Purple rice bran extract attenuates the aflatoxin B1-induced initiation stage of hepatocarcinogenesis by alteration of xenobiotic metabolizing enzymes

Chemical and Bioactive Properties of Red Rice with Potential Pharmaceutical Use

Red rice has been proposed as a super-food. Accordingly, the nutritional properties (AOAC), as well as its chemical composition, including sugars (HPLC-RI), organic acids (UFLC-PDA), tocopherols (HPLD-FD), and phenolic compounds (LC-DAD-ESI/MSn), together with the main bioactive properties (antioxidant, cytotoxic, antiproliferative, and antibacterial activities), were evaluated to access its nutritional benefits and health improvement potential. The most abundant macronutrients found were carbohydrates (87.2 g/100 g dw), proceeded by proteins (9.1 g/100 g dw), fat (2.6 g/100 g dw), and ash (1.1 g/100 g dw). Sucrose and raffinose were the only detected sugars, with sucrose presenting the maximum concentration (0.74 g/100 g dw). MUFAs and PUFAs were the predominant fatty acids (40.7% and 31%, respectively). Among the two detected tocopherol isoforms, γ-tocopherol (0.67 mg/100 g dw) predominated over α-tocopherol. The phenolic compounds profile, majorly composed of flavan-3-ols, should be associated with the detected bioactivities, which may provide biological benefits to human health beyond the primary nutritional effect. Overall, the bioactive potential of red rice was comprehensively accessed.

Berberine-loaded albumin nanoparticles reverse aflatoxin B1-induced liver hyperplasia

Hepatocellular carcinoma (HCC) can be produced from aflatoxin B1 (AFB1) administration. Although berberine (BER) acts as an anticancer agent and can counteract the AFB1 effect, it has low bioavailability. Nanotechnology can overcome this problem. This research aimed to synthesize berberine nanoparticles (NPs) and then estimate their therapeutic effect compared to that of berberine against aflatoxin-induced hepatotoxicity. The desolvation method was used to prepare BER-NPs. Aflatoxicosis was induced by 5 consecutive intraperitoneal injections (IP) of 200 µg/kg/day AFB dissolved in dimethylsulfoxide (DMSO). After the induction period, two treatments were performed: the first with 100 mg/kg BER and the second with 10 mg/kg BER-NPs. Liver, kidney, and diabetic profiles were estimated by using standardized methods. Hepatic oxidative stress, inflammatory, cancer cell proliferation, and invasion markers were used by ELISA and qPCR techniques. The TEM image shows that both BSA NPs and BER-BSA NPs had spherical, regular, and uniform shapes. The BER encapsulation efficiency % was 78.5. The formed-BER-BSA NPs showed a loading capacity % of 7.71 and the synthesis yield % of 92.6. AFB1 increases pro-oxidant markers, decreases antioxidant systems, stimulates inflammatory enzymes, inhibits anti-inflammatory markers, decreases tumor suppressor enzymes, increases oncogenes, increases glycolytic activity, prevents cell death, and promotes cell growth. Most of the biochemical markers and hepatic architecture were normalized in the BER-BSA NP-treated group but not in the BER-treated group. Altogether, the obtained data proved that treatment with BER-NPs was more efficient than treatment with berberine against aflatoxicoses induced in rats.

Antagonism of Cyanamide-3-O-glucoside and protocatechuic acid on Aflatoxin B1-induced toxicity in zebrafish larva (Danio rerio)

The zebrafish model was used to evaluate the antioxidant properties of cyanidin-3-O-glucoside (C₃G) and its metabolite protocatechuic acid (PCA) against aflatoxin B₁ (AFB₁)-induced hepatotoxicity and oxidative stress. In this study, zebrafish larvae were cultured for 3 days post fertilization (dpf) and then induced with AFB₁. After induced 4 h, 8 h, 12 h, and 24 h, 5 μg/mL C₃G/PCA was added and then co-cultured to 5 dpf, respectively. The experiments showed that C₃G/PCA suppressed AFB₁-induced zebrafish liver atrophy and delayed the absorption of the yolk sac. In addition, reactive oxygen species (ROS) and cell death were also significantly decreased by 5 μg/mL C₃G/PCA (P ˂ 0.05). C₃G/PCA significantly reduced hepatic biomarkers in the serum contents (P ˂ 0.05). Besides, glutathione (GSH) contents were significantly upregulated, and the activities of superoxide dismutase (SOD) and catalase (CAT) were significantly elevated in zebrafish (P ˂ 0.05). The addition of 5 μg/mL C₃G/PCA was capable of reducing the apoptotic levels of caspase-9 and caspase-3 after 100 ng/mL AFB₁ intoxication. In conclusion, these results suggested that C₃G and its metabolite PCA might antagonize the hepatotoxicity of AFB₁, reduce oxidative damage and inhibit cell death.

