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Search Results: 1 - 10 of 127002 matches for " Xican Li "
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Antioxidant Activity and Mechanism of Protocatechuic Acid in vitro
Xican Li,Xiaozhen Wang,Xican Li,Shuzhi Chen
Functional Foods in Health and Disease , 2011,
Abstract: Background: Protocatechuic acid (PCA) is a natural phenolic acid widely distributed in plantsand is considered as an active component of some traditional Chinese herbal medicines such as Cibotium barometz (L.) J.Sm, Stenoloma chusanum (L.) Ching, Ilex chinensis Sims. PCA was reported to possess various pharmacological effects which may be closely correlated with its antioxidant activities. However, the antioxidant of PCA has not been investigatedsystematically yet. Methods: In the study, the antioxidant activities of protocatechuic acid were measured in vitrousing various antioxidant assays including 1,1-diphenyl-2-picryl-hydrazyl (DPPH ), 2,2’-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS+ ), superoxide anion radicals ( O2-) and hydroxyl radical ( OH) scavenging activity, ferric ions (Fe3+) and cupric ions (Cu2+) reducing power, ferrous ions (Fe2+) and cupric ions (Cu2+) chelating activity, compared with the positive controls Trolox or BHT.Results: In all assays, PCA along with positive controls exhibited dose-dependently antioxidant ability. Comparing to a standard antioxidant Trolox, the relative antioxidant activity of PCA (i.e. the ratio of IC50(Trolox)/IC50(PCA) ) was calculated as 2.8, 2.3, 3.7, 6.1, 4.2, 1.0, 2.7, 1.5, respectively, for DPPH, ABTS, reducing power (Fe3+), reducing power (Cu2+), superoxide anion radical-scavenging, hydroxyl radical-scavenging, chelating ability (Fe2+) and chelating ability (Cu2+). Functional Foods in Health and Disease 2011; 7:232-244 Conclusion: Comparing to Trolox, PCA shows much more effective antioxidant activity in vitro in both lipid and aqueous media. Hence, it could therefore be used in pharmacological or food industry as a natural antioxidant. It may exhibit antioxidant activity by both chelating metal transition ions as well as by scavenging free radicals via donating hydrogen atom (H ) or electron (e).
Correlation between Antioxidant Activities and Phenolic Contents of Radix Angelicae Sinensis (Danggui)
Xican Li,Xiaoting Wu,Ling Huang
Molecules , 2009, DOI: 10.3390/molecules14125349
Abstract: Radix Angelicae Sinensisis (RAS) is one of the most popular traditional Chinese herbal medicines. In the present study, six RAS extracts (i.e., phenolic extract PE, petroleum ether extract PEE, ethyl acetate extract EAE, absolute ethanol extract AEE, 95% ethanol extract 95 EE, and water extract WE) were prepared and their antioxidant activities measured by DPPH (1,1-diphenyl-2-picrylhydrazyl radical), ABTS [2,2′-azino-bis(3- ethylbenzothiazoline-6-sulfonic acid diammonium salt)], Reducing power, ?O2– and lipid peroxidation assays. In general, PE, PEE and EAE had relatively high antioxidant activity, followed by AEE with moderate activity, as compared with 95 EE and WE that had low activity. Their phenolic contents (including total phenolic, ferulic acid, caffeic acid, same as below) were then determined by HPLC or spectrophotometry. The sequence of phenolic contents was roughly identical with that of antioxidant activity. When the values of 1/IC50 of various antioxidant assays were used to evaluate the level of antioxidant of the RAS extracts, (plot between 1/IC50 values and phenolic contents), the correlation coefficient (R) ranged from 0.642 to 0.941, with an average value of 0.839. Significant positive correlations demonstrated that the antioxidant effects of RAS might generally be considered a result of the presence of the phenolic compounds, especially ferulic acid and caffeic acid.
Widening of Suitable Limits of Grey System GM(1,1) Model
灰色系统GM(1,1)模型适用范围拓广

Li Xican,
李希灿

系统工程理论与实践 , 1999,
Abstract: In this paper, we study the fact that a constant which multiplies all data in the coarse series would influence the values of model and prediction. The result that GM(1,1) model is suitable to negative data sequence is obtained.
