Prevention by natural food anthocyanins, purple sweet potato color and red cabbage color, of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-associated colorectal carcinogenesis in rats initiated with 1,2-dimethylhydrazine

Integrated LC-MS/MS and Transcriptome Sequencing Analysis Reveals the Mechanism of Color Formation During Prickly Ash Fruit Ripening

Prickly ash peel is one of the eight major condiments in China and is widely used in cooking because of its unique fragrance and numbing taste. The color of prickly ash fruit is the most intuitive quality that affects consumer choice. However, the main components and key biosynthetic genes responsible for prickly ash fruit color have not yet been determined. To better understand the biosynthetic mechanisms and accumulation of prickly ash fruit color components, we performed an integrated transcriptomic and metabolomic analysis of red and green prickly ash fruit at different growth periods. The transcriptome analysis identified 17,269 differentially expressed genes (DEGs) between fruit of red and green prickly ash: 7,236 upregulated in green fruit and 10,033 downregulated. Liquid chromatography tandem mass spectrometry (LC-MS/MS) identified 214 flavonoids of 10 types. Flavonoids and flavonols are the main flavonoids in prickly ash, and the total flavonoid content of red prickly ash is higher than that of green prickly ash. Comprehensive analysis showed that the main colored metabolites that differed between green and red prickly ash were cyanidin-3-O-galactoside and cyanidin-3-O-glucoside, and differences in the contents of these metabolites were due mainly to differences in the expression of ANS and UFGT. Our results provide insight into the mechanisms underlying color differences in red and green prickly ash and will be useful for improving the quality of prickly ash fruit.

Purple Sweet Potato Phytochemicals: Potential Chemo-preventive and Anticancer Activities

BACKGROUND: Purple sweet potato (PSP; Ipomoea batatas (L.) lam.) is a perennial plant from the morning glory family Convolvulaceae. This plant contains many functional compounds and a high concentration of anthocyanins and phenols, in contrast to other sweet potato plants of different colors. Both in vitro and in vivo studies have shown that parts of PSP have interesting functions in the setting of cancer. AIM: This article is a collective review of the potential properties of PSP in cancer, with an emphasis on its effects in breast, bladder, colorectal, liver, gastric, and cervical cancers.METHODS: Major English research databases, including PubMed, Web of Science, Scopus, and Google Scholar, were searched for studies evaluating the activity of PSP against cancer published ended in Mei 2020. RESULTS: The search yielded 72 articles relevant to this topic. Of note, PSP phytochemicals such anthocyanins and caffeoylquinic acid derivatives act as an antioxidant that scavenges free radicals and regulates the Keap1-Nrf2 signaling pathway, acts as an antimutagenic agent, and has anti-inflammatory activity by inhibiting activation of mitogen-activated protein kinases and the NF-κB pathway as a Chemo-preventive mechanism. Furthermore, PSP can promote apoptosis, cell cycle arrest, inhibit proliferation, cell growth inhibition, and inhibit cancer progression that actions collectively sum as anticancer activity in many cancer cells. The primary target-signaling pathway that is interfered by PSP is the phosphatidylinositol-3-kinase/protein kinase B pathway, which is a very common mutated pathway in cancer cells that regulates many physiologic processes inside the cells. CONCLUSION: As a promising medicinal plant that may serve as a Chemo-preventive and anticancer agent, further research on PSP is required to determine its clinical uses and potential as a food supplement.

Metabolic profiling and gene expression analysis provides insights into flavonoid and anthocyanin metabolism in poplar

Poplar, a woody perennial model, is a common and widespread tree genus. We cultivated two red leaf poplar varieties from bud mutation of Populus sp. Linn. '2025' (also known as Zhonglin 2025, L2025 for shot): Populus deltoides varieties with bright red leaves (LHY) and completely red leaves (QHY). After measuring total contents of flavonoid, anthocyanin, chlorophyll and carotenoid metabolites, a liquid chromatography-electrospray ionization-tandem mass spectrometry system was used for the relative quantification of widely targeted metabolites in leaves of three poplar varieties. A total of 210 flavonoid metabolites (89 flavones, 40 flavonols, 25 flavanones, 18 anthocyanins, 16 isoflavones, 7 dihydroflavonols, 7 chalcones, 5 proanthocyanidins and 3 other flavonoid metabolites) were identified. Compared with L2025, 48 and 8 flavonoids were more and less abundant, respectively, in LHY, whereas 51 and 9 flavonoids were more and less abundant in QHY, respectively. On the basis of a comprehensive analysis of the metabolic network, gene expression levels were analyzed by deep sequencing to screen for potential reference genes for the red leaves. Most phenylpropanoid biosynthesis pathway-involved genes were differentially expressed among the examined varieties. Gene expression analysis also revealed several potential anthocyanin biosynthesis regulators including three MYB genes. The study results provide new insights into poplar flavonoid metabolites and represent the theoretical basis for future studies on leaf coloration in this model tree species.

