Inhibition Of Low-density Lipoprotein Oxidation Research Articles

Free radical scavenging and anti-isolated human LDL oxidation activities of Butea superba Roxb. extract

BackgroundButea superba Roxb. (B. superba), is an herbal plant traditionally used for rejuvenation. Additionally, there have been reports on its antioxidant properties. Low-density lipoproteins (LDL) oxidation is the leading cause of cardiovascular diseases (CVDs). Natural products with antioxidant properties have the potential to inhibit LDL oxidation. However, no work has been done about the anti-isolated human LDL oxidation of B. superba extract (BSE). This study aimed to investigate the antioxidant potential of BSE and its ability to prevent isolated human (LDL) oxidation induced by free radical agents.MethodsThe antioxidant properties were investigated by antioxidant assays, including 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azinobis-(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS), ferric reducing ability power (FRAP), nitric oxide (NO) and peroxynitrite scavenging assay. More so, anti-isolated human LDL oxidation activities were evaluated by 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) and 3-morpholinosydnonimine hydrochloride (SIN-1) induced LDL oxidation assay.ResultsBSE exhibited a significant (p < 0.05) antioxidant activity in all the test systems, demonstrating its potential as a potent free radical scavenger. It displayed scavenging effects on DPPH (p < 0.05; IC50 = 487.67 ± 21.94 µg/ml), ABTS (p < 0.05; IC50 = 30.83 ± 1.29 µg/ml). Furthermore, it generated significantly (p < 0.05) increased antioxidant capacity in a dose-dependent manner in FRAP assay and exhibited significantly (p < 0.01) higher percent NO scavenging activity than gallic acid. Besides, BSE at 62.5 µg/ml exhibited a considerable percent peroxynitrite scavenging of 71.40 ± 6.59% after a 2 h period. Moreover, BSE demonstrated anti-isolated human LDL oxidation activity induced by AAPH and SIN-1 (p < 0.05) and revealed scavenging activity similar to ascorbic acid (p > 0.05). Identifying the main constituents of BSE revealed the presence of genistein, daidzein, and biochanin A through Liquid Chromatography-Mass Spectrometer/Mass Spectrometer (LC–MS/MS) analysis.ConclusionThis is the first report that the presence of isoflavones in BSE could play an important role in its antioxidation and isolated human LDL oxidation scavenging properties. These findings suggest the potential for developing antioxidant herbal supplements. However, further studies must be investigated, including efficacious and safe human dosages.

Attenuating lipid metabolism in atherosclerosis: The potential role of Anti-oxidative effects on low-density lipoprotein of herbal medicines.

Atherosclerosis (AS) is a multifactorial chronic disease with great harm to the health of human being, which is a basic pathogenesis of many cardiovascular diseases and ultimately threatens human life. Abnormal blood lipid level is one of the most common diagnostic indicators of AS in clinic, and lipid metabolism disorder is often observed in patients with AS. Cholesterol is an important lipid in the human body, which is of great significance for maintaining normal life activities. Generally, cholesterol is transported to peripheral tissues by low-density lipoprotein (LDL), and then transported to the liver by high-density lipoprotein (HDL) via its cholesterol reverse transport function, and finally discharged. Under oxidative stress condition, LDL is commonly oxidized to the form ox-LDL, which is ingested by macrophages in large quantities and further forms foam cells, disrupting the normal metabolic process of cholesterol. Importantly, the foam cells are involved in forming atherosclerotic plaques, whose rupture may lead to ischemic heart disease or stroke. Furthermore, ox-LDL could also promote the development of AS by damaging vascular endothelium, promoting the migration and proliferation of smooth muscle cells, and activating platelets. Therefore, inhibiting LDL oxidation may be an effective way to improve lipid metabolism and prevent AS. In recent years, increasing studies have shown that herbal medicines have great potentiality in inhibiting LDL oxidation and reducing ox-LDL induced foam cell formation. Accordingly, this paper summarized current research on the inhibitory effects of herbal medicines against LDL oxidation and foam cell formation, and made a brief description of the role of cholesterol and LDL in lipid metabolism disorder and AS pathogenesis. Importantly, it is suggested that herbal medicines could inhibit LDL oxidation and regulate cholesterol homeostasis via downregulation of CD36 and SR-A, whereas upregulation of ABCA1 and ABCG1.

