Detection of Volatile Components in Leaves and Bark of Picrasma quassioides by GC-MS

Jingni WANG, Yanqiu DENG, Hongzhen TANG, Hui HUANG, Zhenwei ZHANG,2*

1. Guangxi University of Chinese Medicine, Nanning 530200, China; 2. Guangxi Zhuang Yao Medicine Center of Engineering and Technology, Nanning 530200, China

Abstract [Objectives] This study aimed to analyze the volatile oil components of the leaves and bark of Picrasma quassioides. [Methods] The volatile oils in the leaves and bark of P. quassioides were extracted using steam distillation (SD) method and identified with gas chromatography-mass spectrometry (GC-MS). Based on the mass spectrum database (NiST08), combined with artificial spectrum analysis, referring to relevant literature, the base peak and relative abundance were compared to identify the volatile components of the leaves and bark. The relative content of each component was determined by peak area normalization method. [Results] A total of 24 and 23 chemical components were identified in the leaves and bark of P. quassioides, respectively, including 11 common components. [Conclusions] Leaf and bark are different tissues. They contain different volatile chemical components, of which the contents vary greatly. They should be treated differently in the further research and development of P. quassioides resources.

Key words Picrasma quassioides, Leaf, Bark, Volatile oil, GC-MS

1 Introduction

Picrasmaquassioides(D. Don) Benn (Simaroubaceae:Picrasma) is famous for its bitter taste, also known as Kushu and Kudan. It is mainly distributed in the provinces south of the Yellow River Basin in China, especially in Guangdong and Guangxi. It likes to grow on hillsides and valleys which are wetter[1]. According to the 2015 edition ofChinesePharmacopoeia, dried branches and leaves ofP.quassioidesare usually used as medicine, which has the effect of clearing heat, eliminating dampness, detoxification and diminishing swelling and is used for the treatment of anemopyretic cold, sore throat, warm-heat diarrhea, eczema, snake bite,etc[2]. The leaves and bark ofP.quassioidesare different tissues. From the perspective of growth characteristics, the bark ofP.quassioidesis gray-black. The young branches are gray-green and glabrous, with obvious yellow lenticels.P.quassioideshas singular pinnately compound leaves. The leaflets are oblong oval or ovate-lanceolate, nearly sessile. The tip is sharp, and the base is slanted or slightly rounded, with pure teeth on the edge. Both sides of the leaves are usually green, and some are pale violet red in the lower surface, with pilose along the midrib.

The chemical composition ofP.quassioidesis complex. At present, the chemical components ofP.quassioidesthat have been reported at home and abroad include canthin-6-one alkaloids, carboline alkaloids, quassinoids, tirucallane triterpenoids, phenolic glycosides, phenolic acids, phenylpropanoids and hesperidens. Modern pharmacological studies have shown thatP.quassioideshas antibacterial, anti-inflammatory, antipyretic, antihypertensive, cardiac, blood circulation-improving, transaminase-reducing, anti-cancer, anti-venom, anti-malaria and other biological activities[3-6].

The research on the chemical constituents ofP.quassioideshas been mainly focused on the stems and thick branches. There are few reports on the leaves and bark ofP.quassioides[7-8]. In order to fill the gaps in the research on the chemical constituents ofP.quassioidesleaves and bark, in this study, the volatile oils in the leaves and bark ofP.quassioideswere extracted using the steam distillation (SD) method and identified with gas chromatography-mass spectrometry (GC-MS)[9], to provide a research basis for further research and development ofP.quassioidesresources and expansion of the source of medicine.

2 Materials and methods

2.1 Materials

2.1.1Instruments and equipment. Agilent 7890A-5975C gas chromatography-mass spectrometer (Agilent, USA); DHG-9240A electric heating constant-temperature blast drying oven (Shanghai Precision Testing Equipment Co., Ltd.); DF-20 desktop continuous feeding mill (Wenling Linda Machinery Co., Ltd.); ME204E/02 electronic balance[Mettler-Toledo Instruments (Shanghai) Co., Ltd.].

2.1.2Plant material and reagents. The leaf and bark samples ofP.quassioides, identified by Professor Yong Tan of Guangxi University of Chinese Medicine, were collected in Qintangshan District, Guigang City, Guangxi. The reagents used mainly included anhydrous ether (Tianjin Damao Chemical Reagent Co., Ltd.) and anhydrous sodium sulfate (Tianjin Damao Chemical Reagent Co., Ltd.).

