- Molecules 2018, 23(8), 1850;
- Published: 25 July 2018
by Qianping Chen 1,Lili He 1,*,Changming Mo 2,Zhifeng Zhang 3,Hairong Long 1,Xiaoyu Gu 1 andYing Wei 1
1 National Engineering Institute for the Research and Development of Endangered MedicinalResources in Southwest China, Guangxi Botanical Garden of Medicinal Plants, Nanning 530023, China2 Guangxi Crop Genetic Improvement and Biotechnology Lab, Nanning 530007, China
3 Institute of Qinghai-Tibetan Plateau, Southwest University for Nationalities, Chengdu 610041, China
*Author to whom correspondence should be addressed.
Abstract
Resina Draconis is a highly valued traditional medicine widely used in Arabia since ancient times, and it has been commonly used as an antidiarrheic, antimicrobial, antiulcer, blood circulation promoter as well as an anti-inflammatory agent. The tree source from which this medicine orignates grows extremely slowly, producing a very low yield of Resina Draconis. To meet the increasing market demand, artificial methods for stimulating Resina Draconis formation have been developed and applied. However, the chemical differences between artificially induced Resina Draconis (AIRD) and natural Resina Draconis (NRD) have been rarely studied. The aim of this research was to explore and identify the chemical constituents of AIRD and NRD using ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UHPLC-QTOF-MS/MS) based chemical profiling. A total of 56 chromatographic peaks were detected in AIRD, of these, 44 peaks have had their structures tentatively characterized based on high-resolution mass spectra (HRMS) data, fragmentation ions information, reference standards data and literature review. In total, 40 peaks were found both in AIRD and NRD. The potential chemical transformation mechanisms active in Resina Draconis during formation were explored. To the best of our knowledge, this is the first evaluation of the chemical profiles of both AIRD and NRD. Furthermore, these findings are expected to provide a rational basis for the quality assessment of AIRD and the use of AIRD as a substitute for NRD.
Keywords: Dracaena cochinchinensis (Lour.) S. C. Chen; artificially induced; Resina Draconis; dragon’s blood; UHPLC-QTOF-MS/MS
1. Introduction
Resina Draconis (also called “dragon’s blood”), is a red resin derived from Dracaena cochinchinensis (Lour.) S. C. Chen and called “longxuejie” in China. It is a rare and precious traditional medicine that has been commonly used in China for the treatment of wounds, leucorrhea, fractures, diarrhea, as well as intestinal and stomach ulcers since ancient times [1]. Recent pharmacological research has shown that Resina Draconis has antithrombotic [2], antibacterial [3], anti-inflammatory [4,5], anti-diabetic [6], anti-Helicobacter pylori [7] bioactivity, and with the potential to be a therapeutic agent for neurodegenerative diseases [8]. Previous phytochemical studies of this resin have shown that it mainly contains phenolic compounds, including flavonoids, steroids and stilbenoids, which are considered to be the biologically active components of Resina Draconis [1]. Resina Draconis plants originate from four genera of Dracaena, Daemonorops, Croton and Pterocarpus, which are found all over the world. In China, the main source of Resina Draconis is from Dracaena cochinchinensis (Lour.) S. C. Chen and Dracaena cambodiana Pierre ex Gagnep [9]. In recent years, demand for Resina Draconis in the medicinal market has increased dramatically. However, the natural Dracaena tree grows extremely slowly, taking usually 30–50 years or more, and yields Resina Draconis with a very low efficiency. To meet the increasing demands for Resina Draconis, a considerable number of artificial methods for stimulating resin formation have been developed and applied [10,11]. However, a debate has continued since the emergence of artificially induced Resina Draconis (AIRD). The focus of this controversy is that the chemical components of AIRD are thought to perhaps differ from those of its natural form, which make their efficacy not equivalent. In fact, few of the chemical constituent of AIRD have been reported [10,12,13], however, until now, the chemical profile differences between AIRD and natural Resina Draconis (NRD) have been rarely studied. Whether the chemical constituents of AIRD consistent to that of NRD and how the secondary metabolites produced during Resina Draconis formation have are very important concerns for the efficacy and quality control of AIRD. Therefore, development of a generally reliable, sensitive, and confirmatory analytical method to examine the chemical constituents of both AIRD and NRD is desirable.
In recent years, tandem ultra-high-performance-liquid-chromatography with quadrupole time of flight mass spectrometry (UHPLC-QTOF-MS/MS) has been used as a rapid and effective technique to identify compounds in complex matrices. Compared with the low-resolution MS methods such as quadrupole, triple quadrupole and ion trap mass spectrometry, Q-TOF MS/MS has the ability to measure the exact mass for both precursor and fragment ions, which could be valuable for determination of structural conformation for non-target compounds in complex matrices when the reference compounds are unavailable. Thus, the present study aimed to investigate the chemical constituents in both AIRD and NRD using UHPLC-QTOF-MS/MS based chemical profiling. A salt solution containing 1% zinc sulfate and 2.0 g/L benzoic acid was used to treat the xylem of D. cochinchinensis to induce Resina Draconis formation by transpiration for 80 days. Then the chemical fingerprints of both AIRD and NRD were compared in both negative and positive ion modes by an improved UHPLC–QTOF-MS/MS analysis. The identities of all detected peaks, were confirmed by comparing the mass spectra and retention times with those of available reference compounds, and/or tentatively assigned by matching empirical molecular formula with those of published compounds, elucidating quasi-molecular ions and fragment ions referring to the available literature information. The potential chemical transformation mechanism of Resina Draconis during formation was further explored. The established approach was applied to rapidly identify the chemical profiles of AIRD and NRD, which offered a systematical and reliable approach for quality assessment and control of AIRD.