Eudesmane-Type Sesquiterpene Glycosides from Dictamnus dasycarpus Turcz

Eudesmane-type sesquiterpenoids: Structural diversity and biological activity

Sesquiterpenoids are integral constituents of terpenoid-bearing plants, comprising a diverse and abundant class of natural compounds, among which eudesmane-type sesquiterpenoids have bicyclic structures that feature the fusion of two six-membered carbon rings, thereby attracting considerable attention. They are widespread in nature, with multifaceted biological activities such as anti-inflammatory, anticancer, antimicrobial, antimalarial, and insecticidal activities, thus gaining focus in life science research. The discovery and identification of these active compounds have laid a foundation for unraveling their potential medicinal value. In this review, we comprehensively explore the natural eudesmane-type sesquiterpenoids isolated (totaling 391 compounds) between 2016 and 2022, elucidating their chemical structures, plant distribution patterns, and pertinent biological properties. Accordingly, the study serves not only as a framework for researchers to thoroughly comprehend these compounds but also as a robust reference for future endeavors aimed at exploring the pharmaceutical potential and prospective applications of these molecules.

Five new sesquiterpenoids isolated from Dictamnus dasycarpus Turcz

Five new sesquiterpenoids, dictamtrinorguaianols E and F (1-2), and dictameudesmnosides F, G, and H (3-5), along with seven known sesquiterpenoids (6-12) were isolated from Dictamnus dasycarpus Turcz. The structures of all new compounds were characterized by spectroscopic methods, including UV, IR, HR-ESI-MS, and 1D and 2D NMR. The In-vitro anti-proliferative activities of all the compounds against two human cancer cell lines (SW982 and A549) were evaluated by CCK-8 assay. Compounds 1 and 4 showed medium anti-proliferative activity against SW982 cells, with IC50 values of 3.49 ± 0.10 and 6.42 ± 1.23 μM, respectively. Additionally, compounds 2, 7, and 8 exhibited medium anti-proliferative activity against A549 cells, with IC50 values ranging from 0.80 ± 0.05 to 6.60 ± 0.46 μM.

From immune checkpoints to therapies: understanding immune checkpoint regulation and the influence of natural products and traditional medicine on immune checkpoint and immunotherapy in lung cancer

Lung cancer is a disease of global concern, and immunotherapy has brought lung cancer therapy to a new era. Besides promising effects in the clinical use of immune checkpoint inhibitors, immune-related adverse events (irAEs) and low response rates are problems unsolved. Natural products and traditional medicine with an immune-modulating nature have the property to influence immune checkpoint expression and can improve immunotherapy's effect with relatively low toxicity. This review summarizes currently approved immunotherapy and the current mechanisms known to regulate immune checkpoint expression in lung cancer. It lists natural products and traditional medicine capable of influencing immune checkpoints or synergizing with immunotherapy in lung cancer, exploring both their effects and underlying mechanisms. Future research on immune checkpoint modulation and immunotherapy combination applying natural products and traditional medicine will be based on a deeper understanding of their mechanisms regulating immune checkpoints. Continued exploration of natural products and traditional medicine holds the potential to enhance the efficacy and reduce the adverse reactions of immunotherapy.

The traditional uses, phytochemistry, pharmacology and toxicology of Dictamnus dasycarpus: a review

OBJECTIVES

Dictamnus dasycarpus is a plant of the Rutaceae family, and its root bark is the main part used as a medicine, named 'Bai-Xian-Pi'. It is used to clear away heat, remove dampness, and dispel wind and also used for detoxification. The purpose of this review is to provide a systematic review about the botany, traditional uses, phytochemistry, pharmacology and toxicology of this plant.

KEY FINDINGS

More than 200 compounds have been isolated and identified from the plant, including alkaloids and their glycosides, terpenoids and their derivatives and phenylpropanoids. Extensive pharmacological activities of the extracts or compounds of D. dasycarpus in vivo and in vitro were mainly confirmed, including anti-inflammatory activity, protecting cardiovascular activity, improving liver injury and anti-cancer activity.

SUMMARY

In this paper, the botany, traditional uses, phytochemistry and pharmacology of D. dasycarpus were reviewed. In the future, D. dasycarpus needs further study, such as paying more attention to quality control and the utilization on agriculture. In addition, discussing the medicinal components of decoction as well as the toxicity will also contribute to the progress of clinical trial studies.

Anti-inflammatory Limonoids From Cortex Dictamni

The root barks of perennial herb Dictamnus dasycarpus (Cortex Dictamni) were reported to be rich in anti-inflammation activity constituents, limonoids. Then, the investigation of anti-inflammation therapeutic limonoids from this plant was developed in the present study. Through the combination of various chromatographies isolation, six new limonoids, named dictamlimonol A (1), dictamlimonoside B (2), and dictamlimonols C–F (3–6), along with seven known ones (7–13), were obtained. Their structures were ascertained based on the extensive spectroscopic methods and ECD data analysis. Among them, compound 1 was the first 7,19-epoxy limonoid found in natural products. The anti-inflammatory effects of all limonoids were evaluated in lipopolysaccharide (LPS)-treated RAW 264.7 cell lines. Compounds 5, 7–11, and 13 were found to inhibit LPS-induced nitric oxide (NO) production. Moreover, dictamlimonol D (5), fraxinellone (11), and dasylactone A (13) were found to reduce the LPS-induced expressions of interleukin-6 (IL-6), tumor necrosis factor (TNF-α), inducible nitric oxide synthase (iNOS), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and cyclooxygenase-2 (COX-2) at the protein levels in a dose-dependent manner. These findings support that the administration of Cortex Dictamni may be beneficial for inflammation.

Fraxinellone has anticancer activity in vivo by inhibiting programmed cell death-ligand 1 expression by reducing hypoxia-inducible factor-1α and STAT3

Dictamnus dasycarpus is a traditional Chinese medicine thathas been commonly used in the treatment of cancer. Fraxinellone is a natural product isolated from the D. dasycarpus plant, which has been shown to exhibit neuroprotective and anti-inflammatory activities. However, whether fraxinellone exerts anticancer effects and the mechanisms by which it may inhibit tumor growth remain unknown. Here, we found that fraxinellone, in a dose-dependented manner, inhibited the expression of programmed cell death ligand-1 (PD-L1), which plays a pivotal role in tumorigenesis. It was subsequently shown that fraxinellone reduced HIF-1α protein synthesis via the mTOR/p70S6K/eIF4E and MAPK pathways. It also inhibited activation of STAT3 via the JAK1, JAK2, and Src pathways. Immunoprecipitation and western blotting assays showed that fraxinellone inhibited PD-L1 expression by reducing STAT3 and HIF-1α cooperatively. Flow cytometry, colony formation, and EdU incorporation assays demonstrated that fraxinellone inhibited cell proliferation through suppression of PD-L1. Tube formation, migration, and invasion assays showed that fraxinellone inhibits angiogenesis by suppressing PD-L1. In vivo studies further supported anticancer role for fraxinellone, demonstrating that fraxinellone treatment inhibited the growth of tumor xenografts. We concluded that fraxinellone inhibits PD-L1 expression by downregulating the STAT3 and HIF-1α signaling pathways, subsequently inhibiting proliferation and angiogenesis in cancer cells. These studies reveal previously unknown characteristics of fraxinellone and provide new perspectives into the mechanism of cancer inhibition of the compound.