Study on the Anti inflammatory Activity of Zelanoside Compounds in Purple Stem Zeeland
Eupatorium adenophorum Spreng is a perennial semi shrub herbaceous plant in the Asteraceae family, widely distributed in southwestern China such as Yunnan. Purple loosestrife is an invasive species that was introduced to Yunnan, China around the 1950s. It has a strong reproductive ability and became a weed pest in the 1970s, causing uncontrollable ecological disasters to agriculture, forestry, and animal husbandry in the southwestern region. In order to effectively control the spread of purple loosestrife, some scholars have attempted mechanical, chemical, and biological control methods. Although the combination of these three methods is an effective way of governance, it requires a lot of manpower and material resources to be wasted. Therefore, fully researching, developing, and utilizing this abundant natural resource to turn waste into treasure has become an effective way to solve the problem of purple loosestrife.

The list of medicinal plants in Yunnan once recorded that the whole plant of purple loosestrife has the effects of promoting blood circulation, regulating menstruation, clearing heat and detoxifying. It can be used internally to treat colds, fever, menstrual disorders, and swelling and pain, and externally to treat tinea pedis, unnamed swelling and pain, and external bleeding. In recent years, people have used modern pharmacological research methods to study the biological activity of purple loosestrife, indicating that it has antibacterial, antiviral, anti-tumor, antioxidant, and insecticidal activities. Based on the traditional effects of regulating meridians, promoting blood circulation, reducing fever and swelling, it can be inferred that purple loosestrife may have certain anti-inflammatory activity. However, there is currently only one report on the anti-inflammatory activity of the chemical reaction products of purple loosestrife essential oil, and the anti-inflammatory activity of the inherent natural components in purple loosestrife has not been reported yet. Therefore, it is necessary to study the anti-inflammatory active ingredients of purple loosestrife. The project team has conducted research on the extraction, separation, and purification of purple loosestrife using a new extraction and separation technology, and obtained extraction sites such as supercritical CO2 extraction and supercritical CO2 extraction molecular distillation enrichment, as well as two loosestrife monomers (see Figure 1 for monomer structure). Among them, loosestrife components are the main components of the supercritical CO2 extraction site and the supercritical CO2 extraction molecular distillation enrichment site. On this basis, this article evaluates the anti-inflammatory activity of the supercritical CO2 extraction, molecular distillation enrichment, and methanol extraction parts of purple loosestrife in vitro, searching for effective anti-inflammatory ingredients and providing a basis for the resource utilization of this plant.

Based on an in vitro cellular inflammation model, this study is the first to investigate the anti-inflammatory activities of three extraction sites, namely supercritical CO2 extract, supercritical CO2 extraction molecular distillation extract, and methanol extract, as well as euptox A and 9-oxoagaraphrone, from purple loosestrife. From the perspective of in vitro anti-inflammatory effects, supercritical CO2 extract and supercritical CO2 extraction molecular distillation extract exhibit significant anti-inflammatory activity; Supercritical CO2 extract and supercritical CO2 extraction molecular distillation extract are rich in Zeeland ketone components, suggesting that the anti-inflammatory activity of purple loosestrife is related to Zeeland ketone substances. Euptox A and 9-oxoagaraphrone monomers exhibit significant anti-inflammatory activity, and both monomers outperform the respective extracts. The results have shown that Zeelan ketone substances have good anti-inflammatory activity and are one of the effective anti-inflammatory ingredients of purple loosestrife.

NO is a small gas molecule mainly generated by human vascular endothelial cells. When stimulated by antigens, LPS, and certain cytokines, inducible nitric oxide synthase (iNOS) in tissues is induced to produce a large amount of NO during inflammation. NO combines with O2- to produce a stronger oxidant NO3, thereby promoting inflammatory reactions, including vasodilation, edema, and local erythema, increasing inflammatory exudation. At the same time, NO can enter cells to inhibit the tricarboxylic acid cycle, interfere with energy metabolism, exacerbate tissue damage, and adjust NO levels to help treat inflammatory reactions. TNF – α has a wide range of biological characteristics, participating in inflammatory and immune responses, anti-tumor and other pathological processes. At the same time, TNF – α can further induce the production of cytokines such as IL-6, IL-8, interleukin-10, etc. These pro-inflammatory cytokines participate in acute reactions, fever reactions, and trigger the release of chemokines in the body. They can also activate endothelial cells, leading to increased vascular permeability. Zeranone compounds have a significant inhibitory effect on the production of NO and TNF – α in LPS activated mouse macrophages, and the effect is dose-dependent, indicating that the anti-inflammatory effect of Zeranone compounds is related to their inhibition of NO and TNF – α production. This experiment only explored the in vitro anti-inflammatory activity of the components of the purple loosestrife, while the molecular mechanism of its components, as well as their absorption and metabolism patterns in vitro and in vivo anti-inflammatory mechanisms, deserve further investigation.

This study only investigated the in vitro anti-inflammatory activities of supercritical CO2 extract and supercritical CO2 molecular distillation extract of purple loosestrife, as well as the main single compounds of loosestrife, euptox A and 9-oxogeraphorone. Purple loosestrife may also contain a small amount of structurally similar compounds such as 9-carbonyl-12-hydroxy-10,11-dehydroloosestrife, 9 β – hydroxyloosestrife, and 9-hydroxyloosestrife acetate. The in vivo and in vitro anti-inflammatory activities and mechanisms of other loosestrife components deserve further systematic research.