Inhibitory Effects of JEUD-38, a New Sesquiterpene Lactone from Inula japonica Thunb, on LPS-Induced iNOS Expression in RAW264.7 Cells

Identification of diverse sesquiterpenoids with anti-fibrotic potential from Inula japonica Thunb

In the chemical investigation of Inula japonica, a total of 29 sesquiterpenoids (1-29) were obtained, including pseudoguaine-, xanthane-, eudesmane-, and 1,10-secoeudesmane-type compounds, as well as their dimers. Among them, six new dimeric sesquiterpenoids, bisinulains A-F (1-5, 7), characterized by a [4 + 2] biogenetic pathway between different sesquiterpenoid monomers were identified. Additionally, three new monomers named inulaterins A-C (13, 18 and 21) were discovered. The structures of these compounds were determined through analysis of spectroscopic data, X-ray crystallographic data, and ECD experiments. To assess their potential anti-inflammatory activities, the sesquiterpenoid dimers were tested for their ability to inhibit NO production in LPS-stimulated RAW 264.7 cells. Furthermore, the compounds that exhibited anti-inflammatory effects underwent evaluation for their anti-fibrotic potential using a TGF-β-induced epithelial-mesenchymal transition model in A549 cells. As a result, bisinulain B (2) was screened out to significantly inhibit the production of cytokines involved in pulmonary fibrosis such as NO, α-SMA, collagen I and fibronectin.

1-O-Actylbritannilactone Ameliorates Alcohol-Induced Hepatotoxicity through Regulation of ROS/Akt/NF-κB-Mediated Apoptosis and Inflammation

1-O-Acetylbritannilactone (ABL) is a marker component of Inula britannica L. and is reported to exhibit multiple pharmacological activities, including antiaging, anti-inflammatory, and antidiabetic properties. Although the protective effect of Inula britannica L. on animal models of liver injury has been widely reported, the effect of ABL on alcohol-induced liver damage has not been confirmed. The present study was designed to investigate the protective effect of ABL against alcohol-induced LO2 human normal liver cell injury and to further clarify the underlying mechanism. Our results revealed that ABL at concentrations of 0.5, 1, and 2 μM could remarkably suppress the decreased viability of LO2 cells stimulated by alcohol. In addition, ABL pretreatment improved alcohol-induced oxidative damage by decreasing the level of reactive oxygen species (ROS) and the excessive consumption of glutathione peroxidase (GSH-Px), while increasing the level of catalase (CAT) in LO2 cells. Moreover, Western blotting analysis showed that ABL pretreatment activated protein kinase B (Akt) phosphorylation, increased downstream antiapoptotic protein Bcl-2 expression, and decreased the phosphorylation level of the caspase family including caspase 9 and caspase 3 proteins, thereby attenuating LO2 cell apoptosis. Importantly, we also found that ABL significantly inhibits the activation of the nuclear factor-kappa B (NF-κB) signaling pathway by reducing the secretion of proinflammatory factors including tumor necrosis factor-α (TNF-α) and interleukin (IL-1β). In conclusion, the current research clearly suggests that the protective effect of ABL on alcohol-induced hepatotoxicity may be achieved in part through regulation of the ROS/Akt/NF-κB signaling pathway to inhibit inflammation and apoptosis in LO2 cells. (The article path map has not been seen.).

The Complexity of Sesquiterpene Chemistry Dictates Its Pleiotropic Biologic Effects on Inflammation

Sesquiterpenes (SQs) are volatile compounds made by plants, insects, and marine organisms. SQ have a large range of biological properties and are potent inhibitors and modulators of inflammation, targeting specific components of the nuclear factor-kappaB (NF-κB) signaling pathway and nitric oxide (NO) generation. Because SQs can be isolated from over 1600 genera and 2500 species grown worldwide, they are an attractive source of phytochemical therapeutics. The chemical structure and biosynthesis of SQs is complex, and the SQ scaffold represents extraordinary structural variety consisting of both acyclic and cyclic (mono, bi, tri, and tetracyclic) compounds. These structures can be decorated with a diverse range of functional groups and substituents, generating many stereospecific configurations. In this review, the effect of SQs on inflammation will be discussed in the context of their complex chemistry. Because inflammation is a multifactorial process, we focus on specific aspects of inflammation: the inhibition of NF-kB signaling, disruption of NO production and modulation of dendritic cells, mast cells, and monocytes. Although the molecular targets of SQs are varied, we discuss how these pathways may mediate the effects of SQs on inflammation.