Phenolic Composition and Antioxidant Activity of Purple Sweet Potato (Ipomoea batatas (L.) Lam.): Varietal Comparisons and Physical Distribution

The outer layer of purple sweet potato is removed during processing; however, this layer serves as a potential source of phenolics, especially anthocyanins. Herein, the phenolic composition and antioxidant activity were determined for the inner and outer layers of five purple sweet potato cultivars (‘Sinjami’, ‘Jami’, ‘Danjami’, ‘Yeonjami’, and ‘Borami’) harvested in Korea. Anthocyanins were identified using ultra-high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometer (UHPLC-(ESI)-qTOF-MS) and ultra-high-performance liquid chromatography-linear ion trap mass spectrometer (UHPLC-Ion trap-MS), and their composition was quantified using HPLC-coupled with diode array detector (DAD). Non-anthocyanin phenolic compounds (phenolic acids and flavonols) were quantified using UHPLC-(ESI)-triple quadrupole (QqQ). A total of 20 anthocyanins, including non-acylated or acylated peonidin, cyanidin, and pelargonidin glycosides, were identified. Peonidin 3-caffeoyl-p-hydroxybenzoyl sophoroside-5-glucoside was the major anthocyanin, with the highest level in the ‘Sinjami’ cultivar (outer; 12,366 mg/kg DW, inner; 14,832 mg/kg DW). Additionally, 12 phenolic acids and 6 flavonols (quercetin derivatives) were identified, with the outer layers of all cultivars displaying higher total levels than the inner layers. ‘Sinjami’ and ‘Jami’ had higher phenolic acid and quercetin derivative content and antioxidant activities than the other three cultivars (p < 0.05). Thus, the outer layers of ‘Sinjami’ and ‘Jami’ cultivars could be potential sources of anthocyanins and other phenolics.

Anthocyanin Biosynthesis and Methylation of the MdMYB10 Promoter Are Associated with the Red Blushed-Skin Mutant in the Red Striped-Skin "Changfu 2" Apple

The color of apple skin, particularly anthocyanin-based coloration, is a key factor determining market acceptance. The mechanisms of anthocyanin accumulation in apples with different skin color patterns (i.e., striped and blushed) were analyzed. In total, 14 anthocyanins and 5 procyanidins were simultaneously assayed in red blushed-skin mutants (CF-B1 and CF-B2) and red striped-skin parents (CF-S1 and CF-S2), and 13 significant differences were revealed. Anthocyanin accumulation was significantly higher in the red blushed-skin apples than it was in the parents. The transcript levels of anthocyanin biosynthesis genes and regulatory factors (MdMYB10, MdbHLH3, and MdWD40) were associated with different skin color patterns during the coloring period at 4, 6, and 8 days after the fruits were debagged. The methylation levels of the MdMYB10 promoter regions -1203 to -779 bp, -1667 to -1180 bp, and -2295 to -1929 bp were associated with different skin color patterns, and there was more methylation in red striped-skin apples. These results improve our understanding of anthocyanin accumulation and its underlying molecular mechanism in apples with different skin color patterns, thereby providing valuable information for apple breeding.

Stability and Quality of Anthocyanin in Purple Sweet Potato Extracts

Because of the high nutritional value of anthocyanin in purple sweet potatoes (TN57), the stability and quality of anthocyanin in purple sweet potatoes during and after the processing were investigated in this study. First of all, the extraction methods with different parameters, such as temperature, time, solid-liquid ratio, pH value, and solvent were employed to get better extraction efficiencies. After that, DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS (2,2′-azino-bis (3-ethylbenz thiazoline-6-sulphonic acid) were used to evaluate the anti-oxidation ability of the extracts. Lastly, the thermal degradation kinetics and photodegradation were used to obtain important degradation factors including the content of anthocyanin residue, degradation index (DI), color parameters, reaction rate (k), and chromatic aberration (ΔE). We found that the extraction condition as using 60% ethanol with 1% citric acid under 80 °C for 40 min was optimal for purple sweet potatoes, which obtained antioxidant capacity as 333 μM TE DPPH, 376 μM TE ABTS⁺, and 593.6 μM TE ferric ion reducing antioxidant power (FRAP). The results indicate that the most important parameter for the stability of anthocyanin in the purple sweet potato extract (PSPAE) was the pH value rather than temperature. In addition, there was no significant difference in chromatic aberration between the light and dark storage conditions under 37 °C. Thus, PSPAE has the potential to be developed as health foods and drinks rich in anthocyanin.

Anthocyanins in Colorectal Cancer Prevention. A Systematic Review of the Literature in Search of Molecular Oncotargets

Background: Colorectal cancer (CRC) is the malignant process that surges in the terminal part of gastrointestinal tract when adenomatous polyps convert to neoplastic cells able to infiltrate the submucosa. Despite the constant progress in applying preventive measures (screening, colonoscopy) and developing new cures (surgical and chemotherapy), CRC is still one of the leading causes of cancer death worldwide. The importance of natural dietary components in CRC prevention has been recognized. Defining the precise role of the diet and its particular molecular moieties in CRC prevention is of constant scientific interest years behind. Anthocyanins (AC), phenolic phytochemicals present in pigmented plants and vegetables, have been reported to have some role in counteracting CRC carcinogenesis. Nonetheless, evidence coming out the pre-clinical, clinical, and epidemiological studies is still controversial. This review is addressing the need to better comprehend the causes of missing data and discrepancies in investigations on the role of dietary AC in modulating CRC carcinogenesis. Methods: We have analyzed the scientific literature, available in PubMed database, according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement methodology for systematic reviews. Subsequently, two selection strategies, with their screening and eligibility criteria, were applied to retain research articles reporting in vitro and in vivo studies aimed at exploring the molecular mechanisms underlying the observed effects of AC in CRC prevention. Results: From the pool of 82 identified publications, we selected 19 articles reporting experimental or observational data on the effect of AC-enriched diets in CRC prevention in humans or murine species. Furthermore, we selected 10 articles reporting about molecular mechanisms of action of pure AC in CRC experimental models. Conclusions: The major outcome of this review is that AC showed essentially no effect in human studies, whereas AC-enriched diets proved to be effective in experimental murine models of CRC. In cell culture tests, AC showed to interfere with cell signaling pathways related to cell growth and differentiation, apoptosis, oxygen stress, and inflammation response. Further molecular characterizations are required to include AC in the panel of disease-modifying agents.

