Anthocyanins from buds of Lonicera japonica Thunb. var. chinensis (Wats.) Bak.

Recently, a new kind of Lonicera japonica (FLJ) tea well known for its red color, flavor, and taste has become popular in the market. This tea comes from the buds of Lonicera japonica Thunb. var. chinensis (Wats.) Bak. (rFLJ), a wild mutant of the Lonicerae plant. The present study aimed to identify and quantify, for the first time and in detail, the anthocyanin compounds in the buds of rFLJ. Anthocyanins were extracted with methanol-water-formic acid-trifluoroacetic acid (70:27:2:1, v/v/v/v) and quantified as 108.06 ± 4.32 mg/100 g of fresh weight (cyanidin-3-glucoside equivalent) by using the pH-differential method. Eight different anthocyanins were identified by HPLC-DAD-ESI-MS/MS analysis and were quantitated by HPLC-DAD analysis. The main anthocyanins in the buds of rFLJ were two non-acylated anthocyanins: cyanidin-3,5-diglucoside and cyanidin-3-glucoside. Moreover, orthologous genes in the biosynthesis of anthocyanins were cloned and their structure and transcript levels in the buds of FLJ and rFLJ were further compared. The results revealed a 12-residue insertion (IKPTIEGVLGII) in LjcDFR compared with LjDFR. Furthermore, transcript levels of DFR, LDOX, BZ1 and GT1 were decreased in the buds of FLJ compared with rFLJ, as constitute with the content of cyanidin-3-glucoside. Here, a rapid and effective method to identify and quantify all major anthocyanins in the buds of rFLJ is established. Furthermore, the results of this study may explain which anthocyanin produces the red color of rFJL, an important characteristic that distinguishes it from FLJ.