohumol was also tested for antiproliferative activities on the cancer cell lines, HT‐29 (IC₅₀ = 3.1 ± 0.2 µmol dm^–3) and SW620 (IC₅₀ = 1 ± 0.2 µmol dm^?3), and on the cell line, IEC‐6 (IC₅₀ = 65.5 ± 11.3 µmol dm^?3). The results showed a similar trend to that for pure compounds, suggesting a possible future application of hop extracts in the pharmaceutical industry. Copyright © 2014 The Institute of Brewing & Distilling     

Effects of dried longan seed (Euphoria longana Lam.) extract on VEGF secretion and expression in colon cancer cells and angiogenesis in human umbilical vein endothelial cells

Angiogenesis is a critical event in cancer metastasis, via delivery of needed oxygen and nutrients to tumor cells. Anti-angiogenesis is one strategy for controlling cancer progression. We herein report anti-angiogenesis activity of dried longan seeds using colon adenocarcinoma cells (SW480 cells) and human umbilical vein endothelial cells (HUVECs). Sephadex LH-20 column chromatography was used for separate three dried longan seed fractions. We firstly evaluated vascular endothelial cell growth factor (VEGF) secretion, expression and colony formation of SW480 cells, using enzyme-linked immunosorbent assay (ELISA), Western blot analysis and soft agar assays. Meanwhile cell proliferation, gelatinase activity and tube formation of HUVECs were determined via proliferation assay, gelatin zymography and in vitro tube formation assay, respectively. The results suggest that dried longan seed fractions could be potential angiogenic inhibitors not only interruption of VEGF secretion and expression in SW480 cells but also abrogation of cell proliferation, the activity of gelatinase and tube formation of HUVECs.     

鲟鱼硫酸软骨素对结直肠癌细胞抑制作用

探究鲟鱼硫酸软骨素对结直肠癌细胞的生长抑制能力,并初步确定影响结直肠癌细胞生长的主要原因。选取3株具有代表性的结直肠癌细胞Caco-2、HCT-116、SW480,采用CCK-8法测定细胞生长曲线、硫酸软骨素对癌细胞增殖的抑制能力;以其中一株结直肠癌细胞HCT-116为模型,用流式细胞仪测定其周期和凋亡情况,用细胞核染色法观察处理前后细胞形态,结合caspase-3凋亡酶活力的测定,考察鲟鱼硫酸软骨素对结直肠癌细胞的促凋亡能力,并初步确定作用途径。研究结果表明,鲟鱼硫酸软骨素对结直肠癌细胞Caco-2、HCT-116、SW480的增殖具有一定抑制作用,最高抑制率分别为70.94%、90.00%和75.00%,明显高于阳性对照处理组;处理后,细胞周期G1/G0期比例升高至88.56%,S期比例降低至4.47%,阻滞细胞G1/G0期;同时,使用鲟鱼硫酸软骨素处理细胞后,细胞形态发生变化,出现细胞核固缩以及细胞破碎等现象,细胞主要的凋亡酶活力显著升高,酶活力可达1 645 IU/μg,使细胞发生凋亡,凋亡率可达63.73%。研究结果证明,鲟鱼硫酸软骨素具有促进结直肠癌细胞凋亡、抑制细胞增殖的能力。     

Lunasin induces apoptosis and modifies the expression of genes associated with extracellular matrix and cell adhesion in human metastatic colon cancer cells

Scope: Lunasin is an arginine‐glycine‐aspartic acid (RGD) cancer preventive peptide. The objective was to evaluate the potential of lunasin to induce apoptosis in human colon cancer cells and their oxaliplatin‐resistant (OxR) variants, and its effect on the expression of human extracellular matrix and adhesion genes. Methods and results: Various human colon cancer cell lines which underwent metastasis were evaluated in vitro using cell flow cytometry and fluorescence microscopy. Lunasin cytotoxicity to different colon cancer cells correlated with the expression of α₅b₁ integrin, being most potent to KM12L4 cells (IC₅₀ = 13 μM). Lunasin arrested cell cycle at G2/M phase with concomitant increase in the expression of cyclin‐dependent kinase inhibitors p21 and p27. Lunasin (5–25 μM) activated the apoptotic mitochondrial pathway as evidenced by changes in the expressions of Bcl‐2, Bax, nuclear clusterin, cytochrome c and caspase‐3 in KM12L4 and KM12L4‐OxR. Lunasin increased the activity of initiator caspase‐9 leading to the activation of caspase‐3 and also modified the expression of human extracellular matrix and adhesion genes, downregulating integrin α₅, SELE, MMP10, integrin β₂ and COL6A1 by 5.01‐, 6.53‐, 7.71‐, 8.19‐ and 10.10‐fold, respectively, while upregulating COL12A1 by 11.61‐fold. Conclusion: Lunasin can be used in cases where resistance to chemotherapy developed.     