Sesame Extract Promotes Chemopreventive Effect of Hesperidin on Early Phase of Diethylnitrosamine-Initiated Hepatocarcinogenesis in Rats

The combination of natural products is an alternative approach to achieving chemopreventive potential. Accordingly, citrus hesperidin exhibits numerous biological activities, including anticarcinogenic activities, while the sesamin in sesame exhibits potent anticancer activities and lipid-lowering effects. We investigated the cancer chemopreventive effects of mixed sesame and orange seed extract (MSO) containing hesperidin and sesamin in diethylnitrosamine (DEN)-induced hepatocarcinogenesis. Rats were injected with DEN once a week for 3 weeks to induce hepatocarcinogenesis. Rats were fed with MSO and various compositions that included sesame extract (SE) and hesperidin. The 10-week administration of MSO more effectively inhibited the number and size of hepatic GST-P-positive foci than hesperidin in DEN-initiated rats. MSO and hesperidin decreased the number of PCNA-positive hepatocytes but increased the apoptotic cells in DEN-induced rats. Furthermore, MSO and its constituents suppressed hepatic triglyceride content concurrently along with the expression of fatty acid synthase. Although the 5-week administration of MSO or hesperidin did not alter hepatic, preneoplastic lesion formation in DEN-initiated rats, it alleviated DEN-induced hepatotoxicity. MSO and its applied compositions did not impact upon the cytochrome P450 system. In conclusion, sesame extract promoted the chemopreventive effect of hesperidin on DEN-induced early stage of hepatocarcinogenesis in rats. The inhibitory mechanisms are likely involved with the induction of cell apoptosis, suppression of cell proliferation and modulation of hepatic lipogenesis. This study may provide revelations in the development of alternative treatments against hepatocellular carcinoma.

Antigenotoxic Effects and Possible Mechanism of Red Yeast (Sporidiobolus pararoseus) on Aflatoxin B1-Induced Mutagenesis

Red yeast (Sporidiobolus pararoseus), obtained from glycerol waste in the biodiesel process, has been used as a mycotoxin sorbent in some agricultural products. This study focused on the antigenotoxic effects of red yeast on aflatoxin B₁ (AFB₁)-induced mutagenesis, using a Salmonella mutation assay and a rat liver micronucleus test. Red yeast was sequentially extracted to obtain hexane, acetone, hot water, and residue fractions. Carbohydrates were mainly found in hot water extract (HWE), while proteins were observed in the residue fraction. The amount of lycopene in hexane extract (HE) was higher than the amount of β-carotene in HE. All red yeast extracts were not mutagenic in the Salmonella typhimurium strains TA98 and TA100 under the presence and absence of metabolic activation. Among the extracts obtained from red yeast, HE presented the strongest antimutagenicity against AFB₁-induced mutagenesis in both strains, but HWE did not show any antimutagenicity. The oral administration of red yeast, HE, and HWE for 28 days was further investigated in rats. These extracts did not induce micronucleated hepatocytes. Furthermore, they modulated the activities of some detoxifying enzymes but did not alter the activities of various cytochrome P450 isozymes. Notably, they significantly decreased hepatic micronucleus formation in AFB₁-initiated rats. HE altered the activity of hepatic glutathione-S-transferase but did not affect its protein expression. Taken together, the antigenotoxicity of red yeast against AFB₁-induced mutagenesis might be partly due to the modulation of some detoxifying enzymes in AFB₁ metabolism. β-Carotene and lycopene might be promising antigenotoxic compounds in red yeast.

