Antioxidant activity of chlorophylls and their derivatives (original) (raw)
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Journal of the Science of Food and Agriculture, 2001
Reactive oxygen species are potentially damaging molecules. An important function of antioxidants is to intercept harmful triplet states, in order to prevent the formation of singlet oxygen, or to quench singlet oxygen directly. However, antioxidants are also reactive towards other active oxygen species such as the hydroxyl radical, the superoxide anion and the non-excited oxygen ground state in the presence of radical initiators. It is well known that¯avonoids and carotenoids show strong antioxidant properties. Polyenes and carotenoids are the best known among the compounds that quench singlet oxygen by ef®cient energy transfer. A large number of modi®ed, synthetic analogues and derivatives have been synthesised to prepare even better quenchers than the natural carotenoids. Phenols are also excellent chain-breaking antioxidants. Recently, many indigoid dyes (including bacterial indigoids) were studied, with the remarkable result that most, but not all, members of this class of chromophores quench singlet oxygen at the diffusion limit and some of them are excellent radical traps. It has been shown in this study that a quantitative assessment of antioxidant properties of avonoids, carotenoids, phenols and natural indigoids can be achieved using the following three assays: (1) oxygen pressure dependence; (2) peroxide formation; (3) singlet oxygen quenching. Reactivities towards both excited states and ground state radicals can be properly described by these assays. The remarkable role of b-carotene as an`unusual antioxidant' (Burton GW and Ingold KU, Science 224: 569±573 (1984)) in reactions using various oxygen pressures becomes clearer. The socalled`pro-oxidant effects' concern primarily the antioxidant itself and its degradation, since no or very little damage to the substrate occurs in this type of experiment. Three main categories of antioxidants may be classi®ed: (1) excellent antioxidants that perfectly quench excited states as well as ground state radicals (eg actinioerythrol, astaxanthin); (2) good antioxidants that strongly inhibit peroxide formation but are less ef®cient in quenching excited states (eg¯avonols, tocopherols) or lead to considerable degradation of the antioxidant itself (eg b-carotene, lycopene); (3) moderate antioxidants that fail to excel in both reactivities (eg z-carotene,¯avone).
THE MEDICAL IMPORTANCE OF CHLOROPHYLLS AND THEIR DERIVATIVES
Plant pigments exist in varied forms, some with highly complex chemical structures. Chlorophylls represent the most important natural plant pigments. They are the green pigments that contribute in photosynthesis, and they are found in all the organisms preforming this process. Chlorophylls are complex liposoluble organic compounds, consisting of a porphyrin ring (tetrapyrroles macrocycle) with a central magnesium atom, a cyclopentanone ring and a side phytol chain. Two forms of chlorophylls (chlorophyll a and chlorophyll b) are embedded within the thylakoid membranes of higher plants" chloroplasts. Chlorophylls have various semi-synthetic derivatives, and chlorophyllins are the most studied among them. The synthesis of different chlorophyllins occurs by removing the phytol chain to increase the solubility in water, and replacing the central magnesium by a divalent cation such as copper, iron or zinc, which is important to retain the green colour of the pigments. Decades ago, human have taken chlorophylls to treat many medical conditions. In this review, we will summarize the potential health benefits and side effects for chlorophylls and their derivatives.
Chlorophylls and their Derivatives Used in Food Industry and Medicine
Mini-reviews in Medicinal Chemistry, 2017
Thylakoids and chloroplasts harbor several vital metabolic processes, but are most importantly associated with photosynthesis. The undisturbed functioning of this process necessitates the ceaseless synthesis of photosynthetic pigments, including closed tetrapyrroles such as chlorophylls (Chls). Chls probably represent the most abundant natural pigment molecules which are via photosynthesis not only crucial for the autotrophic production of food sources for heterotrophic organisms but have also contributed to oxygen production essential for aerobic metabolism. This review first briefly discusses the physico-chemical properties, biosynthesis, occurrence, in vivo localization and roles of the different Chl pigments. Then we provide a detailed overview about their potential applications in the food industry and medicine. These include the use of Chls and their derivatives (different chlorophyllins) as food colorants (identified as E140 and E141 in the European Union). Different sources used for industrial extraction as well as different factors influencing pigment stability during processing are also critically reviewed. The problems surrounding the nomenclature, the production and the composition of different chlorophyllin mixtures are also discussed. Finally, a comprehensive overview of the health benefits and potential medicinal applications of these pigments and the future directions of research in these fields are provided.
Antioxidative Activity of Porphyrin Derivatives
Bioscience, Biotechnology, and Biochemistry, 1993
In order to prevent lipid peroxidation in foods, antioxidants of natural origin have been widely investigated. 1) In the previous paper,2) we reported pyropheophytin a, one of the chlorophyll a~related compounds, as an anti oxidative component from Eisenia bicyclis (Japanese name "Arame").
Scientific Reports
The physicochemical and antioxidant properties of seven carotenoids: antheraxanthin, β-carotene, neoxanthin, peridinin, violaxanthin, xanthrophyll and zeaxanthin were studied by theoretical means. Then the Optoelectronic properties and interaction of chlorophyll-carotenoid complexes are analysed by TDDFT and IGMPLOT. Global reactivity descriptors for carotenoids and chlorophyll (Chla, Chlb) are calculated via conceptual density functional theory (CDFT). The higher HOMO–LUMO (HL) gap indicated structural stability of carotenoid, chlorophyll and chlorophyll-carotenoid complexes. The chemical hardness for carotenoids and Chlorophyll is found to be lower in the solvent medium than in the gas phase. Results showed that carotenoids can be used as good reactive nucleophile due to lower µ and ω. As proton affinities (PAs) are much lower than the bond dissociation enthalpies (BDEs), it is anticipated that direct antioxidant activity in these carotenoids is mainly due to the sequential proton...
