69573-61-1Relevant articles and documents
Optimizing the efficiency of antioxidants in emulsions by lipophilization: Tuning interfacial concentrations
Costa, Marlene,Losada-Barreiro, Sonia,Paiva-Martins, Fátima,Bravo-Díaz, Carlos
, p. 91483 - 91493 (2016)
Optimization of the efficiency of antioxidants, AOs, in lipid-based emulsions via chemical modifications of their reactive moieties is not always possible because of the inherent experimental difficulties and because of the regulatory status of AOs. Esterification of hydrophilic AOs may be a practical, convenient, alternative approach. Here we employed a series of caffeic acid derivatives bearing the same reactive moiety but of different hydrophobicity (alkyl chain lengths of 1 to 16 carbon atoms) to investigate the effects of hydrophobicity on the oxidative stability of stripped corn oil-in-water emulsions. AO efficiency was determined by monitoring the production of primary oxidation products (conjugated dienes) with time and a non-linear, parabolic-like, variation of their efficiency with the number of C atoms in their alkyl chain, with a maximum at the C8 derivative, found. To rationalize the results, we also determined the distribution of the AOs between the oil, interfacial and aqueous regions of the same emulsions by employing a recently developed kinetic method that provides the partition constants of the AO between the oil-interfacial, PIO, and water-interfacial, PIW, regions of the intact emulsions. Values of both PIO and PIW range between 180-2000, suggesting that the transfer of the AOs to the interfacial region is spontaneous. The results indicate that the variations of both the percentage of AO in the interfacial region, % AOI, of the emulsions and the AO efficiency with the number of C atoms in the AO alkyl chain parallel each other with a maxima at the C8 derivative. The results illustrate an effective and convenient way to control lipid oxidation by modulation of the hydrophobicity (HLB) of the AOs. An increase in the alkyl chain length of the AOs promote their incorporation into the interfacial region of emulsions but only up to a critical chain length, after which a further increase makes their efficiency decrease as a consequence of the decrease in their % AOI.
Antioxidant properties and efficacies of synthesized alkyl caffeates, ferulates, and coumarates
Sorensen, Ann-Dorit Moltke,Jacobsen, Charlotte,Durand, Erwann,Laguerre, Mickal,Bayrasy, Christelle,Lecomte, Jrme,Villeneuve, Pierre
, p. 12553 - 12562 (2015/04/21)
Caffeic, ferulic, and coumaric acids were lipophilized with saturated fatty alcohols (C1-C20). The antioxidant properties of these hydroxycinnamic acids and their alkyl esters were evaluated in various assays. Furthermore, the antioxidant efficiency of the compounds was evaluated in a simple o/w microemulsion using the conjugated autoxidizable triene (CAT) assay. All evaluated phenolipids had radical scavenging, reducing power, and metal chelating properties. Only caffeic acid and caffeates were able to form a complex with iron via their catechol group in the phenolic ring. In the o/w emulsion, the medium chain phenolipids of the three homologues series were most efficient. The antioxidant properties and efficacies were dependent upon functional groups substituted to the ring structure and were in the following order: caffeic acid and caffeates > ferulic acid and ferulates > coumaric acid and coumarates. Moreover, the results demonstrated that the test system has an impact on the antioxidative properties measured.
