Odnos između fitokemijskog sastava, udjela mineralnih tvari i antioksidacijske aktivnosti mekinja crne slatke riže, te njihova moguća primjena u kemoprevenciji

In this work total anthocyanin content (TAC), total flavonoid content (TFC), total phenolic content (TPC) and minerals found in five black glutinous rice cultivars (MS, SK, PY, PC and KK) from Thailand were analyzed. The antioxidant activity of anthocyanin-rich black glutinous rice bran extracts against nitric oxide radical (NO˙), superoxide radical (O2˙¯) and lipid peroxyl radical (LOO˙) was also determined. Potential chemopreventive property of rice bran extract was screened based on cellular bioassays for phase II detoxification enzyme induction. Quinone reductase (QR) induction in murine hepatoma cells was used as a marker for this effect. Rice bran extract of cultivar KK had the highest TAC, of SK the highest TFC and of PC the highest TPC. The best antioxidants against NO˙, O2˙¯ and LOO˙ were cultivars KK, MS, and SK, respectively. Overall, TAC, TFC and TPC had a combinatorial effect on the antioxidant activities of all extracts; none of them dominated. Minerals may not play a role in the antioxidant activity of the extracts because most correlations between them and the antioxidant activity were unpredictable. However, rice bran contained high mass fractions of some essential minerals on dry mass basis, including Zn (103–133 μg/g), Se (11–18 μg/g) and Cu (3.8–7.1 μg/g). Chemopreventive study indicated that PC cultivar was the most potent chemopreventor with the lowest concentration of an inducer needed to double the QR activity (CD value) of 0.7 μg/mL. These findings showed that black glutinous rice bran is rich in phytochemicals and some essential minerals, and has a potential chemopreventive property.U ovom su radu određeni udjeli ukupnih antocijana, flavonoida, fenolnih spojeva i mineralnih tvari u pet kultivara (MS, SK, PY, PC i KK) crne slatke (ljepljive) riže, porijeklom iz Tajlanda. Ispitana je antioksidacijska aktivnost ekstrakata rižinih mekinja bogatih antocijanima, i to: sposobnost uklanjanja dušikovog(II) oksida (NO˙), superoksidnog aniona (O2˙ˉ) i lipidnih peroksida (LOO˙). Također je ispitan mogući kemoprevencijski učinak ekstrakata, uzrokovan indukcijom enzima koji sudjeluju u drugoj fazi detoksikacije stanica. Taj je učinak praćen mjerenjem povećanja aktivnosti kinon reduktaze u stanicama hepatoma murine. Ekstrakt kultivara KK imao je najveći udjel ukupnih antocijana, ekstrakt kultivara SK najveći udjel ukupnih flavonoida, a kultivara PC najveći udjel fenolnih spojeva. Kultivar KK imao je najveću sposobnost uklanjanja NO˙ radikala, kultivar MS najveću sposobnost uklanjanja O2˙ˉ radikala, a kultivar SK najveću sposobnost uklanjanja LOO˙ radikala. Antioksidacijska aktivnost ekstrakata ovisila je o zbirnom utjecaju ukupnih antocijana, flavonoida i fenolnih spojeva; niti jedna od tih skupina spojeva nije imala prevladavajući učinak. Odnos između udjela mineralnih tvari i antioksidacijske aktivnosti uglavnom nije pratio određeni trend, pa je zaključeno da mineralne tvari ne utječu na antioksidacijsku aktivnost ekstrakata. Rižine mekinje sadržavale su velike udjele nekih esencijalnih mineralnih tvari: 103-133 μg cinka, 11-18 μg selena i 3,8-7,1 μg bakra u gramu suhe tvari. Kultivar PC imao je najjači kemoprevencijski učinak, s najnižom vrijednosti CD (koncentracijom potrebnom da se udvostruči aktivnost kinon reduktaze) od 0,7 μg/mL. Rezultati pokazuju da su mekinje crne slatke riže bogate fitokemijskim spojevima i nekim esencijalnim mineralnim tvarima, te da bi se mogle upotrijebiti za kemoprevenciju

Chemical profiles of three varieties of germinated rice based on LC-MS and their antioxidant activity

In this study,chemical profiles in different germinated rice extracts (GREs) using different solvent extraction ratio were investigated.Three varieties of germinated rice (GR), including germinated white rice(GWR), germinated black rice (GBR) and germinated red rice(GRR) were extracted using 70and 100% ethanol(v/v). Both extracts were characterized for their chemical profiles using liquid chromatography-electrospray ionization−quadrupole−time−of−flight mass spectrometry (LC−ESI−Q−TOF−MS). The content of γ−aminobutyric acid (GABA), total phenolic content (TPC), and antioxidant activities were also determined. The chemical profiles of GREs are composed of organic acids, amino acids, vitamins, flavonoids,and phenolic compounds. The GABA content of all rice varieties presented the same pattern in both ethanolic extracts. The TPC of GRE extracted by 70% ethanol (v/v) showed significant higher amount than that in the 100%v/vethanolic extract(p<0.05). The highest TPC was obtained from GBR, followed by GRR and GWR, respectively(p<0.05). The antioxidant activity from three assays, including DPPH, ABTS, and FRAP showed higher activities in the 100% v/vethanolic extracts than their 70% v/v counterparts(p<0.05). The phenolic content showed a low positive Pearson correlation with antioxidant activities, however,the strong positive Pearson’s correlation coefficients were observed among these activities (r= 0.846-0.935). The results suggested that the GR was composed of potential bioactive compounds such as GABA and other phytochemical contents possessing high antioxidant bioactivity which can be used as functional food or as part of nutraceutical products

