Significant enhancement in radical-scavenging activity of curcuminoids conferred by acetoxy substituent at the central methylene carbon

Kim, Mi Kyoung; Jeong, Wooseong; Kang, Jihoon; Chong, Youhoon

doi:10.1016/j.bmc.2011.04.055

Cited by 28 publications

(18 citation statements)

References 21 publications

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“…Barclay et al [25] observed that the antioxidant activities of o-methoxyphenols decreased in hydrogen bond accepting media. According to some authors the OH groups on the two phenyl rings participate in the reactions [e.g., 13,14,25], others claim that the β-diketone moiety is responsible for the antioxidant action [12], while other publications [26,27] indicate that the strong antioxidant activity of curcumin originates mainly from the phenolic OH groups, but a small fraction is due to the >CH 2 site in the β-diketone moiety. Not only the site but also the reaction mechanism of antioxidant activity is controversial.…”

Section: Introductionmentioning

confidence: 99%

Processing stabilisation of PE with a natural antioxidant, curcumin

Tátraaljai

Kirschweng

Kovács

et al. 2013

European Polymer Journal

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The potential use of natural antioxidants for polyolefin stabilisation came into the centre of attention because of some doubts about the effects of the reaction products of synthetic phenolic antioxidants on human health. The effect of curcumin on the melt stability of polyethylene was investigated in this paper with and without a phosphonite stabiliser by using multiple extrusions. Irganox 1010 was applied as reference phenolic antioxidant.Curcumin was characterised by FT-IR and UV-VIS spectroscopy, as well as by thermal analysis. Its stabilisation efficiency was determined by measuring the chemical structure, the rheological properties, the residual thermo-oxidative stability, and the colour of the polymer.The results reveal that the melt stabilising efficiency of curcumin is superior to that of the synthetic antioxidant investigated and is further enhanced by the addition of the phosphonite secondary antioxidant. The changes in the characteristics of the polymer indicate that besides the phenolic OH groups also the linear linkage between the two methoxyphenyl rings of curcumin participates in the stabilisation reactions.

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Section: Introductionmentioning

confidence: 99%

Processing stabilisation of PE with a natural antioxidant, curcumin

Tátraaljai

Kirschweng

Kovács

et al. 2013

European Polymer Journal

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“…The actual reaction site and the mechanism of free radical scavenging have not been clarified unambiguously yet. According to some authors the OH groups on the two phenyl rings participate in the reactions [e.g., 29,33,34], others claim that the β-diketone moiety is responsible for the antioxidant action [35], while other publications [36][37][38] indicate that the strong antioxidant activity of curcumin originates mainly from the phenolic OH groups, but the central methylene group of the heptadione link plays also a role. However, the site of double bond in the β-diketone moiety participating in addition reactions depends also the chemical nature of the reaction partner [39].…”

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confidence: 99%

Efficiency of curcumin, a natural antioxidant, in the processing stabilization of PE: Concentration effects

Kirschweng

Tátraaljai

Földes

et al. 2015

Polymer Degradation and Stability

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The stabilising efficiency of curcumin was studied in polyethylene during processing and under oxygen at high temperature. The effect of the natural antioxidant was investigated at concentrations of 0 to 1000 ppm in combination with a phosphonite secondary antioxidant (Sandostab P-EPQ) of 1000 and 2000 ppm, respectively. The polymer was homogenized with the additives then processed by six consecutive extrusions taking samples after each processing step. The samples were characterized by FT-IR spectroscopy, melt flow index, colour, and OIT measurements. Compared to the effect of pure phosphorous antioxidant, the melt stability of PE is increased already at 5 ppm curcumin content. The melt as well as the high temperature oxidative stability (OIT) of the polymer are controlled by both types of antioxidants. Curcumin hinders the oxidation of polyethylene and the formation of long chain branches during processing, which can be attributed to the fact that curcumin is not only a hydrogen donor but its unsaturated linear moiety can also scavenge alkyl and oxygen centred macroradicals. Curcumin discolours polyethylene already at small concentrations but the colour fades with increasing number of extrusions.Keywords: curcumin, natural antioxidant, polyethylene, stabilisation, phosphonite 3 IntroductionStabilisation of polyolefins with natural antioxidants got into the focus of attention recently because of the unknown effects of the reaction products of synthetic phenolic antioxidants on human health [1]. Health safety has vital importance in many application areas, like food contacting objects (e.g., packaging materials, water pipes), medical applications, toys, etc. The small molecular mass additives used in polyolefins for stabilisation, colouring, or antiblocking are generally polar compounds, therefore their solubility is small and migrate onto the surface of the polymer during application [2]. Their dissolution into contacting substances cannot be avoided but any harmful effect must be prevented.Among the natural antioxidants, first α-tocopherol was studied extensively for the stabilisation of polyolefins [e.g., 3-9]. Intensive research resulted in the application of α-tocopherol for the stabilisation of ultra high molecular mass polyethylene (UHMWPE) used as total joint implant [e.g., 10-15]. Even an ASTM standard specification was implemented for medical grade UHMWPE blended with vitamin E [16]. The study of different natural antioxidants in polymers has been widely extended lately. The goals of the investigations are mainly the improvement of the safety of packaging materials and the development of functional packaging [e.g., 17-25].Curcumin, 1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, is the principal curcuminoid of Curcuma longa rhizomes (turmeric). The powdered root is used as a spice, food colorant, and food preservative. The effects and reactions of curcumin have been the subject of investigation in the fields of biology, medicine, pharmacology, and in the food industry yielding a la...

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“…Previously reported methods for decomplexation of curcumin‐BF 2 adducts employed NaOH in MeOH under heating, or aq. AcOH . Decomplexation of 3‐BF 2 can be conveniently effected in MeOH/H 2 O, by microwave irradiation (MWI), or by using a Monowave reactor, in the presence of sodium oxalate, to afford the decomplexed CUR compounds 3 , Scheme .…”

Section: Resultsmentioning

confidence: 99%

A Flexible Strategy for Modular Synthesis of Curcuminoid‐BF₂/Curcuminoid Pairs and Their Comparative Antiproliferative Activity in Human Cancer Cell Lines

et al. 2020

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Significant enhancement in radical-scavenging activity of curcuminoids conferred by acetoxy substituent at the central methylene carbon

Cited by 28 publications

References 21 publications

Processing stabilisation of PE with a natural antioxidant, curcumin

Processing stabilisation of PE with a natural antioxidant, curcumin

Efficiency of curcumin, a natural antioxidant, in the processing stabilization of PE: Concentration effects

A Flexible Strategy for Modular Synthesis of Curcuminoid‐BF₂/Curcuminoid Pairs and Their Comparative Antiproliferative Activity in Human Cancer Cell Lines

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Significant enhancement in radical-scavenging activity of curcuminoids conferred by acetoxy substituent at the central methylene carbon

Cited by 28 publications

References 21 publications

Processing stabilisation of PE with a natural antioxidant, curcumin

Processing stabilisation of PE with a natural antioxidant, curcumin

Efficiency of curcumin, a natural antioxidant, in the processing stabilization of PE: Concentration effects

A Flexible Strategy for Modular Synthesis of Curcuminoid‐BF2/Curcuminoid Pairs and Their Comparative Antiproliferative Activity in Human Cancer Cell Lines

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A Flexible Strategy for Modular Synthesis of Curcuminoid‐BF₂/Curcuminoid Pairs and Their Comparative Antiproliferative Activity in Human Cancer Cell Lines