Chemopreventive properties of dietary rice bran: current status and future prospects

Evaluation of the cytotoxic effects of Cyperus longus extract, fractions and its essential oil on the PC3 and MCF7 cancer cell lines

Cyperus longus is one of the Iranian endemic species. However, to date, and to the best of our knowledge, there are no availale academic reports on the cytotoxicity of this plant. Thus, this study was carried out to examine the in vitro anti-proliferative and anti-apoptotic effects of Cyperus longus extract, fractions and essential oil (EO) on MCF7 and PC3 cell lines. The chemical constituents of EO were identified using gas chromatography (GC)-mass spectrometry (MS) analysis. The cells were cultured in RPMI-1640 medium and incubated with various concentrations of the plant extract and fractions. Cell viability was quantified by MTT assay following 24, 48 and 72 h of exposure to (12.5–200 µg/ml) of the methanol extract, the dichloromethane (CH₂Cl₂), ethyl acetate (EtOAc) and water fractions, as well as the EO of the plant. The percentage of apoptotic cells was determined using propidium iodide staining of DNA fragments by flow cytometry (sub-G1 peak). The most effective fraction in the MCF7 cell line was the CH₂Cl₂ fraction (IC₅₀ after 48 h, 25.34±2.01). The EtOAc fraction (IC₅₀ after 48 h, 35.2±2.69) and the methanol extract (IC₅₀ after 48 h, 64.64±1.64) were also found to be effective. The IC₅₀ values obtained for the PC3 cell line were 37.97±3.87, 51.57±3.87 and 70.33±2.36 for the CH₂Cl₂ fraction, the EtOAc fraction and the methanol extract, respectively. Based on these data and due to the partial polarity of the most effective fraction (the CH₂Cl₂ fraction), we also examined the cytotoxicity of the plant EO. The IC₅₀ values after 48 h were 22.25±4.25 and 12.55±3.65 in the PC3 and MCF7 cell lines, respectively. DNA fragmentation assay also confirmed these data. Performing GC-MS analysis for the plant EO revealed that β-himachalene (10.81%), α-caryophyllene oxide (7.6%), irisone (4.78%), β-caryophyllene oxide (4.36%), humulene oxide (12%), viridiflorol (4.73%), aristolone (6.39%) and longiverbenone (6.04%) were the main constituents. Our results demonstrated that two of the constituents of Cyperus longus, viridiflorol and longiverbenone, should be investigated further as possible promising chemotherapeutic agents in cancer treatment.

Food supplementation with rice bran enzymatic extract prevents vascular apoptosis and atherogenesis in ApoE-/- mice

PURPOSE

Atherosclerosis is associated with reduced mononuclear cell (MNC) telomere length, and senescent cells have been detected in atherosclerotic plaques. Rice bran is a source of γ-oryzanol, phytosterols and tocols with potential lipid-lowering, antioxidant and anti-inflammatory activities. Here, we tested the hypothesis that rice bran enzymatic extract (RBEE) impacts on apoptosis, telomere length and atherogenesis in mice.

METHODS

Seven-week-old male ApoE-/- mice were fed high-fat diet (HFD) or isocaloric HFD supplemented with 5 % (w/w) RBEE for 23 weeks. Wild-type mice of the same age were kept under standard diet as controls.

RESULTS

RBEE treatment reduced total cholesterol (19.24 ± 1.63 vs 24.49 ± 1.71 mmol/L) and triglycerides (1.13 ± 0.18 vs 1.75 ± 0.22 mmol/L) and augmented HDL-cholesterol (1.86 ± 0.20 vs 1.07 ± 0.20 mmol/L). RBEE attenuated macrophage infiltration by 56.69 ± 4.65 % and plaque development (7737 ± 836 vs 12,040 ± 1001 μm²) in the aortic sinus. In the aorta, RBEE treatment reduced expression of the apoptosis pathway components p16, p53 and bax/bcl-2 ratio. RBEE prevented apoptosis of aortic endothelial cells (2.81 ± 0.71-1.14 ± 0.35 apoptotic nuclei/ring for ApoE-/- HFD and ApoE-/- HFD 5 % RBEE, respectively). In contrast, MNC of RBEE-fed mice exhibited enhanced apoptosis marker expression with increased p53 and bax/bcl-2 protein levels. Compared to WT, ApoE-/- mice on HFD were characterized by significant telomere shortening in aorta (11 ± 2 %) and MNC (73 ± 7 %), which was reduced by supplementation with RBEE (aorta: 40 ± 7 %; MNC: 105 ± 10 %). Expression of telomere repeat-binding factor 2 was increased in RBEE-fed mice.

