Enzymatic Synthesis of Lipophilic Esters of Phenolic Compounds, Evaluation of Their Antioxidant Activity and Effect on the Oxidative Stability of Selected Oils

Abstract

The aim of the study was to compare the effect of the substituent and its position in the aromatic ring on the antioxidant activity of hexanoic acid esters obtained in reactions catalyzed by immobilized lipase B from Candida antarctica. 4-Hydroxybenzyl hexanoate, 2-hydroxybenzyl hexanoate, 4-methoxybenzyl hexanoate, and vanillyl hexanoate were obtained with conversion yields of 50 to 80%. The antioxidant activity of synthesized esters, their alcohol precursors and BHT (Butylated HydroxyToluene) was compared with DPPH (2,2-diphenyl-1-picrylhydrazyl), CUPRAC (cupric ion reducing antioxidant capacity), and CBA (crocin bleaching assay) methods. Furthermore, it was investigated whether the presence of vanillyl hexanoate in a concentration of 0.01 and 0.1% affected the oxidative stability of sunflower and rapeseed oils in the Rancimat test. It was observed that the antioxidant activity of hexanoic acid esters depends on the presence and position of the hydroxyl group in the aromatic ring. The highest activities were found for vanillyl alcohol, vanillyl hexanoate, and BHT. The addition of the ester and BHT significantly extended the induction times of the tested oils, and these compounds exhibited similar activity. Vanillyl hexanoate increased the induction time from 4.49 to 5.28 h and from 2.73 to 3.12 h in the case of rapeseed and sunflower oils, respectively.

Lipase-Catalyzed Synthesis, Antioxidant Activity, Antimicrobial Properties and Molecular Docking Studies of Butyl Dihydrocaffeate

“…As a consequence of enzymatic esterification, vanillyl hexanoate was synthesized and compared with its precursor, vanillyl alcohol in DPPH and CUPRAC tests. In both assays, the more lipophilic compound had lower activity [ 18 ]. The same may be concluded after analyzing the data from papers of Roleira et al [ 19 ] and Gaspar et al [ 20 ] where it was stated that phenolic acids exhibited higher antioxidant capacity than their esters or amides, which can be related to the steric hindrances of alkyl groups, but on the other hand, the change of the lipophilicity through esterification enhances the applicability of such derivatives in other systems, e.g., lipid-rich matrices.…”

Antifungal, Antioxidant and Antibiofilm Activities of Essential Oils of Cymbopogon spp.

“…Interestingly, in this study, the antibiofilm activity should also be related to the antioxidant activities of C. citratus and C. proximus EOs. Indeed, both EOs, at very low concentrations, showed radical activities scavenging DPPH and ABTS in vitro (50%) comparable to those of synthetic antioxidants (i.e., butylated hydroxytoluene -BHT), possibly due to the high content of monoterpenes activities [ 43 ]. In particular, monoterpenes are able to absorb or neutralize free radicals due to their phenolic structure and redox properties [ 44 , 45 ].…”

Bioactive Compounds from Cardoon as Health Promoters in Metabolic Disorders

“…Furthermore, scopoline was only reported in the capitula and florets [44]. Aromatic compounds have been described as antioxidant and antimicrobial agents [97]. These compounds have been studied due to their advantages over antibiotics as growth promoters, being reported as residue-free and generally recognized as safe (GRAS) [98].…”