Development of a comprehensive quality control method for the quantitative analysis of volatiles and lignans in Magnolia biondii Pamp. by near infrared spectroscopy

Highlights

• 13 quantitative models of index components in Magnolia biondii Pamp. were established by NIRS combined with PLSR.

• Develop a comprehensive quality control method for Magnolia biondii Pamp..

• The systematic analysis method was proposed for the first time.

Abstract

The quality of drug is vital to its curative effect, thus it is important to develop a comprehensive quality control method for commonly used drugs. In this study, we developed a Gas chromatography-mass spectrometry separation method for the qualitative and quantitative analysis of volatiles, together with a High-performance liquid chromatography-mass spectrometry separation method for lignans in Magnolia biondii Pamp.. 79 volatiles and 11 lignans were identified via comparing their chromatographic behavior and mass spectra data with those in the literature. The methods were then used to determine the contents of volatiles (1, 8-cineole, d-Limonene, α-terpineol, linalool, L-camphor brain and bornyl acetate) and lignans (epieudesmin, magnolin, epi-magnolin A and fargesin) in Magnolia biondii Pamp.. Subsequently, 13 qualitative models including volatiles (1, 8-cineole, d-Limonene, α-terpineol, linalool, L-camphor brain and bornyl acetate), water-soluble extractive, lignans (pinoresinol dimethyl ether, magnolin, epi-magnolin A and fargesin) and moisture were developed by Near-Infrared Spectroscopy based on partial least square regression herein. The reference values were obtained by High-performance liquid chromatography, Gas chromatography and etc., while the predicted values were attained from the NIR spectrum. Compared with the traditional detection methods, NIR technique methodology significantly improved the ability to evaluate the quality of Magnolia biondii Pamp., which had the advantages of convenience, celerity, highly efficiency, low cost, no harm to samples, no reagent consumption, and no pollution to the environment. Moreover, the systematic analysis method combined pharmaceutical analysis with pharmacochemistry was proposed to prepare volatiles, water-soluble extractive and lignans parts from the same sample. This way could extract more index components to be beneficial in the quality control of Magnolia biondii Pamp. roundly.

Introduction

Recently, Traditional Herbal Medicine has aroused great interest for its potential to treat a variety of ailments, and no secondary action to the health. Traditional Herbal Medicine has been used for 5000 years, and now it is widely used in the treatment of various diseases, especially in Asian countries. Tu Youyou Research Group has discovered and extracted artemisinin from a Traditional herbal medicine - Artemisia apiacea, saving the lives of millions of people around the world and effectively reducing the mortality rate of malaria patients, especially in developing countries [1]. Aimed at the resistance of artemisinin reported in recent years, Tu youyou Research Group proposed a new temporizing solution to artemisinin resistance [2]. The statements demonstrated that Traditional Herbal medicine is worth to be fostered and enhanced. But there are many inferior and false Traditional Herbal medicines in the market, which cannot produce the due effect but cause the harm to the human body. Therefore, it is important and urgent to develop a reasonable, high-speed, precise and comprehensive quality control method for the qualitative and quantitative analysis in commonly used Traditional Herbal Medicines.

High performance liquid chromatography-mass spectrometry (HPLC-MS) is capable of providing the molecular weights, elemental compositions and fragment information of unknown components, and achieve a separation, purification, enrichment of the specific component in complex mixture. In general, it is difficult to separate and purify the components of Traditional Herbal Medicines, while these complicated pretreatments are not necessary to be carried out in the analysis by HPLC-MS. Recently, HPLC-MS has been demonstrated to be an invaluable tool for the analysis of complex mixtures derived from certain Traditional Herbal Medicines [[3], [4], [5], [6]]. It can not only be used to study the index constituents of Traditional Herbal Medicines qualitatively and quantitatively, but also used to infer some unknown components by the fragment information, which could guide the further research work. Gas chromatography-mass spectrometry (GC–MS) is a highly efficient, selective and sensitive analytical method, especially suitable for the analysis of volatile compounds [7,8].