Low-polar extract from seed of Cleistocalyx nervosum var. paniala modulates initiation and promotion stages of chemically-induced carcinogenesis in rats

BACKGROUND

Cleistocalyx nervosum var. paniala is a local fruit mainly cultivated in the north of Thailand. Our previous study has reported that the methanol extract of C. nervosum seed presented antimutagenicity in a Salmonella mutation assay. The present study focused on the effect of a low-polar extract of C. nervosum seed on the early stages of diethylnitrosamine (DEN)- and dimethylhydrazine (DMH)-induced carcinogenesis in rats.

METHODS

Dried C. nervosum seed powder was extracted using dichloromethane. To study its effect on the initiation stage of carcinogenesis of rats, they were fed with various doses of C. nervosum seed extract (CSE) for 21 days. DEN injection was used to initiate hepatocarcinogenesis and partial hepatectomy was performed to amplify mutated hepatocytes resulting in micronucleated hepatocyte formation. To study the role of CSE on the promotion stage, rats were injected with DEN and DMH to induce preneoplastic lesions and the numbers of glutathione S-transferase placental form (GST-P) positive foci in the liver and aberrant crypt foci (ACF) in the colon were measured. This was followed by CSE administration for 10 weeks. The inhibitory mechanisms of CSE on initiation and promotion stages, including xenobiotic metabolism, cell proliferation and apoptosis, were investigated.

RESULTS

The total phenolic content in CSE was 80.34 ± 2.29 mg gallic acid equivalents (GAE) per g of extract and 2,4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone was found to be a major flavonoid. The main terpenoids in CSE were β-selinene, α-selinene, γ-selinene and o-cymene while 24(Z)-methyl-25-homocholesterol was a major phytosterol. CSE significantly decreased the number of micronucleated hepatocytes in DEN-initiated rats and enhanced the activities of hepatic glutathione S-transferase and UDP-glucuronyltransferase. Furthermore, the formation of preneoplastic lesions in the liver and colon was statistically reduced by CSE. CSE also diminished cell proliferation in the liver and colon indicated by the number of PCNA positive cells. However, CSE did not alter the numbers of apoptotic hepatocytes and colonocytes in DEN- and DMH-initiated rats.

CONCLUSIONS

The dichloromethane extract of C. nervosum seed demonstrated chemopreventive effects on chemically-induced carcinogenesis in both initiation and promotion stages in rats. The inhibitory mechanism might be involved in the modulation of hepatic detoxifying enzymes and suppression of hepatocyte and colonocyte proliferation.

Chemopreventive Effect of Dietary Anthocyanins against Gastrointestinal Cancers: A Review of Recent Advances and Perspectives

Anthocyanins are a group of dietary polyphenols, abundant mainly in fruits and their products. Dietary interventions of anthocyanins are being studied extensively related to the prevention of gastrointestinal (GI) cancer, among many other chronic disorders. This review summarizes the hereditary and non-hereditary characteristics of GI cancers, chemistry, and bioavailability of anthocyanins, and the most recent findings of anthocyanin in GI cancer prevention through modulating cellular signaling pathways. GI cancer-preventive attributes of anthocyanins are primarily due to their antioxidative, anti-inflammatory, and anti-proliferative properties, and their ability to regulate gene expression and metabolic pathways, as well as induce the apoptosis of cancer cells.

The Genetic Basis and Nutritional Benefits of Pigmented Rice Grain

Improving the nutritional quality of rice grains through modulation of bioactive compounds and micronutrients represents an efficient means of addressing nutritional security in societies which depend heavily on rice as a staple food. White rice makes a major contribution to the calorific intake of Asian and African populations, but its nutritional quality is poor compared to that of pigmented (black, purple, red orange, or brown) variants. The compounds responsible for these color variations are the flavonoids anthocyanin and proanthocyanidin, which are known to have nutritional value. The rapid progress made in the technologies underlying genome sequencing, the analysis of gene expression and the acquisition of global 'omics data, genetics of grain pigmentation has created novel opportunities for applying molecular breeding to improve the nutritional value and productivity of pigmented rice. This review provides an update on the nutritional value and health benefits of pigmented rice grain, taking advantage of both indigenous and modern knowledge, while also describing the current approaches taken to deciphering the genetic basis of pigmentation.

