UPLC-Q-Orbitrap HRMS technology for rapid identification of chemical components in hibiscus flowers
Hibiscus mutabilis L. is a dried flower of Hibiscus mutabilis L., a plant in the Malvaceae family. According to the Compendium of Materia Medica, “this flower is as beautiful as a lotus, hence it is called Hibiscus or Magnolia.” It is also known as Huamu, Frost resistant, Frost Falling Flower, and other names. It has a slightly pungent taste and a cool nature, and belongs to the lung and liver meridians. It has the effects of clearing the lungs, cooling blood, dissipating heat and detoxifying, reducing swelling and pus discharge. In clinical practice, it is commonly used to treat lung heat cough, scrofula, intestinal abscess, vaginal discharge, etc. It can also be used topically to treat abscess, purulent ear, unnamed swelling and scalding, etc. It is included in the 2019 edition of the “Guangdong Province Traditional Chinese Medicine Standards Volume 3”.
Since ancient times, Chengdu, Sichuan has been thriving in the cultivation of hibiscus flowers. The hibiscus flower has been designated as the “city flower” of Chengdu since 1983 and is an important component of Tianfu culture. It is not only a condensed and symbolic representation of the cultural characteristics of the city, but also an important symbol and characteristic business card of the city’s image. In addition to its profound cultural heritage, hibiscus is also a medicinal and edible Chinese medicine with both nutritional and medicinal value. Modern pharmacological research has shown that it has anti allergic and blood sugar lowering effects, as well as strong inhibitory effects on hemolytic streptococcus. Its extract is also widely used as a raw material or additive in cosmetics and food. However, due to relatively few reports on the chemical composition of Hibiscus syringae both domestically and internationally, related pharmacological research mainly focuses on crude extracts, and insufficient exploration of the discovery and mechanism of action of pharmacological substances, its clinical application is relatively limited, with only reports on the treatment of abscesses and inflammation. This not only affects the discovery and expansion of Hibiscus syringae in medical basic research and clinical applications, but also poses a bottleneck for its development in food, cosmetics and other fields. Therefore, clarifying the material basis of Hibiscus syringae and conducting relevant pharmacological research is of great significance for its application and development. Ultra high performance liquid chromatography tandem quadrupole electrostatic field orbital trap mass spectrometry technology is a new type of liquid chromatography-mass spectrometry technology developed in recent years. It has the characteristics of high resolution, good quality accuracy, strong qualitative and quantitative capabilities, and has shown great application prospects in the field of traditional Chinese medicine analysis. Therefore, in order to further understand the chemical composition of hibiscus flowers, UPLC-Q-Orbitrap HRMS was used for chemical analysis in this experiment, in order to elucidate the material basis of hibiscus flowers.

In recent years, UPLC-Q-Orbitrap HRMS technology has been widely used in the fields of traditional Chinese medicine chemical composition analysis and complex multi-component quality control due to its advantages of high resolution, high quality accuracy, fast and accurate qualitative and quantitative analysis. In this experiment, 0.1% formic acid water acetonitrile was used as the mobile phase for gradient elution of the chemical components of Hibiscus flowers. To better explore the chemical components of Hibiscus flowers, positive and negative ion scanning methods were used for data collection. Based on the retention time, relative molecular weight, quasi molecular ion peak, and fragment ion of secondary mass spectrometry reported in existing literature, combined with the fragmentation law of secondary mass spectrometry and the mass spectrometry information of chemical reference standards, the attribution analysis of each mass spectrometry peak was carried out. A total of 54 compounds were detected from the ethanol extract of Hibiscus syringae, including 7 types of components (flavonoids and their glycosides, organic acids, coumarins, amino acids, nucleosides, alkaloids, etc.). Combining literature and the SciFinder database, it was found that 33 components were reported for the first time in Hibiscus, and 11 components were reported for the first time in the genus Hibiscus. Eleven newly discovered flavonoids in flowers, such as naringin and guava glycosides, exhibit hypoglycemic effects by reducing the release of free fatty acids, while naringin-7-O-glucoside activates PPAR γ receptors and phosphorylates the PI3K/AKT signaling pathway; Vitexin can inhibit the migration and invasion of breast cancer cells by down regulating PI3K/Akt signaling pathway, and combine with tubulin to promote the G2/M phase arrest of MCF7 breast cancer cells, and parasitide and iristein can induce the apoptosis of MDA-MB-231 cells by inhibiting PI3K/Akt signaling pathway and ROS mediated mitochondrial functional barrier; Cherry glycoside has a repairing effect on human keratinocyte (HaCaT) damage caused by medium wave ultraviolet (UVB) radiation, which has certain significance for the expansion of clinical applications of hibiscus flowers. From the perspective of structure-activity relationships, the various pharmacological activities of flavonoids, such as anti-tumor and anti-inflammatory effects, are mainly influenced by the degree of hydroxylation, C2-3 double bonds, glycosylation, and maternal nucleus structure. There are numerous types of flavonoids in hibiscus flowers, with strong structural diversity and diverse biological activities. This article improves the chemical composition library of Hibiscus syringae, providing a basis for the development and utilization of Hibiscus syringae flowers, research on pharmacological substances, and quality control in the future.
Mu Fu Rong is a commonly used traditional Chinese medicine. The leaves of Mu Fu Rong are included in the 2020 edition of the Chinese Pharmacopoeia, and both the leaves and flowers can be used as medicine. This experiment compared the chemical composition of hibiscus leaves with previously reported ones, and found that there were 14 identical flavonoids, 5 organic acids, and coumarins, indicating a certain degree of similarity in the chemical composition of different parts of the same medicinal plant. In addition, some known components in hibiscus flowers were not detected in this analysis, which may be related to the ionization efficiency of ESI; The identification of isomeric compounds has always been a difficult point in mass spectrometry analysis, so relying solely on mass spectrometry for identification has certain limitations and requires further confirmation through spectroscopic analysis such as nuclear magnetic resonance. By observing the total ion chromatogram, it can be found that there are few compounds identified during the retention time of 11-17 minutes. Therefore, in order to further understand the composition of this compound, we can use different polar solvents to extract its parts, and perform peak analysis under the same high-performance liquid chromatography conditions to find the possible polar parts. This can also serve as a certain indicator for our subsequent material basis research on compound separation in hibiscus flowers.