Acylation Reaction Of Blueberry Anthocyanins With Gallic Acid And Its Activity Research

Anthocyanins are a group of widespread natural active substances in plants, having some kinds of important physiological functions and prospects for the development and utilization. However, anthocyanin molecules have some disadvantage in vitro, such as structural unstability, undissolved in oil, low bioavailability. These restrict application and development of anthocyanin. In this study, under the precondition of not damaging its premier physiological active function, anthocyanin was chemical modified. Gallic acyl anthocyanin (GAA) was prepared by chemical acylation with blueberry anthocyanins and gallic acid, and triacetyl gallic acid chloride was synthetized as a relevant acylating agent. The reaction process was monitored by thin-layer chromatography, and purity of the product was determined by melting point measured with capillary tube method. The infrared spectra of GAA, triacetyl gallic acyl anthocyanins, and original anthocyanins were compared and the results proved synthesis successfully. Acylation degree was measured with HPLC. The antioxidant activity of GAA was tested through comparison with original blueberry anthocyanin extracts by using different techniques, inclouding DPPH free radical, ABTS free radical, superoxide anion, hydroxyl radical and lecithin liposome. In addition, cell experiment was carried out and results showed that gallic acyl anthocyanin potently suppressed the proliferation of Hep G2cells and Caco-2cells. Results were as follows:(1) The synthetic method for gallic acyl anthocyanin was established:a. to protect the active group; b. to prepare acyl chloride acylating agent; c. to prepare triacetyl gallic acyl anthocyanins; d. wipe off covering group. Acylation degree was2.1. Total phenols content of gallic acyl anthocyanin was179.7±8.7mg/g, that of blueberry anthocyanin was58.1±6.4mg/g. The total phenols content of modified anthocyanin was3times more than the original.(2) Antioxident activity was enhanced by chemical modification. Gallic acyl anthocyanin showed more effective antioxident activity than blueberry anthocyanin in the series of antioxidant assays except hydroxyl radical scavenging assay. The IC50values of GAA and blueberry anthocyanin for DPPH radical scavenging assay were39.8μg/mL and26.8μg/mL. The IC50values of GAA and blueberry anthocyanin for ABTS radical scavenging assay were57.5μg/mL and22.1μg/mL. The IC50values of GAA and blueberry anthocyanin for superoxide anion scavenging assay were27.0μg/mL and17.5μg/mL. The IC50values of GAA and blueberry anthocyanin for hydroxyl radical scavenging assay were153.6μg/mL and160.3μg/mL. The IC50values of GAA and blueberry anthocyanin for lipid peroxidation inhibiting assay were219.7μg/mL and171.7μg/mL.(3) MTT assay showed that gallic acyl anthocyanin and blueberry anthocyanin exhibited certain inhibition effect on proliferation of human hepatoma Hep G2cells and human colon cancer Caco-2cells. The inhibition effect of gallic acyl anthocyanin was more potently than that of blueberry anthocyanin. The IC50values of GAA and blueberry anthocyanin for Hep G2cells in24h were309.3μg/mL and717.8μg/mL, for Caco-2cells in24h were605.1μg/mL and2929.3μg/mL.