Effect of blackberry juice (Rubus fruticosus L.) on anxiety-like behaviour in Wistar rats

The present study evaluated the effects of blackberry juice that is rich in different concentrations of anthocyanins and polyphenols (2.6 mg/kg anthocyanins, 14.57 mg/kg polyphenols; 5.83 mg/kg anthocyanins, 27.10 mg/kg polyphenols; 10.57 mg/kg anthocyanins, 38.40 mg/kg polyphenols) on anxiety-like behaviour in Wistar rats. The rats were treated with blackberry juice for 21 days and then tested in the elevated plus maze, locomotor activity test and forced swim test. The results were compared with a reference anxiolytic drug diazepam (2.0 mg/kg) and vehicle (8.7 ml/kg). The intermediate dose of blackberry juice exerted an anxiolytic-like effect that was similar to diazepam, without affecting locomotive activity. The low and high doses of blackberry juice exerted no significant effects on anxiety-like behaviour compared with vehicle. In the forced swim test, both the high and intermediate doses of blackberry juice reduced total immobility time, suggesting a protective effect against behavioural changes that are induced by acute stress. These findings suggest a potential therapeutic effect of blackberry juice on anxiety that is associated with a stressful event.

Anti-breast Cancer Activity of SPG-56 from Sweet Potato in MCF-7 Bearing Mice in Situ through Promoting Apoptosis and Inhibiting Metastasis

SPG-56 is a newly isolated glycoprotein from sweet potatoes (Zhongshu NO. 1), but its value for suppressing breast cancer progression remains unknown. This study was designed to investigate the potential anti-cancer effects of SPG-56, which consists of 2.9% sugar and 97.1% protein. The effects of SPG-56 on the proliferation and apoptosis of breast cancer cells were determined using CCK-8 and Hoechst 33342 assays and flow cytometry, after staining with Annexin V and PI respectively. The activities of SPG-56 against breast cancer were examined using female BALB/c nude mice orthotopically implanted with human breast carcinoma cells of the types MCF-7 and 4T1-Luc. The cellular experiments showed that SPG-56 inhibited proliferation and promoted apoptosis of MCF-7 cells dose- and time-dependently. Oral administration of SPG-56 significantly suppressed the development of MCF-7 tumor cells (P < 0.01) as compared with an untreated group. The serum tumor markers CEA, CA125 and CA153 in a 240 mg/kg/d SPG-56 decreased by 54.8%, 91.8%, and 90.3%, respectively. The experiments further demonstrated that SPG-56 inhibited the metastasis of breast cancer in MCF-7 and 4T1-bearing mice by altering the expression of MMP2, MMP9, VEGF, Occludin and Claudin. It is concluded that SPG-56 may have potential as a novel anti-tumor candidate for breast cancer.

Anthocyanins accumulation and molecular analysis of correlated genes by metabolome and transcriptome in green and purple asparaguses (Asparagus officinalis, L.)

Asparagus (A. officinalis L.) is a highly nutrition vegetable crop. Here, three purple asparagus cultivars, namely, Jing Zi-2, Purple Passion and Pacific Purple, and one green cultivar, namely, Jing Lv-1 were studied. At least 16 kinds of anthocyanins were identified in purple and green cultivars, and peonidin, cyanidin and their glycoside derivatives were found to be the major anthocyanins. Transcriptome data showed that most anthocyanin biosynthetic genes and at least 5 kinds of transcription factors were significantly differentially expressed significantly between the green and purple cultivars. Dark-treated experiments revealed that anthocyanins are not produced in the absence of light, and both the anthocyanin biosynthetic and regulatory genes were down-regulated greatly in the dark, implying that anthocyanins accumulation in asparagus is light-dependent. Overall, the results of this study provide useful information for understanding anthocyanin accumulation and the molecular mechanism of anthocyanin biosynthesis in asparagus.

Purple sweet potato anthocyanin exerts antitumor effect in bladder cancer

Bladder cancer (BC) is the most common malignant disease. The developing of economically sustainable and available agents for the treatment of BC is required. Purple sweet potato anthocyanin (PSPA) has been shown to have antitumor abilities. The present study aimed to evaluate the potential role of PSPA in BC treatment. CCK-8 assay was used to assess the viability of BC cells. Flow cytometry assays were performed to evaluate the mitochondrial membrane potential (MMP), cell apoptosis and cell-cycle distribution. Real-time PCR (RT-PCR) and western blot analysis were performed to determine the expression of the target genes. The results of this study revealed that PSPA reduced the viability of BC in a dose-dependent manner. The MMP collapse was aggravated by the PSPA treatment. The apoptosis rate was higher in the PSPA groups than that in the control group. The expression of the pro-apoptosis genes, including cleaved caspase-3, Fas, Fasl, Bcl-2-associated X proteins (Bax) and anti-apoptotic gene (Bcl-2) was induced and decreased by PSPA, respectively. The cell-cycle progression was suppressed by the presence of PSPA. The activation of the phosphatidylinositol-4,5-bisphosphate 3-kinase/Akt (PI3K/Akt) signaling pathway was suppressed by PSPA treatment during BC treatment. The PI3K/Akt signaling was closely related to the antitumor effect of PSPA in BC. The present study provided evidence regarding the treatment of BC and enhanced the understanding of the potential role that PSPA plays in cancer prevention.

