Studies on the Antioxidative Constituents of Hops (Humulus lupulus)

• Main Authors: Chien-Nan Chen, 陳建男
• Other Authors: Kow-Jen Duan
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/e6vec7

碩士 === 大同大學 === 生物工程學系(所) === 95 === Recently, there was increasing interest in finding natural antioxidants from plants, which protect human body against free radical insult and ameliorate the progress of many chronic diseases. This study aimed at evaluating the in vitro antioxidative activity of Hops (Humulus lupulus) phytochemicals. The phytochemicals of Hops were extracted with 75% alcohol, separated by semi-preparative HPLC system with isocratic solvent methanol-water-phosphoric acid (900:190:3, v/v/v), and identified by HPLC photodiode array (HPLC-PDA). Seven constituents were isolated from alcoholic extraction of Hops that including: Mix Fraction 1, Mix Fraction 2, Xanthohumol (XN), n-humulone+adhumulone (H), cohumulone (coH), n-lupulone+adlupulone (L), and colupulone (coL). The antioxidative activities, including α,α-diphenyl-β-picrylhydrazyl (DPPH) radical-scavenging ability, Fe2+-chelating ability, reducing power, and ultraweak chemiluminescence assay for assessing the superoxide (O2-．)-scavenging activity. The results showed that H had the greatest DPPH radical scavenging effect (IC50 = 0.36 mg/mL), but at the concentration of 2.0 mg/ml that Mix Fraction 1 could scavenge 91% DPPH radical similar to BHA and Resveratrol. In Fe2+-chelating ability that β-acids of Hops L and coL had the best activities with IC50 values of 0.19 and 0.22 mg/ml, and L could reach more than 98% of Fe2+-chelating power at the concentration of 0.625 mg/ml. However, the results showed that seven constituents of Hops have poor reducing power than BHA. In the present study, Ultra-weak chemiluminescence analytical technology was used to detect the generation of oxygen free radicals. And we used the lucigen-base ultra-weak chemiluminescence (LBCL) method to estimate the superoxide (O2-．)-scavenging activity. coL had a strong superoxide (O2-．)-scavenging activity (IC50 = 4.63 μg) about 30- and 96-fold more potent than BHA and Resveratrol. Further research works were needed to investigate the inhibitory effect of Hops phytochemicals against oxidative damage in in vivo systems.