Isolation, Purification And Structure Identification Of Anthocyanins And Its Antioxidant Activity From Lichi Pericarp

Litchi is a kind of subtropical fruit with high commercial value, and the litchi pericarp is rich in anthocyanins that is a good source of natural antioxidant. Specially, Guangdong Nuomici litchi was used to study the technics of extraction and purification, the stability. a series of researches was carried out including structural identification of anthocyanins and antioxidantion in vitro and in vivo from lichi pericarp, with a view to provide experimental basis for the utilization of litchi pericarp as a natural resources. the main results are as follows:1. The extraction and purification of lichi pericarp pigmentThe XAD-7HP resin was the best one for the purification of Lichi pericarp pigment by a comparative analysis of the absorption rate and the desorption rate. The purification conditions included the optimal pH of 1.0, the sample adding concentration of 20 mg/L, and using ethanol concentration of 80% for desorption including 0.1% hydrochloric acid. The anthocyanin was well separated from polyphenols using of Sephadex LH-20. after purified by Sephadex LH-20, the anthocyanins content of lichi pericarp pigment reached 82.7%.2. The stability of lichi pericarp pigmentThe stability of Litchi pericarp pigment was poor when it exposed to different pHs, light, heat, and oxidants; sodium benzoate and glucose reduced its stability.3.The preliminary structure characterization of litchi pericarp anthocyaninsThe main anthocyanins of litchi pericarp after purified by the macroporous resin iscyanidin-3-rutinoside, Results from the analysis of UV spectroscopy, paper chromatogramphy, infrared spectrum, and HPLC chromatogramphy of cyanidin-3-rutinoside indicated that the basic skeleton of the molecular structure was in accord with the one reported before.4. The antioxidant effect of litchi pericarp anthocyanins in vitroThe total antioxidant capacity and the radical scavenging effect of DPPH, hydroxyl radical, superoxide anion were studied to evaluate the antioxidant effect In vitro. which the results suggested LPA had excellent antioxidant ability. The IC50 (half-inhibitory concentration) of LPA on DPPH, hydroxyl radical, and superoxide were 1.31 mg/L, 0.69 mg/L, 1.78 mg/L, respectively, indicating that the antioxidant effect of LPA was greater than Vc under the same concentrations and could be used as an good natural antioxidant.5. Anti-lipid peroxidation effect of litchi pericarp anthocyanins invitroStudy on anti-lipid peroxidation in vitro and antioxidant animal model in vivo showed that LPA was also an effective antioxidant, which could increase the ability of anti-reactive oxygen serum in vitro in a certain range of concentrations, could restrain MDA formation of liver mitochondria in mice liver tissue homogenate, and could restrain the liver mitochondria swelling. The dose-response relationship was obvious. The results suggested that LPA could be used as an antioxidant and might protect mice organelle and cells and tissues from the injury of oxidation.6. Anti-lipid peroxidation effect of litchi pericarp pigment in vivoStudying on the litchi anti-lipid peroxidation effects of LPP in vitro in anti-lipid peroxidation model of mice showed that addition of LPP reduced the MDA content of percutaneous liver homogenate of mice serum and increased the activity of SOD and GSH-Px.