Determination of volatile components in different stages and parts of sour orange using HS-SPME-GC-MS method
Aurantii Fructus is an immature fruit of Citrus aurantium L. and its cultivated varieties in the Rutaceae family. It has a warm nature and is mainly used for treating chest and diaphragmatic fullness, rib pain, and has the effects of regulating qi, widening the chest, promoting stagnation, and reducing accumulation. Modern pharmacological studies have shown that Fructus Aurantii has pharmacological effects such as regulating gastrointestinal function, promoting bile and stone secretion, lowering blood lipids, and anti-tumor effects. Citrus aurantium contains various chemical components, such as flavonoids, volatile compounds, alkaloids, etc. The volatile components of Fructus Aurantii have the functions of regulating qi, promoting stagnation, relieving cough, eliminating phlegm, and inhibiting bacteria, which are important material basis for its regulating qi function; Linalool, limonene and other substances are the main sources of the fruity aroma of Fructus Aurantii, and are widely used in food, daily chemical and other fields. Sour oranges are harvested in July when the skin is still green. For sour oranges, research and utilization mainly focus on the flavonoids in the fruit, but the fruit is also rich in volatile components such as limonene and linalool; There is relatively little research on different parts of sour oranges, and further research and development are needed for non medicinal parts such as stems and leaves. If a systematic detection and analysis of volatile components in lime can be conducted, and a simple and rapid method for detecting volatile components can be established, it will provide new ideas for the diversified utilization of lime.

The headspace solid-phase microextraction (HS-SPME-GC-MS) technology has gradually been applied in multiple fields, such as food, medicine and health, clinical chemistry, biochemistry, forensic science, etc. It has the characteristics of fast, efficient, sensitive, and pollution-free. In the detection of plant volatile components, it has been successfully applied in Chuanxiong, Yingchun, Shiwei, day lily and other species, and even successfully used in the detection and analysis of volatile components of traditional Chinese patent medicines and simple preparations Hansen Simo Decoction, which contains complex volatile components, but in general, the application of traditional Chinese medicine is still rare.
At present, although there are many studies on the components of sour oranges, they mainly focus on the research and utilization of flavonoids in their fruits, with relatively less attention paid to volatile components; The volatile components in the fruit of sour orange are key components of its pharmacological and pharmacological effects; The non medicinal parts such as leaves and stems of sour oranges also have a distinct odor, and the content of volatile components is relatively rich, which is of great significance for the growth and development of sour oranges. At present, the function and efficacy of volatile components from plant sources have become a research hotspot both domestically and internationally. Therefore, this experiment uses headspace solid-phase microextraction combined with gas chromatography-mass spectrometry technology to determine and analyze the volatile components in lime fruits at different stages, and selects key periods based on specific harvesting times; Detecting and analyzing the volatile components in the roots, stems, and leaves of non medicinal parts of sour oranges during critical periods, studying the differences in volatile component composition between different parts, and providing reference for better development and utilization of sour orange resources.

 

The chemical composition of sour orange fruit is rich and diverse, among which volatile oils, flavonoids, and alkaloids are the material basis of its pharmacological effects. The volatile components of sour orange fruit are mainly monoterpenes and oxygen-containing derivatives of monoterpenes. Currently, more than 50 volatile components have been determined, such as limonene, linalool, α – pinene, β – pinene, etc. The main components of volatile oil in most sour oranges are limonene and linalool; Oranges from different regions contain different main components of volatile oil, which are also closely related to subsequent processing techniques and other factors. Limonene is the most abundant volatile oil component in lime fruit, with physiological activities such as cough suppressant, expectorant, antibacterial, and cholelithiasis dissolving. Through pharmacological analysis, it is believed that limonene is a component of its decoction pieces, Fructus Aurantii and Fructus Aurantii, that has a regulating effect on qi. Linalool is also one of the important components of volatile compounds in lime fruit. It is a linear monoterpene widely used in various fields such as medicine, food, and daily chemical products. It is an important intermediate for the synthesis of vitamins E and A; In addition, it has analgesic, anti anxiety, sedative hypnotic, anti-inflammatory, anti-tumor, antibacterial, and antioxidant effects, and natural linalool has more medical value due to its optical rotation. At the same time, it was found that in addition to the fruit of sour orange, the content of effective volatile components in sour orange stems and leaves also had a high level. For example, the relative content of linalool in sour orange leaf samples exceeded 24%, and the relative content in sour orange stem samples exceeded 8%; Elephantol (23.98%) and thymol (17.29%) also have relatively high relative contents in the stems of sour oranges, and their relative contents in leaf samples are also relatively high (23.49%, 10.35%). The research group used UHPLC-ESI-Q-TOF/MS to determine the phytochemical composition and main active ingredient content of different parts of sour orange in the early stage. The sour orange fruits harvested from mid to late June to early July showed strong antioxidant capacity, and it was found that the extracts of sour orange leaves and stems also showed a certain degree of potential antioxidant activity.
At present, there is relatively little analysis and research on the effective components in the roots, stems, and leaves of sour oranges. The traditional way of harvesting sour oranges is mainly based on fruit harvesting, and their roots, stems, and leaves have not been developed and utilized during the harvesting process. However, these non medicinal parts have high biological yields and rich medicinal ingredients, and have great prospects for development and utilization. Many volatile components also have functions such as promoting seed dispersal, plant interactions, and stress resistance, which are of great significance to the environment, plants themselves, and human survival; The use of metabolomics detection combined with transcriptome analysis to elucidate the biosynthetic pathways of plant volatile components at the molecular level has become a hot topic in the study of plant derived volatile components.
In this experiment, headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) was used to determine the volatile components in fruits and different parts of sour oranges at different stages, elucidating the temporal changes in the relative content of key components and the compositional differences between different parts, providing data reference for further development and utilization of volatile components in sour oranges; At the same time, a volatile component detection method based on headspace solid-phase microextraction technology was established, which has the characteristics of fast, efficient, and sensitive. It can accurately reflect the composition of volatile components in the sample and provide new technical ideas for the detection and identification of volatile components in lime. It also provides data and technical references for further development and utilization of non medicinal parts of lime.