Generation of novel antioxidant peptides from silver carp muscle hydrolysate: Gastrointestinal digestion stability and transepithelial absorption property

Oxidative stress is a major cause of cardiovascular diseases (CVDs). Antioxidant peptides have potential to improve CVDs. The aim of this study was to develop novel antioxidant peptides from silver carp muscle hydrolysates (SCHs) and investigate their gastrointestinal digestion (GID) stability, and bioavailability. Results showed that SCHs generated by Alcalase and Papain exhibited the highest free radical scavenging activity, peroxynitrite scavenging activity and low density lipoprotein (LDL) oxidation inhibitory capacity. All these antioxidant activities were enhanced in different SCHs after GID. Notably, the GID products of Papain-SCH and Alcalase-SCH possessed potent ameliorating effects on oxidative stress injury in endothelial cells. After transepithelial transport, total of nine peptides was identified from permeates of GID products of Papain-SCH and Alcalase-SCH. The VKVGNEF and MEAPPH were both novel peptides in the current study that possess the highest activities in scavenging free radicals, inhibiting LDL oxidation and alleviating oxidative stress injury in endothelial cells.

Antioxidant interactions among hydrophilic and lipophilic dietary phytochemicals based on inhibition of low-density lipoprotein and DNA damage.

Antioxidant interaction among hydrophilic phytochemicals (caffeic acid, p-coumaric acid) and lipophilic phytochemicals (β-carotene, lycopene) in different mole ratios (n/n, 1:9, 3:7, 5:5, 7:3, 9:1) was evaluated. Assays performed were based on the scavenging activity of hydrogen peroxide (H2 O2 ), the inhibition of low-density lipoprotein oxidation (ox-LDL) and DNA damage in vitro, using isobological analysis, synergistic rate (SR), and combination index (CI). Results showed that groups containing higher ratios of hydrophilic phytochemicals exhibited synergism while those containing higher ratios of lipophilic phytochemicals showed antagonism. Meanwhile, groups containing caffeic acid (e.g., caffeic acid:β-carotene, 9:1) with more hydroxyl groups showed higher synergism (SR=0.76 ± 0.02, CI=0.77 ± 0.03) than groups containing p-coumaric acid (e.g., p-coumaric acid:β-carotene, 9:1, SR=0.88 ± 0.04, CI=0.82 ± 0.05) on the scavenging activity of H2 O2 . Groups that contained lycopene (caffeic acid: lycopene, 9:1) with a higher ability of regeneration by phenolic acids showed more significant synergism (SR=0.70 ± 0.02, CI=0.79 ± 0.03) than groups containing β-carotene (e.g., caffeic acid:β-carotene, 9:1, SR=1.00 ± 0.03, CI=0.98 ± 0.04) on the inhibition of DNA damage. This study provided a basis for antioxidant interactions among phytochemicals against ox-LDL and DNA damage in vivo. In addition, the choice of appropriate ratios and structures of hydrophilic and lipophilic phytochemicals should be considered in the diet and formulation of functional foods.

Antioxidant, anti-proliferative, and anti-atherosclerotic effect of phytochemicals isolated from Trachyspermum ammi with honey in RAW 264.7 and THP-1 cells