Protective Effect against Hydroxyl-induced DNA Damage and Antioxidant Activity of Citri reticulatae Pericarpium
Xican Li,Yanping Huang,Dongfeng Chen
Advanced Pharmaceutical Bulletin , 2013, DOI: 10.5681/apb.2013.029
Abstract: Purpose: As a typical Chinese herbal medicine, Citri reticulatae pericarpium (CRP) possesses various pharmacological effects involved in antioxidant ability. However, its antioxidant effects have not been reported yet. The objective of this work was to investigate its antioxidant ability, then further discuss the antioxidant mechanism. Methods: CRP was extracted by ethanol to obtain ethanol extract of Citri reticulatae pericarpium (ECRP). ECRP was then measured by various antioxidant methods, including DNA damage assay, DPPH assay, ABTS assay, Fe3+-reducing assay and Cu2+-reducing assay. Finally, the content of total flavonoids was analyzed by spectrophotometric method. Results: Our results revealed that ECRP could effectively protect against hydroxyl-induced DNA damage (IC50 944.47±147.74 μg/mL). In addition, it could also scavenge DPPH· radical (IC50349.67±1.91 μg/mL) and ABTS+ radical (IC5011.33±0.10 μg/mL), reduce Fe3+ (IC50 140.95±2.15 μg/mL) and Cu2+ (IC50 70.46±1.77 μg/mL). Chemical analysis demonstrated that the content of total flavonoids in ECRP was 198.29±12.24 mg quercetin/g. Conclusion: Citri reticulatae pericarpium can effectively protect against hydroxyl-induced DNA damage. One mechanism of protective effect may be radical-scavenging which is via donating hydrogen atom (H·), donating electron (e). Its antioxidant ability can be mainly attributed to the flavonoids, especially hesperidin and narirutin.
Antioxidant Activity of Rhizoma Cibotii in vitro
Wenqiong Mai,Dongfeng Chen,Xican Li
Advanced Pharmaceutical Bulletin , 2012,
Abstract: Purpose: The paper tried to systematically investigate the in vitro antioxidant activity of Rhizoma Cibotii (RC) for the first time. Method: The methanol extract from RC (MERC) was prepared then systematically investigated by various antioxidant assays, including: DPPH (1, 1-diphenyl-2-picrylhydrazyl radical), ABTS + (3-ethylbenzthiazoline-6- sulfonic acid diammonium salt radical), O2- (superoxide anion radical), OH (hydroxyl radical) scavenging assays, Fe3+ reducing power, Cu2+ reducing power assays, compared with positive controls Trolox (± -6 -hydroxyl -2,5, 7, 8-tetramethlychromane-2-carboxylic acid) and BHA (butylated hydroxyanisole). Its total phenolics and caffeic acid content were also measured by Folin-Ciocalteu method and HPLC, respectively. Result: MERC exhibited effective antioxidant activity in dose-dependent manners and its IC50 values were calculated as 44.2 ± 0.62, 19.84 ± 0.31, 137.66 ± 2.90, 22.94 ± 0.90, 289.73 ± 46.17, 53.52 ± 1.51 μg /mL,for DPPH , ABTS +, O2-, OH scavenging assays, Fe3+ reducing power, Cu2+ reducing power assays, respectively. Its total phenolics content was 50.88 ± 1.24 mg CAE /g and the caffeic acid content was 1.82 ± 0.19 mg/g. Conclusion: Rhizoma Cibotii has effective in vitro antioxidant activity which may attribute to its total phenolics, among which caffeic acid can be considered as one of the active components. The pharmacological effects or healthcare functions of whole RC may result from the synergistic effects caused by the combination of its components and its antioxidant effect plays an important role in the synergistic effects.