Cancer-preventive Properties of an Anthocyanin-enriched Sweet Potato in the APCMIN Mouse Model

Background

Anthocyanin-rich foods and preparations have been reported to reduce the risk of life-style related diseases, including cancer. The SL222 sweet potato, a purple-fleshed cultivar developed in New Zealand, accumulates high levels of anthocyanins in its storage root.

Methods

We examined the chemopreventative properties of the SL222 sweet potato in the C57BL/6J-APC^MIN/+ (APC^MIN) mouse, a genetic model of colorectal cancer. APC^MIN and C57BL/6J wild-type mice (n=160) were divided into four feeding groups consuming diets containing 10% SL222 sweet potato flesh, 10% SL222 sweet potato skin, or 0.12% ARE (Anthocyanin rich-extract prepared from SL222 sweet potato at a concentration equivalent to the flesh-supplemented diet) or a control diet (AIN-76A) for 18 weeks. At 120 days of age, the mice were anaesthetised, and blood samples were collected before the mice were sacrificed. The intestines were used for adenoma enumeration.

Results

The SL222 sweet potato-supplemented diets reduced the adenoma number in the APC^MIN mice.

Conclusions

These data have significant implications for the use of this sweet potato variant in protection against colorectal cancer.

AtMYB12 expression in tomato leads to large scale differential modulation in transcriptome and flavonoid content in leaf and fruit tissues

Plants synthesize secondary metabolites, including flavonoids, which play important role during various stresses for their survival. These metabolites are also considered as health-protective components in functional foods. Flavonols, one of the important groups of flavonoids, apart from performing several roles in plants have been recognized as potent phytoceuticals for human health. Tomato fruits are deficient in this group of flavonoids and have been an important target for enhancing the accumulation of flavonols through genetic manipulations. In the present study, AtMYB12 transcription factor of the Arabidopsis has been expressed under constitutive promoter in tomato. Transgenic tomato lines exhibited enhanced accumulation of flavonols and chlorogenic acid (CGA) in leaf and fruit accompanied with elevated expression of phenylpropanoid pathway genes involved in flavonol biosynthesis. In addition, global gene expression analysis in leaf and fruit suggested that AtMYB12 modulates number of molecular processes including aromatic amino acid biosynthesis, phytohormone signaling and stress responses. Besides this, a differential modulation of the genes in fruits and leaves is reported in this study. Taken together, results demonstrate that modulation of primary carbon metabolism and other pathways by AtMYB12 in tomato may lead to sufficient substrate supply for enhanced content of phenolics in general and flavonols in particular.

Effects of Purple-fleshed Sweet Potato (Ipomoera batatas Cultivar Ayamurasaki) Powder Addition on Color and Texture Properties and Sensory Characteristics of Cooked Pork Sausages during Storage

This study was conducted to evaluate the effects of adding purple-fleshed sweet potato (PFP) powder on the texture properties and sensory characteristics of cooked pork sausage. Sodium nitrite alone and sodium nitrite in combination with PFP were added to five different treatments sausages (CON (control) = 0.01% sodium nitrite, SP25 = 0.005% sodium nitrite and 0.25% purple-fleshed sweet potato powder combination, SP50 = 0.005% sodium nitrite and 0.5% purple-fleshed sweet potato powder combination, PP25 = 0.25% purple-fleshed sweet potato powder, PP50 = 0.5% purple-fleshed sweet potato powder). The sausages were cooked to 74°C, stored at 4°C for 6 wks, and used for chemical analysis, textural properties, and a sensory evaluation on 0, 2, 4 and 6 wks of storage, respectively. Similar CIE a* and b* values were determined in sausages from CON, SP25 and SP50 at the end of storage, and they were higher in CIE a* but lower in CIE b* than that of the PP25 and PP50 sausages. Significant differences were observed for brittleness and hardness when PFP was added to the sausages but were not confirmed after 4 wks of storage. The objective color score was influenced by adding PFP; however, the effect was not dose dependent. In overall acceptability, panelists favored the CON, SP25, SP50, and PP50 sausages but did not prefer PP25 sausages at the end of storage. Therefore, adding PFP to cooked pork sausages improved color and texture properties and sensory characteristics, but further study is needed to determine the proper ratio of sodium nitrite and PFP.

Novel Application ofShochuDistillery By-products to Prophylaxis against Mammary Carcinogenesis Induced by 7,12-Dimethylbenz[a]anthracene in Rats

The effect of the heat-dried product of Shochu distillery by-products (HSDB) derived from sweet potato on mammary carcinogenesis in rats was investigated. HSDB was fed at 2.5% or 5% of the total feed weight. Dietary HSDB at the 5% level suppressed the incidence and number of tumors, and delayed the latency of mammary tumor development relative to the control diet. Experiments were conducted to determine the relative polarity of the anticarcinogenic constituent(s). The number of tumors per tumor-bearing rat was lower in the diet group fed with an ethyl acetate extract of HSDB than in the control group. The tumor incidence evaluated at both palpation and autopsy was slightly lower in the group fed with a methanol extract than in the control group. These results suggest that HSDB contained at least two constituents of differing polarity that counteracted mammary carcinogenesis.

Ipomoea batatas (L.) Lam.: a rich source of lipophilic phytochemicals

The lipophilic extracts from the storage root of 13 cultivars of sweet potato (Ipomoea batatas (L.) Lam.) were evaluated by gas chromatography-mass spectrometry with the aim to valorize them and offer information on their nutritional properties and potential health benefits. The amount of lipophilic extractives ranged from 0.87 to 1.32% dry weight. Fatty acids and sterols were the major families of compounds identified. The most abundant saturated and unsaturated fatty acids were hexadecanoic acid (182-428 mg/kg) and octadeca-9,12-dienoic acid (133-554 mg/kg), respectively. β-Sitosterol was the principal phytosterol, representing 55.2-77.6% of this family, followed by campesterol. Long-chain aliphatic alcohols and α-tocopherol were also detected but in smaller amounts. The results suggest that sweet potato should be considered as an important dietary source of lipophilic phytochemicals.