CONCLUSION

Long-term food supplementation with RBEE lowers cholesterol and prevents atherosclerotic plaque development in ApoE-/- mice. Differential regulation of vascular and MNC apoptosis and senescence were identified as potential mechanisms.

Beneficial effect of rice bran extract against 3-nitropropionic acid induced experimental Huntington's disease in rats

Huntington's disease (HD) is a neurodegenerative disorder, characterized by progressive motor and non-motor dysfunction due to degeneration of medium spiny neurons in striatum. 3-Nitropropionic acid is commonly used to induce the animal model of HD. Rice bran is supposed to have beneficial effects on mitochondrial function. The present study has been designed to explore the effect of rice bran extract against 3-Nitropropionic acid induced neurotoxicity in rats. 3-Nitropropionic acid (10 mg/kg, i.p) was administered systemically for 21 days. Hexane and ethanol extract of rice bran were prepared using Soxhlation. Hexane (250 mg/kg) and ethanol extract (250 mg/kg) were administered per os for 21 days in 3-NP treated groups. Behavioral parameters (body weight, grip strength, motor coordination, locomotion) were conducted on 7th, 14th and 21st day. Animals were sacrificed on 22nd day for biochemical, mitochondrial dysfunction (Complex II), neuroinflammatory and neurochemical estimation in striatum. This study demonstrates significant alteration in behavioral parameters, oxidative burden (increased lipid peroxidation, nitrite concentration and decreased glutathione), mitochondrial function (decreased Complex II enzyme activity), pro-inflammatory mediators and neurochemical levels in 3-nitropropionic acid treated animals. Administration of hexane and ethanol extract prevented the behavioral, biochemical, neuroinflammatory (increased TNF-α, IL-1β and IL-6) and neurochemical alterations (decreased dopamine, norepinephrine, serotonin, 5-hydroxy indole acetic acid, GABA and increased 3,4-dihydro phenyl acetaldehyde, homovanillic acid and glutamate levels) induced by 3-nitropropionic acid. The outcomes of present study suggest that rice bran extract is beneficial and might emerge as an adjuvant or prophylactic therapy for treatment of HD like symptoms.

γ-Oryzanol reduces caveolin-1 and PCGEM1 expression, markers of aggressiveness in prostate cancer cell lines

BACKGROUND

Prostate cancer is a leading cause of death among men due to the limited number of treatment strategies available for advanced disease. γ-oryzanol is a component of rice bran, rich in phytosterols, known for its antioxidant, anti-carcinogenic and endocrinological effects. It is known that γ-oryzanol may affect prostate cancer cells through the down regulation of the antioxidant genes and that phytosterols have anti-proliferative and apoptotic effects. There are evidences showing that some of the components of γ-oryzanol can modulate genes involved in the development and progression of prostate cancer, as caveolin-1 (Cav-1) and prostate specific androgen-regulated gene (PCGEM1).

METHODS

To determine the effects of γ-oryzanol on prostate cancer cell survival we evaluated the cell viability and biomass by MTT and sulforhodamine B assays, respectively. Cell death, cell cycle and pERK1/2 activity were assessed by flow cytometry. The changes in gene expression involved in the survival and progression of prostate cancer cav-1 and PCGEM1 genes were evaluated by quantitative real time reverse transcriptase polymerase chain reaction (RT-PCR) and cav-1 protein by immunofluorescence followed by confocal microscopy analysis.

RESULTS

We found that γ-oryzanol decreases cell viability and culture biomass by apoptosis and/or necrosis death in androgen unresponsive (PC3 and DU145) and responsive (LNCaP) cell lines, and signals through pERK1/2 in LNCaP and DU145 cells. γ-oryzanol also appears to block cell cycle progression at the G2/M in PC3 and LNCaP cells and at G0/G1 in DU145 cells. These effects were accompanied by a down regulation in the expression of the cav-1 in both androgen unresponsive cell lines and PCGEM1 gene in DU145 and LNCaP cells.

CONCLUSION

In summary, we used biochemical and genetics approaches to demonstrate that γ-oryzanol show a promising adjuvant role in the treatment of prostate cancer.

Anti-invasive activity against cancer cells of phytochemicals in red jasmine rice (Oryza sativa L.)

