Study of Volatiles in Lysimachia parvifolia Flower Using HS-SPME-GC-MS

Abstract

Lysimachia parvifolia Hemsl. belongs to the Primulaceae family and is widely distributed in Yunnan, Guizhou, Hunan, Jiangxi, and Zhejiang Provinces in China. It is used as traditional chinese medicine to promote blood circulation clear away heat and toxic material, to relieve cough and asthma, to promote diuresis, and to expel stone [1]. Phytochemical research has shown that the main compounds in plants of Lysimachia genus are flavonoids and triterpenoid saponins. L. pentapetala, L. clethroides, and L. paridiformis contain essential oil [2–4]. Pharmacological investigations have shown that plants of Lysimachia have antitumor, bacteriostatic, anthelminthic, and antioxidation activities [5–8]. No research has so far been conducted concerning the chemical composition and pharmacological activity of L. parvifolia. In order to identify the volatiles in the flowers of L. parvifolia, we report on their essential oils using the HS-SPME technique, which was subsequently supplemented by GC-MS. The air-dried L. parvifolia flowers were collected in Raoren Mountain of Guizhou Province, China, in July 2010. The sample was identified by Prof. Zhiyou Guo (Qiannan Normal College for Nationalities). A voucher specimen was deposited in the Huanghe Science and Technology College (No. 20100729). Volatile organic compounds were extracted by a manual SPME holder together with 5 mL vials and PDMS-DVB fibers purchased from Supelco Inc. (Bellefonte, USA). The powder of L. parvifolia flowers, about 0.7 g, was placed in vials (5 mL); then the SPME fiber was exposed to the upper space of the sealed vial for 30 min at 50 C to adsorb the analytes. After that, the fiber was withdrawn and directly inserted into the GC-MS inlet for desorption of the volatiles for 1 min. Volatile constituents were analyzed by HS-SPME-GC-MS using an Agilent 6890 N gas chromatograph equipped with an DB-5 MS capillary column (5% phenylmethylsiloxane, 30 m 0.25 mm, film thickness 0.10 m, Agilent Technologies, USA) and coupled with a 5975 B mass selective detector spectrometer from the same company. The front inlet was kept at 250 C in the split-less mode. The temperature program was as below: initial column temperature 50 C, held for 2 min, then programmed to 120 C at a rate of 4 C/min and held for 2 min and finally programmed to 230 C at a rate of 6 C/min and held at 230 C for 10 min. As a carrier gas helium at 1.0 mL·min–1 was used. The MS detector was used in the EI mode with an ionization voltage of 1555 eV. The ion source temperature was at 230 C. The transfer line was at 150 C. The spectra were collected at 3 scans/s over the mass range (m/z) 30–400. Retention indices were calculated by using the retention times of n-alkanes that were injected at the same chromatographic conditions [9]. The volatile constituents (Table 1) were identified by comparison of their linear retention indices (relative to C8–C26 alkanes on the DB-5MS column) and their mass spectra with those of authentic standards, as well as those from RTLPEST 3.L and NIST 05.L. The percentage composition of the volatiles was computed from GC peak area normalization without any corrections [10, 11]. The volatiles in the flower of L. parvifolia were presented in Table. Twenty eight compounds were identified, which comprised 93.1% of the volatile fraction. Table 1 showed that the main volatiles in the flower of L. parvifolia were limonene (35.9%), -citral (17.6%) and -citral (15.0%). Limonene is a kind of natural function monoterpene widely used as flavor additive in food. Recently study showed that limonene has a variety of physiological function, especially royal bacteriostasis, antisepticize and anticancer activity [12, 13]. Citral could be used as food flavor, also had the effects of anti-asthmatic and antisepsis. The most widely research was about its effect of inhibition of aspergillus flavus growth [14, 15].