In vivo antioxidant, hypoglycemic, and anti-tumor activities of anthocyanin extracts from purple sweet potato

Anthocyanin from purple sweet potato (PSP) extracted by microwave baking (MB) and acidified electrolyzed water (AEW) exhibited antioxidant activity. After further purification by macroporous AB-8 resin, the color value of PSP anthocyanin (PSPA) reached 30.15 with a total flavonoid concentration of 932.5 mg/g. The purified extracts had more potent antioxidant activities than the crude extracts. After continuously administering the PSP extracts to 12-mo-old mice for 1 mo, the anti-aging index of the experimental group was not significantly different from that of 5-mo-old mice. To a certain degree, PSPA was also effective for controlling plasma glucose levels in male Streptozocin (STZ)-treated diabetic mice. In addition, the extracts inhibited Sarcoma S180 cell growth in ICR mice. Mice consuming the PSP extracts formed significantly fewer and smaller sarcomas than mice consuming the control diets. The highest inhibition rate was 69.03%. These results suggest that anthocyanin extracts from PSP not only exert strong antioxidant effects in vitro, but also had anti-aging, anti-hyperglycemic, and anti-tumor activities.

Abnormal Savda Munziq, an Herbal Preparation of Traditional Uighur Medicine, May Prevent 1,2-dimethylhydrazine-Induced Rat Colon Carcinogenesis

The study tried to assess the chemoprotective effect of abnormal Savda Munziq (ASMq) on 1,2-dimethylhydrazine (DMH)-induced rat colon carcinogenesis. Male F344 rats were randomized into eight groups: Group 1 was served as control, no DMH injection was given and treated daily with normal saline. Rats in Groups 2–8 were given a single intraperitoneal injection of DMH (20 mg/kg body weight) at the beginning of the study. Group 2 was served as negative control, administered with normal saline until the end of the experiment after the single DMH injection. Groups 3–5 were served as pretreatment group, administered with ASMq ethanol extract at 400, 800 and 1600 mg/kg body weight, respectively, until the 45th day, continued by normal saline administration for another 45 days. Groups 6–8 were served as the treatment group, administered with normal saline for the first 45 days from the day of DMH injection, ASMq ethanol extract at three different doses to be administered until the end of the second 45th day. All rats were sacrificed at 91st day and the colons were analyzed for aberrant crypt foci (ACF) formation and crypt multiplicity. Results showed that ASMq ethanol extract reduced the number of ACF, AC and crypt multiplicity significantly (P < .05). It suggested that ASMq ethanol extract had chemoprotective effects on DMH-induced colon carcinogenesis, by suppressing the development of preneoplastic lesions, and probably exerted protection against the initiation and promotion steps of colon carcinogenesis.

Flavonoids in Cancer Prevention and Therapy: Chemistry, Pharmacology, Mechanisms of Action, and Perspectives for Cancer Drug Discovery

Among the numerous products available from plants, the flavonoid superfamily plays a central role by its large number of molecules (over 6000) and also by the role these products occupy in the normal physiology of plants. Flavonoids are secondary plant metabolites involved in several biological processes (e.g., germination, UV protection, insecticides) and are also involved in the attraction of pollinating agents via the vivid colors of the anthocyanin pigments found in flowers (e.g., blue, purple, yellow, orange, and red) [1–3]. Flavonoids are found in the normal human diet composed of green vegetables, onions, fruits (apples, grapes, strawberries, etc.), beverages (coffee, tea, beer, red wine) [4, 5], and isoflavonoids are mainly found in soya bean-derived products [6].

Anthocyanin-rich red grape extract impedes adenoma development in the Apc(Min) mouse: pharmacodynamic changes and anthocyanin levels in the murine biophase

PURPOSE

Red grape pomace extract (oenocyanin) is a cheap and rich source of anthocyanins, the agents suggested to possess cancer chemopreventive properties. Here the hypothesis was tested that oenocyanin added to the diet can interfere with intestinal adenoma development in the Apc(Min) mouse, a model of intestinal carcinogenesis linked to an Apc mutation.

METHODS

Mice received oenocyanin (0.3%) in their diet until week 16, when adenoma number and burden were recorded. Expression of Akt and ERK proteins was studied by Western blot in adenomas to discover effects of anthocyanins on cellular signalling via the PI3 and MAP kinase pathways. Levels of anthocyanins were measured by HPLC with visible spectroscopic or mass spectrometric detection.

RESULTS

In mice which had consumed oenocyanin, overall adenoma burden was halved and adenoma number was marginally reduced when compared with mice on control diet. The proliferation index in colonic adenomatous crypts, as reflected by Ki-67 staining, was significantly decreased from 88.14% in control mice to 75.6+/-4% in mice on oenocyanin (P=0.014). Expression of Akt in small intestinal adenomas from Apc(Min) mice on oenocyanin was reduced by 54% (P=0.003), when compared to controls. Oenocyanin anthocyanins and glucuronide metabolites were found in the urine and intestine but not in plasma.

CONCLUSIONS

The results suggest that oenocyanin may be a viable and economical alternative to anthocyanin-rich berry extracts for chemopreventive intervention. Akt and pErk might be suitable biomarkers of anthocyanin target organ efficacy.