Background: Trachyspermum ammi is a common spice with vital medicinal properties used in Ayurveda to treat many ailments. Furthermore, natural Honey is said to have high levels of antioxidants and anti-inflammatory properties. While the combination of both T. ammi and Honey is unexplored in anti-atherosclerotic activity. Materials and Methods: Assays guided isolation of carotenoids, phenolics, and tannins were performed by methanol and aqueous extraction from T. ammi seed powder and honey mixture. Phytochemical screening for antioxidant activity (superoxide radical scavenging activity, nitric oxide radical scavenging activity, and 2, 2-diphenyl-1-picrylhydrazyl scavenging activity) and antilipidemic activity by inhibition of low-density lipoprotein (LDL) oxidation were investigated. Sample showing highest activity with lowest IC50 value from antioxidant and antilipidemic activity was further evaluated on RAW 264.7, THP-1 cells for foam cell inhibition activity, anti-proliferation, antiapoptotic activity, and nitric oxide assay. The sample was characterized using high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). Results: Out of the phytochemicals screened, tannin methanol extract (TME) showed the highest antioxidant activity with IC50 value having 7.11 μg/mL in superoxide scavenging assay, the IC50 value of 1.46 μg/mL by nitric oxide scavenging assay, and followed by IC50 value of 20.83 μg/mL in 2, 2-diphenyl-1-picrylhydrazyl activity. The results showed that it also efficiently inhibited LDL oxidation at 240 μg/mL (71.29% at 5 h)., thus inhibiting foam cell development, preventing proliferation, apoptosis, and nitrate production in cultured RAW 264.7 and THP-1 cells. HPLC analysis showed the presence of tannin in the extract. TME was characterized in GC-MS, which showed 13 prominent compounds. Conclusion: The scientific evidence in the present study showed that the TME from T. ammi seed powder and honey act as an antioxidant and antiatherogenic properties in inhibiting foam cell formation. Hence, this phytochemical can be used for the treatment of atherosclerosis.

Investigation of S.limacinum microalgae digestibility and production of antioxidant bioactive peptides

Schizochytrium limacinum (S. limacinum) has potential as a high protein food ingredient. The digestibility of this protein was performed in the conditions of simulated stomach phase (with pepsin enzyme) and simulated small intestine phase (with α-chymotrypsin and trypsin). The whole hydrolysate was fractionated into various ranges of molecular weight cutoff (MWCO) by using ultrafiltration (UF) technique. Antioxidant activities of hydrolysate fractions were evaluated using direct free radical scavenging activity such as 2,2-diphenyl-1-picrylhydrazyl Radical (DPPH•) scavenging, activity, 2,2-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acidradical cation (ABTS•+) sscavengin activity and reducing power activity. In addition, the protective effect of purified peptide against oxidation of low-density lipoprotein (LDL) was determined. The microalgae proteins were completely hydrolyzed by digestive enzymes and the enzymatic hydrolysis of proteins resulted in increased antioxidant activity of peptides. The peptide fraction F3 (MWCO = 5–10 kDa) presented the highest antioxidant activity out of all the methods described. The protein hydrolysates showed higher reducing power, radical scavenging capacity and significantly inhibited LDL oxidation. These results suggest that the enzymatic hydrolysates from S. limacinum can act as novel antioxidants in functional foods.

Procyanidin B2-induced relaxation as a mechanism of its cardioprotective effect

Background and Aims: Health-promoting properties of procyanidin-rich food, like free radical scavenging activity and inhibition of low-density lipoprotein oxidation, keep them very interesting subject for investigation as promising agents for protection against cardiovascular diseases. Procyanidins’ cardioprotective abilities partly attribute to their vasodilator properties. Considering that exact mechanisms of procyanidin B2-induced vasodilation are still undefined, we aimed to investigate and characterize vasorelaxant effect of procyanidin B2 on human saphenous vein (HSV) as one of its protective mechanisms.