Genetic toxicity assessment using liver cell models: past, present, and future

Genotoxic compounds may be detoxified to non-genotoxic metabolites while many pro-carcinogens require metabolic activation to exert their genotoxicity in vivo. Standard genotoxicity assays were developed and utilized for risk assessment for over 40 years. Most of these assays are conducted in metabolically incompetent rodent or human cell lines. Deficient in normal metabolism and relying on exogenous metabolic activation systems, the current in vitro genotoxicity assays often have yielded high false positive rates, which trigger unnecessary and costly in vivo studies. Metabolically active cells such as hepatocytes have been recognized as a promising cell model in predicting genotoxicity of carcinogens in vivo. In recent years, significant advances in tissue culture and biological technologies provided new opportunities for using hepatocytes in genetic toxicology. This review encompasses published studies (both in vitro and in vivo) using hepatocytes for genotoxicity assessment. Findings from both standard and newly developed genotoxicity assays are summarized. Various liver cell models used for genotoxicity assessment are described, including the potential application of advanced liver cell models such as 3D spheroids, organoids, and engineered hepatocytes. An integrated strategy, that includes the use of human-based cells with enhanced biological relevance and throughput, and applying the quantitative analysis of data, may provide an approach for future genotoxicity risk assessment.

Inhibitory effect of purple rice husk extract on AFB1-induced micronucleus formation in rat liver through modulation of xenobiotic metabolizing enzymes

Background

Rice husk, a waste material produced during milling, contains numerous phytochemicals that may be sources of cancer chemopreventive agents. Various biological activities of white and colored rice husk have been reported. However, there are few comparative studies of the cancer chemopreventive effects of white and colored rice husk.

Methods

This study investigated the cancer chemopreventive activities of two different colors of rice husk using in vitro and in vivo models. A bacterial mutation assay using Salmonella typhimurium strains TA98 and TA100 was performed; enzyme induction activity in murine hepatoma cells was measured, and a liver micronucleus test was performed in male Wistar rats.

Results

The white rice husk (WRHE) and purple rice husk (PRHE) extracts were not mutagenic in Salmonella typhimurium TA98 or TA100 in the presence or absence of metabolic activation. However, the extracts exhibited antimutagenicity against aflatoxin B₁ (AFB₁) and 2-amino-3,4 dimethylimidazo[4,5-f]quinolone (MeIQ) in a Salmonella mutation assay. The extracts also induced anticarcinogenic enzyme activity in a murine Hepa1c1c7 hepatoma cell line. Interestingly, PRHE but not WRHE exhibited antigenotoxicity in the rat liver micronucleus test. PRHE significantly decreased the number of micronucleated hepatocytes in AFB₁-initiated rats. PRHE contained higher amounts of phenolic compounds and vitamin E than WRHE in both tocopherols and tocotrienols as well as polyphenol such as cyanidin-3-glucoside, protocatechuic acid and vanillic acid. Furthermore, PRHE increased CYP1A1 and 1A2 activities while decreasing CYP3A2 activity in the livers of AFB₁-treated rats. PRHE also enhanced various detoxifying enzyme activities, including glutathione S-transferase, NAD(P)H quinone oxidoreductase and heme oxygenase.

Conclusions

PRHE showed potent cancer chemopreventive activity in a rat liver micronucleus assay through modulation of phase I and II xenobiotic metabolizing enzymes involved in AFB₁ metabolism. Vitamin E and phenolic compounds may be candidate antimutagens in purple rice husk.

Electronic supplementary material

The online version of this article (10.1186/s12906-019-2647-9) contains supplementary material, which is available to authorized users.

Protective Effects of Defatted Sticky Rice Bran Extracts on the Early Stages of Hepatocarcinogenesis in Rats

Use of natural products is one strategy to lessen cancer incidence. Rice bran, especially from colored rice, contains high antioxidant activity. Cancer chemopreventive effects of hydrophilic purple rice bran extract (PRBE) and white rice bran extract (WRBE) on carcinogen-induced preneoplastic lesion formation in livers of rats were investigated. A 15-week administration of PRBE and WRBE did not induce hepatic glutathione S-transferase placental form (GST-P) positive foci formation as the biomarker of rat hepatocarcinogenesis. PRBE and WRBE at 500 mg/kg body weight significantly decreased number and size of GST-P positive foci in diethylnitrosamine (DEN)-initiated rats. The number of proliferating nuclear antigen positive hepatocytes were also reduced in preneoplastic lesions in both PRBE and WRBE fed DEN-treated rats. Notably, the inhibitory effect on GST-P positive foci formation induced by DEN during the initiation stage was found only in rats treated by PRBE for five weeks. Furthermore, PRBE attenuated the expression of proinflammatory cytokines involving genes including TNF-α, iNOS, and NF-κB. PBRE contained a higher number of anthocyanins and other phenolic compounds and vitamin E. PRBE might protect DEN-induced hepatocarcinogenesis in rats via attenuation of cellular inflammation and cell proliferation. Anthocyanins and other phenolic compounds, as well as vitamin E, might play a role in cancer chemopreventive activity in rice bran extract.

