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

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

Development and study on physical and sensory properties of dark chocolates fortified with anthocyanin from broken riceberry rice

วารสารวิชาการและวิจัย มทร.พระนคร, ปีที่ 14, ฉบับที่ 2 (ก.ค.-ธ.ค. 2563), หน้า 45-56Broken rice of Thai cross breed black rice, Riceberry, was an under-utilized agricultural by-product that contains high content of anthocyanins, the multiple health benefits flavonoid. In this study, these anthocyanins were used to develop healthy dark hocolates. The anthocyanin extract from the broken Riceberry rice was prepared into anthocyanin powder using freeze-drying technique in which maltodextrin was used as a carrier material. Healthy dark chocolates were prepared by replacing cocoa powder with anthocyanin powder by 5, 10 and 15 g/g cocoa powder, which respectively delivers DC5, DC10, and DC15 anthocyanin-fortified dark chocolate bars. The color analysis showed no blooming (undesired white color at the chocolate surface) in all chocolates. The increase the anthocyanin powder content significantly decreased the hardness of the dark chocolates (33.9-27.2 N). Total anthocyanin content (TAC) in the dark chocolates increased respectively as anthocyanin powder content increased. The health benefit of the anthocyanin-fortified dark chocolates was improved as the DPPH antioxidant activity of all treatments was 4-9% higher than that of the control DC0. Sensory evaluation revealed that DC10 received higher liking scores (6.4-7.5) than the DC0 indicating more consumer preference. The anthocyanin-fortified dark chocolate delivers an alternative strategy to improve the health property of chocolates. This application of anthocyanin from the broken Riceberry rice could help increase the value and the utilization of Thai agricultural by-product.Rajamangala University of Technology Phra Nakho