Vitamins E and C do not effectively inhibit low density lipoprotein oxidation by ferritin at lysosomal pH

Low density lipoprotein (LDL) might be oxidized by iron in the lysosomes of macrophages in atherosclerotic lesions. We have shown previously that the iron-storage proteinferritin can oxidize LDL at lysosomal pH. We have now investigated the roles of the most important antioxidant contained in LDL, α-tocopherol (the main form of vitamin E) and of ascorbate (vitamin C), a major water-soluble antioxidant, on LDL oxidation by ferritin at lysosomal pH (pH 4.5). We incubated LDL with ferritin at pH 4.5 and 37 °C and measured its oxidation by monitoring the formation of conjugated dienes at 234 n min a spectrophotometer. α-Tocopherol is well known to inhibit LDL oxidation at pH 7.4, but enrichment of LDL with α-tocopherol was unable to inhibit LDL oxidation by ferritin at pH 4.5. Ascorbate had a complex effect on LDL oxidation by ferritin at lysosomal pH and exhibited both antioxidant and pro-oxidant effects. It had no antioxidant effect on partially oxidized LDL, only a pro-oxidant effect. Ascorbate completely inhibited LDL oxidation by copper at pH 7.4 for a long period, but in marked contrast did not inhibit LDL oxidation by copper at lysosomal pH. Dehydroascorbate, the oxidation product of ascorbate, had a pronounced pro-oxidant effect on LDL incubated with ferritin at pH 4.5. The inability of α-tocopherol and ascorbate to effectively inhibit LDL oxidation by ferritin at lysosomal pH might help to explain why the large clinical trials with these vitamins failed to show protection against cardiovascular diseases.

The Bioactive Compound Contents and Potential Protective Effects of Royal Jelly Protein Hydrolysates against DNA Oxidative Damage and LDL Oxidation.

In this study, the inhibition of DNA oxidative damage and low-density lipoprotein (LDL) oxidation of royal jelly protein (RJP) hydrolysates obtained from two commercial proteases were investigated. The results showed that the inhibition of DNA oxidative damage induced by the Fenton reaction, RJP, RJPs hydrolyzed by alcalase (RJP-A), RJPs hydrolyzed by flavourzyme (RPJ-F) and RJP two-stage hydrolysates (RPJ-AF) all had the effect of inhibiting deoxyribose oxidative damage. The inhibition effect of RJP, RJP-A, RJP-F and RJP-AF (1.0 mg/mL) were 47.06%, 33.70%, 24.19% and 43.09%, respectively. In addition, studies have also found that both RJP and RJP hydrolysates can reduce the production of 8-OH-2′-dG and the order of its inhibitory ability is RJP-AF ≒ RJP-A > RJP-F > RJP. The inhibition of DNA damage induced by bleomycin-Fe3+/ascorbic acid (Asc) with the addition of RJP, RJP-A, RPJ-F and RPJ-AF were 17.16%, 30.88%, 25.00% and 37.25%, respectively. The results of LDL oxidation inhibition showed that RJP-AF (1 mg/mL) not only had the most effective inhibitory Cu2+-induced LDL oxidation to produce a thiobarbituric acid reactive substance (TBARS) but also extended the lag time of conjugated diene formation to 300 min, which was 3.3 times that of the control group.

Pengaruh Pemberian Alpukat Terhadap Kadar Kolesterol Total Darah Pada Mahasiswa/i Obesitas Di Fakultas Kedokteran Universitas HKBP Nommensen Medan Tahun 2019

Background: Cholesterol is a fat that does not dissolve easily in the blood. Most of the cholesterol in the blood is attached to specific protein carriers in the plasma in the form of lipoprotein complexes, which are soluble in water. Lipoprotein which carries cholesterol throughout the body. namely LDL (Low Density Lipoprotein) and HDL (High Density Lipoprotein). An increase in LDL in the body tends to form atherosclerosis. In contrast HDL cholesterol inhibits LDL oxidation so that atherosclerotic plaque formation does not occur. Obesity is one of the risk factors for atherosclerosis with manifestations of coronary heart disease. Handling of obesity has been done by many researchers and implemented. One ingredient from nature that serves as an alternative ingredient to lower blood cholesterol levels is avocado.&#x0D; Objective: To determine the effect of avocado administration on total blood cholesterol levels in the obese college students at the Medical Faculty of Nommensen HKBP University in 2019.&#x0D; Methods :This research is a pre-experimental study with a pre-post test design in one group. The sample was selected by purposive sampling method and obtained 20 obese students. Subjects consumed avocado juice every day for 14 days. Total cholesterol levels were measured before (day 0) and after (day 14) treatment.&#x0D; Results: The mean total cholesterol level of the subject's blood on the pretest examination was 188.10 mg / dL and the posttest examination was 180.05 mg / dL. There was a decrease in the average total blood cholesterol level of 8.05 mg / dl. Paired T-test showed that there was a non-significant decrease in mean total blood cholesterol level with a value of p = 0.068 (p &lt;0.05).&#x0D; Conclusion: In this study there was no effect of avocado administration on total blood cholesterol levels in obese students.