Protective Effect against Hydroxyl-induced DNA Damage and Antioxidant Activity of Radix Glycyrrhizae (Liquorice Root)
Xican Li,Weikang Chen,Dongfeng Chen
Advanced Pharmaceutical Bulletin , 2013, DOI: 10.5681/apb.2013.028
Abstract: Purpose: As a typical Chinese herbal medicine, Radix Glycyrrhizae (RG) possesses various pharmacological effects involved in antioxidant ability. However, its antioxidant has not been explored so far. The aim of the study was to investigate its antioxidant ability, then further discuss the antioxidant mechanism. Methods: RG was extracted by ethanol to obtain ethanolic extract of Radix Glycyrrhizae (ERG). ERG was then determined by various antioxidant methods, including DNA damage assay, DPPH assay, ABTS assay, Fe3+-reducing assay and Cu2+-reducing assay. Finally, the contents of total phenolics and total flavonoids were analyzed by spectrophotometric methods. Results: Our results revealed that ERG could effectively protect against hydroxyl-induced DNA damage (IC50 517.28±26.61μg/mL). In addition, ERG could scavenge DPPH· radical (IC50165.18±6.48μg/mL) and ABTS+ radical (IC507.46±0.07μg/mL), reduce Fe3+ (IC50 97.23±2.88 μg/mL) and Cu2+ (IC50 59.21±0.18 μg/mL). Chemical analysis demonstrated that the contents of total phenolics and flavonoids in ERG were 111.48±0.88 and 218.26±8.57 mg quercetin/g, respectively. Conclusion: Radix Glycyrrhizae can effectively protect against hydroxyl-induced DNA damage. One mechanism of protective effect may be radical-scavenging which is via donating hydrogen atom (H·), donating electron (e). Its antioxidant ability can be mainly attributed to the flavonoids or total phenolics.
Protective Effect against Hydroxyl-induced DNA Damage and Antioxidant Activity of Radix Codonopsis
Xican Li,Yaoting Zheng,Dongfeng Chen
Journal of Intercultural Ethnopharmacology , 2013, DOI: 10.5455/jice.20121225011845
Abstract: Aim: As a typical Chinese herbal medicine, Radix Codonopsis has been used in traditional Chinese medicine for about 250 years. The study tried to investigate its antioxidant activity, then to discuss the antioxidant mechanism. Methods: Radix Codonopsis was extracted by ethanol to obtain ethanolic extract of Radix Codonopsis. The extract was then determined by various antioxidant methods, including DNA damage assay, DPPH (1,1-diphenyl-2-picryl-hydrazl radical), ABTS [2,2′-azino-bis(3-ethylbenzo- thiazoline-6-sulfonic acid) radical] assay, Fe3+-reducing assay and Cu2+-reducing assay. Finally, the contents of total phenolics and flavonoids in the extract were determined by spectrophotometric method. Results: The ethanolic extract of Radix Codonopsis showed protective effect against hydroxyl-induced DNA damage (IC50 1180.28±137.73 μg/mL ) and exhibited DPPH· scavenging, ABTS+ scavenging, Fe3+ reducing, and Cu2+ reducing abilities, and the IC50 values were 3857.79±35.51, 271.82±5.66, 759.99±31.65, and 733.02±9.67 μg/mL, respectively. The contents of total phenolics and flavonoids in the extract were calculated as 12.56±0.56 and 11.95±0.52 mg quercetin/g, respectively. Conclusion: Radix Codonopsis can effectively protect against hydroxyl-induced DNA damage. One mechanism of protective effect may be radical-scavenging which is via donating hydrogen atom (H·), donating electron (e). Its antioxidant ability can be mainly attributed to the existences of flavonoids or phenolic acids. [J Intercult Ethnopharmacol 2013; 2(1.000): 1-8]
GM(1,1) Model of Time Sequence Error
时序残差GM (1, 1) 模型

Li Xican,Li Li,
李希灿
,李 丽

系统工程理论与实践 , 1998,
Abstract: 顾及时序残差对灰色x(0)-GM(1,1)模型精度的影响,提出时序残差ε(0)t-GM(1,1)模型,并利用时序残差ε(0)t-GM(1,1)模型和x(0)-GM(1,1)模型联合进行精度检验和预测,能较好地提高模型精度和预测精度,实例说明是有效的。
Antioxidant activity and mechanism of Rhizoma Cimicifugae
Xican Li, Jing Lin, Yaoxiang Gao, Weijuan Han, Dongfeng Chen
