Analysis Of Major Anthocyanins Composition And Correlation Properties Of Myrobalan Plum (Prunus Cerasifera Ehrh.) Fruit

Wild Myrobalan plum （Prunus cerasifera Ehrh.） which belongs to Rosaceae Prunusplants is a rare endangered wild fruit tree found on the Big West Ditch and Small West Ditchof Huocheng town, Xinjiang, China. It is the third century warm temperate broad-leavedforest relict community.Recently. The number of wild Myrobalan plum trees is reducingsharply because of reclamation, overstocking and natural disaster. To protect the wildresource, a lot of researches were carried out, which mainly focused on the genetic diversity,organic acids, pectin, VC, mineral and amino acids of Myrobalan plums. The peels of theMyrobalan plum come in three colors: yellow, red, and purple. In this article, Myrobalanplum fruits of different colour were used as materials to study the antioxidant activities ofextracts of the fruits and detect the main anthocyanins of Myrobalan plum peel with theirprofiles. The result is as follows:1. The phenolic contents of extracts of Myrobalan plum fruits were determined by Folin–Ciocalteau method and the antioxidant activities of extracts of Myrobalan plum fruits weredetected by FRAP （ferric reducing antioxidant power） method. The results showed that thephenolic content of purple fruits (3.32-6.11g kg^-1FW) was1.08-3.47times of the phenoliccontent (1.76-3.08g kg^-1FW) of red fruits，and the phenolic content(1.34-2.13g kg^-1FW) of the yellow fruits was the lowest; total phenolic contents of the fruit in the same colourof different plants were different obviously. The antioxidant activities (24.65-44.83umolTrolox g^-1FW) of purple fruits was higher obviously than that of red fruits (11.59-23.14umolTrolox g^-1FW) and the yellow fruits had the lowest antioxidant activities which was from11.20to16.17umol Trolox g^-1FW. The antioxidant activities of different Myrobalan plumfruits had the same trend with the phenolic contents and the correlation between theantioxidant activities of fruit extracts and the phenolic contents was analysed by Excel2003and the result demonstrated the coefficient was0.9918.2. The UV-2450Shimadzu UV-visible spectrophotometer was used to analyse thespectrum characteristic of0.1%hydrochloric acid methanol extracts of Myrobalan plumspulps and peels and the total anthocyanin content of the Myrobalan plum peel extracts wasmeasured with the pH differential method. The result showed that the yellow peels and theMyrobalan plum pulps had no anthocyanins; the peel of purple and red fruits contained anthocyanins which had acetyl and the anthocyanin content (11.18-19.86g kg^-1FW) ofpurple peel is2.89^-10.29times of anthocyanin content in red peel (1.93-3.87g kg^-1FW).3. The HPLC analysis of anthocyanins in Myrobalan plum peels by ZORBAX SB-C18（4.6×250mm,5μm） was established. The gradient of the mobile phase A （acetonitrile） andmobile phase B （2%aqueous formic acid） at the flow rate of0.8ml min^-1was adapted. Theenlution conditions were:0-20min, linear gradient from6%to16%A;20-30min: lineargradient from16%to23.5%A;30-40min, linear gradient from23.5%to50%A;40-45min:50%A isocratic;45-46min, from50%to6%A. The running temperature was at28°C and theinjection volume was10μL. DAD detector was used. Chromatograms were carried out at520nm for anthocyanins.4. LC-MS/MS was used to detect the anthocyanin composition of Myrobalan plum peel.The result showed that the purple fruit mainly contained4compositions which were cyanidin3-glucoside, cyanidin3-rutinoside, cyanidin3-galactoside and cyanidin （acetyl）3-glucoside,respectively. And the red fruits also contained cyanidin3-xyloside and an unkownedcomposition except above four kinds of anthocyanins. Cyanidin3-glucoside and cyaniding3-galactoside had the most content which exceeded60%. Compared with purple fruits, the redfruit contained more cyanidin3-rutinoside.5. The stability of the anthocyanins was studied and found that the anthocyanins wassensitive to light; the anthocyanins were more stable in aqoeous solution which pH value wasbetween2and3; the high temperature over60oC accelerated degradation of the anthocyanins;citric acid had good hyperchromic effect; metal ions at low concentration had little effect toanthocyanins, but Zn²⁺and Mg²⁺at high concentration were easy to get stable complex with it,which increased the stability of the anthocyanins.