A white mutant of Malay apple fruit (Syzygium malaccense) lacks transcript expression and activity for the last enzyme of anthocyanin synthesis, and the normal expression of a MYB transcription factor

The fruit skin of the mature Malay apple (Syzygium malaccense (L.) Merr. & L.M. Perry) is initially glossy red, then changes to purple. A mutant having mature fruits with white skin has been identified. The skin of wild-type fruit contained five glucose-based anthocyanins (cyanidin-3-O-glucoside, pelargonidin-3-O-glucoside, peonidin-3-O-glucoside, cyanidin-3,5-O-diglucoside and peonidin-3,5-O-diglucoside). Cyanidin-3-O-glucoside accounted for a large proportion of the total anthocyanin content. The accumulation cyanidin-3-O-glucoside during fruit maturation was correlated with increased activities of phenylalanine ammonia lyase (PAL) and UDPglucose:flavonoid 3-O-glucosyltransferase (UF3GlucT, F3GT). In the wild-type fruit skin, transcripts of seven genes that encode enzymes in the anthocyanin biosynthetic pathway were detected. No anthocyanins were found in the white mutant fruit skin. The skin of the white mutant fruit contained transcripts of all seven genes identified, except F3GT. It also showed no F3GT activity. The data indicate that the lack of anthocyanins in the mutant is due to lack of F3GT expression. In addition, the transcript of a MYB transcription factor, highly homologous to three Arabidopsis MYBs involved in anthocyanin synthesis, was virtually absent in the mutant but very high in the wild-type fruit. It is suggested that the lack of MYB expression is part of the cause of the lack of F3GT expression and anthocyanin synthesis during fruit maturation.

Transcriptional regulation of anthocyanin biosynthesis in red cabbage

The color of red cabbage (Brassica oleracea var. capitata) is due to anthocyanin accumulation. To investigate the regulatory control of anthocyanin production in red cabbage, the expression of anthocyanin biosynthetic and regulatory genes from eight commercial cultivars was examined. While the four green varieties had negligible amount of anthocyanins under normal growth condition, the four red cultivars contained up to 1.60 mg g(-1) fresh weight. HPLC analysis of the four red cultivars revealed that they produced similar composition of various forms of cyanidin glucosides but at different concentrations. Molecular analysis indicated that all the red cabbage shared common mechanism of regulatory control for anthocyanin biosynthesis. Except CHI which showed similar expression levels between green and red cultivars, the other structural genes, CHS, F3H, F3'H, DFR, LDOX, and GST, were constitutively up-regulated during all stages of vegetative growth in red varieties. The expression of these structural genes was also dramatically increased in green and red cabbage under nutrient stresses. The increased expression of the structural genes coincided with a coordinated increase in transcript levels of a bHLH gene, BoTT8, and a MYB transcription factor, BoMYB2. These results indicate that activation of these two regulatory factors by unknown mechanisms constitutively up-regulates nearly the entire pathway genes for the onset of anthocyanin biosynthesis in red cabbage. Moreover, the amount of total anthocyanins in red cabbage was found to be positively correlated with total antioxidant power, implicating the potential health benefit of red cabbage to human health.

Pilot study of oral anthocyanins for colorectal cancer chemoprevention

Naturally occurring anthocyanins possess colorectal cancer chemopreventive properties in rodent models. We investigated whether mirtocyan, an anthocyanin-rich standardized bilberry extract, causes pharmacodynamic changes consistent with chemopreventive efficacy and generates measurable levels of anthocyanins in blood, urine, and target tissue. Twenty-five colorectal cancer patients scheduled to undergo resection of primary tumor or liver metastases received mirtocyan 1.4, 2.8, or 5.6 grams (containing 0.5-2.0 grams anthocyanins) daily for 7 days before surgery. Bilberry anthocyanins were analyzed by high performance liquid chromatography (HPLC) with visible or mass spectrometric detection. Proliferation was determined by immunohistochemistry of Ki-67 in colorectal tumor. Concentrations of insulin-like growth factor (IGF)-I were measured in plasma. Mirtocyan anthocyanins and methyl and glucuronide metabolites were identified in plasma, colorectal tissue, and urine, but not in liver. Anthocyanin concentrations in plasma and urine were roughly dose-dependent, reaching approximately 179 ng/gram in tumor tissue at the highest dose. In tumor tissue from all patients on mirtocyan, proliferation was decreased by 7% compared with preintervention values. The low dose caused a small but nonsignificant reduction in circulating IGF-I concentrations. In conclusion, repeated administration of bilberry anthocyanins exerts pharmacodynamic effects and generates concentrations of anthocyanins in humans resembling those seen in Apc(Min) mice, a model of FAP adenomas sensitive to the chemopreventive properties of anthocyanins. Studies of doses containing <0.5 gram bilberry anthocyanins are necessary to adjudge whether they may be appropriate for development as colorectal cancer chemopreventive agents.