Natural products: The role and mechanism in low-density lipoprotein oxidation and atherosclerosis.

Atherosclerosis is a chronic inflammatory, metabolic, and epigenetic disease, which leads to the life-threatening coronary artery disease. Emerging studies from bench to bedside have demonstrated the pivotal role of low-density lipoprotein (LDL) oxidation in the initiation and progression of atherosclerosis. This article hereby reviews oxidation mechanism of LDL, and the pro-atherogenic and biomarker role of oxidized LDL in atherosclerosis. We also review the pharmacological effects of several representative natural products (vitamin E, resveratrol, quercetin, probucol, tanshinone IIA, epigallocatechin gallate, and Lycopene) in protecting against LDL oxidation and atherosclerosis. Clinical and basic research supports the beneficial effects of these natural products in inhibiting LDL oxidation and preventing atherosclerosis, but the data are still controversial. This may be related to factors such as the population and the dosage and time of taking natural products involved in different studies. Understanding the mechanism of LDL oxidation and effect of oxidized LDL help researchers to find novel therapies against atherosclerosis.

Berberis microphylla G. Forst (Calafate) Berry Extract Reduces Oxidative Stress and Lipid Peroxidation of Human LDL.

Calafate (Berberis microphylla G. Forst) is a Patagonian barberry very rich in phenolic compounds. Our aim was to demonstrate, through in vitro models, that a comprehensive characterized calafate extract has a protective role against oxidative processes associated to cardiovascular disease development. Fifty-three phenolic compounds (17 of them not previously reported in calafate), were tentatively identified by Ultra-Liquid Chromatography with Diode Array Detector, coupled to Quadrupole-Time of Fly Mass Spectrometry (UHPLC-DAD-QTOF). Fatty acids profile and metals content were studied for the first time, by Gas Chromatography Mass Spectrometry (GC-MS) and Total X-ray Fluorescence (TXRF), respectively. Linolenic and linoleic acid, and Cu, Zn, and Mn were the main relevant compounds from these groups. The bioactivity of calafate extract associated to the cardiovascular protection was evaluated using Human Umbilical Vein Endothelial Cells (HUVECs) and human low density lipoproteins (LDL) to measure oxidative stress and lipid peroxidation. The results showed that calafate extract reduced intracellular Reactive Oxygen Species (ROS) production (51%) and completely inhibited LDL oxidation and malondialdehyde (MDA) formation. These findings demonstrated the potential of the relevant mix of compounds found in calafate extract on lipoperoxidation and suggest a promising protective effect for reducing the incidence of cardiovascular disease.

Abstract 15015: Eicosapentaenoic Acid, but Not Docosahexaenoic Acid or a Mixed Omega-3 Fatty Acid Supplement, Inhibits Low-density Lipoprotein Oxidation in a Time-dependent Manner