Red rice contains pharmacological substances including phenolics, oryzanol, tocotrienol and tocopherol. Recently, red rice extract has been employed as a source of antioxidants for inhibition of tumor growth. This study was carried out to evaluate the anti-invasion effects of red rice extract fractions on cancer cells. It was found that at 100 μg/ml of crude ethanolic extract (CEE), hexane fraction (Hex) and dichloromethane fraction (DCM) could reduce HT1080 and MDA-MB-231 cancer cell invasion. Hex and DCM revealed higher potency levels than CEE, whereas an ethyl acetate fraction (EtOAc) had no effect. Gelatin zymography revealed that Hex decreased the secretion and activity of matrix metalloproteinase-2 and -9 (MMP-2 and-9). In contrast, the DCM fraction exhibited slightly effect on MMPs secretion and had no effect on MMPs activity. Collagenase activity was significantly inhibited by the Hex and DCM fractions. High amounts of γ-oryzanol and γ-tocotrienol were found in the Hex and DCM fractions and demonstrated an anti-invasion property. On the other hand, proanthocyanidin was detected only in the CEE fraction and reduced MDA-MB-231 cells invasion property. These observations suggest that proanthocyanidin, γ-oryzanol and γ-tocotrienol in the red rice fractions might be responsible for the anti invasion activity. The red rice extract may have a potential to serve as a food-derived chemotherapeutic agent for cancer patients.

Pilot dietary intervention with heat-stabilized rice bran modulates stool microbiota and metabolites in healthy adults

Heat-stabilized rice bran (SRB) has been shown to regulate blood lipids and glucose, modulate gut mucosal immunity and inhibit colorectal cancer in animal and human studies. However, SRB’s effects on gut microbial composition and metabolism and the resulting implications for health remain largely unknown. A pilot, randomized-controlled trial was developed to investigate the effects of eating 30 g/day SRB on the stool microbiome and metabolome. Seven healthy participants consumed a study meal and snack daily for 28 days. The microbiome and metabolome were characterized using 454 pyrosequencing and gas chromatography-mass spectrometry (GC-MS) at baseline, two and four weeks post-intervention. Increases in eight operational taxonomic units (OTUs), including three from Bifidobacterium and Ruminococcus genera, were observed after two and four weeks of SRB consumption (p < 0.01). Branched chain fatty acids, secondary bile acids and eleven other putative microbial metabolites were significantly elevated in the SRB group after four weeks. The largest metabolite change was a rice bran component, indole-2-carboxylic acid, which showed a mean 12% increase with SRB consumption. These data support the feasibility of dietary SRB intervention in adults and support that SRB consumption can affect gut microbial metabolism. These findings warrant future investigations of larger cohorts evaluating SRB’s effects on intestinal health.

Cytotoxic and apoptotic-inducing effects of purple rice extracts and chemotherapeutic drugs on human cancer cell lines

Pigmented rice is mainly black, red, and dark purple, and contains a variety of flavones, tannin, polyphenols, sterols, tocopherols, γ-oryzanols, amino acids, and essential oils. The present study evaluated the cytotoxic effects of purple rice extracts (PREs) combined with chemotherapeutic drugs on human cancer cells and mechanisms of cell death. Methanolic (MeOH) and dichloromethane (DCM) extracts of three cultivars of purple rice in Thailand: Doisaket (DSK), Nan and Payao (PYO), were tested and compared with white rice (KK6). Cytotoxicity was determined by 3-(4, 5-dimethyl)-2, 5-diphenyltetrazolium bromide (MTT) assay in human hepatocellular carcinoma HepG2, prostate cancer LNCaP and murine normal fibroblast NIH3T3 cells. MeOH-PYO-PRE was the most cytotoxic and inhibited HepG2 cell growth more than that of LNCaP cells but was not toxic to NIH3T3 cells. When PREs were combined with paclitaxel or vinblastine, they showed additive cytotoxic effects on HepG2 and LNCaP cells, except for MeOH-PYO-PRE which showed synergistic effects on HepG2 cells when combined with vinblastine. MeOH-PYO-PRE plus vinblastine induced HepG2 cell apoptosis with loss of mitochondrial transmembrane potential (MTP) but no ROS production. MeOH-PYO-PRE-treated HepG2 cells underwent apoptosis via caspase-9 and-3 activation. The level of γ-oryzanol was highest in DCM-PYO-PRE (44.17 mg/g) whereas anthocyanin content was high in MeOH-PYO-PRE (5.80 mg/g). In conclusion, methanolic Payao purple rice extract was mostly toxic to human HepG2 cells and synergistically enhanced the cytotoxicity of vinblastine. Human HepG2 cell apoptosis induced by MeOH-PYO-PRE and vinblastine was mediated through a mitochondrial pathway.