A review of the botany, traditional uses, phytochemistry, and pharmacology of the Flos Inulae

ETHNOPHARMACOLOGICAL RELEVANCE

Plants of the genus Inula have long been used as an ethnomedicine in Asia, Europe, and North America for its high medicinal value and health benefits. Inula japonica Thunb. (I. japonica) and Inula britanica L. (I. britanica) are included in Chinese Pharmacopoeia (2020 edition) as the traditional Chinese medicine Flos inulae (FI). In TCM, FI tastes bitter, pungent, and salt, with warm nature and has the functions of water removal, reduction in nausea, and prevention of vomiting and is often used for cold-related coughs, sputum, wheezing coughs, vomiting, belching and other related diseases. In addition, Inula japonica Thunb is used as a botanical medicine in Korea and Inula britannica L. is also used as a traditional plant medicine in Iran.

AIM OF THE STUDY

This paper collects the relevant research literature (1970-2021) and provides a systematic summary of the botany, ethnopharmacology, processing, phytochemistry, pharmacology, toxicity, analytical methods and quality control of FI to explore its potential and expand its scope for better clinical application.

MATERIALS AND METHODS

Information on Inula japonica Thunb. and Inula britanica L. was collected from scientific databases (1970-2021), including Google Scholar, Baidu Scholar, Springer, PubMed, CNKI and Wan Fang DATA. Information was also collected from classic books of Chinese herbal medicine and Ph.D. and M.Sc. theses.

RESULTS

More than 200 chemical compounds have been isolated from Inula japonica Thunb. and Inula britanica L., including sesquiterpenes, flavonoids, volatile oils, triterpenoids, diterpenoid glycosides, monoterpenoids, polysaccharides, steroid and small molecule acids. Based on a wide variety of chemically active ingredients, FI has a wide range of pharmacological effects. Modern pharmacological research has proven that the pharmacological effects of FI include anti-inflammatory, antitumor, antioxidant, antiallergy, antidiabetic, blood lipid reduction, skin whitening, liver protection, anticonstipation, and antinociceptive effects.

CONCLUSIONS

FI is a very important traditional Chinese herbal medicine with anti-inflammatory antitumor, antioxidant, antiallergy, antidiabetic and other pharmacological effects that can treat a variety of related diseases. This paper summarizes the botany, ethnopharmacology, processing, phytochemistry, pharmacology, toxicity, analytical methods, and quality control of FI. However, the research on the processing, toxicity and quality control of FI is currently too shallow, especially concerning the relationship between the changes in active components before and after processing and the changes in its pharmacological action, which remains unclear. There are few toxicity experiments conducted with FI, so it is impossible to evaluate the safety of FI objectively and impartially. There are also few studies on the material basis and doses of FI causing toxicity and side effects, and more in-depth and concrete researches should be carried out in the future regarding these aspects. Furthermore, to ensure effective and safe clinical medication, we should also pay attention to the mixed use of FI in various regions of China to control the quality of the FI plant.

