Trioxolone Methyl, a Novel Cyano Enone-Bearing 18βH-Glycyrrhetinic Acid Derivative, Ameliorates Dextran Sulphate Sodium-Induced Colitis in Mice

Protective effect of soloxolone derivatives in carrageenan- and LPS-driven acute inflammation: Pharmacological profiling and their effects on key inflammation-related processes

The anti-inflammatory potential of three cyanoenone-containing triterpenoids, including soloxolone methyl (SM), soloxolone (S) and its novel derivative bearing at the C-30 amidoxime moiety (SAO), was studied in murine models of acute inflammation. It was found that the compounds effectively suppressed the development of carrageenan-induced paw edema and peritonitis as well as lipopolysaccharide (LPS)-driven acute lung injury (ALI) with therapeutic outcomes comparable with that of the reference drugs indomethacin and dexamethasone. Non-immunogenic carrageenan-stimulated inflammation was more sensitive to the transformation of C-30 of SM compared with immunogenic LPS-induced inflammation: the anti-inflammatory properties of the studied compounds against carrageenan-induced paw edema and peritonitis decreased in the order of SAO > S > > SM, whereas the efficiency of these triterpenoids against LPS-driven ALI was similar (SAO ≈ S ≈ SM). Further studies demonstrated that soloxolone derivatives significantly inhibited a range of immune-related processes, including granulocyte influx and the expression of key pro-inflammatory cytokines and chemokines in the inflamed sites as well as the functional activity of macrophages. Moreover, SM was found to prevent inflammation-associated apoptosis of A549 pneumocytes and effectively inhibited the protease activity of thrombin (IC₅₀ = 10.3 µM) tightly associated with rodent inflammatome. Taken together, our findings demonstrate that soloxolone derivatives can be considered as novel promising anti-inflammatory drug candidates with multi-targeted mechanism of action.

Novel Epoxides of Soloxolone Methyl: An Effect of the Formation of Oxirane Ring and Stereoisomerism on Cytotoxic Profile, Anti-Metastatic and Anti-Inflammatory Activities In Vitro and In Vivo

It is known that epoxide-bearing compounds display pronounced pharmacological activities, and the epoxidation of natural metabolites can be a promising strategy to improve their bioactivity. Here, we report the design, synthesis and evaluation of biological properties of αO-SM and βO-SM, novel epoxides of soloxolone methyl (SM), a cyanoenone-bearing derivative of 18βH-glycyrrhetinic acid. We demonstrated that the replacement of a double-bound within the cyanoenone pharmacophore group of SM with α- and β-epoxide moieties did not abrogate the high antitumor and anti-inflammatory potentials of the triterpenoid. It was found that novel SM epoxides induced the death of tumor cells at low micromolar concentrations (IC₅₀^(24h) = 0.7–4.1 µM) via the induction of mitochondrial-mediated apoptosis, reinforced intracellular accumulation of doxorubicin in B16 melanoma cells, probably by direct interaction with key drug efflux pumps (P-glycoprotein, MRP1, MXR1), and the suppressed pro-metastatic phenotype of B16 cells, effectively inhibiting their metastasis in a murine model. Moreover, αO-SM and βO-SM hampered macrophage functionality in vitro (motility, NO production) and significantly suppressed carrageenan-induced peritonitis in vivo. Furthermore, the effect of the stereoisomerism of SM epoxides on the mentioned bioactivities and toxic profiles of these compounds in vivo were evaluated. Considering the comparable antitumor and anti-inflammatory effects of SM epoxides with SM and reference drugs (dacarbazine, dexamethasone), αO-SM and βO-SM can be considered novel promising antitumor and anti-inflammatory drug candidates.

Core genes involved in the regulation of acute lung injury and their association with COVID-19 and tumor progression: A bioinformatics and experimental study

