Preliminary Study On The Identification Of Anthocyanins In Edible Plant Fruits And The Antioxidant Activity Of Extracts

Anthocyanins are one of the most important natural pigments in nature. They have the vast potential for future development for a lot of advantages including safety, non-toxicity, source extensiveness, good health-care efficacy and nutritional values. In this study, six plant fruits (blueberry, grape, raisin, hawthorn, pomegranate, red pitaya) were used for experiments. The major research contents are as follows.(1) Extraction, purification and identification of anthocyaninsA combination of solvent extraction method and ultrasonic assisted extraction method (UAE) was used to extract anthocyanins from six plant fruits. The optimum extraction conditions (37℃, pH=2,60% ethanol solution, solid-liquid ratio of 1:8 (g/mL),1 h of ultrasonic treatment (40 kHz,250 W), repeating 2-3 times) were obtained by optimizing the acidity of the extraction solvent. A combination of solvent extraction method and HP2MGL macroporous resin chromatography method was used to purify the anthocyanin, which provides a theoretical basis for anthocyanin products from plant fruits.The qualitative analyses of active ingredients of anthocyanins from six plant fruits were determined using high performance liquid chromatography (HPLC) equipped with a diode array detector (DAD) and characterized by UV-visible spectra and electrospray ionization tandem mass spectrometry (ESI-MS2). The results show that anthocyanins from six plant fruits have various species, from which blueberry are at most, followed by raisin and pomegranate.(2) The study on antioxidant activities of extracts from plant fruitsAn initial comparison of antioxidant activities of six plant fruits were used by the DPPH method with their ICso values. The order of the antioxidant activity was raisin> hawthorn> blueberry> pomegranate> grape> red pitaya. The DPPH-HPLC method was used to analyze the reduction rate of antioxidant ingredients of extractive matters from six plant fruits. The results show that antioxidant activities of raisin and pomegranate extracts are the strongest in six plant fruits, which is followed by hawthorn. The ABTS method was used to determine total antioxidant activities (TAA) of extraction contents from six plant fruits. The results show that all the extracts from six plant fruits have the antioxidant activity, of which blueberry extract is the strongest, reaching 2.83 mmol/g. Antioxidant activities of crude extracts and the corresponding refined extracts from six plant fruits were evaluated in hydrogen peroxide (H2O2)-induced rattus norvegicus adrenal pheochromocytoma PC 12 cell injury model experiment. The results show that refined extracts from 3 plant fruits (grape, hawthorn, red pitaya) have significantly higher cell survival rate compared with model cells and lower cell survival rate compared with Trolox. Although antioxidant activities of active ingredients of extractions from six plant fruits failed to be analyzed by using high performance liquid chromatography-chemiluminescence technique (HPLC-CL), it also provides a method and technical support for the related experiments in further study.The above experimental results show that antioxidant activity of raisin extract is the strongest in six plant fruits, and hawthorn is at the second place.