Background: Eicosapentaenoic acid (EPA), an omega-3 fatty acid (O3FA), reduces oxidation of low-density lipoproteins (LDL) in patients with hypertriglyceridemia, an effect that may contribute to lower cardiovascular (CV) events as reported in the REDUCE-IT trial. By contrast, DHA-containing products have failed to show a reduction in CV events, which may be due, in part, to differences in antioxidant activity. We compared the effects of EPA versus DHA and a mixed O3FA (EPA/DHA) supplement on oxidation of human LDL in vitro . Methods: LDL was isolated from human plasma by isopycnic centrifugation, separated into test samples of 100 μg/mL, and incubated at 37°C for 30 min in the absence (vehicle) or presence of EPA, DHA, or mixed O3FA supplement at equimolar levels (2.5 μM). All samples were then subjected to copper-induced oxidation (20 μM) as measured by formation of malondialdehyde (MDA). The FA content of the O3FA supplement was measured using gas chromatography/mass spectrometry. Results: EPA significantly inhibited LDL oxidation in a time-dependent manner compared with vehicle; after 4 hours, EPA inhibited MDA levels by 96% compared with the vehicle oxidation level (0.51 ± 0.01 vs 11.4 ± 0.4 μM; p &lt;0.001). While DHA exhibited antioxidant activity at 2 hours at a level below EPA (2.5 ± 0.1 vs 11.4 ± 0.4; p &lt;0.001), even this level of activity was lost by 4 hours. The mixed O3FA supplement failed to show any antioxidant activity through 4 hours (11.4 ± 0.5 μM). Fatty acid analysis showed that the O3FA supplement, in addition to EPA and DHA, contained more than 30 other fatty acids, including saturated fats, that may have nullified any potential benefits. Conclusions: These data support potent LDL antioxidant effects of EPA that were sustained over time compared with DHA, which had a weaker, transient effect, or a mixed O3FA supplement, which had no beneficial effect at all. This potent antioxidant mechanism of EPA may contribute to reduced CV risks seen in REDUCE-IT compared with negative findings from trials using DHA-containing formulations.

Abstract 15019: Differential Effects of Omega-3 Fatty Acid Combinations on the Inhibition of Oxidation Of Human Low-density Lipoproteins in vitro

Background: Omega-3 fatty acids (O3FAs) reduce levels of triglyceride but may also have additional atheroprotective benefits. Randomized trials have suggested potential clinical outcome differences among O3FAs formulations. Oxidative modification of low-density lipoproteins (LDL) contributes to endothelial dysfunction, inflammation, and other aspects of atherogenesis. Individual O3FAs have been shown to inhibit LDL oxidation to varying degrees, but the antioxidant effects of combining O3FAs is unknown. Objective: To compare the dose- and time-dependent antioxidant effects of eicosapentaenoic acid (EPA, 20:5) alone and in combination with either docosapentaenoic acid (DPA, 22:5) or docosahexaenoic acid (DHA, 22:6) in human LDL in vitro . Methods: Human LDL was isolated from healthy subjects and adjusted to a final ApoB concentration of 100 μg/mL in physiologic buffer (PBS) before being incubated with O3FAs at 37°C. The EPA levels in the combinations were fixed at either 2.0, 3.0, or 4.5 μM, while the DPA or DHA levels were set at 0, 0.5, 1.0, and 2.0 μM. Oxidation was initiated by copper sulfate (10 μM) and measured over time by formation of malondialdehyde (MDA), a lipid oxidation product. Results: When combined with EPA, both DPA and DHA increased inhibition of oxidation in a dose- and time-dependent manner, with DPA showing a greater effect and more prolonged inhibition. At high levels of EPA (4.5 μM), DPA showed significantly greater antioxidant activity than equimolar DHA; these differences were more apparent with time. After 8 hours, adding 1.0 μM DPA reduced MDA formation by 61% versus vehicle (3.10 ± 0.42 vs. 7.98 ± 0.56, p &lt;0.001), while adding 1.0 μM DHA only reduced MDA formation by 20% (6.40 ± 1.23, p &lt;0.05). When 2 μM DPA or DHA were added, after 10 hours only DPA still had a significant degree of inhibition versus vehicle (37%; 6.65 ± 0.95 vs. 8.21 ± 0.53, p &lt;0.05). Similar trends were observed in combinations containing 2.0 and 3.0 μM EPA. Conclusion: Adding DPA or DHA to EPA provide dose-dependent incremental antioxidant effects, with DPA providing a larger degree and a longer duration of inhibition. These observations highlight potential differences among O3FAs (and their combinations) in novel mechanisms of atheroprotection.

