Phenolipids, Amphipilic Phenolic Antioxidants with Modified Properties and Their Spectrum of Applications in Development: A Review

Abstract

Polyphenols, as secondary metabolites from plants, possess a natural antioxidant capacity and biological activities attributed to their chemical and structural characteristics. Due to their mostly polar character, polyphenols present a low solubility in less polar environments or hydrophobic matrices. However, in order to make polyphenols able to incorporate in oils and fats, a transformation strategy is necessary. For the above, the functionalization of polyphenols through chemical or enzymatic lipophilization has allowed the synthesis of phenolipids. These are amphipilic molecules that preserve the natural phenolic core to which an aliphatic motif is attached by esterification or transesterification reactions. The length of the aliphatic chain in phenolipids allows them to interact with different systems (such as emulsions, oily molecules, micelles and cellular membranes), which would favor their use in processed foods, as vehicles for drugs, antimicrobial agents, antioxidants in the cosmetic industry and even in the treatment of degenerative diseases related to oxidative stress.

Keywords: amphipilic molecules; antioxidant capacity; biological activity; lipophilization; phenolipids; polyphenolic compounds.

Figure 1

Graphical abstract of synthesis of phenolipids.

Figure 2

Fischer Esterification: (A) general esterification reaction by the Fischer method, which consists of the coupling between a carboxylic acid and an alcohol in the presence of an acid catalyst. (B) esterification reaction mechanism, in which a proton is transferred to the carbonyl oxygen; subsequently, the carbon undergoes a nucleophilic attack that leads to the transfer of the proton and finally to the formation of the ester with loss of water.

Figure 3

Transesterification. (A) general transesterification reaction, which consists of the process of exchanging the alkoxy group of an ester with another alcohol. The reaction is catalyzed by the addition of an acid that protonates the carbonyl group and makes the ester more electrophilic or by the addition of a base (that makes the alcohol more nucleophilic). (B) transesterification reaction mechanism, in which the carbon of the carbonyl group of the initial ester reacts to form a tetrahedral intermediate, which can revert to the initial compound or proceed to the transesterified product.