Sesquiterpene Lactones: Promising Natural Compounds to Fight Inflammation

Inflammation is a crucial and complex process that reestablishes the physiological state after a noxious stimulus. In pathological conditions the inflammatory state may persist, leading to chronic inflammation and causing tissue damage. Sesquiterpene lactones (SLs) are composed of a large and diverse group of highly bioactive plant secondary metabolites, characterized by a 15-carbon backbone structure. In recent years, the interest in SLs has risen due to their vast array of biological activities beneficial for human health. The anti-inflammatory potential of these compounds results from their ability to target and inhibit various key pro-inflammatory molecules enrolled in diverse inflammatory pathways, and prevent or reduce the inflammatory damage on tissues. Research on the anti-inflammatory mechanisms of SLs has thrived over the last years, and numerous compounds from diverse plants have been studied, using in silico, in vitro, and in vivo assays. Besides their anti-inflammatory potential, their cytotoxicity, structure–activity relationships, and pharmacokinetics have been investigated. This review aims to gather the most relevant results and insights concerning the anti-inflammatory potential of SL-rich extracts and pure SLs, focusing on their effects in different inflammatory pathways and on different molecular players.

Medicinal Inula Species: Phytochemistry, Biosynthesis, and Bioactivities

As a genus of the Asteraceae, Inula is widely distributed all over the world, and several of them are being used in traditional medicines. A number of metabolites were isolated from Inula species, and some of these have shown to possess ranges of pharmacological activities. The genus Inula contains abundant sesquiterpenoids, such as eudesmanes, xanthanes, and sesquiterpenoid dimers and trimers. In addition, other types of terpenoids, flavonoids, and lignins also exist in the genus Inula. Since 2010, more than 300 new secondary metabolites, including several known natural products that were isolated for the first time from the genus Inula. Most of them exhibited potential bioactivities in various diseases. The review aimed to summarize the advance of recent researches (2010-2020) on phytochemical constituents, biosynthesis, and pharmacological properties of the genus Inula for providing a scientific basis and supporting its application and exploitation for new drug development.

Cudraflavanone B Isolated from the Root Bark of Cudrania tricuspidata Alleviates Lipopolysaccharide-Induced Inflammatory Responses by Downregulating NF-κB and ERK MAPK Signaling Pathways in RAW264.7 Macrophages and BV2 Microglia

A prenylated flavonoid, cudraflavanone B, is isolated from Cudrania tricuspidata. In this study, we investigated its anti-inflammatory and anti-neuroinflammatory effects in lipopolysaccharide (LPS)-induced RAW264.7 and BV2 cells. In our initial study of the anti-inflammatory effects of cudraflavanone B the production of nitric oxide and prostaglandin E2 was attenuated in LPS-stimulated RAW264.7 and BV2 cells. These inhibitory effects were related to the downregulation of inducible nitric oxide synthase and cyclooxygenase-2. In addition, cudraflavanone B suppressed the production of pro-inflammatory cytokines such as interleukin-6 and tumor necrosis factor-α in LPS-induced RAW264.7 and BV2 cells. Moreover, the evaluation of the molecular mechanisms underlying the anti-inflammatory effects of cudraflavanone B revealed that the compound attenuated the nuclear factor-kappa B signaling pathway in LPS-induced RAW264.7 and BV2 cells. In addition, cudraflavanone B inhibited the phosphorylation of extracellular signal-regulated kinase mitogen-activated protein kinase signaling pathways in these LPS-stimulated cells. Thus, cudraflavanone B suppressed nuclear factor-κB, and extracellular signal-regulated kinase mitogen-activated protein kinase mediated inflammatory pathways, demonstrating its potential in the treatment of neuroinflammatory conditions.

Advances in Pharmacological Activities of Terpenoids

Terpenoids, the most abundant compounds in natural products, are a set of important secondary metabolites in plants with diverse structures. Terpenoids play key roles in plant growth and development, response to the environment, and physiological processes. As raw materials, terpenoids were also widely used in pharmaceuticals, food, and cosmetics industries. Terpenoids possess antitumor, anti-inflammatory, antibacterial, antiviral, antimalarial effects, promote transdermal absorption, prevent and treat cardiovascular diseases, and have hypoglycemic activities. In addition, previous studies have also found that terpenoids have many potential applications, such as insect resistance, immunoregulation, antioxidation, antiaging, and neuroprotection. Terpenoids have a complex structure with diverse effects and different mechanisms of action. Activities and mechanisms of terpenoids were reviewed in this paper. The development and application prospect of terpenoid compounds were also prospected, which provides a useful reference for new drug discovery and drug design based on terpenoids.