Механізми кардіо- та вазопротекторної дії ресвератролу

У статті наведено огляд сучасних даних щодо механізмів реалізації кардіо- та вазопротекторної дії ресвератролу. Наведені результати експериментальних і клінічних досліджень, що підтверджують можливість включення ресвератролу в фармакотерапію серцево-судинних захворювань. Вплив ресвератролу на серцево-судинну систему полягає в підвищенні продукції NO, зниженні синтезу ендотеліну-1, проявів оксидативного стресу, запобіганні проліферації клітин гладеньких м’язів, ремоделюванні судин та посиленні жорсткості артерій. Крім того, ресвератрол знижує інфільтрацію імунних клітин у судинну стінку та зменшує запалення судинної стінки. Ресвератрол має значну біологічну активність та може застосовуватися не тільки як кардіопротекторний, але й як протизапальний, антидіабетичний, нейротропний, протипухлинний засіб.

Effect of vitamin E on low density lipoprotein oxidation at lysosomal pH

Many cholesterol-laden foam cells in atherosclerotic lesions are macrophages and much of their cholesterol is present in their lysosomes and derived from low density lipoprotein (LDL). LDL oxidation has been proposed to be involved in the pathogenesis of atherosclerosis. We have shown previously that LDL can be oxidised in the lysosomes of macrophages. α-Tocopherol has been shown to inhibit LDL oxidation in vitro, but did not protect against cardiovascular disease in large clinical trials. We have therefore investigated the effect of α-tocopherol on LDL oxidation at lysosomal pH (about pH 4.5). LDL was enriched with α-tocopherol by incubating human plasma with α-tocopherol followed by LDL isolation by ultracentrifugation. The α-tocopherol content of LDL was increased from 14.4 ± 0.2 to 24.3 ± 0.3 nmol/mg protein. LDL oxidation was assessed by measuring the formation of conjugated dienes at 234 nm and oxidised lipids (cholesteryl linoleate hydroperoxide and 7-ketocholesterol) by HPLC. As expected, LDL enriched with α-tocopherol was oxidised more slowly than control LDL by Cu2+ at pH 7.4, but was not protected against oxidation by Cu2+ or Fe3+ or a low concentration of Fe2+ at pH 4.5 (it was sometimes oxidised faster by α-tocopherol with Cu2+ or Fe3+ at pH 4.5). α-Tocopherol-enriched LDL reduced Cu2+ and Fe3+ into the more pro-oxidant Cu+ and Fe2+ faster than did control LDL at pH 4.5. These findings might help to explain why the large clinical trials of α-tocopherol did not protect against cardiovascular disease.

HDL Cholesterol Efflux Capacity is Impaired in Severe Short-Term Hypothyroidism Despite Increased HDL Cholesterol.

Severe hypothyroidism has profound effects on lipoprotein metabolism including high-density lipoprotein (HDL) cholesterol elevations but effects on HDL function metrics are unknown. To determine the impact of severe short-term hypothyroidism on HDL particle characteristics, HDL cholesterol efflux capacity (CEC), and HDL antioxidative capacity. Observational study with variables measured during severe short-term hypothyroidism (median TSH 81 mU/L) and after 20 weeks of thyroid hormone supplementation (median TSH 0.03 mU/L) (Netherlands Trial Registry ID 7228). University hospital setting in The Netherlands. Seventeen patients who had undergone a total thyroidectomy for differentiated thyroid carcinoma. HDL particle characteristics (nuclear magnetic resonance spectrometry), CEC (human THP-1-derived macrophage foam cells and apolipoprotein B-depleted plasma), and HDL anti-oxidative capacity (inhibition of low-density lipoprotein oxidation). During hypothyroidism plasma total cholesterol, HDL cholesterol and apolipoprotein A-I were increased (P ≤ 0.001). HDL particle concentration was unchanged, but there was a shift in HDL subclasses toward larger HDL particles (P < 0.001). CEC was decreased (P = 0.035), also when corrected for HDL cholesterol (P < 0.001) or HDL particle concentration (P = 0.011). HDL antioxidative capacity did not change. During severe short-term hypothyroidism CEC, an important antiatherogenic metric of HDL function, is impaired. HDL cholesterol and larger HDL particles are increased but HDL particle concentration is unchanged. Combined, these findings suggest that HDL quality and quantity are not improved, reflecting dysfunctional HDL in hypothyroidism.