New screw lactam and two new carbohydrate derivatives from the methanol extract of rice bran

A new screw lactam and two new carbohydrate derivatives, oryzalactam (1), oryzasaccharide A (2), and oryzasaccharide B (3), have been isolated from the methanol extract of rice bran together with four other known compounds, including momilactone A (4), butyl β-d-xylopyranose (5), ethyl β-d-xylopyranose (6), and methyl β-d-xylopyranose (7). The structures of these compounds were determined using a combination of spectroscopic methods and chemical analysis. This work represents the first recorded example of the isolation of compounds 1, 2, 3, 5, 6, and 7 from rice bran. The antioxidant experiments revealed that compound 1 possessed strong ABTS(+) (ABTS = 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid)) and DPPH (DPPH = diphenyl(2,4,6-trinitrophenyl) iminoazanium) radical scavenging with IC50 values of 33.38 ± 1.58 and 40.20 ± 1.34 μM, respectively. Antimicrobial assays revealed that compound 4 showed high levels of selectivity toward Escherichia coli with a minimal inhibitory concentration value of 5 μM.

Strategies of functional food for cancer prevention in human beings

Functional food for prevention of chronic diseases is one of this century's key global challenges. Cancer is not only the first or second leading cause of death in China and other countries across the world, but also has diet as one of the most important modifiable risk factors. Major dietary factors now known to promote cancer development are polished grain foods and low intake of fresh vegetables, with general importance for an unhealthy lifestyle and obesity. The strategies of cancer prevention in human being are increased consumption of functional foods like whole grains (brown rice, barley, and buckwheat) and by-products, as well some vegetables (bitter melon, garlic, onions, broccoli, and cabbage) and mushrooms (boletes and Tricholoma matsutake). In addition some beverages (green tea and coffee) may be protective. Southwest China (especially Yunnan Province) is a geographical area where functional crop production is closely related to the origins of human evolution with implications for anticancer influence.

Rice brans, rice bran oils, and rice hulls: composition, food and industrial uses, and bioactivities in humans, animals, and cells

Rice plants produce bioactive rice brans and hulls that have been reported to have numerous health-promoting effects in cells, animals, and humans. The main objective of this review is to consolidate and integrate the widely scattered information on the composition and the antioxidative, anti-inflammatory, and immunostimulating effects of rice brans from different rice cultivars, rice bran oils derived from rice brans, rice hulls, liquid rice hull smoke derived from rice hulls, and some of their bioactive compounds. As part of this effort, this paper also presents brief summaries on the preparation of health-promoting foods including bread, corn flakes, frankfurters, ice cream, noodles, pasta, tortillas, and zero-trans-fat shortening as well as industrial products such bioethanol and biodiesel fuels. Also covered are antibiotic, antiallergic, anticarcinogenic, antidiabetic, cardiovascular, allelochemical, and other beneficial effects and the mechanisms of the bioactivities. The results show that food-compatible and safe formulations with desirable nutritional and biological properties can be used to develop new multifunctional foods as well as bioethanol and biodiesel fuel. The overlapping aspects are expected to contribute to a better understanding of the potential impact of the described health-promoting potential of the rice-derived brans, oils, and hulls in food and medicine. Such an understanding will enhance nutrition and health and benefit the agricultural and industrial economies.

Inhibition of human MCF-7 breast cancer cells and HT-29 colon cancer cells by rice-produced recombinant human insulin-like growth binding protein-3 (rhIGFBP-3)

Background

Insulin-like growth factor binding protein-3 (IGFBP-3) is a multifunctional molecule which is closely related to cell growth, apoptosis, angiogenesis, metabolism and senescence. It combines with insulin-like growth factor-I (IGF-I) to form a complex (IGF-I/IGFBP-3) that can treat growth hormone insensitivity syndrome (GHIS) and reduce insulin requirement in patients with diabetes. IGFBP-3 alone has been shown to have anti-proliferation effect on numerous cancer cells.

Methodology/Principal Findings

We reported here an expression method to produce functional recombinant human IGFBP-3 (rhIGFBP-3) in transgenic rice grains. Protein sorting sequences, signal peptide and endoplasmic reticulum retention tetrapeptide (KDEL) were included in constructs for enhancing rhIGFBP-3 expression. Western blot analysis showed that only the constructs with signal peptide were successfully expressed in transgenic rice grains. Both rhIGFBP-3 proteins, with or without KDEL sorting sequence inhibited the growth of MCF-7 human breast cancer cells (65.76 ± 1.72% vs 45.00 ± 0.86%, p < 0.05; 50.84 ± 1.97% vs 45.00 ± 0.86%, p < 0.01 respectively) and HT-29 colon cancer cells (65.14 ±3.84% vs 18.01 ± 13.81%, p < 0.05 and 54.7 ± 9.44% vs 18.01 ± 13.81%, p < 0.05 respectively) when compared with wild type rice.