Spinacetin Suppresses the Mast Cell Activation and Passive Cutaneous Anaphylaxis in Mouse Model

We previously reported the anti-inflammatory and anti-asthmatic activities of the extract of the Inula japonica Thunb. Aiming for discovery of a novel anti-inflammatory compound, we isolated spinacetin from the extract and investigated its in vitro and in vivo anti-inflammatory effect and the related mechanism. Effect of spinacetin on the Syk signaling pathway was studied in bone marrow-derived mast cells (BMMCs), and that on the nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPKs) was investigated in Rat basophilic leukemia (RBL)-2H3 cells and human mast cell line (HMC-1). The in vivo anti-inflammatory activity was assessed with passive cutaneous anaphylaxis (PCA) reaction assay. Spinacetin significantly inhibited the release of histamine, and production of inflammatory mediators such as leukotriene C₄ (LTC₄) and interlukin-6 (IL-6) in IgE/Ag stimulated BMMCs. Analysis of the signaling pathways demonstrated that spinacetin inhibited activation of Syk, linker of activated T cells (LAT), phospholipase Cγ (PLCγ), cytosolic phospholipase A₂ (cPLA₂), MAPKs, Akt/NF-κB, and intracellular Ca²⁺ mobilization but with no effect on Fyn and Lyn. On the other hand, spinacetin suppressed IgE/Ag-induced activation of RBL-2H3 cells with inhibition against phosphorylation of extracellular signal regulated-protein kinase (ERK), c-Jun-NH₂-terminal kinase (JNK), p38 MAPKs, PLCγ, translocation of cPLA₂, and Akt/IκBα/NF-κB signal. However, spinacetin had no effect on PMA and A23187-induced activation of HMC-1. Furthermore, oral administration of spinacetin dose-dependently attenuated IgE/Ag-mediated PCA reaction in mouse model. Taken together, spinacetin showed the activities in preventing inflammatory processes, which might be at least partially attributed to the abolishment of Syk-dependent activation of IgE/Ag-mediated mast cells.

Roburic Acid Suppresses NO and IL-6 Production via Targeting NF-κB and MAPK Pathway in RAW264.7 Cells

In the present study, we investigated the anti-inflammatory effect of roburic acid on production of nitric oxide (NO) and interlukin-6 (IL-6) in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells. We found that roburic acid reduced production of NO and IL-6, and the expression of inducible nitric oxide synthases (iNOS). Meanwhile, phosphorylation of inhibitor of κBα (IκBα) and IκB kinase α/β (IKKα/β), as well as translocation of nuclear factor-κB (NF-κB) to the nucleus, was suppressed by roburic acid treatment. In addition, phosphorylation of mitogen-activated protein kinase (MAPKs) including p38 and c-Jun-NH₂-terminal kinase (JNK) was inhibited. Roburic acid exhibited inhibitory activities on production of NO and IL-6 via blocking IKK/IκB/NF-κB and MAPKs pathway, suggesting the potential application as a drug candidate for therapy of inflammatory diseases.

Antiproliferative effect of ZSTK474 alone or in combination with chemotherapeutic drugs on HL60 and HL60/ADR cells

