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Fulltext Antioxidant capacity and nitrosation inhibition of cruciferous vegetable extracts

Konsue, N., Amron, N.A.

International Food Research Journal, 2018;25(1):65-73.
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Cruciferous vegetables belong to the mustard family of plants such as Brussels sprouts, kale, broccoli, cabbage and cauliflower. They are well known for their cancer prevention properties which are due to high content of bioactive compounds, isothiocyanates (ITCs). This study was aimed to investigate nitrosation inhibition ability of the cruciferous vegetables commonly consumed with meat products namely, broccoli, cauliflower and cabbage. Aqueous extracts of fresh and steamed (2 and 4 min) vegetables were subjected to determination of antioxidant capacity (DPPH and FRAP assay) and chemical composition i.e. total phenolic and isothiocyanate (ITC) content. It was found that TPC, DPPH and FRAP values of raw vegetables were different in each vegetable and ranged from 17.12-38.91 mg GAE/100 ml, 44.09-63.31% and 1.36-6.81 mg TE/100 ml, respectively. Among three types of cruciferous vegetable, broccoli had the highest PEITC content being 0.21 mmol/100 g compared to cauliflower (0.15 mmol/100 g) and cabbage (0.06 mmol/100 g). Moreover, it was found that steaming process significantly enhanced antioxidant activity, TPC as well as PEITC content in a timedependent manner up to 4 min (p
Inhibitory effect of phenethyl isothiocyanate against benzo[a] pyrene-induced rise in CYP1A1 mRNA and apoprotein levels as its chemopreventive properties

Abdull Razis AF, Konsue N, Ioannides C

Asian Pac J Cancer Prev, 2015;16(7):2679-83.
PMID: 25854346

BACKGROUND: Phenethyl isothiocyanate (PEITC), the most comprehensively studied aromatic isothiocyanate, has been shown to act as an anti-cancer agent mainly through modulation of biotransformation enzymes responsible for metabolizing carcinogens in the human body. Humans are often exposed to carcinogenic factors, some of which through the diet, such as polycyclic aromatic hydrocarbon benzo[a]pyrene via the consumption of over-cooked meats. Inhibition of the enzymes responsible for the bioactivation of this carcinogen, for example CYP1A1, the major enzyme required for polycyclic aromatic hydrocarbons (PAHs) bioactivation, is recognized as a chemoprevention strategy.
OBJECTIVE: To evaluate the inhibitory effects of PEITC against benzo[a]pyrene-induced rise in rat liver CYP1A1 mRNA and apoprotein levels.
MATERIALS AND METHODS: Precision cut rat liver slices were treated with benzo[a]pyrene at 1 and 5 μM in the presence of PEITC (1-25 μM) for 24 hours, followed by determination of CYP1A1 mRNA and apoprotein levels using quantitative polymerase chain reaction and immunoblotting.
RESULTS: Findings revealed that PEITC inhibited benzo[a]pyrene-induced rise in rat liver CYP1A1 mRNA in a dose-dependent manner as well as the apoprotein levels of CYP1A.
CONCLUSIONS: It was demonstrated that PEITC can directly inhibit the bioactivation of benzo[a]pyrene, indicating chemopreventive potential.
Isothiocyanates and Xenobiotic Detoxification

Abdull Razis AF, Konsue N, Ioannides C

Mol Nutr Food Res, 2018 09;62(18):e1700916.
PMID: 29288567 DOI: 10.1002/mnfr.201700916

