Chinese Yam Extracts Containing β‐Sitosterol and Ethyl Linoleate Protect against Atherosclerosis in Apolipoprotein E‐Deficient Mice and Inhibit Muscular Expression of VCAM‐1 In Vitro

Atherosclerosis is a chronic inflammatory disease, which is associated with increased expression of adhesion molecules and monocyte recruitment into the arterial wall. This study evaluated whether hexane extracts from the edible part (DB‐H1) or bark region (DB‐H2) of Dioscorea. batatas Decne have anti‐atherosclerotic properties in vivo and in vitro experiments. We also identified bioactive components in the hexane extracts. Thirty‐six apolipoprotein E (ApoE^?/?) mice and 12 control (C57BL/6J) mice were given a Western‐type diet for 11 or 21 wk. To examine the effects of yam extracts on lesion development, ApoE^?/? mice were orally administered DB‐H1 or DB‐H2 for the duration of the study (200 mg/kg b.w./day, 3 times per wk). Both DB‐H1 and DB‐H2 significantly reduced the total atherosclerotic lesion area in the aortic root. In addition, plasma concentrations of total cholesterol, oxidized‐low‐density lipoprotein, and c‐reactive protein were decreased by administration of DB‐H1 and DB‐H2. Consistent with the in vivo observations, DB‐H1 and DB‐H2 inhibited tumor necrosis factor (TNF)‐α–induced vascular cell adhesion molecule‐1 expression and adhesion of THP‐1 monocytes to TNF‐α–activated vascular smooth muscle cells. It was also found that treatment with DB‐H1 or DB‐H2 resulted in the inhibition nitric oxide (NO) and reactive oxygen species production and iNOS expression in macrophages. Thus, DB‐H1 and DB‐H2 seem to influence atherosclerosis by affecting the production of inflammatory mediators in vivo. Our results suggest that yam extracts have the potential to be used in the prevention of atherosclerosis.     

产酶培养条件对一株嗜酸乳杆菌亚油酸异构酶活力的影响

本实验用MRS培养基嗜酸乳杆菌,并通过添加亚油酸(LA)诱导其产亚油酸异构酶。单因素试验结果表明,在MRS培养基中添加糖类物质总体上不利于产酶,添加尿素、牛肉膏、酵母膏、酪蛋白等有机氮源后,酶活力比对照组有较大幅度提高,而添加无机氮源酶活力增加幅度不如有机氮源。在培养基中添加一定量的NaCl和卵磷脂也有助于酶活力的提高。由正交试验结果确定的最佳产酶条件为:培养温度37℃,培养时间24h,每100ml培养基中添加10mgLA,接种量3%(V/V)。     

透性化处理对嗜酸乳杆菌细胞亚油酸异构酶表观活力的影响

来源嗜酸乳杆菌的亚油酸异构酶是胞内酶,完整的细胞呈现较低的酶活。研究了乙醇、乙醚、甲苯、溴化十六烷三甲基铵(CTAB)等透性剂对嗜酸乳杆菌细胞亚油酸异构酶活力的影响。结果表明,经过透性化处理的细胞亚油酸异构酶活力显著提高,其中最好的透性剂为CTAB。当CTAB的浓度为1%,30℃保温20～30min,酶活高达405.6U/g,是超声波破碎的细胞表观酶活的5.4倍。透性化细胞中亚油酸异构酶热稳定性提高,60℃保温2h,残余酶活为80%。透性化细胞生物转化共轭亚油酸转化率达84.5%,用透性化细胞可有效转化亚油酸为共轭亚油酸。     

亚油酸异构酶研究进展

亚油酸异构酶可催化亚油酸异构化为共轭亚油酸.随着共轭亚油酸的应用日益广泛,人们对亚油酸异构酶的研究也日益深入.在查阅大量文献的基础上,对亚油酸异构酶国内外的研究情况进行了综述.     

Flavonoids quercetin,myricetin, kaemferol and (+)‐catechin as antioxidants in methyl linoleate

The antioxidant effect of the flavonoids quercetin, myricetin, kaemferol, (+)‐catechin and rutin on methyl linoleate oxidation was investigated. In addition, the synergistic effects of flavonoids and α‐tocopherol were studied. Oxidation was monitored by conjugated diene measurement and by determining the formation of hydroperoxide isomers by HPLC. The antioxidant activity of flavonoids in non‐polar methyl linoleate differ from that previously reported in water‐containing systems, such as LDL and liposome systems. The activity of antioxidants (10–1000 μM ) measured by hydroperoxide formation decreased in the order: myricetin>quercetin>α‐tocopherol>(+)‐catechin >kaemferol=rutin. The antioxidant activity of flavonoids increased as the number of phenolic hydroxyl groups increased. In addition to the number of hydroxyl groups, other structural features such as the 2,3 double bond in the C‐ring and a glycoside moiety in the molecule had an effect on the antioxidant activity. Myricetin and rutin, especially had a synergistic effect with α‐tocopherol. Myricetin, quercetin and rutin protected α‐tocopherol from decomposition, myricetin being the most protective. The relative hydrogen‐donating activity measured by the ratio of cis,trans‐ to trans,transhydroperoxide isomers formed during oxidation decreased in the order: α‐tocopherol >myricetin>quercetin. Hydroperoxide isomeric distribution of the samples containing kaemferol or rutin did not differ from the control. Thus, although α‐tocopherol was the most effective hydrogendonor, myricetin and quercetin were more effective antioxidants in inhibiting the hydroperoxide formation in methyl linoleate. © 1999 Society of Chemical Industry     