Lycopene‐derived bioactive retinoic acid receptors/retinoid‐X receptors‐activating metabolites may be relevant for lycopene's anti‐cancer potential

Dietary consumption of tomato products and especially the red tomato pigment lycopene has been associated with lower risk of cancer. New evidence is emerging toward metabolic pathways mediating the anti‐cancer activities of lycopene. In this review, we explore associations between tomatoes and lycopene intake and cancer and relate this to the metabolic activation pathways of lycopene via carotene oxygenases and further carotenoid/retinoid‐metabolizing enzymes to apo‐lycopenoids. Several of these apo‐lycopenoids have already been identified but up to date no direct connection between lycopene metabolism and apo‐lycopenoids mediated receptor activation pathways has been established. Retinoic acid receptors/retinoid‐X receptors activation pathways in particular, may be mediated via lycopene metabolites that are related to retinoic acids. Various studies have shown an association between lower concentration of insulin‐like growth factor‐1 upon lycopene treatment, cancer incidences, and retinoid‐mediated signaling. In this review, we interrelate tomato/lycopene ingestion and cancer incidence, with metabolic activation of lycopene and retinoid‐mediated signaling. The aim is to discuss a potential mechanism to explain lycopene related anti‐cancer activities by modulation of insulin‐like growth factor‐1 concentrations via lycopene metabolite activation of retinoid‐mediated signaling.     

Anti-tumorigenic activity of five culinary and medicinal herbs grown under greenhouse conditions and their combination effects

BACKGROUND: Herbs and spices have been used as food preservatives, flavorings, and in traditional medicines for thousands of years. More and more scientific evidence supports the medicinal properties of culinary herbs. Colon cancer is the third leading cause of cancer death in the USA, and the fourth most common form of cancer worldwide. The objectives of this study were to evaluate the antitumor activity of five selected herbs grown under greenhouse conditions, and to study the potential synergistic effects among different herbal extract combinations. RESULTS: Thyme, rosemary, sage, spearmint, and peppermint extracts significantly inhibited SW‐480 colon cancer cell growth, with sage extracts exhibiting the highest bioactivity, with 50% inhibition at 35.9 µg mL^?1, which was equivalent to 93.9 µg dried leaves mL^?1 of culture medium. Some mixtures of different herbal extracts had combination effects on cancer cell growth. The inhibitory effects of peppermint + sage combinations at a 1:1 ratio were significantly higher than rosemary + sage combinations at 1:1 ratio, although peppermint extracts showed lower inhibition than rosemary extracts. CONCLUSION: Extracts from herb species (thyme, rosemary, sage, spearmint and peppermint) can significantly inhibit the growth of human colon cancer cells. Mixtures of herb extracts can have combination effects on cancer cell growth. The study suggests that these five herbs may have potential health benefits to suppress colon cancer. Copyright © 2011 Society of Chemical Industry     

Lycopene inhibits growth of human colon cancer cells via suppression of the Akt signaling pathway

The aberrant regulation of the phosphoinositide 3-kinase/Akt survival signaling pathway in cancer has prompted significant interest in suppression of this pathway to treat cancer. Previous studies identified an important role for phosphoinositide 3-kinase/Akt in colon cancer progression. Lycopene, a major component in tomato, exhibited potential anti-carcinogenic activity. Consumption of tomato has been associated with reduced risk of several types of human cancer. However, the inhibitory mechanisms of lycopene on the proliferation of human colon cancer have not been studied well yet. Thus we investigated the inhibitory effects of lycopene on the Akt signaling pathway in human colon cancer HT-29 cells. Lycopene inhibited cell proliferation in human colon cancer HT-29 cells with a IC(50) value of 10 microM. Lycopene treatment suppressed Akt activation and non-phosphorylated beta-catenin protein level in human colon cancer cells. Immunocytochemical results indicated that lycopene increased the phosphorylated form of beta-catenin proteins. These effects were also associated with reduced promoter activity and protein expression of cyclin D1. Furthermore, lycopene significantly increased nuclear cyclin-dependent kinase inhibitor p27(kip)abundance and inhibited phosphorylation of the retinoblastoma tumor suppressor protein in human colon cancer cells. In conclusion, lycopene inhibited cell proliferation of human colon cancer cells via suppression of the Akt signaling pathway and downstream targeted molecules.     

