The combined effect of pycnogenol with ascorbic acid and trolox on the oxidation of lipids and proteins (original) (raw)
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Free Radical Biology and Medicine, 1999
There is growing interest in the biologic activities of plant extracts such as that obtained from the bark of the French maritime pine Pinus maritima, Pycnogenol. Pycnogenol (PYC) is a standardized extract composed of a mixture of flavonoids, mainly procyandins and phenolic acids. Studies indicate that PYC components are highly bioavailable. Uniquely PYC displays greater biologic effects as a mixture than its purified components do individually indicating that the components interact synergistically. PYC has been reported to have cardiovascular benefits, such as a vasorelaxant activity, angiotensin-converting enzyme (ACE) inhibiting activity, and the ability to enhance the microcirculation by increasing capillary permeability. Investigations of the cellular mechanisms of these therapeutic effects have demonstrated that PYC has strong free radical-scavenging activity against reactive oxygen and nitrogen species. The oligomeric components of PYC contribute significantly to the ESR free radical signal. PYC also participates in the cellular antioxidant network as indicated by its ability to regenerate the ascorbyl radical and to protect endogenous vitamin E and glutathione from oxidative stress. PYC modulates NO metabolism in activated macrophages by quenching the NO radical and inhibiting both iNOS mRNA expression and iNOS activity. The spectrum of different effects of NO in the circulation and the nervous system suggest the potential applications of PYC in immune and circulatory disorders as well as in neurodegenerative disease. PYC can bind to proteins, altering their structure and thereby modulating the activity of key enzymes and proteins involved in metabolic pathways. PYC effects redox-sensitive signal transduction pathways and alters gene expression. Aspects of PYC's activity are presented and discussed together with possible future implications and directions in the field of flavonoid research.
Chemistry and Physics of Lipids, 2002
In an attempt to deepen our understanding of the mechanisms responsible for lipoprotein peroxidation, we have studied the kinetics of copper-induced peroxidation of the polyunsaturated fatty acid residues in model membranes (small, unilamellar liposomes) composed of palmitoyllinoleoylphosphatidylcholine (PLPC). Liposomes were prepared by sonication and exposed to CuCl 2 in the absence or presence of naturally occurring reductants (ascorbic acid (AA) and/or a-tocopherol (Toc)) and/or a Cu(I) chelator (bathocuproinedisulfonic acid (BC) or neocuproine (NC)). The resultant oxidation process was monitored by recording the time-dependence of the absorbance at several wavelengths. The observed results reveal that copper-induced peroxidation of PLPC is very slow even at relatively high copper concentrations, but occurs rapidly in the presence of ascorbate, even at sub-micromolar copper concentrations. When added from an ethanolic solution, tocopherol had similar pro-oxidative effects, whereas when introduced into the liposomes by co-sonication tocopherol exhibited a marked antioxidative effect. Under the latter conditions, ascorbate inhibited peroxidation of the tocopherol-containing bilayers possibly by regeneration of tocopherol. Similarly, both ascorbate and tocopherol exhibit antioxidative potency when the PLPC liposomes are exposed to the high oxidative stress imposed by chelated copper, which is more redox-active than free copper. The biological significance of these results has yet to be evaluated. : S 0 0 0 9 -3 0 8 4 ( 0 1 ) 0 0 2 0 8 -0 O. Bittner et al. / Chemistry and Physics of Lipids 114 (2002) 81-98 82
Natural Product Research, 2015
Two new protocols for exploring antioxidant-related chemical composition and reactivity are described: one based on a chronometric variation of a hemoglobin ascorbate peroxidase assay and one based on cytochrome c-induced oxidation of lecithin liposomes. Detailed accounts are given on their design, application, critical correlations with established methods, and mechanisms. These assays are proposed to be physiologically relevant and bring new information regarding a real sample, both qualitative and quantitative. The well-known assays used for evaluation of antioxidant (re)activity are revisited and compared with these new methods. Principal component analysis (PCA) allow straightforward comparisons of these antioxidant assays based on mechanism and reinforce the need to use more than a single parameter in examining such reactivity. Extracts of the Hedera helix L. are examined as test case, with focus on seasonal variation and on leaf, fruit and flower with respect to chromatographic, spectroscopic and reactivity properties. Keywords: antioxidant (re)activity assays; hemoglobin ascorbate peroxidase assay; liposome peroxidation; principal component analysis; Hedera helix. Experimental section 1.1. Chemicals. AAPH (2,2'-azobis-2-methyl-propanimidamide dihydrochloride), DPPH (di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium), beta-carotene, rutin, kaempferol, tween, linoleic acid, methanol, ethanol, trolox, soy lecithin, chloroform, horse heart cytocrom c, ascorbic acid, sodium hydroxide are of high analytical purity and obtained from several companies (Sigma, Fluka, Merck). Standards: chlorogenic acid, p-coumaric acid, caffeic acid, rutin, apigenin, quercitrin, isoquercitrin, hyperoside, kaempferol, quercetol, myricetol and fisetin from Sigma (Germany); ferulic acid, sinapic acid, gentisic acid, patuletin and luteolin from Roth (Germany); and cichoric acid and caftaric acid from Dalton (USA). Methanol of HPLC analytical-grade and hydrochloric acid of analytical-grade were purchased from Merck (Germany). Methanolic stock solutions (100 mg mL-1) of the above standards were prepared and stored at 4ºC, and protected from daylight. They were appropriately diluted with double distilled water before being used as working solutions. 1.2. Extract preparation. Ivy (Hedera helix L.) was collected from the A. Borza Botanical Garden of Cluj-Napoca (46°45′36″N and 23°35′13″E) and was identified by Dr. M. Parvu, Babes-Bolyai
Chemistry and Physics of Lipids, 2003
Peroxidation of membrane phospholipids is an important determinant of membrane function. Previously we studied the kinetics of peroxidation of the polyunsaturated fatty acid (PUFA) residues in model membranes (liposomes) made by sonication of palmitoyllinoleoylphosphatidylcholine (PLPC). Since most biomembranes are negatively-charged, we have now studied the effect of negative surface charge on the kinetics of peroxidation of liposomes made of PLPC and 9% of one of the negatively-charged phospholipids phosphatidylserine (PS) or phosphatidic acid (PA). Peroxidation was initiated by either CuCl 2 or AAPH and continuously monitored spectrophotometrically. The following results were obtained: (i) The negative charge had only a slight effect on AAPH-induced peroxidation, but accelerated markedly copper-induced peroxidation of the liposomes, probably by increasing the binding of copper to the membrane surface. (ii) Ascorbic acid (AA) inhibited AAPH-induced but promoted copper-induced peroxidation in all the studied liposomes, probably by enhancing the production of free radicals upon reduction of Cu(II) to Cu(I). (iii) ␣-Tocopherol (Toc) inhibited AAPH-induced peroxidation in all the studied liposomes, whereas the effect of tocopherol on copper-induced peroxidation varied from being pro-oxidative in PA-containing liposomes, to being extremely anti-oxidative in PS-containing liposomes, even at very low tocopherol concentrations. The significance of the latter unusual protective effect, which we attribute to recycling of tocopherol by a PS-Cu complex, requires further investigation.