Induction of apoptosis and inhibition of invasion in human hepatoma cells by anthocyanins from meoru

Anthocyanins belong to a class of flavonoids exhibiting antioxidant and anti-inflammatory actions as well as a variety of chemotherapeutic effects. However, little is known about the cellular and molecular mechanism of anticancer activity. In this study, we investigated if the anthocyanins (delphinidin-3,5-diglucoside: cyanidin-3,5-diglucoside: petunidin-3,5-diglucoside: delphinidin-3-glucoside: malvdin-3,5-diglucoside: peonidin-3,5-diglucoside: cyanidin-3-glucoside: petunidin-3-glucoside: peonidin-3- glucoside: malvidin-3- glucoside = 27:63:8.27:1:2.21:2.21:6.7:1.25:5.72:1.25) [corrected] isolated from meoru (Vitis coignetiae Pulliat) exerted antiproliferative and anti-invasive and apoptotic effects on human hepatoma Hep3B cells. It was found that the anthocyanins could inhibit cell growth by 75% at the concentration of 400 microg/mL for 48 h. Flow cytometric analysis showed that the anthocyanins increased the amount of DNA fragments (sub-G1 fraction) in a dose-dependent manner, which is closely related to mitochondrial dysfunction and reduction in antiapoptotic proteins (Bcl-2, xIAP, cIAP-1, and cIAP-2). The anthocyanins also significantly inhibited the migration and invasion of Hep3B cells through a matrigel-coated chamber. Taken together this study indicates that the anthocyanins from meoru have antiproliferative and anti-invasive effects and may induce apoptosis through the activation of the mitochondrial pathway and inhibition of antiapoptotic proteins. This study provides evidence that the anthocyanins isolated from meoru might be useful in the treatment of human hepatitis B-associated hepatoma.

Anthocyanins from purple sweet potato Ipomoea batatas cultivar Ayamurasaki suppress the development of atherosclerotic lesions and both enhancements of oxidative stress and soluble vascular cell adhesion molecule-1 in apolipoprotein E-deficient mice

We evaluated the protective potential of anthocyanins from purple sweet potato Ipomoea batatas cultivar Ayamurasaki (APSP) against low-density lipoprotein (LDL) oxidation in vitro and atherosclerotic lesion development in apolipoprotein E-deficient mice given a cholesterol- and fat-enriched diet with or without 1% APSP for 4 weeks. APSP protected LDL against oxidation more potently than other anthocyanins and l-ascorbic acid in vitro. In mice, APSP significantly lowered the atherosclerotic plaque area to about half of the control, the liver level of thiobarbituric acid-reactive substances as an oxidative stress marker, and the plasma level of soluble vascular cell adhesion molecule-1 (sVCAM-1). However, APSP showed no effects on body weight and cholesterol and lipid levels in the plasma. The results suggest that APSP can suppress the development of atherosclerotic lesions and both enhancements of oxidative stress and sVCAM-1 independently of the changes in cholesterol and lipid levels in mice.

Purple corn color suppresses Ras protein level and inhibits 7,12-dimethylbenz[a]anthracene-induced mammary carcinogenesis in the rat

Anthocyanins belong to the class of phenolic compounds collectively named flavonoids. Many anthocyanins are reported to have inhibitory effects on carcinogenesis. Purple corn color (PCC), an anthocyanin containing extract of purple corn seeds, is used as a food colorant. The major anthocyanin in PCC is cyanidin 3-O-beta-D-glucoside (C3-G). The present study was conducted to assess the influence of dietary PCC on 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary carcinogenesis in rats. PCC significantly inhibited DMBA-induced mammary carcinogenesis in human c-Ha-ras proto-oncogene transgenic (Hras128) rats and in their non-transgenic counterparts. PCC and C3-G also inhibited cell viability and induced apoptosis in mammary tumor cells derived from Hras128 rat mammary carcinomas. At the molecular level, PCC and C3-G treatment resulted in a preferential activation of caspase-3 and reduction of Ras protein levels in tumor cells. It is proposed that C3-G could act as a chemopreventive and possibly chemotherapeutic agent for cancers with mutations in ras. Secondly, the in vitro-in vivo system used in this study can be utilized for screening for cancer preventive compounds that act via Ras down-regulation.

Antioxidant effects of flavonoids used as food additives (purple corn color, enzymatically modified isoquercitrin, and isoquercitrin) on liver carcinogenesis in a rat medium-term bioassay

To clarify the effects of purple corn color, enzymatically modified isoquercitrin (EMIQ), and isoquercitrin (IQ), registered as natural food additives in Japan, on liver carcinogenesis in vivo, a medium-term bioassay was employed. A total of 100 male F344 rats were divided into 5 groups; groups 1 to 4 were given a single intraperitoneal injection of diethylnitrosamine (200 mg/kg b.w.) on day 1. From weeks 2 to 8, they were administered basal diet purple corn color, EMIQ, or IQ as containing test chemicals at doses of 1.0% (groups 1 and 5), 0.1% (group 2), 0.01% (group 3), or 0% (group 4) (experiments 1, 4, and 5). All rats were subjected to two-thirds partial hepatectomy at week 3 and were sacrificed at week 8. Purple corn color exerted no significant modifying effects on GST-P positive foci, preneoplastic foci, development in the liver. However, serum of rats treated with purple corn color provided evidence of antioxidant power significantly by potential antioxidant (PAO) test in vivo (experiment 2). And microarray analyses showed purple corn color to induce RNA expression such as P450 (cytochrome) oxidoreductase, phosphatidylinositol 3-kinase, and phospholipase A2 (experiment 3). Higher doses of EMIQ or IQ with strong antioxidant power in vivo by PAO test treated groups were correlated with smaller numbers of GST-P positive foci, with Spearman's rank correlation coefficients of P= 0.002 and P= 0.049, respectively (experiments 4 and 5). Therefore, the tested food additives may be effective as antioxidants in vivo and have chemopreventive potential against liver preneoplastic lesion development.

