Securinine inhibits the tumor growth of human bladder cancer cells by suppressing Wnt/ß-catenin signaling pathway and activating p38 and JNK signaling pathways.

Bladder cancer (BC) is the most common malignant tumor in urinary system. Although chemotherapy is one of the most important adjuvant treatments for BC, drug resistance, non-specific toxicity and severe side effects are the major obstacles to BC chemotherapy. Natural products have always been a leading resource of antitumor drug discovery, with the advantages of excellent effectiveness, low toxicity, multi-targeting potency and easy availability. In this study, we evaluated the potential anti-tumor effect of securinine (SEC), a natural alkaloid from Securinega suffruticosa, on BC cells in vitro and in vivo, and delineated the underlying mechanism. We found that SEC inhibited the proliferation, migration and invasion, induced the apoptosis of BC cells in vitro, and retarded the xenograft tumor growth of BC cell in vivo. Notably, SEC had a promising safety profile because it presented no or low toxicity on normal cells and mice. Mechanistically, SEC inactivated Wnt/ß-catenin signaling pathway while activated p38 and JNK signaling pathway. Moreover, ß-catenin overexpression, the p38 inhibitor SB203580 and the JNK inhibitor SP600125 both mitigated the inhibitory effect of SEC on BC cells. Furthermore, we demonstrated a synergistic inhibitory effect of SEC and gemcitabine (GEM) on BC cells in vitro and in vivo. Taken together, our findings suggest that SEC may exert anti-BC cell effect at least through the activation of p38 and JNK signaling pathways, and the inhibition of Wnt/ß-catenin signaling pathway. More meaningfully, the findings indicate that GEM-induced BC cell killing can be enhanced by combining with SEC.

Levistilide A Exerts a Neuroprotective Effect by Suppressing Glucose Metabolism Reprogramming and Preventing Microglia Polarization Shift: Implications for Parkinson's Disease.

The microglia, displaying diverse phenotypes, play a significant regulatory role in the development, progression, and prognosis of Parkinson's disease. Research has established that glycolytic reprogramming serves as a critical regulator of inflammation initiation in pro-inflammatory macrophages. Furthermore, the modulation of glycolytic reprogramming has the potential to reverse the polarized state of these macrophages. Previous studies have shown that Levistilide A (LA), a phthalide component derived from Angelica sinensis, possesses a range of pharmacological effects, including anti-inflammatory, antioxidant, and neuroprotective properties. In our study, we have examined the impact of LA on inflammatory cytokines and glucose metabolism in microglia induced by lipopolysaccharide (LPS). Furthermore, we explored the effects of LA on the AMPK/mTOR pathway and assessed its neuroprotective potential both in vitro and in vivo. The findings revealed that LA notably diminished the expression of M1 pro-inflammatory factors induced by LPS in microglia, while leaving M2 anti-inflammatory factor expression unaltered. Additionally, it reduced ROS production and suppressed IκB-α phosphorylation levels as well as NF-κB p65 nuclear translocation. Notably, LA exhibited the ability to reverse microglial glucose metabolism reprogramming and modulate the phosphorylation levels of AMPK/mTOR. In vivo experiments further corroborated these findings, demonstrating that LA mitigated the death of TH-positive dopaminergic neurons and reduced microglia activation in the ventral SNpc brain region of the midbrain and the striatum. In summary, LA exhibited neuroprotective benefits by modulating the polarization state of microglia and altering glucose metabolism, highlighting its therapeutic potential.

Synthesis, biological activity and mechanism of action of novel allosecurinine derivatives as potential antitumor agents.

Cancer with low survival rates is the second main cause of death among all diseases in the world and consequently, effective antineoplastic agents are urgently needed. Allosecurinine is a plant-derived indolicidine securinega alkaloid shown bioactivity. The object of this study is to investigate synthetic allosecurinine derivatives with considerable anticancer capacity against nine human cancer cell lines as well as mechanism of action. We synthesized twenty-three novel allosecurinine derivatives and evaluated their antitumor activity against nine cancer cell lines for 72 h by MTT and CCK8 assays. FCM was applied to analyze the apoptosis, mitochondrial membrane potential, DNA content, ROS production, CD11b expression. Western blot was selected to analyze the protein expression. Structure-activity relationships were established and potential anticancer lead BA-3 which induced differentiation of leukemia cells towards granulocytosis at low concentration and apoptosis at high concentration was identified. Mechanism studies showed that mitochondrial pathway mediated apoptosis within cancer cells with cell cycle blocking was induced by BA-3. In addition, western blot assays revealed that BA-3 induced expression of the proapoptotic factor Bax, p21 and reduced the levels of antiapoptotic protein such as Bcl-2, XIAP, YAP1, PARP, STAT3, p-STAT3, and c-Myc. Collectively, BA-3 was a lead compound for oncotherapy at least in part, through the STAT3 pathway. These results were an important step in further studies on allosecurinine-based antitumor agent development.