Natural antioxidants–properties and possible applications
Journal of Applied Biotechnology & Bioengineering
There is an interest in the use of compounds able to prevent organism damages. Antioxidants are such compounds that can protect from cells damages caused by free radicals and may be used in the treatment and prevention on many diseases, such as cancer, cardiovascular disease, diabetes, brain stroke, skin diseases as well as they delay the aging process. There are many sources of antioxidants. They can be synthetic or natural and especially those derived from natural sources, demand special attention. Phenolic compounds are substances which mainly possess such activity, but also vitamins and minerals. There are a lot of antioxidants, but in that review, the chosen compounds with outstanding antioxidant activity, mainly used in pharmaceuticals and cosmetics were described. The review shows the activity of phenolic acids (ferulic acid and caffeic acid) and polyphenols (ellagic acid, curcumin, genistein, hydroxytyrosol, resveratrol) and vitamins (C and E).
Estimation of free radical-quenching activity of leaf pigment extracts
Phytochemical Analysis, 2001
The chromogen 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) radical (ABTS Á ) can be directly generated by the enzymatic system formed by hydrogen peroxide and horseradish peroxidase in ethanolic media. The reaction is time-and concentration-dependent, and the ABTS Á generated shows excellent stability. The method is an adaptation of the decolouration method previously reported (Cano et al. 1998. Phytochem Anal 9:196-202), which was used for estimating anti-oxidant activity in aqueous media. When the assay described here was used to quantify the anti-oxidant activity of two anti-oxidants, Trolox (an analogue of vitamin E) and b-carotene, the latter had 2.5 times better anti-oxidant capacity than Trolox at the same concentration. The free radical quenching activity (anti-oxidant activity) of leaf pigment extracts was measured and related to the the carotenoid contents in leaf extracts of barley, oat and citrus. The possibilities of using this experimental approach to evaluate the status of photoprotective pigments are discussed.
Antiradical Methods in Evaluating Antioxidant Potential of Preparations of Plant Origin
Medicinal and Aromatic Plant Science and Biotechnology, 2007
The formula for antioxidants is very difficult to define, although they had been used in food for centuries. Antioxidants are compounds used to delay the accumulation of free radicals and strengthen the oxidative stability of food. According to the activity mechanism of antioxidants, they can act by means of many different processes. The properties of antioxidants are also the result of many factors, like mixing ability and activity in different reaction environment systems, stability in processing time, as well as research methods used. However, there exist limitations concerning the use of these substances. Research reflects much interest on the influence of radicals generated by different environmental factors on human health and food stability, but there is still a need to find the substances that have wide antiradical properties. There are many methods for evaluating antiradical activity. This manuscript discusses the most popular and adequate methods. Widely used parameters of free radical scavenging ability as well as the evaluation of antioxidant potential are reactions with ABTS +• and DPPH • radicals, the luminol chemiluminescence method, ORAC, FRAP, TRAP and many other assays. The aim of the comparison of these methods and this review is to qualify the effectiveness of different natural substances as scavengers possessing antiradical activity.
Free Radicals and Antioxidants, 2014
Introduction: The antioxidant and radical scavenging properties of some of the hydroxy phenyl derivatives such as 4-Hydroxybenzoic acid (1), 3-Hydroxy-4-methoxycinnamic acid (2), 3-(4-Hydroxy-3,5-dimethoxyphenyl)prop-2enoic acid (Sinapic acid) (3), 4-Hydroxy-3,5-dimethoxybenzoic acid (4), 3,4-Dihydroxycinnamic acid (Caffeic acid) (5) and 5-Isopropyl-2-methylphenol (6), which are naturally present in fruits and vegetables, were investigated. Methods: The following analysis were conducted: The total antioxidant activity via the ferric thiocyanate method; 2,2'-azinobis-(3-ethylbenzothiazole-6-sulphonate) (ABTS) radical scavenging activity; superoxide anion radical (O 2 •-) scavenging activity; the total reduction power through potassium ferricyanide reduction method; Cupric ions (Cu 2+) reduction capacity through Cuprac method; hydrogen peroxide scavenging activity and chelating activity of ferrous ions (Fe 2+). Furthermore, α-tocopherol, butylatedhydroxyanisole (BHA) and quercetin were used as the reference antioxidant compounds. Results: In the comparison of initial states and the products, it's observed that at the 50th hour the linoleic acid emulsion at 30 μg/mL concentration inhibited the lipid peroxidation by 85%, 60.7%, 69%, 45.4%, 80.4% and 31%, respectively. On the other hand, it's observed that the linoleic acid emulsion of α-tocopherol, (BHA) and quercetin inhibited the lipid peroxidation by 62.65%, 35.84% and 34.82% respectively, at the same concentration. Conclusions: It's found as a result of our studies that some of the phenolic compounds such as 4-Hydroxybenzoic acid (1), 3-Hydroxy-4-methoxycinnamic acid (2), 3-(4-Hydroxy-3,5-dimethoxyphenyl)prop-2-enoic acid (3), 4-Hydroxy-3,5dimethoxybenzoic acid (4), 3,4-Dihydroxycinnamic acid (5) and 5-Isopropyl-2-methylphenol (6) which are naturally present in foods. They have higher total antioxidant activity, radical scavenging and metal chelating activities than the widely used powerful antioxidant compounds such as BHA, Quercetin and α-tocopherol.