Exploring quality biomarkers for antibacterial activity of Artemisia argyi essential oil based on spectral correlation analysis
Ai Ye is the dried leaf of Artemisia argyi Levl. et Vane., a plant in the Asteraceae family. It has the functions of warming meridians, stopping bleeding, dispersing cold, and relieving pain; The external application has the effect of dispelling dampness and relieving itching. As the main active ingredient of Artemisia argyi essential oil, it is internationally known as the soft gold. Currently, various components have been identified, including terpenes (such as eucalyptol), ketone aldehydes (such as thujone), alcohol phenols (such as turpentine alcohol), acid esters (such as acetoacetate), and alkenes (such as caryophyllene). Modern pharmacological research has shown that it has various pharmacological effects such as antibacterial, anti-inflammatory, analgesic, and anticancer. However, there is a significant difference in the quality of Artemisia argyi essential oil, which is influenced by various factors such as the origin, extraction method, harvesting time, and aging of Artemisia argyi leaves. Moreover, there are no relevant quality standards or evaluation indicators to study, making it difficult to evaluate the quality of Artemisia argyi essential oil. Therefore, it is urgent to screen its quality biomarkers.

Since ancient times, our country has the custom of hanging wormwood leaves at the door on Loong Boat Festival as a way to ward off evil spirits and avoid pollution, to eliminate bacteria in the air. Its main active ingredient is the volatile oil of wormwood leaves. Literature reports that the volatile oil of Artemisia argyi can exert inhibitory effects on bacterial growth by altering the permeability of bacterial cell walls and membranes, disrupting cell structure, and also exhibiting good inhibitory effects on fungi. Therefore, this study chose antibacterial activity as the quality testing standard for Artemisia argyi volatile oil. Based on existing literature reports, Staphylococcus aureus, Escherichia coli, and Candida albicans were selected to test the antibacterial activity of Artemisia argyi volatile oil. At present, spectral effect correlation is one of the important methods for screening quality biomarkers of traditional Chinese medicine, and the commonly used analysis method is grey relational analysis. Grey correlation analysis is a multi factor statistical analysis method that can explore the complex correlations between various variables and factors in the process of system development. This study established fingerprint spectra of 15 batches of Artemisia argyi essential oil using GC-MS, and used thermography to search for differential components in different batches of Artemisia argyi essential oil. At the same time, grey correlation analysis was used to correlate the components of Artemisia argyi essential oil with antibacterial activity, screen and verify quality markers for the antibacterial activity of Artemisia argyi essential oil, and provide reference for the future development and utilization of Artemisia argyi essential oil.

As the main active ingredient of Artemisia argyi leaves, the volatile oil of Artemisia argyi leaves has good antibacterial activity. However, the growth environment, harvesting time, and aging process of Artemisia argyi leaves can all affect its composition. Antibacterial experiments have found that the volatile oil from Artemisia argyi leaves in Henan and Hubei production areas has the best inhibitory effect on three types of bacteria, which is consistent with the authentic nature of Artemisia argyi leaves. GC-MS data also showed that the relative content of P10 (camphor) and P11 (camphora) in the volatile oil of Artemisia argyi leaves from Hubei and Henan production areas was relatively high in the 15 batches, which is consistent with the results of grey correlation analysis. Among them, the volatile oil from Hubei Artemisia argyi has the best inhibitory effect on Escherichia coli and Staphylococcus aureus, while the volatile oil from Henan Artemisia argyi has the best inhibitory effect on Candida albicans. Through monomer verification experiments, it was found that P12 (turpentine alcohol) has a good inhibitory effect on Escherichia coli and Staphylococcus aureus, but slightly weaker inhibition on Candida albicans. The results of principal component analysis also showed that P12 (turpentine alcohol) and P13 (α – terpineol) contribute significantly to the differences in the volatile oil of Artemisia argyi leaves in different production areas. Therefore, it is speculated that the two may be the reasons for the differences in their inhibitory effects on different bacteria in Hubei and Henan production areas. However, the results of grey correlation analysis and monomer antibacterial experiments show that their contributions are relatively small, so it is speculated that P12 (pine oil alcohol) and P13 (α – terpenol) play a synergistic role rather than the main role in the antibacterial process.

The results of grey correlation analysis and monomer antibacterial experiments have shown that camphor and borneol are quality markers of the antibacterial activity of Artemisia argyi essential oil. Modern research has also confirmed that both have good antibacterial activity. Dong Jie’s research has shown that the diameter of the antibacterial zone of 100% camphor essential oil against Escherichia coli is 0.2-1.1cm, which exerts antibacterial effects by affecting protein synthesis and regulating gene expression in E. coli. Xiao Shanshan’s research shows that right-handed Longnao can damage the bacterial cell membrane by forming pores, allowing the contents to leak out and exert antibacterial effects. Wang Yuanhui’s research has shown that when levonorgestrel inhibits Staphylococcus aureus and Escherichia coli, it does not damage their cell membrane integrity. By changing the membrane potential, cell depolarization, and affecting ion channels, it leads to their destruction.

In summary, this study found that various components of Artemisia argyi essential oil have antibacterial activity, among which camphor and camphora have made significant contributions, which can be used as quality markers for the antibacterial activity of Artemisia argyi essential oil, providing reference for the quality control and subsequent research of Artemisia argyi essential oil.