| Purple sweet potato (Ipomoea batatas), a special variety of sweet potato, was rich in essential nutrients of human and was always showing the purple flesh since the plant pigment anthocyanins. Anthocyanins, as flavonoid compounds, had attracted lot of attention because of its good antioxidant activity and bright color. The two major anthocyanidin types of purple sweet potato anthocyanins were cyanidin and peonidin. The bioactivities of anthocyanins were broad as antioxidant, antitumor, antidiabetic, anti-inflammatory and hepatoprotective effect. Moreover, purple sweet potato anthocyanins containing aromatic acylated glycosyl groups have been shown to have high pH and thermo stability. It was our goal that the key components to antioxidant activities of purple sweet potatoes were found and the regulation mechanism of biosynthesis of transcription factor Lc was research.In part one, the identification of 13 common peaks of fingerprints from 30 purple sweet potato cultivars was carried out by LC-MS/MS, the results were following as: cyanidin 3-sophoroside-5-glucoside (PI), peonidin 3-sophoroside-5-glucoside (P2), cyanidin 3-p-hydroxybenzoyl sophoroside-5-glucoside (P3), peonidin 3-p-hydroxy-benzoyl sophoroside-5-glucoside (P4), cyanidin 3-feruloyl sophoroside-5-glucoside (P5), peonidin 3-feruloyl sophoroside-5-glucoside (P6), cyanidin 3-caffeoyl sophoroside-5-glucoside (P7), cyanidin 3-caffeoyl-p-hydroxybenzoyl sophoroside-5- glucoside (P8), cyanidin 3-caffeoyl-feruloyl sophoroside-5-glucoside (P9), peonidin 3-caffeoyl sophoroside-5-glucoside (P10), peonidin 3-dicaffeoyl sophoroside-5-glucoside (P11), peonidin 3-caffeoyl-p-hydroxybenzoyl sophoroside-5-glucoside (P12), and peonidin 3-caffeoyl-feruloyl sophoroside-5-glucoside (P13). Total anthocyanin contents were determined by pH-differential method and the results were frome 74.3 to 607.0 mg/100 g dw with a maximum ratio of about 8. Fingerprinting profiles of 30 cultivars with a similarity higher than 0.78. The results of principal component analysis showed that principal component PCI distinguished betwteen cyanidin-or peonidin-based anthocyanins, while the number of acylated group(s) on the anthocyanins could be identified by PC2. The comprehensive analysis showed that most ratios of peonidin:cyanidin derivatives of 30 cultivars were higher than 1. Finally, data mining of the obtained data on bioactivities and compounds identified by LC-MS was carried out. Profile-effect research was directed by the Grey relational analysis in the theory of Grey system. Based on the order of contribution of different anthocyanin compounds on bioactivities,13 anthocyanin compounds were classed into 4 classes. Compounds in Class I, P4, P11 and P12, showed the highly consistent of high influence on 4 kinds of antioxidant systems. Practically speaking, P11 had the highest contributions on reducing power, DPPH radical scavenging and linoleic acid autoxidant inhibiting, while P12 showed an optimal performance on hydroxyl radical scavenging, and P4 as well as P11 showed a well influence on DPPH radical scavenging.In part two, agrobacterium-mediated maize heterologous transcription factor Lc transferred to purple sweet potato Ayamurasaki, transgenic lines were studied by metabolite profile with LC-MS. The results showed as following:(1) By comparing with the wild type, four transgenic purple sweet potato lines by Lc showed increase with a range from 1.50 to 1.66 in the total anthocyanin content. (2) 19 anthocyanins was identifited from wild type and its transgenic lines by LC-MS/MS, they were cyanidin 3-sophoroside-5-glucoside (1), pelargonidin 3-sophoroside-5-glucoside (2), peonidin 3-sophoroside-5-glucoside (3), cyanidin 3-p-hydroxybenzoyl sophoroside-5-glucoside (4), cyanidin 3-(6’"-caffeoyl sophoroside)-5-glucoside (5), peonidin 3-p-hydroxybenzoyl sophoroside-5-glucoside (6), cyanidin 3-feruloyl sophoroside-5-glucoside (7), peonidin 3-feruloyl sophoroside-5-glucoside (8), cyanidin 3-dicaffeoyl sophoroside-5-glucoside (9a), cyanidin 3-caffeoyl sophoroside-5-glucoside (9b), cyanidin 3-caffeoyl-p-hydroxybenzoyl sophoroside-5-glucoside (10), cyanidin 3-caffeoyl-feruloyl sophoroside-5-glucoside (11), peonidin 3-caffeoyl sophoroside-5-glucoside (12), peonidin 3-dicaffeoyl sophoroside-5-glucoside (13), pelargonidin 3-dicaffeoyl sophoroside-5-glucoside (14), Peonidin 3-caffeoyl-p-hydroxybenzoyl sophoroside-5-glucoside (15a), pelargonidin 3-caffeoyl-p-hydroxybenzoyl sophoroside-5-glucoside (15b), peonidin 3-caffeoyl-feruloyl sophoroside-5-glucoside (16), and pelargonidin 3-caffeoyl-feruloyl sophoroside-5-glucoside (17). Compounds 1, 4,5,7,9a,9b,10, and 11 were cyanidin-based anthocyanins, while compounds 2,14, 15b, and 17 belonged to pelargonidin-based ones, and rest of them share the same aglycone of peonidin. Two extra anthocyanins in transgenic lines, compounds 14 and 15b, were foundagainst wild type one. (3) The change of relative content for three types of anthocyanins, as the rise of cyanidin-based and pelargonidin-based anthocyanins;the drop of peonidin-based one.In this study, firstly,the influenced on antioxidant activities from different anthocyanin compounds were evaluated. It was helpful for plant breeding of purple sweet potatoes. In addition, the research on transgenic varieties of purple sweet potato found that heterologous transcription factor Lc could affect the biosynthesis of anthocyanins. It was meant a lot for its research of biosynthesis pathway. |
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