2.2 Methods

2.2.1Experimental parameters and analysis conditions. Column: quartz capillary column HP-5ms (30 m × 25 μm × 0.25 μm); carrier gas: high-purity He (99.995%); injection temperature: 250 ℃; sample size: 1 μL; split ratio: 20∶1. Program heating: 70-250 ℃; initial temperature: 70 ℃ (retention for 1 min), rising to 250 ℃ at 10 ℃/min (retention for 1 min). Ionization method: EI; energy: 70 eV; ion source temperature: 230 ℃; electron multiplication: 1.933 kV; scanning mass range: 33-800 m/z.

2.2.2Extraction of volatile oils fromP.quassioides[10]. A certain amount (50 g) of the powder of eachP.quassioidessample was added with 1 000 mL of distilled water, distilled for 5 h until the amount of oils in the collector no longer increased, and let standard for 1 h without heating. The volatile oils were transferred from the measuring device with ether, added with anhydrous sodium sulfate to remove residual water, and filtered through 0.45 μm microporous membrane to obtain light yellow mint-scented transparent liquid, which was refrigerated for later use.

2.2.3Determination of volatile oil composition. Under the above experimental parameters and conditions, the volatile oils extracted from the leaves and bark ofP.quassioideswere identified with gas chromatography-mass spectrometer (GC-MS). Using Agilent GC-MS ChemStation data processing system, the relative content of each component was determined by the peak area normalization method. The total ion current chromatograms of the volatile oils extracted from the leaves and bark ofP.quassioidesare shown in Fig.1-2, respectively. Each peak in the total ion current chromatogram was searched in the mass spectrum database (NiST08), combined with artificial spectrum analysis. The matching degree (SI) with the data of the spectrum database reached more than 90%. Referring to relevant literature, the base peak, relative abundant,etc. were compared. The identified volatile components in the leaves and bark ofP.quassioidesare shown in Table 1.

Fig.1 Total ion current chromatogram of volatile oils in leaves of Picrasma quassioides

Fig.2 Total ion current chromatogram of volatile oils in bark of Picrasma quassioides

Table 1 Volatile components and relative contents in leaves and bark of Picrasma quassioides

3 Results and analysis

A total of 24 kinds of volatile components were detected from the leaves ofP.quassioides, mainly alkanes, among which tetracosane had the highest content (14.01%), followed by nonadecane (13.24%). The non-alkanes with higher content were caryophyllin (5.45%), oleamide (4.25%), palmitic acid (2.73%), humulene epoxide II (2.02%), β-caryophyllene (2.00%), α-caryophyllene (1.40%), β-elemene (1.32%),etc. The contents of other ingredients such as 2-methoxy-4-vinylphenol, nerolidol, spathulenol, cedrol, 17-pentatriacontanone and stearamide were all below 1%.

A total of 23 volatile components were detected in the bark ofP.quassioides, similar to the leaves ofP.quassioides. Alkanes also showed the highest content. Non-alkanes, such as palmitic acid (12.47%) and γ-tocotrienol (6.58%), also had a high content. The contents of nonanal, α-pinene, cubebene, lauric acid, caryophyllin, cedrol, myristic acid, cembrane, 9,10-methy linoleate and other volatile components were all below 1%.

In this study, the volatile oils in the leaves and bark ofP.quassioideswere extracted using steam distillation method and identified with gas chromatography-mass spectrometry technology. The relative content of each component was calculated with the peak area normalization method. Total 24 and 23 volatile components were identified from the leaves and bark ofP.quassioides, respectively. In addition to common alkanes, β-elemene with significant anti-cancer activity was also detected in the leaves ofP.quassioides. In addition, 11 common components including spathulenol, caryophyllin, cedrol, phytone, palmitic acid, hexadecane, 17-pentatriacontanone and cerotene were detected in the leaves and bark ofP.quassioides. But the contents of these components were different in both. For example, the content of palmitic acid in the bark ofP.quassioidesreached 12.47%, but it was only 2.73% in the leaves ofP.quassioides; caryophyllin had a content of 5.45% in the leaves ofP.quassioides, but had a content of only 0.88% in the bark ofP.quassioides. In the experiment, affected by the experimental conditions, such as steam distillation, part of the product was lost, which might also affect the experimental results. During the storage of the product, the experimental data was also affected.

For a long time, the research on the chemical composition ofP.quassioideshas mainly focused on the stems and branches. In this study, the volatile components of the leaves and bark ofP.quassioideswere analyzed to provide a powerful space and research ideas for the related research ofP.quassioides, and a certain research foundation and reference for the expansion of the source of medicine and the further development and utilization of the medicinal resources ofP.quassioides.