Ascorbic acid-induced degradation of liposome-encapsulated acylated and non-acylated anthocyanins of black carrot extract

Abstract

Background: In the presence of ascorbic acid, the degradation of acylated (sinapic, ferulic and p-coumaric acid derivatives of cyanidin-3-xylosylglucosylgalactoside) and non-acylated anthocyanins of black carrot extract (BCE) encapsulated in liposomes was studied. BCEs (0.2% and 0.4% w/w) were encapsulated in liposomes using different lecithin concentrations (1%, 2% and 4% w/w).

Results: The liposomes were prepared with particle diameters of less than 50 nm and zeta potentials of about -21.3 mV for extract-containing liposomes and -27.7 mV for control liposomes. The encapsulation efficiency determined using high-performance liquid chromatography (HPLC) showed that increasing lecithin levels increased the efficiency to 59% at the same extract concentration. The concentrations of total anthocyanins and individual anthocyanins were determined for ascorbic acid (0.1% w/w)-degraded extract and liposomes (containing 0.2% w/w extract). Anthocyanin quantification of both liposomal and extract samples was performed by HPLC using cyanidin-3-O-glucoside chloride as standard. Five anthocyanins in the extract and encapsulated liposomes were quantified during 24 h (0-24 h): cyanidin-3-xylosylglucosylgalactoside 1.0-0.51 and 0.82-0.58 mg g^-1 , cyanidin-3-xylosylgalactoside 2.5-1.1 and 2.2-1.7 mg g^-1 , cyanidin-3-xylosyl(sinapoylglucosyl)galactoside 0.51-0.14 and 0.35-0.28 mg g^-1 , cyanidin-3-xylosyl(feruloylglucosyl)galactoside 1.37-0.41 and 1.06-0.98 mg g^-1 , and cyanidin-3-xylosyl(coumaroylglucosyl)galactoside 0.28-0.08 mg g^-1 for extract and 0.27-0.26 mg g^-1 for liposomes, respectively.

Conclusions: This study demonstrates the potential beneficial effect of liposomal encapsulation on individual, particularly acylated, anthocyanins after addition of ascorbic acid during a storage time of 24 h.

Keywords: acylation; anthocyanins; ascorbic acid; black carrot; encapsulation; liposomes.