Enzymatic synthesis, structural characterization and antioxidant capacity assessment of a new lipophilic malvidin-3-glucoside–oleic acid conjugate

Abstract

The chemical modification of anthocyanins (water-soluble pigments) into more lipophilic compounds is very important to expand their application in the food, medical and cosmetic industries. In this work, the synthesis of a pure malvidin-3-glucoside-oleic acid ester derivative was achieved by enzymatic catalysis. This approach allowed us to synthesize a novel compound, malvidin-3-O-(6''-oleoyl)glucoside (Mv3glc-OA), which was structurally characterized by mass spectrometry and for the first time by NMR spectroscopy. The enzymatic reaction revealed to be regioselective giving only one ester product. Antioxidant features of the malvidin-3-glucoside lipophilic derivative by means of DPPH, FRAP and lipid peroxidation assays were assessed, which confirmed that the structural modification of the genuine malvidin-3-glucoside into a more lipophilic compound did not compromise its antioxidant potential and protected more effectively a lipidic substrate from oxidation, which is an important insight for future technological applications.

Selective enzymatic lipophilization of anthocyanin glucosides from blackcurrant (Ribes nigrum L.) skin extract and characterization of esterified anthocyanins

“…As shown in two acylated glucosides. 13 C NMR spectra confirmed that acylation took place at the primary hydroxyl group of glucose because of the C6'' signal downfield to 63.5 ppm, as already reported for analogous compounds (Cruz et al, 2016). Using NMR, it was determined that the ratio between Cy3glc-C8 and Dp3glc-C8 is 3:1, which is interesting considering the relative ratio of Cy3glc and Dp3glc in the extract, is approximately 0.5:1.…”

“…Previous work has reported the chemical acylation of a pure malvidin-3-O-glucoside Mv3glcto yield the stearic acid derivative, using stearoyl chloride in anhydrous acetonitrile (Cruz et al, 2015); however, the reaction was not regioselective and a complex mixture of mono-, di-, and tri-ester derivatives was obtained. In contrast, the regioselective synthesis of a pure malvidin-3-glucoside-oleic acid ester derivative was achieved by enzymatic catalysis with CalB, yielding only one ester product (21% conversion) (Cruz et al, 2016). The more lipophilic derivative did not show any reduction in antioxidant potential and protected more effectively a lipidic substrate from oxidation.…”

Food colorants: their past, present and future

“… successfully acylated malvidin‐3‐glucoside with stearoyl chloride to provide the stearic acid derivative, but the reaction was not regioselective and mono‐, di‐ and tri‐ester derivatives were isolated that were very difficult to separate. In contrast, the research group showed that regioselective synthesis (where only the primary –OH on the glucose moiety was derivatised) of a malvidin‐3‐glucoside‐oleic acid ester derivative was achieved by enzymatic catalysis with Candida antarctica Lipase B ( Ca lB), giving only one ester product ; the derivative was more lipophilic and more stable to oxidation.…”

Impact of a Water‐Soluble Gallic Acid‐Based Dendrimer on the Color‐Stabilizing Mechanisms of Anthocyanins

“…[13] Other strategies for color stabilization of anthocyanins found in plants is to make acylated derivatives, which are usually used as food colorants because of their superior stabilityo vern on-acylated anthocyanins. [14,15,32,54] Supramolecular host-guest interactions have been widely applied in chemicala nd biochemical fields. Host-guest systems are formed by molecular recognition of ar eceptor (host) and a ligand (guest) by means of noncovalent interactions, such as electrostatic, hydrogen bonds, hydrophobic interactions,chemical coordination, van der Waals forces, and p-p stacking.…”