Traditional analysis techniques, such as HPLC, GC, ultraviolet spectrophotometry and etc., have the disadvantages of complicated pretreatment and operation, time consuming, high cost, reagent pollution in the analysis process. As a fast developing green analysis technique, near infrared spectroscopy (NIRS) has some individual characteristics. The absorption coefficient of many substances in the near infrared region is small and the analysis process is simple. The light scattering effect and penetration in the near infrared region are large enough to be directly measured by diffuse reflection technique, and near infrared light can penetrate through glass and quartz medium. Moreover, as a fast-nondestructive and environmental analysis technology, NIRS is mainly combined with spectral measuring technology, chemometrics and basic measurement technology, which can objectively reflect the overall material base of Traditional Chinese Medicine (TCM), and reflect its organic composition, mineral composition and characteristic components. NIRS technology can be rapid, simple and accurate to overall control over the quality of TCM and the raw medicinal materials, and the researchers demonstrated that the technology could achieve relatively satisfactory results. Therefore, it has been successfully applied in the fields of agriculture [9], food [[10], [11], [12], [13], [14], [15]], petrochemical, tobacco [16], wine [17,18] and medicine [[19], [20], [21], [22], [23], [24]]. It has also been widely used in the quality analysis of the index components in Traditional Herbal Medicines [25,26].

Magnolia biondii Pamp. (M. biondii) is a traditionally medicinal plant grown in Henan, Sichuan, Anhui, Shanxi, and Gansu of China. The dried flower buds of the plant can be used for the treatment of chill, headache, nasal congestion, anti-inflammatory, allergic rhinitis and nasosinusitis [27], which has been listed in the Chinese Pharmacopeia since 1990. Modern Pharmacological study demonstrated the essential oil, water-soluble extractive and lignans from M. biondii possessed its individual biological effects. The essential oil can be bacteriostatic, analgesic, antitussive, antiasthmatic and sedative [[28], [29], [30], [31]], water-soluble extract is antibacterial, anti-inflammatory, and antihypertensive [32], while lignans would be melanogenesis inhibition, anti-inflammatory and anti-allergic, inducing apoptosis [[33], [34], [35], [36], [37], [38], [39]]. In the 2015 Chinese Pharmacopeia, the total volatile oil no <1.0% (mL/g) and magnolin no <0.4% were regarded as the evaluation index to control the quality of M. biondii. Nevertheless, as a holistic approach to the treatment of diseases, Traditional Herbal Medicines are believed to exert their therapeutic or preventive effects through the interaction of multiple components rather than the bioactivity of single chemicals. In consideration of these, all of three extracted parts were selected as the objects of our study to develop a comprehensive quality control method for M. biondii.

In this study, a systematic analysis method was proposed based on pharmaceutical analysis and pharmacochemistry. The volatiles, water-soluble extractive and lignans parts from the same sample were prepared in turn. And then the volatiles were analyzed by GC–MS and the lignans by HPLC-MS. This multiple techniques methodology was utilized to provide components information, which could achieve a fast automation of separation, purification, enrichment and identification of complex mixture, and could be anticipated to be a useful analysis tool for other Traditional Herbal Medicines. Finally, some identified components with their individual biological effects were selected as index components. And these index components' quantitative models were developed by NIRS based on partial least square regression (PLSR). This methodology, combined with GC–MS, HPLC-MS and NIR, was utilized to evaluate and control the quality of M. biondii in a holistic approach. Up to now, no comprehensive analysis to volatiles, lignans and water-soluble extracts from M. biondii was reported in this way. The systematic analysis method can make the substances analyzed more pure and free from the interference of other types of substances, which can be beneficial to the further accurate qualitative and quantitative analysis by GC–MS and HPLC-MS. This research can also provide new ideas for other Traditional Herbal Medicines basic research.