Anti-proliferative effect of curcumin on melanoma cells is mediated by PDE1A inhibition that regulates the epigenetic integrator UHRF1

Scope: Curcumin inhibits proliferation of many cancer cells. Cyclic nucleotide phosphodiesterases (PDEs), by hydrolyzing intracellular cyclic adenosine‐3′,5′‐monophosphate (cAMP) and/or cyclic guanosine‐3′,5′‐monophosphate (cGMP), play a pivotal role in signalling pathways involved in cell proliferation. Therefore, this study investigated PDE1–5 participations in the anti‐proliferative properties of curcumin in B16F10 murine melanoma cells. Methods and results: We report that curcumin inhibits PDE1–5 activities (IC₅₀?10^?5 M), indicating that curcumin acts as a non‐selective PDE inhibitor. In melanoma cells, PDE4 and PDE1 represent the major cAMP‐PDEs and cGMP‐PDEs activities, respectively. Curcumin treatment decreased PDE1 and PDE4 activities and dose dependently increased intracellular cGMP levels, whereas cAMP levels were unchanged. Curcumin inhibited cell proliferation and cell cycle progression by accumulating cells in the S‐ and G2/M‐phases with enhanced expressions of cyclin‐dependent kinase inhibitors. In contrast, expressions of PDE1A, cyclin A and the epigenetic integrator ubiquitin‐like containing PHD and Ring Finger domains 1 (UHRF1) and DNA methyltransferase 1 (DNMT1) were decreased by curcumin. Interestingly, PDE1A overexpression increased UHRF1 and DNMT1 expressions and rescued the B16F10 cells from curcumin anti‐proliferative effects. Nimodipine, a PDE1 inhibitor, mimicked the curcumin effects. Conclusion : Curcumin exerts its anti‐cancer property by targeting PDE1 that inhibits melanoma cell proliferation via UHRF1, DNMT1, cyclin A, p21 and p27 regulations. This suggests that natural PDE1 inhibitors present in food might be effective in preventing cancer.     

地皮菜中一种新型水应激蛋白基因的克隆表达及其抗人结肠癌细胞SW480的作用

利用聚合酶链式反应（polymerase chain reaction,PCR）扩增出地皮菜（Nostoc commune Vauch.）一种新型水应激蛋白（water stress protein,WSP）的基因（GenBank 序列号：KF003026）,连接到原核表达载体pET28a上,测序鉴定后转化入大肠杆菌BL21,获得一种新型水应激蛋白表达工程菌;经异丙基-β-D-硫代半乳糖苷（isopropyl-β-D-thiogalactopyranoside,IPTG）诱导表达及镍离子亲和层析柱（Ni-NTA）纯化后,得到了带6×His标签、分子质量大小为40 kD的可溶性目的蛋白,称其为重组水应激蛋白1（recombinant water stress protein 1,Re-WSP1）。细胞增殖抑制实验结果表明,Re-WSP1蛋白可以抑制结肠癌细胞SW480的增殖,而对正常结肠上皮FHC细胞无明显作用;DAPI细胞核染色结果表明,该蛋白能够诱导SW480细胞凋亡小体的形成;Western blotting结果显示,Re-WSP1蛋白能够促进Procaspase-3和Procaspase-8的活化剪切。以上结果表明：Re-WSP1蛋白能够明显的抑制结肠癌SW480细胞的增殖,并可能通过Caspase依赖途径诱导SW480细胞凋亡。     