The potential of isothiocyanates to antagonize the carcinogenicity of structurally diverse chemicals has been established in animals. A feasible mechanism of action involves protecting DNA by reducing the availability of the genotoxic metabolites of chemical carcinogens by either inhibiting their generation and/or stimulating their detoxification. In vivo as well as in vitro studies conducted in rat/human primary hepatocytes and precision-cut tissue slices have revealed that isothiocyanates can impair cytochrome P450 activity, including the CYP1 family which is the most active in the bioactivation of carcinogens, by virtue of being mechanism-based inactivators. The aromatic phenethyl isothiocyanate is the most effective of those studied, whereas aliphatic isothiocyanates such as sulforaphane and erucin necessitate high doses in order to manifest such effects that may not always be achievable through the diet. In all systems studied, isothiocyanates are strong inducers of detoxification enzyme systems including quinone reductase, glutathione S-transferase, epoxide hydrolase, and UDP-glucuronosyl transferase. Indeed, in smokers phenethyl isothiocyanate intake increases the urinary excretion of inactive mercapturate metabolites of toxic chemicals present in tobacco. Glucosinolates, the precursors of isothiocyanates, have also the potential to upregulate detoxification enzyme systems, but their contribution to the cancer chemoprevention linked to cruciferous vegetable consumption remains to be evaluated.
Fulltext Induction of epoxide hydrolase, glucuronosyl transferase, and sulfotransferase by phenethyl isothiocyanate in male Wistar albino rats

Abdull Razis AF, Mohd Noor N, Konsue N

Biomed Res Int, 2014;2014:391528.
PMID: 24592387 DOI: 10.1155/2014/391528

Phenethyl isothiocyanate (PEITC) is an isothiocyanate found in watercress as the glucosinolate (gluconasturtiin). The isothiocyanate is converted from the glucosinolate by intestinal microflora or when contacted with myrosinase during the chopping and mastication of the vegetable. PEITC manifested protection against chemically-induced cancers in various tissues. A potential mechanism of chemoprevention is by modulating the metabolism of carcinogens so as to promote deactivation. The principal objective of this study was to investigate in rats the effect of PEITC on carcinogen-metabolising enzyme systems such as sulfotransferase (SULT), N-acetyltransferase (NAT), glucuronosyl transferase (UDP), and epoxide hydrolase (EH) following exposure to low doses that simulate human dietary intake. Rats were fed for 2 weeks diets supplemented with PEITC at 0.06 µmol/g (low dose, i.e., dietary intake), 0.6 µmol/g (medium dose), and 6.0 µmol/g (high dose), and the enzymes were monitored in rat liver. At the Low dose, no induction of the SULT, NAT, and EH was noted, whereas UDP level was elevated. At the Medium dose, only SULT level was increased, whereas at the High dose marked increase in EH level was observed. It is concluded that PEITC modulates carcinogen-metabolising enzyme systems at doses reflecting human intake thus elucidating the mechanism of its chemoprevention.
Fulltext Effects of gamma irradiation on tropomyosin allergen, proximate composition and mineral elements in giant freshwater prawn (Macrobrachium rosenbergii)

Muanghorn W, Konsue N, Sham H, Othman Z, Mohamed F, Mohd Noor N, et al.

J Food Sci Technol, 2018 May;55(5):1960-1965.
PMID: 29666550 DOI: 10.1007/s13197-018-3104-3

Effects of food irradiation on allergen and nutritional composition of giant freshwater prawn are not well documented. Thus, this study aimed to investigate the effects of gamma irradiation on tropomyosin allergen, proximate composition, and mineral elements in Macrobrachium rosenbergii. In this study, prawn was peeled, cut into small pieces, vacuum packaged and gamma irradiated at 0, 5, 7, 10 and 15 kGy with a dose rate of 0.5 kGy/h using cobalt-60 as the source, subsequently determined the level of tropomyosin, proximate composition and mineral elements respectively. The results showed that band density of tropomyosin irradiated at 10 and 15 kGy is markedly decreased. Proximate analysis revealed that moisture, protein, and carbohydrate content were significantly different as compared with non-irradiated prawn. Meanwhile, gamma irradiated M. rosenbergii at 15 kGy was observed to be significantly higher in nickel and zinc than the non-irradiated prawn. The findings provide a new information that food irradiation may affect the tropomyosin allergen, proximate composition and mineral elements of the prawn.