Antimutagenic and Antioxidant Activities of Thai Rice Brans

Background

Rice bran is the outer layer of the rice grain, and contains high amounts of bioactive phytochemicals. Here, we investigated and compared chemopreventive properties of purple and white rice bran extracts.

Methods

Rice bran was extracted with dichloromethane and methanol. Chemical constituents in the extracts were analyzed by colorimetric assay and high performance liquid chromatography. The mutagenicity and antimutagenicity of the extracts were determined via the Salmonella mutation assay. The anticarcinogenic enzyme induction and antioxidant activities of the extracts were examined using Hepa1c1c7 cells and 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay, respectively.

Results

The methanol extracts of rice bran contained high amounts of phenolic acids, flavonoids, anthocyanins, and phytic acid, whereas large amounts of γ-oryzanol and vitamin E were presented in the dichloromethane extract. None of the extracts were mutagenic to Salmonella typhimurium. All rice bran extracts had strong antimutagenic effects against aflatoxin B₁- and 2-amino-3,4-dimethylimidazo [4,5-f]quinoline-induced mutagenesis. The inhibitory effect against 2-aminofluorene-induced mutagenesis was found in the dichloromethane extract, while only the methanol extract of purple rice bran exhibited antimutagenic effects against benzo(a)pyrene. None of the extracts induced quinone reductase activity in Hepa1c1c7 cells. Additionally, the greatest antioxidant capacity was found in the methanol extract of purple rice bran.

Conclusions

The methanol extract of purple rice bran containing high amount of phenolic acids, flavonoids, anthocyanins, and phytic acid showed the most effective antioxidant and antimutagenic activities by inhibiting mutagenic metabolizing enzymes and/or scavenging free radicals. These results demonstrate the nutritional and medical value of Thai rice for cancer prevention.

Effect of Spirogyra neglecta on the early stages of 1, 2-dimethylhydrazine-induced colon carcinogenesis in rats

This study focused on the chemopreventive effects of Spirogyra neglecta extract (SNE) and dried S. neglecta mixed diet on the early stages of 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis in rats. Male Wistar rats were injected with DMH to initiate aberrant crypt foci (ACF) formation. In the initiation stage, SNE significantly decreased the number of ACF in the colon of DMH-treated rats. Rats that received a low dose of SNE showed enhanced activity of several detoxifying and antioxidant enzymes. In the postinitiation stage, a low dose of SNE significantly decreased the number of ACF in the colon of DMH-treated rats. It significantly reduced the number of proliferating cell nuclear antigen-positive cells and increased the number of apoptotic cells in colonic crypts. S. neglecta thus inhibited the development of the early stages of DMH-induced colon carcinogenesis in rats by modulation of xenobiotic metabolizing enzymes and inhibition of cell proliferation as well as induction of apoptosis.

Chemopreventive effect of natural dietary compounds on xenobiotic-induced toxicity

Contaminants (or pollutants) that affect human health have become an important issue, spawning a myriad of studies on how to prevent harmful contaminant-induced effects. Recently, a variety of biological functions of natural dietary compounds derived from consumed foods and plants have been demonstrated in a number of studies. Natural dietary compounds exhibited several beneficial effects for the prevention of disease and the inhibition of chemically-induced carcinogenesis. Contaminant-induced toxicity and carcinogenesis are mostly attributed to the mutagenic activity of reactive metabolites and the disruption of normal biological functions. Therefore, the metabolic regulation of hazardous chemicals is key to reducing contaminant-induced adverse health effects. Moreover, promoting contaminant excretion from the body through Phase I and II metabolizing enzymes is also a useful strategy for reducing contaminant-induced toxicity. This review focuses on summarizing the natural dietary compounds derived from common dietary foods and plants and their possible mechanisms of action in the prevention/suppression of contaminant-induced toxicity.