Chemistry Central Journal , 2012, DOI: 10.1186/1752-153x-6-140
Abstract: Firstly, five RC extracts (i.e. petroleum ether extract PERC, ethyl acetate extract EARC, absolute ethanol extract AERC, 95% ethanol extract 95ERC, and water extract WRC) were prepared and determined by various antioxidant methods, including anti-lipidperoxidation, protection against DNA damage, ·OH scavenging, ·O2- scavenging, DPPH· (1,1-diphenyl-2-picryl-hydrazl radical) scavenging, ABTS+· (2,2’-azino-bis (3-ethylbenzo- thiazoline-6-sulfonic acid radical ion) scavenging, Cu2+-chelating, and Fe3+ reducing assays. Subsequently, we measured the chemical contents of five RC extracts, including total phenolics, total saponins, total sugars, caffeic acid, ferulic acid and isoferulic acid. Finally, we quantitatively analyzed the correlations between antioxidant levels (1/IC50 values) and chemical contents.In the study, the antioxidant levels and chemical contents (including total phenolics, total saponins, total sugars, caffeic acid, ferulic acid and isoferulic acid) of five RC extracts were determined by various methods. In all antioxidant assays, five RC extracts increased the antioxidant levels in a dose-dependent manner. However, their antioxidant levels (IC50 values) and chemical contents significantly differed from each other. Quantitative analysis of the correlation showed that total phenolic was of significant positive correlations (average R value was 0.56) with antioxidant levels; In contrast, total sugars and total saponins had no positive correlation with antioxidant (the average R values were ?0.20 and ?0.26, for total sugars and total saponins, respectively); Among total phenolics, three phenolic acids (caffeic acid, ferulic acid and isoferulic acid) also displayed positive correlations (the average R values were 0.51, 0.50, and 0.51, for caffeic acid, ferulic acid and isoferulic acid, respectively).As an effective antioxidant, Rhizoma Cimicifugae can protect DNA and lipids against oxidative damage. Its antioxidant ability can be responsible for its various
Antioxidant Ability and Mechanism of Rhizoma Atractylodes macrocephala
Xican Li,Jian Lin,Weijuan Han,Wenqiong Mai,Li Wang,Qiang Li,Miaofang Lin,Mingsong Bai,Lishan Zhang,Dongfeng Chen
Molecules , 2012, DOI: 10.3390/molecules171113457
Abstract: Rhizoma Atractylodes macrocephala (AM) has been used in Traditional Chinese Medicine (TCM) for about 2,000 years. In the study, we firstly determined the antioxidant levels of five AM extracts by ?OH-scavenging, ?O2?-scavenging, Fe2+-chelating, Cu2+-chelating, DPPH·-scavenging, and ABTS+·-scavenging assays. After measurement of the chemical contents in five AM extracts, we quantitatively analyzed the correlations between antioxidant levels and chemical contents. It was observed that total phenolics and total flavonoids had significant positive correlations with antioxidant levels (R = 0.685 and 0.479, respectively). In contrast, total sugars and total saponins presented lower correlations with antioxidant levels (R = ?0.272 and 0.244, respectively). It means that antioxidant activity of AM should be attributed to total phenolics (including phenolic acids and flavonoids), and not total sugars and total saponins. Further analysis indicated that phenolic acids exhibited higher R values with radical-scavenging assays (R = 0.32–1.00), while flavonoids showed higher R values with metal-chelating assays (R= 0.86 and 0.90). In conclusion, AM exerts its antioxidant effect through metal-chelating, and radical-scavenging which is via donating hydrogen atom and donating electron. Its metal-chelating may result from flavonoids, while its radical-scavenging can be attributed to phenolic acids, especially caffeic acid, ferulic acid, and protocatechuic acid.
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