Chemistry and Physics of Lipids, 2007
Copper-induced peroxidation of liposomal palmitoyllinoleoyl-phosphatidylcholine (PLPC) is inhibited by ␣-tocopherol at micromolar concentrations. In our previous study we found that when the liposomes contain phosphatidylserine (PS), nanomolar concentrations of Toc were sufficient to inhibit peroxidation. In an attempt to gain understanding of the origin of this extreme antioxidative potency, we tested the antioxidative potency of 36 additional antioxidants and the dependence of their potency on the presence of PS in the liposomes. The results of these studies reveal that only 11 of the tested antioxidants possess similar antioxidative potency to that of Toc. These include trolox, butylated hydroxytoluene (BHT), curcumin, nordihydroguaiaretic acid (NDGA), diethylstilbestrol (DES), 2 of the 13 tested flavonoids (luteolin and 7,3 ,4 -trihydroxyflavone; T-414), ␣-naphthol, 1,5-, 1,6-and 1,7-dihydroxynaphthalenes (DHNs). Propyl gallate (PG), methyl syringate, rosmarinic acid, resveratrol, other flavonoids, as well as -naphthol, 1,2-, 1,3-, 1,4-, 2,3-, 2,6-, and 2,7-DHNs were either moderately antioxidative or pro-oxidative. For liposomes made of PLPC (250 M) and PS (25 M) the "lag" preceding copper-induced peroxidation (5 M copper) was doubled upon addition of 30-130 nM of the "super-active" antioxidants.
Functional Food Science, 2021
Background: Interest in the positive impact of naturally occurring polyphenols is still increasing in the scientific community. Research is focused mainly on their antioxidant properties, due to their significant effects in the prevention of diseases associated with oxidative stress. Pycnogenol is an extract from French maritime pine bark (Pinus pinaster), which is composed of a mixture of phenolic compounds: monomers (catechin, epicatechin, taxifolin), flavonoids (classed as procyanidins/proanthocyanidins), phenolic or cinnamic acids and their glycosides. Due to its composition, it has a high antioxidant capacity, and is used in traditional folk medicine, cosmetics and medicine. Purpose of the study: The aim is to study the antioxidant properties of pycnogenol in order to obtain experimental information on the antioxidant effect of pycnogenol in terms of concentration dependence and pH conditions. Methods: In our study, we used a methionine-riboflavin superoxide generator, and focused on determining the antioxidant capacity of Pycnogenol against the superoxide radical in different pH values (range 6.5 – 8) using the spectroscopic method. Results: Our results showed that the antioxidant properties increased with a higher concentration of the tested compound in the tested pH range. Amongst all tested pH values, the most appropriate for pycnogenol antioxidant capacity is slightly basic pH (pH 8). Conclusion: Information on the antioxidant and prooxidant properties of naturally occurring compounds is very important for understanding their activity and their proper use in prevention, disease treatment, and detection of pathological processes. The antioxidant activity of pycnogenol depends on the structure and concentration of antioxidants; it only slightly changes at different pH values. Increasing concentration of pycnogenol enhances its antioxidant properties. Keywords: Pycnogenol, reactive oxygen species, spectrophotometry, pH dependency
Evaluating the In Vitro Potential of Natural Extracts to Protect Lipids from Oxidative Damage
Antioxidants
Lipid peroxidation is a chemical reaction known to have negative impacts on living organisms’ health and on consumer products’ quality and safety. Therefore, it has been the subject of extensive scientific research concerning the possibilities to reduce it, both in vivo and in nonliving organic matrices. It can be started by a variety of oxidants, by both ROS-dependent and -independent pathways, all of them reviewed in this document. Another feature of this reaction is the capacity of lipid peroxyl radicals to react with the non-oxidized lipids, propagating the reaction even in the absence of an external trigger. Due to these specificities of lipid peroxidation, regular antioxidant strategies—although being helpful in controlling oxidative triggers—are not tailored to tackle this challenge. Thus, more suited antioxidant compounds or technologies are required and sought after by researchers, either in the fields of medicine and physiology, or in product development and biotechnology....