While chemotherapy remains to be one of the main approaches in the clinical treatment of acute myeloid leukemia (AML), multidrug resistance (MDR) has become a serious problem which limits the therapeutic efficacy. The important roles of the PI3K/Akt pathway in modulating cell proliferation and MDR suggest that PI3K inhibitor might be effective for treatment of AML. In the present study, the antiproliferative effects of PI3K inhibitor ZSTK474 on AML cell HL60 and the adriamycin (ADR)-resistant HL60/ADR cells were investigated. Our data indicated that ZSTK474 exhibited potent antiproliferative activity, induced G1 cell cycle arrest, but no obvious apoptosis in both cell lines. Moreover, ZSTK474 affected the protein levels of cell-cycle-related molecules including increased p27, decreased cyclin D1 and phosphorylated Rb in dose-dependent manner. The proteins downstream of PI3K including phosphorylated PDK1, Akt and GSK-3β were reduced in a dose-dependent manner after ZSTK474 treatment. ZSTK474 reversed ADR resistance, increased the intracellular accumulation of ADR, and reduced the expression and function of multidrug resistance (MDR) proteins including both P-gp and MRP1 in HL60/ADR cells. The combination of ZSTK474 and chemotherapeutic drugs cytarabine or vincristine led to a synergistic effect in HL60 and HL60/ADR cells. In conclusion, ZSTK474 showed potent antiproliferative effect on HL60 and HL60/ADR cells; combination with cytarabine or vincristine resulted in synergistic effect. Our results suggest ZSTK474 has the potential to be applied in the treatment of AML patients, while further evidences particularly those about in vivo efficacy are needed.

Role of Antioxidants and Natural Products in Inflammation

Inflammation is a comprehensive array of physiological response to a foreign organism, including human pathogens, dust particles, and viruses. Inflammations are mainly divided into acute and chronic inflammation depending on various inflammatory processes and cellular mechanisms. Recent investigations have clarified that inflammation is a major factor for the progression of various chronic diseases/disorders, including diabetes, cancer, cardiovascular diseases, eye disorders, arthritis, obesity, autoimmune diseases, and inflammatory bowel disease. Free radical productions from different biological and environmental sources are due to an imbalance of natural antioxidants which further leads to various inflammatory associated diseases. In this review article, we have outlined the inflammatory process and its cellular mechanisms involved in the progression of various chronic modern human diseases. In addition, we have discussed the role of free radicals-induced tissue damage, antioxidant defence, and molecular mechanisms in chronic inflammatory diseases/disorders. The systematic knowledge regarding the role of inflammation and its associated adverse effects can provide a clear understanding in the development of innovative therapeutic targets from natural sources that are intended for suppression of various chronic inflammations associated diseases.

Sesquiterpenes from Inula japonica with Inhibitory Effects on Nitric Oxide Production in Murine Macrophage RAW 264.7 Cells

Eight new sesquiterpenes (1-8), along with seven known sesquiterpenes (9-15), were isolated from a methanol extract of the flowers of Inula japonica. Their structures were elucidated by a combination of 1D and 2D NMR spectroscopic and HRESIMS data. All of isolates were evaluated for their inhibitory effects on nitric oxide production in LPS-induced RAW 264.7 cells, with their IC50 values ranging from 1.9 to 15.4 μM.

In Vitro Antileukemia Activity of ZSTK474 on K562 and Multidrug Resistant K562/A02 Cells

Chronic myelogenous leukemia (CML) is a malignant hematological disorder mainly caused by the Bcr-Abl tyrosine kinase. While Bcr-Abl inhibitors including Imatinib showed antitumor efficacy on many CML patients, resistance was frequently reported in recent years. Therefore, novel drugs for CML are still expected. ZSTK474 is a specific phosphatidylinositol 3-kinase (PI3K) inhibitor that we identified. In the present study, the efficacy of ZSTK474, alone or in combination with Imatinib, on K562 CML cells as well as on its multidrug resistance counterpart K562/A02 cells, was investigated. ZSTK474 inhibited the cell proliferation with an IC₅₀ of 4.69 μM for K562 and 7.57 μM for K562/A02 cells, respectively. Treatment by ZSTK474 resulted in cell cycle arrest in G1 phase, which might be associated with upregulation of p27, and downregulation of cyclin D1. ZSTK474 also inhibited phosphorylation of Akt and GSK-3β, which might be involved in the effect on the above cell cycle-related proteins. Moreover, combination of ZSTK474 and Imatinib indicated synergistic effect on both cell lines. In conclusion, ZSTK474 exhibited antileukemia activity alone, and showed synergistic effect when combined with Imatinib, on CML K562 cells as well as the multidrug resistant ones, providing a potential therapeutic approach for CML patients.