Decursin inhibits the oxidation of low-density lipoprotein and protects human aortic endothelial cells against oxidative damage

Atherosclerosis is the pathological basis of cardiovascular diseases (CVDs) which are the leading cause of death worldwide. The pathogenesis of atherosclerosis itself is complex. Low-density lipoprotein (LDL) oxidation has been shown to increase lipid peroxide levels in arterial wall of atherosclerosis lesion site. Decursin is a coumarin with a range of pharmacological effects. The present study investigated the inhibitory effect of decursin on LDL oxidation, and its protective effect against oxidative damage in human aortic endothelial cells (HAECs). Two models of oxidative damage were used in this study: Cu2+-induced LDL oxidative damage and 2,2'-azobis-2-methyl-propanimidyl, dihydrochloride (AAPH)-induced oxidative damage of HAECs. The inhibitory effect of decursin on LDL oxidation, and its protective effect on oxidative damage of HAECs were determined. The results showed that the level of thiobarbituric acid reactive substances (TBARS) was significantly increased by Cu2+, but was significantly and concentration-dependently reduced after treatment with decursin (p &lt; 0.05). There were only a few viable cells in AAPH-treated group, but treatment with decursin led to significant, time- and concentration-dependent increases in their viability (p &lt; 0.05). The AAPH-induced oxidative damage significantly increased the activity of lactate dehydrogenase (LDH) and level of reactive oxygen species (ROS), but significantly reduced the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) (p &lt; 0.05). However, treatment of HAECs with decursin significantly and concentration-dependently reduced the LDH activity and level of ROS, but significantly increased the activities of SOD and GPx, concentration-dependently (p &lt; 0.05). It also significantly and concentration-dependently reduced apoptosis induced by AAPH (p &lt; 0.05). These results show that decursin effectively inhibits LDL oxidation induced by Cu2+, and protects HAECs from oxidative damage caused by AAPH in vitro via a mechanism involving activation of SOD and GPx.

Eicosapentaenoic Acid (Epa) Inhibits Human Low-Density Lipoprotein Oxidation In A Concentration- And Time-Dependent Manner At Pharmacologic Doses In Vitro

Background and Aims: Eicosapentaenoic acid (EPA) reduces oxidation of low-density lipoproteins (LDL) in patients with hypertriglyceridemia, a benefit that may contribute to lower cardiovascular events. EPA may inhibit LDL oxidation through free radical scavenging at a pharmacologic dose (4 g/d) as measured in plasma in the micromolar range.

Inhibitory effects of compounds isolated from roots of Cynanchum wilfordii on oxidation and glycation of human low-density lipoprotein (LDL)

Abstract Low-density lipoprotein (LDL) modification such as oxidation and glycation has been known to play a significant role in the initiation and progression of atherosclerosis. The inhibitors on LDL modification have been emerged as a new strategy to be a supplement for prevention of atherosclerosis. In an effort to discover inhibitors on LDL modification from natural products, phytochemical investigation on Cynanchum wilfordii roots were performed, leading to isolation of acetophenones (1–6) including a new one (1) and nine pregnane-type steroids (7–15). The structure of the compound 1 was determined by analysis of 1D and 2D NMR spectral data analysis. All the isolated compounds were evaluated for their inhibitory activities against LDL modification. Among them, compounds 2 and 5 strongly inhibited LDL oxidation and glycation. These results suggest that compounds 2 and 5 from C. wilfordii may provide potential protective effects against atherosclerosis via inhibition of LDL oxidation and glycation.