Correlation Between Phytochemical and Mineral Contents and Antioxidant Activity of Black Glutinous Rice Bran, and Its Potential Chemopreventive Property

In this work total anthocyanin content (TAC), total flavonoid content (TFC), total phenolic content (TPC) and minerals found in five black glutinous rice cultivars (MS, SK, PY, PC and KK) from Thailand were analyzed. The antioxidant activity of anthocyanin-rich black glutinous rice bran extracts against nitric oxide radical (NO˙), superoxide radical (O2˙¯) and lipid peroxyl radical (LOO˙) was also determined. Potential chemopreventive property of rice bran extract was screened based on cellular bioassays for phase II detoxification enzyme induction. Quinone reductase (QR) induction in murine hepatoma cells was used as a marker for this effect. Rice bran extract of cultivar KK had the highest TAC, of SK the highest TFC and of PC the highest TPC. The best antioxidants against NO˙, O2˙¯ and LOO˙ were cultivars KK, MS, and SK, respectively. Overall, TAC, TFC and TPC had a combinatorial effect on the antioxidant activities of all extracts; none of them dominated. Minerals may not play a role in the antioxidant activity of the extracts because most correlations between them and the antioxidant activity were unpredictable. However, rice bran contained high mass fractions of some essential minerals on dry mass basis, including Zn (103–133 μg/g), Se (11–18 μg/g) and Cu (3.8–7.1 μg/g). Chemopreventive study indicated that PC cultivar was the most potent chemopreventor with the lowest concentration of an inducer needed to double the QR activity (CD value) of 0.7 μg/mL. These findings showed that black glutinous rice bran is rich in phytochemicals and some essential minerals, and has a potential chemopreventive property

Metabolite profiles of red and white rice aqueous extracts derived at different temperatures and their relationship with biological propertiesas determined using 1H-NMR-based metabolomics analysis

Consumption of pigmented rice has continued to increase in recent years, due in part to its potential health promoting properties, especially protection against chronic diseases. Chemical extracts of red rice have demonstrated strong ability to scavenge free radicals, however little is yet known about water extracts of red rice. The antioxidant activity, α-glucosidase inhibition, nitric oxide inhibition, and metabolic profiling of this cultivar’s water extracts have yet to be investigated. In this study, red rice and white rice were extracted using ultrasound-assisted hydrothermal extraction at three different temperatures. The total phenolic content (TPC) as well as the DPPH radical scavenging, α-glucosidase inhibitory, and nitric oxide (NO) inhibitory activities of each extract were determined. NMR analysis was performed to find out the metabolite profiles of the extracts. Correlations between the metabolites and the biological activities of the rice extracts were then investigated using metabolomics analysis. Results show that the red rice aqueous extracts had a higher TPC than the white rice extracts. The highest extraction temperature led to a decrease in the TPC. However, the extraction temperature did not affect the radical scavenging, α-glucosidase inhibitory, or NO inhibitory activities of the red rice extracts. The PCA results indicated extract discrimination by extraction temperature. The PLS score plot exhibited the potentials of red rice aqueous extracts on the α-glucosidase and NO inhibitory activities. The 1H-NMR-based metabolomics analysis shows that red rice aqueous extract possesses beneficial properties which can make it useful as an ingredient for functional foods or other products

Metabolite profiling, antioxidant, and α-glucosidase inhibitory activities of germinated rice: nuclear-magnetic-resonance-based metabolomics study

In an attempt to profile the metabolites of three different varieties of germinated rice, specifically black (GBR), red, and white rice, a 1H-nuclear-magnetic-resonance-based metabolomics approach was conducted. Multivariate data analysis was applied to discriminate between the three different varieties using a partial least squares discriminant analysis (PLS-DA) model. The PLS model was used to evaluate the relationship between chemicals and biological activities of germinated rice. The PLS-DA score plot exhibited a noticeable separation between the three rice varieties into three clusters by PC1 and PC2. The PLS model indicated that α-linolenic acid, γ-oryzanol, α-tocopherol, γ-aminobutyric acid, 3-hydroxybutyric acid, fumaric acid, fatty acids, threonine, tryptophan, and vanillic acid were significantly correlated with the higher bioactivities demonstrated by GBR that was extracted in 100% ethanol. Subsequently, the proposed biosynthetic pathway analysis revealed that the increased quantities of secondary metabolites found in GBR may contribute to its nutritional value and health benefits

Bioactive compounds of pigmented rice extracts reveal by NMR-based metabolomics

The present study determined total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, ±-glucosidase, and nitric oxide (NO) inhibitory activities of black (BR), purple (PR), and red rice (RR) extracted with different polarity solvents and characterized the metabolites by using the 1H NMR-based metabolomics approach. The methanol extract of RR had the highest DPPH scavenging and ±-glucosidase inhibitory activities. The water extracts of PR and RR exhibited the highest NO inhibitory activity with IC50 values of 176.28 ± 18.78 and 160.69 ± 14.83 µg/mL, respectively. The metabolites that contribute to radical scavenging and ±-glucosidase inhibitory activities of RR methanol extract were chlorogenic acid, protocatechuic acid, and tyrosine, whereas nicotinic acid, ³-aminobutyric acid, and citric acid were the metabolites that contributed to the NO inhibitory activity of RR water extract. The RR extracts are potential sources of bioactive compounds with antioxidant and NO inhibitory properties