Acute lung injury (ALI) is a specific form of lung damage caused by different infectious and non-infectious agents, including SARS-CoV-2, leading to severe respiratory and systemic inflammation. To gain deeper insight into the molecular mechanisms behind ALI and to identify core elements of the regulatory network associated with this pathology, key genes involved in the regulation of the acute lung inflammatory response (Il6, Ccl2, Cat, Serpine1, Eln, Timp1, Ptx3, Socs3) were revealed using comprehensive bioinformatics analysis of whole-genome microarray datasets, functional annotation of differentially expressed genes (DEGs), reconstruction of protein-protein interaction networks and text mining. The bioinformatics data were validated using a murine model of LPS-induced ALI; changes in the gene expression patterns were assessed during ALI progression and prevention by anti-inflammatory therapy with dexamethasone and the semisynthetic triterpenoid soloxolone methyl (SM), two agents with different mechanisms of action. Analysis showed that 7 of 8 revealed ALI-related genes were susceptible to LPS challenge (up-regulation: Il6, Ccl2, Cat, Serpine1, Eln, Timp1, Socs3; down-regulation: Cat) and their expression was reversed by the pre-treatment of mice with both anti-inflammatory agents. Furthermore, ALI-associated nodal genes were analysed with respect to SARS-CoV-2 infection and lung cancers. The overlap with DEGs identified in postmortem lung tissues from COVID-19 patients revealed genes (Saa1, Rsad2, Ifi44, Rtp4, Mmp8) that (a) showed a high degree centrality in the COVID-19-related regulatory network, (b) were up-regulated in murine lungs after LPS administration, and (c) were susceptible to anti-inflammatory therapy. Analysis of ALI-associated key genes using The Cancer Genome Atlas showed their correlation with poor survival in patients with lung neoplasias (Ptx3, Timp1, Serpine1, Plaur). Taken together, a number of key genes playing a core function in the regulation of lung inflammation were found, which can serve both as promising therapeutic targets and molecular markers to control lung ailments, including COVID-19-associated ALI.

Uncovering the anti-angiogenic effect of semisynthetic triterpenoid CDDO-Im on HUVECs by an integrated network pharmacology approach

AIM

To reveal the molecular mechanism of anti-angiogenic activity of semisynthetic triterpenoid CDDO-Im.

MATERIALS AND METHODS

Using re-analysis of cDNA microarray data of CDDO-Im-treated human vascular endothelial cells (HUVECs) (GSE71622), functional annotation of revealed differentially expressed genes (DEGs) and analysis of their co-expression, the key processes induced by CDDO-Im in HUVECs were identified. Venn diagram analysis was further performed to reveal the common DEGs, i.e. genes both susceptible to CDDO-Im and involved in the regulation of angiogenesis. A list of probable protein targets of CDDO-Im was prepared based on Connectivity Map/cheminformatics analysis and chemical proteomics data, among which the proteins that were most associated with the angiogenesis-related regulome were identified. Finally, identified targets were validated by molecular docking and text mining approaches.

KEY FINDINGS

The effect of CDDO-Im in HUVECs can be divided into two main phases: the short early phase (0.5-3 h) with an acute FOXD1/CEBPA/JUNB-regulated pro-angiogenic response induced by xenobiotic stress, and the second anti-angiogenic step (6-24 h) with massive suppression of various angiogenesis-related processes, accompanied by the activation of cytoprotective mechanisms. Our analysis showed that the anti-angiogenic activity of CDDO-Im is mediated by its inhibition of the expression of PLAT, ETS1, A2M, SPAG9, RASGRP3, FBXO32, GCNT1 and HDGFRP3 and its direct interactions with EGFR, mTOR, NOS2, HSP90AA1, MDM2, SYK, IRF3, ATR and KIF14.

SIGNIFICANCE

Our findings provide valuable insights into the understanding of the molecular mechanisms of the anti-angiogenic activity of cyano enone-bearing triterpenoids and revealed a range of novel promising therapeutic targets to control pathological neovascularization.

Boswellic acids: privileged structures to develop lead compounds for anticancer drug discovery

Introduction: Cancer has been identified to be the second major cause of death internationally as exemplified by ca. 9.6 million deaths in 2018 along with ca. 18 million new patients in 2018 that have been recorded. Natural boswellic acids (BAs) and their source, frankincense, have been reported to possess in vitro and in vivo anticancer effects toward various cancer cells.Areas covered: This comprehensive review focuses on the importance of boswellic acids (BAs) for the establishment of future treatments of cancer. Moreover, potent semisynthetic derivatives of BAs have been described along with their mode of action. In addition, important structural features of the semisynthetic BAs required for cytotoxic effects are also discussed.Expert opinion: Numerous semisynthetic BAs illustrate excellent cytotoxic effects. Of note, compounds bearing cyanoenone moieties in ring A, endoperoxides and hybrids display increased and more potent cytotoxic effects compared with other semisynthetic BAs. Moreover, BAs have the potential to conjugate or couple with other anticancer compounds to synergistically increase their combined anticancer effects. In addition, to get derived BAs to become lead anticancer compounds, future research should focus on the preparation of ring A cyanoenones, endoperoxides, and C-24 amide analogs.