inlA和inlB基因缺失对单核细胞增生性李斯特菌侵袭HT29结肠癌细胞的影响

单核细胞增生性李斯特菌（Listeria monocytogenes,LM）是人畜共患的食源性致病菌,其可以穿透多个宿主屏障,而内化素蛋白家族被认为是LM穿透宿主屏障过程中起重要作用的毒力因子。本研究利用同源重组的方法构建了LM野生菌株EGDe的inlA和inlB基因双缺失菌株,利用实时荧光定量聚合酶链式反应检测其主要毒力基因表达的变化,并以HT29结肠癌细胞为对象,研究inlA和inlB基因缺失对LM侵袭宿主细胞能力的影响。结果表明基因的缺失对其生长能力没有影响,但多个毒力基因的表达发生了不同程度的变化,同时发现inlA和inlB基因的缺失使LM侵袭HT29结肠癌细胞的能力显著下降（P＜0.05）。本研究成功构建LM的inlA和inlB基因双缺失菌株,并初步研究了基因缺失对LM侵袭宿主细胞能力的影响,为深入研究内化素InlA和InlB在LM入侵宿主细胞过程中的具体作用提供了支持。     

Comparative post‐harvest behaviour of traditional and virus‐resistant Muchamiel tomatoes

BACKGROUND: Nowadays, organoleptic quality is the primary objective for almost all tomato breeding programmes. In this study, post‐harvest behaviour of a breeding line with genetic resistance to important viruses (tomato mosaic virus, tomato spotted wilt virus and tomato yellow leaf curl virus) has been compared with the original traditional landrace (Muchamiel). The breeding line has been obtained by backcrossing, introgressing three resistance genes but aiming to keep the quality characteristics of the traditional variety. Tomatoes were picked at random and stored at 10 °C for 13 days. Quality analyses were made in both tomato samples: weight loss, colour, respiration rate, ethylene production, maturity index, instrumental hardness and sensory evaluation with trained panel. RESULTS: Fruits of the breeding line were characterized by higher hardness even with a higher maturity index. Results of sensory tests were in agreement with instrumental measurements. Organoleptic quality of Muchamiel virus‐resistant tomatoes was at least as high as that of traditional tomatoes, reaching the best scores in odour and aroma at the 13th storage day. CONCLUSION: Although a long time has been required to develop the breeding line, results indicate that organoleptic fruit quality has been recovered through backcrossing, confirming the success of the breeding programme. Copyright © 2010 Society of Chemical Industry     

Antioxidant effectiveness of coffee extracts and selected constituents in cell‐free systems and human colon cell lines

Scope: Epidemiological studies suggest that coffee can reduce the risk of degenerative diseases such as diabetes type 2, cardiovascular disease and cancer. These beneficial effects have partly been attributed to the antioxidant activity of coffee. We determined composition and antioxidant potential of differentially roasted coffee extracts and investigated the impact of selected original constituents and roast products. Methods and results: Parameters studied were direct antioxidant activity (trolox equivalent antioxidant capacity/oxygen radical absorbing capacity), cellular reactive oxygen species (ROS) level, DNA damage and protein expression of NAD(P)H: quinone oxidoreductase, γ‐glutamylcysteine ligase and glutathione reductase in HT‐29/Caco‐2 cells at 24‐h incubation. All extracts showed distinct direct antioxidant activity: medium roasts>light roast AB1 (caffeoylquinic acid (CQA)‐rich Arabica Brazil extract); dark roast AB2 (N‐methylpyridinium (NMP)‐rich Arabica Brazil extract), and diminished t‐butylhydroperoxide‐induced ROS level in HT‐29 cells (AB2>medium roasts>AB1). NAD(P)H:quinone oxidoreductase 1 expression and γ‐glutamylcysteine ligase expression were distinctly induced by AB1 and 5‐CQA, but not by AB2 and NMP. 5‐CQA and caffeic acid exhibited highest trolox equivalent antioxidant capacity/oxygen radical absorbing capacity values (5‐CQA: 1.3/3.5 mM and caffeic acid: 1.3/3.9 mM trolox); ROS level was distinctly diminished by 5‐CQA (≥3 μM), catechol (30 μM) and trigonelline (≥30 μM), whereas menadione‐induced DNA damage in Caco‐2 cells was reduced by NMP compounds (1–30 μM). Conclusion: The results emphasize that both original constituents and roast products contribute to the cellular antioxidant effectiveness of coffee.