Potential anticancer activities of securinine and its molecular targets.

BACKGROUND: Securinine is an alkaloid identified from the roots and leaves of the shrub Flueggea suffruticosa (Pall.) Baill. The molecular structure of securinine consists of four rings, including three chiral centers. It has been suggested that securinine can be chemically synthesized from tyrosine and lysine. Securinine has long been used to treat central nervous system diseases. In recent years, more and more evidence shows that securinine also has anticancer activity, which has not been systematically discussed and analyzed. PURPOSE: This study aims to propose an overall framework to describe the molecular targets of securinine in different signal pathways, and discuss the current status and prospects of each pathway, so as to provide a theoretical basis for the development securinine as an effective anticancer drug. METHODS: The research databases on the anticancer activity of securinine from PubMed, Scopus, Web of Science and ScienceDirect to 2021 were systematically searched. This paper follows the Preferred Reporting Items and Meta-Analysis guidelines. RESULTS: Securinine has the ability to kill a variety of human cancer cells, including, leukemia as well as prostate, cervical, breast, lung, and colon cancer cells. It can regulate the signal pathways of phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin, Wnt and Janus kinase-signal transducer and activator of transcription, promote cancer cell apoptosis and autophagy, and inhibit cancer cell metastasis. Securinine also has the activity of inducing leukemia cell differentiation. CONCLUSION: Although there has been some experimental evidence indicating the anticancer effect of securinine and its possible pharmacology, in order to design more effective anticancer drugs, it is necessary to study the synergy of intracellular signaling pathways. More in vivo experiments and even clinical studies are needed, and the synergy between securinine and other drugs is also worth studying.

Levistilide a Induces Ferroptosis by Activating the Nrf2/HO-1 Signaling Pathway in Breast Cancer Cells.

Introduction: Breast cancer (BC) is the leading female malignancy, with one million new cases diagnosed worldwide per year. However, the current treatment options for BC patients have difficulty achieving satisfactory efficacy. Ferroptosis is a new mode of regulated cell death that plays a key role in the inhibition of tumorigenesis. Levistilide A (LA), as an active compound extracted from Chuanxiong Rhizoma, might prevent the development of tumors by regulating the critical cellular processes of ferroptosis. Methods: In this study, the underlying mechanisms of LA on ferroptosis in BC were explored in vitro. The effect of LA on the viability and mitochondrial function of BC cells was determined. Moreover, the effect of LA on the expression levels of key molecules involved in ferroptosis and the nuclear factor erythroid-2-related factor 2/heme oxygenase 1 (Nrf2/HO-1) signaling pathway was evaluated. Results: LA significantly reduced cell viability and damaged the mitochondrial structure and function of BC cells in a dose-dependent manner. Furthermore, LA treatment markedly enhanced reactive oxygen species (ROS)-induced ferroptosis by activating the Nrf2/HO-1 signaling pathway. Conclusion: These findings suggest that LA may be a potential lead compound for breast cancer therapy by inducing ferroptosis in tumor cells.

Collective total synthesis of C4-oxygenated securinine-type alkaloids via stereocontrolled diversifications on the piperidine core.

Securinega alkaloids have fascinated the synthetic chemical community for over six decades. Historically, major research foci in securinega alkaloid synthesis have been on the efficient construction of the fused tetracyclic framework that bears a butenolide moiety and tertiary amine-based heterocycles. These "basic" securinega alkaloids have evolved to undergo biosynthetic oxidative diversifications, especially on the piperidine core. However, a general synthetic solution to access these high-oxidation state securinega alkaloids is lacking. In this study, we have completed the total synthesis of various C4-oxygenated securinine-type alkaloids including securingines A, C, D, securitinine, secu'amamine D, phyllanthine, and 4-epi-phyllanthine. Our synthetic strategy features stereocontrolled oxidation, rearrangement, and epimerization at N1 and C2-C4 positions of the piperidine core within (neo)securinane scaffolds. Our discoveries provide a fundamental synthetic solution to all known securinine-type natural products with various oxidative and stereochemical variations around the central piperidine ring.