Grafting of 18β-Glycyrrhetinic Acid and Sialic Acid onto Chitosan to Produce a New Amphipathic Chitosan Derivative: Synthesis, Characterization, and Cytotoxicity

Chitosan is the only cationic polysaccharide found in nature. It has broad application prospects in biomaterials, but its application is limited due to its poor solubility in water. A novel chitosan derivative was synthesized by amidation of chitosan with 18β-glycyrrhetinic acid and sialic acid. The chitosan derivatives were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and measurement of the zeta potential. We also investigated the solubility, cytotoxicity, and blood compatibility of chitosan derivatives. 18β-glycyrrhetinic acid and sialic acid could be grafted onto chitosan molecular chains. The thermal stability of the synthesized chitosan derivatives was decreased and the surface was positively charged in water and phosphate-buffered saline. After chitosan had been modified by 18 β-glycyrrhetinic acid and sialic acid, the solubility of chitosan was improved greatly in water and phosphate-buffered saline, and percent hemolysis was <5%. Novel amphiphilic chitosan derivatives could be suitable polymers for biomedical purposes.

Cyano Enone-Bearing Triterpenoid Soloxolone Methyl Inhibits Epithelial-Mesenchymal Transition of Human Lung Adenocarcinoma Cells In Vitro and Metastasis of Murine Melanoma In Vivo

Introduction of α-cyano α,β-unsaturated carbonyl moiety into natural cyclic compounds markedly improves their bioactivities, including inhibitory potential against tumor growth and metastasis. Previously, we showed that cyano enone-bearing derivatives of 18βH-glycyrrhetinic (GA) and deoxycholic acids displayed marked cytotoxicity in different tumor cell lines. Moreover, GA derivative soloxolone methyl (SM) was found to induce ER stress and apoptosis in tumor cells in vitro and inhibit growth of carcinoma Krebs-2 in vivo. In this work, we studied the effects of these compounds used in non-toxic dosage on the processes associated with metastatic potential of tumor cells. Performed screening revealed SM as a hit compound, which inhibits motility of murine melanoma B16 and human lung adenocarcinoma A549 cells and significantly suppresses colony formation of A549 cells. Further study showed that SM effectively blocked transforming growth factor β (TGF-β)-induced epithelial-mesenchymal transition (EMT) of A549 cells: namely, inhibited TGF-β-stimulated motility and invasion of tumor cells as well as loss of their epithelial characteristics, such as, an acquisition of spindle-like phenotype, up- and down-regulation of mesenchymal (vimentin, fibronectin) and epithelial (E-cadherin, zona occludens-1 (ZO-1)) markers, respectively. Network pharmacology analysis with subsequent verification by molecular modeling revealed that matrix metalloproteinases MMP-2/-9 and c-Jun N-terminal protein kinase 1 (JNK1) can be considered as hypothetical primary targets of SM, mediating its marked anti-EMT activity. The inhibitory effect of SM on EMT revealed in vitro was further confirmed in a metastatic model of murine B16 melanoma: SM was found to effectively block metastatic dissemination of melanoma B16 cells in vivo, increase expression of E-cadherin and suppress expression of MMP-9 in lung metastatic foci. Altogether, our data provided valuable information for a better understanding of the antitumor activity of cyano enone-bearing semisynthetic compounds and revealed SM as a promising anti-metastatic drug candidate.

Dual Effect of Soloxolone Methyl on LPS-Induced Inflammation In Vitro and In Vivo

Plant-extracted triterpenoids belong to a class of bioactive compounds with pleotropic functions, including antioxidant, anti-cancer, and anti-inflammatory effects. In this work, we investigated the anti-inflammatory and anti-oxidative activities of a semisynthetic derivative of 18βH-glycyrrhetinic acid (18βH-GA), soloxolone methyl (methyl 2-cyano-3,12-dioxo-18βH-olean-9(11),1(2)-dien-30-oate, or SM) in vitro on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and in vivo in models of acute inflammation: LPS-induced endotoxemia and carrageenan-induced peritonitis. SM used at non-cytotoxic concentrations was found to attenuate the production of reactive oxygen species and nitric oxide (II) and increase the level of reduced glutathione production by LPS-stimulated RAW264.7 cells. Moreover, SM strongly suppressed the phagocytic and migration activity of activated macrophages. These effects were found to be associated with the stimulation of heme oxigenase-1 (HO-1) expression, as well as with the inhibition of nuclear factor-κB (NF-κB) and Akt phosphorylation. Surprisingly, it was found that SM significantly enhanced LPS-induced expression of the pro-inflammatory cytokines interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) in RAW264.7 cells via activation of the c-Jun/Toll-like receptor 4 (TLR4) signaling axis. In vivo pre-exposure treatment with SM effectively inhibited the development of carrageenan-induced acute inflammation in the peritoneal cavity, but it did not improve LPS-induced inflammation in the endotoxemia model.