Identification and evaluation of Lonicera japonica flos introduced to the Hailuogou area based on ITS sequences and active compounds

PeerJ. 2019 Sep 3;7:e7636. doi: 10.7717/peerj.7636. eCollection 2019.

Abstract

Lonicera japonica flos (LJF), the dried flower buds of L. japonica Thunb., have been used in traditional Chinese herbal medicine for thousands of years. Recent studies have reported that LJF has many medicinal properties because of its antioxidative, hypoglycemic, hypolipidemic, anti-allergic, anti-inflammatory, and antibacterial effects. LJF is widely used in China in foods and healthcare products, and is contained in more than 30% of current traditional Chinese medicine prescriptions. Because of this, many Chinese villages cultivate LJF instead of traditional crops due to its high commercial value in the herbal medicine market. Since 2005, the flower buds of L. japonica are the only original LJF parts considered according to the Chinese Pharmacopoeia of the People's Republic of China. However, for historical and commercial reasons, some closely related species of Lonicera Linn. continue to be mislabeled and used as LJF. Currently, there are hundreds of commercial varieties of LJF on the market and it is difficult to choose fine LJF varieties to cultivate. In this study, a total of 21 varieties labeled as LJF on the market were planted in the Hailuogou area. In order to choose the optimum variety, internal transcribed spacer (ITS) sequence alignment analysis was used to test whether the 21 varieties were genuine LJF or not. Cluster analysis of active components based on the content of chlorogenic acid and luteoloside in flower buds, stems and leaves was used to evaluate the quality of the varieties. Results demonstrated that four of the varieties were L. macranthoides Hand.-Mazz., while the other 17 varieties were L. japonica, and genuine LJF. The ITS sequence analysis was proven to be highly effective in identifying LJF and Lonicerae flos. Among the 17 L. japonica varieties, the amounts of chlorogenic acid and luteoloside in flower buds, stems and leaves were significantly different. Based on the cluster analysis method, the variety H11 was observed to have the highest level of active components, and is therefore recommended for large-scale planting in the Hailuogou area.

Keywords: Chlorogenic acid; Evaluation; ITS sequence; Identification; Lonicera japonica Thumb.; Luteoloside.

Grant support

This work was supported by the National Natural Science Foundation of China (NO. 41571315) and the CAS President’s International Fellowship Initiative (PIFI) (NO. 2018VCB0018). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.