Conclusion/Significance

These findings demonstrated the feasibility of producing biological active rhIGFBP-3 in rice using a transgenic approach, which will definitely encourage more research on the therapeutic use of hIGFBP-3 in future.

Phytochemical profile of a Japanese black-purple rice

Black-purple rice is becoming popular with health conscious food consumers. In the present study, the secondary metabolites in dehulled black-purple rice cv. Asamurasaki were analysed using HPLC-PDA-MS(2). The seeds contained a high concentration of seven anthocyanins (1400 μg/g fresh weight) with cyanidin-3-O-glucoside and peonidin-3-O-glucoside predominating. Five flavonol glycosides, principally quercetin-3-O-glucoside and quercetin-3-O-rutinoside, and flavones were detected at a total concentration of 189 μg/g. The seeds also contained 3.9 μg/g of carotenoids consisting of lutein, zeaxanthin, lycopene and β-carotene. γ-Oryzanol (279 μg/g) was also present as a mixture of 24-methylenecycloartenol ferulate, campesterol ferulate, cycloartenol ferulate and β-sitosterol ferulate. No procyanidins were detected in this variety of black-purple rice. The results demonstrate that the black-purple rice in the dehulled form in which it is consumed by humans contains a rich heterogeneous mixture of phytochemicals which may provide a basis for the potential health benefits, and highlights the possible use of the rice as functional food.

Rice varietal differences in bioactive bran components for inhibition of colorectal cancer cell growth

Rice bran chemical profiles differ across rice varieties and have not yet been analysed for differential chemopreventive bioactivity. A diverse panel of seven rice bran varieties was analysed for growth inhibition of human colorectal cancer (CRC) cells. Inhibition varied from 0% to 99%, depending on the variety of bran used. Across varieties, total lipid content ranged 5-16%, individual fatty acids had 1.4- to 1.9-fold differences, vitamin E isoforms (α-, γ-, δ-tocotrienols, and tocopherols) showed 1.3- to 15.2-fold differences, and differences in γ-oryzanol and total phenolics ranged between 100-275ng/mg and 57-146ngGAE/mg, respectively. Spearman correlation analysis was used to identify bioactive compounds implicated in CRC cell growth inhibitory activity. Total phenolics and γ-tocotrienol were positively correlated with reduced CRC cell growth (p<0.05). Stoichiometric variation in rice bran components and differential effects on CRC viability merit further evaluation elucidate their role in dietary CRC chemoprevention.

Stabilized rice bran improves weaning pig performance via a prebiotic mechanism

Stabilized rice bran (SRB) is classified as a "functional food" because of its prebiotic characteristics. With increasing grain prices and the pressure to remove antibiotics from swine diets because of concern over antibiotic resistance, SRB was investigated as a nursery diet ingredient with and without the addition of antibiotics (ANT). Two hundred pigs were weaned at 21 d of age, blocked by BW, and allotted to diets containing 0 or 10% SRB ± ANT according to a 2 × 2 factorial arrangement of treatments. Five animals were housed per pen throughout a 28-d growth period. At the end of the trial, 1 pig from each pen was euthanized for measurement of intestinal morphology. Antibiotic supplementation improved ADG by 6.4% during Phase 2 (d 14 to 28; P = 0.02), but other production variables were unaffected by ANT. During Phase 2 and cumulatively (d 0 to 28), the supplementation of SRB improved G:F by 10% in ANT-free pigs but not in pigs fed ANT (ANT × SRB, P < 0.03). Ileal histology revealed an increase in crypt depth of pigs fed the diet containing ANT plus SRB and corresponding decreases in villi:crypt associated with both ANT and SRB supplementation (P < 0.05). Intraepithelial lymphocytes were increased by 15% in pigs fed SRB without ANT, but were unaffected by SRB in pigs fed ANT (ANT x SRB, P = 0.003). Colonic bifidobacteria tended to increase with SRB supplementation (P < 0.10). Differences in ileal and cecal digesta short-chain fatty acid concentrations were not detected. In summary, SRB improved the efficiency of nutrient utilization in nursery diets lacking antibiotics and tended to increase intestinal bifidobacteria concentrations, indicating that SRB may exert beneficial prebiotic effects in weanling pigs.