Anthocyanins and their role in cancer prevention

Anthocyanins are the most abundant flavonoid constituents of fruits and vegetables. The conjugated bonds in their structures, which absorb light at about 500 nm, are the basis for the bright red, blue and purple colors of fruits and vegetables, as well as the autumn foliage of deciduous trees. The daily intake of anthocyanins in residents of the United States is estimated to be about 200 mg or about 9-fold higher than that of other dietary flavonoids. In this review, we summarize the latest developments on the anti-carcinogenic activities of anthocyanins and anthocyanin-rich extracts in cell culture models and in animal model tumor systems, and discuss their molecular mechanisms of action. We also suggest reasons for the apparent lack of correlation between the effectiveness of anthocyanins in laboratory model systems and in humans as evidenced by epidemiological studies. Future studies aimed at enhancing the absorption of anthocyanins and/or their metabolites are likely to be necessary for their ultimate use for chemoprevention of human cancer.

Cruciferous vegetables reduce morphological markers of colon cancer risk in dimethylhydrazine-treated rats

Consumption of cruciferous vegetables has been associated with reduced colon cancer risk in human populations. However, little experimental evidence exists to support this association. Here, we report the effects of diets containing cruciferous vegetables on colon cancer risk. In Expt. 1, rats were fed a vegetable-free (basal) diet or diets containing different lyophilized cruciferous vegetables in concentrations between 4 and 10%. In Expt. 2, rats were fed the basal diet or diets containing 10-22.6% fresh cruciferous vegetables. Diets were fed for 2 wk (Expt. 1) or 3 wk (Expt. 2) before and 7 wk (Expt. 1) or 12 wk (Expt. 2) after administration of the colon carcinogen 1,2-dimethylhydrazine. Rats fed fresh vegetables were also injected with a low dose of carcinogen 18-24 h prior to termination. Groups fed lyophilized vegetables did not differ in aberrant crypt foci (ACF), sialomucin-producing foci, or mucin-depleted foci (MDF) numbers. However, all fresh vegetable diets significantly decreased ACF (approximately 40%) and MDF numbers. Activities of the hepatic phase I enzyme CYP2E1 did not differ among groups in either experiment. Hepatic glutathione S-transferase (GST) and quinone reductase activities did not differ among groups fed fresh vegetables, whereas the lyophilized cabbage diets decreased GST activity compared with the basal diet. Groups did not differ in apoptosis and cell proliferation labeling indices in colonic mucosa. This study indicates that fresh but not lyophilized cruciferous vegetables reduce colon cancer risk in rats. These results do not support changes in hepatic carcinogen metabolism or colonic crypt cytokinetics as a mechanism.

Response of cell cycle/stress-related protein expression and DNA damage upon treatment of CaCo2 cells with anthocyanins

Anthocyanins are a class of flavonoids, widely spread throughout the plant kingdom, exhibiting important antioxidant and anti-inflammatory actions as well as chemotherapeutic effects; nonetheless, little is known about the molecular mechanisms by which these activities are exerted. The present study is aimed at investigating molecular mechanisms involved in the chemotherapeutic effects induced by both cyanidin-3-O-beta glucopyranoside (CY3G) and its aglycon form, cyanidin chloride (CY), in human colon cancer cells (CaCo2). The effect on cell growth, reactive oxygen species (ROS) formation and cell cycle/stress proteins modification, including ataxia teleangectasia mutated protein (ATM), p53, p21, 8-oxoguanine DNA glycosylase (OGG1), 70 kDa heat shock protein (HSP70) and topoisomerase IIbeta, as well as on DNA fragmentation, was determined. CY and CY3G treatment affect cell growth and cell proliferation, this latter in a moderately dose-dependent way. Interestingly, ROS level is decreased by any concentration of CY and, only at the lowest concentration, by CY3G. Moreover, the two molecules exert their activities increasing ATM, topoisomerase II, HSP70 and p53 expression. The analysis of DNA fragmentation by Comet assay evidences: (1) a dose-dependent increase in DNA damage only after treatment with CY3G; (2) a more evident trend in the DNA fragmentation when the treatment is performed on agarose embedded cells (cellular atypical Comet); (3) a highly dose-dependent DNA fragmentation induced by CY when the treatment is carried out on agarose embedded naked DNA (acellular atypical Comet). The present findings substantiate a possible chemotherapeutic role of anthocyanins and suggest that CY and CY3G act on CaCo2 by different mechanisms, respectively, ROS-dependent and ROS-independent.

Anthocyanins induce the activation of phase II enzymes through the antioxidant response element pathway against oxidative stress-induced apoptosis

Reactive oxygen species (ROS)-induced cell damage is inevitable and severe and is involved in numerous diseases, including cancer. Reducing oxidative stress is one of the strategies of chemoprevention. Anthocyanins are naturally occurring flavonoids that show multiple benefits. We first pointed out the effects of anthocyanins in the contributions to activation of phase II antioxidant and detoxifying enzymes, chemopreventive potency, and involved transcriptional regulation. Our results obtained in rat liver Clone 9 cells showed that treatment of anthocyanins leads to positive effects on elevating the antioxidant capacity, including activated expression of glutathione-related enzymes (glutathione reductase, glutathione peroxidase, and glutathione S-transferase) and recruited GSH content. In addition, the activity of NAD(P)H: quinone oxidoreductase (NQO1) was also promoted under the treatment of anthocyanin. This influential functions as the defense system against programmed cell death induced by H2O2. The capacity for induction of luciferase expression by anthocyanins in cells transfected with rat nqo1-promoter constructed plasmid was further investigated; we found that the molecular mechanism is related to the activation of antioxidant response element (ARE) upstream of genes that are involved in antioxidation and detoxification. Our data suggest that natural anthocyanins are recommended as chemopreventive phytochemicals and could stimulate the antioxidant system to resist oxidant-induced injury. And, more important, the promoting effect of anthocyanins on ARE-regulated phase II enzyme expression seems to be a critical point in modulating the defense system against oxidative stress.