Moderate antioxidative efficiencies of flavonoids during peroxidation of methyl linoleate in homogeneous and micellar solutions

The relative reactivities as well as the stoichiometric coefficients for a number of flavonoids, catechols, and—for comparison—standard phenolic antioxidants were determined by analyzing the kinetics of oxygen consumption in organic and micellar systems, with peroxidation initiated by lipid- and water-soluble azo initiators. The results demonstrated that the flavonoids did not behave as classic phenolic antioxidants such as α-tocopherol, but showed only moderate chain-breaking activities. The results were in line with other structure-activity relationship studies on the importance of the B-ring catechol structure, the 2,3-double bond, and the 3,5-hydroxy groups. The data are discussed in view of possible explanations of the deviations flavonoids reveal in their behavior compared with regular phenolic antioxidants.     

Antioxidant efficacy of amino acids in methyl linoleate at different relative humidities

Antioxidant efficacy of the amino acids methionine, tryptophan, aspartic acid, serine, alanine and arginine in methyl linoleate were compared to a methyl linoleate control at 2,50 or 79% relative humidity (RH) at 37°C. Antioxidant efficacy varied with RH and the individual amino acids. Arginine had the highest antioxidant efficacy at all RH values compared to the control. The efficacy of alanine was equal to that of arginine at RHs of 50 and 79% but was lower at 2% RH. The presence of aliphatic, alkaline amino, hydroxyl or thiol groups in the side chain of the amino acids increased the antioxidant efficacy at high RHs.     

Biobased Poly-phosphonate Additives from Methyl Linoleates‡

Poly-dialkyl phosphonates were synthesized by reacting methyl linoleate with dimethyl, diethyl, and di-n-butyl phosphites in the presence of free radical initiator and positively identified and characterized using gas chromatography–mass spectrometry (GC-MS), nuclear magnetic resonance (NMR; ¹H, ¹³C, ³¹P), and Fourier transform infrared (FTIR). Neat poly-dialkyl phosphonates and their blends in high-oleic sunflower oil (HOSuO) and polyalphaolefin (PAO-6) base oils were investigated for their physical, chemical, and tribological properties. At room temperature, the poly-dialkyl phosphonates displayed much better solubility in HOSuO than in PAO-6. Solubility in the base oils increased in the order dimethyl?<?diethyl?<?di-n-butyl. Relative to methyl linoleate, the neat poly-dialkyl phosphonates displayed higher density, higher kinematic viscosity, higher oxidation stability, and better cold flow (lower pour point and cloud point) properties. As an additive (0–10% w/w) in HOSuO, increasing concentration of poly-di-n-butyl phosphonate resulted in increasing onset and peak oxidation temperatures and decreasing cloud point. Poly-di-n-butyl phosphonate blends in HOSuO also showed lower four-ball antiwear (AW) coefficient of friction (COF) and wear scar diameter (WSD) than corresponding blends with zinc dialkyl dithiophosphate (ZDDP). As an additive (0–10% w/w) in PAO-6 base oil, poly-di-n-butyl phosphonate displayed lower four-ball antiwear COF and comparable WSD relative to similar blends of ZDDP in PAO-6. The results indicate that poly-dialkyl phosphonates are promising biobased AW additives with comparable or better performance than current petroleum-based commercial AW additives such as ZDDP.     

Esterification affects phytosterol oxidation

The effect of esterification with rapeseed oil fatty acids on the oxidation reactions of sitosterol, campesterol and sitostanol was investigated, as well as the interactions between phytosterol/stanol compounds and the saturated lipid matrix at 100 °C and 180 °C. Free and esterified phytosterols differed in their reactivity in terms of the formation and profile of secondary oxidation products. Phytosteryl esters were more reactive than free phytosterols during prolonged heating at 100 °C. In contrast, free phytosterols were slightly more reactive than phytosteryl esters at 180 °C. The oxidation reactions of phytostanol compounds were low under all conditions studied. Changes in the phytosterol compounds during heating were also studied via the losses in the original phytosterol contents. This study revealed that the formation of secondary oxides did not account for all the phytosterol losses; this indicates the presence of other oxidation products, especially at 180 °C, and during the heating of free sitosterol. Thus, in order to understand the overall deterioration of phytosterol and phytostanol compounds, both the secondary oxide formation and the sterol loss need to be studied. The deterioration of the saturated lipid matrix used in this study was rather low and was mainly associated with the heating temperature and time.