Structure simplification of the Securinine skeleton reveals the importance of BCD ring system for the cytotoxic activity on HCT116 and HL60 cell lines.

Function-oriented molecular editing of the polycyclic scaffold of securinine led to the preparation of a library of simplified analogs that have been evaluated for their cytotoxicity potential against HCT116 and HL60 human cell lines. Chemical diversity at the C14 position (securinine numbering) was generated through the site-selective γ-iodination followed by Pd-catalyzed Sonogashira and Suzuki-Miyaura reactions. To explain the selectivity in the iodination step, a reaction mechanism has been proposed. Surprisingly, the piperidine ring (ring A) of the securinine skeleton has been found to be irrelevant for the cytotoxic activity. Based on this finding, the pharmacophoric core of securinine could be simplified to the key BCD motif. The nature of the substituent at the nitrogen can vary from a methyl or an isobutyl group to a benzyl or a carbamate moiety. Interestingly, the N-benzyl substituted simplified analog exhibited the same cytotoxic activity as the parent compound securinine. This functional group tolerance paves the way for the installation of reactive handles for the synthesis of molecular probes for target identification.

Securinine Induces Differentiation of Human Promyelocytic Leukemic HL-60 Cells through JNK-Mediated Signaling Pathway.

Acute myeloid leukemia is characterized by abnormal differentiation of hematopoietic stem cells, leading to the accumulation of immature myeloid cells. Differentiation therapy has been a successful treatment option for acute promyelocytic leukemia but suffers from adverse effects. Therefore, search for novel differentiation-inducing agents with minimal side effects is desirable. Securinine, a naturally-occurring alkaloid, induces differentiation in various leukemic cells and apoptosis in other types of cancers. However, the underlying molecular mechanism(s) remain elusive. Our study aimed to elucidate the possible molecular mechanism(s) and signaling events involved in securinine-induced differentiation of HL-60 cells. Securinine inhibited proliferation in a time- and dose-dependent manner and triggered differentiation. A higher CD14+ population indicated maturation toward monocytic lineage. Securinine caused cell cycle arrest at the G0/G1 phase and enhanced ROS generation. Quantitative gene expression analysis showed significant down-regulation of C/EBP-α, C/EBP-ε, GAΤΑ, and c-myc and up-regulation of the PU.1 gene. The expression of distinct protein kinases Lyn, Chk-2, Yes, FAK, c-Jun, and JNK were enhanced. Use of specific inhibitors of crucial intracellular signaling proteins indicated that JNK and ERK blockade resulted in a significant decline in differentiation. These data thus confirm that securinine induces differentiation through the activation of the JNK-ERK signaling pathway in HL-60 cells.

Securinine induces mitotic block in cancer cells by binding to tubulin and inhibiting microtubule assembly: A possible mechanistic basis for its anticancer activity.

AIM: Analysis of the anticancer and antimitotic activity of the plant derived alkaloid securinine along with its effect on the organization of cellular microtubules as well as its binding with purified goat brain tubulin in-vitro. MATERIALS AND METHODS: The cytotoxicity of securinine on different cell lines was conducted using SRB assay. The effect of securinine on the cellular microtubules was analyzed using immunofluorescence microscopy. The binding of securinine on purified goat brain tubulin was evaluated using fluorescent spectroscopy. KEY FINDINGS: Securinine effectively prevented the proliferation of cervical, breast and lung cancer cells with an IC50 of 6, 10 and 11 µM respectively and induced minimal toxicity in HEK cell line. Securinine at concentrations higher than IC50 induced significant depolymerization in interphase and mitotic microtubules and it suppressed the reassembly of cold depolymerized spindle microtubules in HeLa cells. In the wound healing assay, securinine effectively suppressed the migration of HeLa cells to close the wound. Securinine bound to tubulin with a Kd of 9.7 µM and inhibited the assembly of tubulin into microtubules. The treatment with securinine induced a mitochondrial dependent ROS response in HeLa cells which enhanced the cytotoxic effect of securinine. The result from gene expression studies indicates that securinine induced apoptosis in MCF-7 cells through p53 dependent pathway. SIGNIFICANCE: Considering the strong anticancer and anti-metastatic property and low toxicity in non-malignant cell lines, we suggest that securinine can be used as a chemotherapeutic drug either alone or in combination with other known anticancer molecules.

