title: Seasonal difference in antioxidant capacity and active compounds contents of Eucommia ulmoides oliver leaf.
abstract: Leaf of Eucommia ulmoides Oliver (EU) is a Traditional Chinese Medicine and a functional food in China. Antioxidant contents of EU leaves, which were collected monthly during the period of May-October in three years, were determined. Samples' antioxidant capacity was characterized by DPPH radical scavenging activity, hydroxyl radical scavenging activity, ferrous chelating ability, and antioxidant capacity in linoleic acid emulsion and in rapeseed oil assays. The results showed that contents of some active compounds and antioxidant activity were related to a certain time of the year. Samples collected in August showed high content of phenolics, and the samples collected in May contained higher amount of flavonoids than other samples. Leaves collected in May or June exhibited high contents of rutin, quercetin, geniposidic acid and aucubin. The August leaves showed stable and high DPPH radical scavenging activity, and ferrous chelating ability. May samples showed strong inhibitory effects on oxidation of rapeseed oil and linoleic acid. The DPPH radical scavenging activity was related to the total phenolics content. Flavonoids played an important role in the inhibitory effects on rapeseed oil and linoleic acid oxidation. Therefore, August and May were indicated as the best months to harvest EU leaves for industry.
authors: College of Forestry, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, China.
authors: Qiang
authors: Q
authors: Zhang
authors: Yinquan
authors: Y
authors: Su
authors: Jingfang
authors: J
authors: Zhang
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D031283:Eucommiaceae / Q000737:chemistry*; D005419:Flavonoids / Q000032:analysis; D010636:Phenols / Q000032:analysis; D018515:Plant Leaves / Q000737:chemistry*; D012621:Seasons
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D010636:Phenols
references: Mutat Res. 1996 Dec 20;371(3-4):203-14
references: 9008721
references: Acta Pharmacol Sin. 2001 Dec;22(12):1057-70
references: 11749801
references: Free Radic Res. 1997 Nov;27(5):511-32
references: 9518068
references: J Nutr Biochem. 2002 Oct;13(10):572-584
references: 12550068
references: J Agric Food Chem. 2000 Aug;48(8):3431-6
references: 10956129
references: J Agric Food Chem. 2003 Sep 24;51(20):5906-10
references: 13129293
references: J Nat Prod. 2007 Aug;70(8):1312-6
references: 17691745
references: J Chromatogr A. 2003 Jun 6;1000(1-2):657-91
references: 12877194
references: Curr Med Chem. 2001 Jun;8(7):797-807
references: 11375750
references: Food Chem Toxicol. 1994 Jul;32(7):671-83
references: 8045480
references: Mutat Res. 1997 Jan 15;388(1):7-20
references: 9025787
references: Life Sci. 2000 Mar 3;66(15):1387-400
references: 11210714
references: Br Med Bull. 1993 Jul;49(3):481-93
references: 8221017
references: Zhongguo Zhong Yao Za Zhi. 2000 May;25(5):284-6
references: 12512449
references: J Agric Food Chem. 2001 Aug;49(8):4083-9
references: 11513714