Securinine Promotes Neuronal Development and Exhibits Antidepressant-like Effects via mTOR Activation.

Impaired differentiation of newborn neurons or abnormalities at the synapses resulted from stress maladaptation could be the key etiology of depression. Recent studies have shown that mTOR, a crucial factor for neuronal differentiation and synapse development, acts as a common factor that mediates the rapid antidepression effects of several new-class antidepressants. In this study, the antidepressant-like activity of securinine, an alkaloid that has central nervous system stimulation ability, was investigated. Both securinine and its enantiomer virosecurinine exhibited potent in vitro activity on neuronal differentiation and synapse development in Neuro-2a cells and cultured hippocampal neurons, and this activity was dependent on the activation of the AKT-mTOR-S6K pathway. Interestingly, only securinine but not virosecurinine showed mTOR stimulation and antidepressant-like activity in mice. Importantly, a single dose of securinine was capable of alleviating the behavioral deficits induced by both acute and chronic stress models within 30 min of administration, suggesting that securinine has rapid onset of action. Moreover, neither a single dose nor a 3 week treatment of securinine had adverse effects on exploratory locomotion of mice. Together, this study identifies that securinine is a potent agent in promoting neuronal differentiation and synapse formation and shows rapid antidepressant-like activity, without inducing abnormal locomotion, via mTOR activation.

Chuanxiongdiolides R4 and R5, phthalide dimers with a complex polycyclic skeleton from the aerial parts of Ligusticum chuanxiong and their vasodilator activity.

Chuanxiongdiolides R4-R6 (1-3), three novel phthalide dimers featuring two classes of unreported monomeric units (ligustilide/senkyunolide A and ligustilide/neocnidilide) with an unprecedented linkage style (3a,7'/7a,7'a), were isolated from the aerial parts of Ligusticum chuanxiong, together with three pairs of enantiomeric phthalide dimers [(-)/(+)-4a/4b, 5a/5b, and 6a/6b]. The bioassays revealed that compounds 1, 3, 4, 5, and 6 showed significant vasodilation effects, and the mechanism may be attributed to Cav1.2 activation blockade. Based on the established compounds library, the structure activity relationship of the phthalides was proposed. Our findings afford possible leads for developing new vasodilator against cardiovascular and cerebrovascular diseases such as hypertension and ischemic stroke.

Identification of securinine as vascular protective agent targeting atherosclerosis in vascular endothelial cells, smooth muscle cells, and apolipoprotein E deficient mice.

BACKGROUND: Atherosclerosis is a chronic vascular disease and characterized by accumulation within the intima of inflammatory cells, smooth muscle cells, lipid, and connective tissue. PURPOSE: The purpose of the present study was to identify natural agents that commonly reverse advanced atherosclerotic plaque to early atherosclerotic plaque. METHODS: Differentially expressed genes (DEGs) were analyzed in silico. The differentially expressed genes from 9 intimal thickening and 8 fibrous cap atheroma tissue which were collected from GEO data were assessed by the connectivity map. Natural candidate securinine, a main compound from Securinega suffruticosa, was selected and administrated 1, 5 mg/kg/day in apolipoprotein-E-deficient (ApoE KO) mice for 18 weeks. RESULTS: Securinine significantly showed lowered blood pressure and improvement of metabolic parameters with hyperlipidemia. The impairment in vasorelaxation was remarkably decreased by treatment with securinine. H&E staining revealed that treatment with securinine reduced atherosclerotic lesions. Securinine suppressed the expression of adhesion molecules and matrix metalloproteinase-2/-9 in both ApoE KO and vascular endothelial cells (HUVEC). In HUVEC pretreatment with securinine significantly inhibited ROS generation and NF-κB activation. Growth curve assays using the real-time cell analyzer showed that securinine significantly decreased TNF-α-induced aortic smooth muscle cell proliferation and migration in a dose-dependent manner. CONCLUSION: Securinine may be a potential natural candidate for the treatment of atherosclerosis because it attenuates vascular inflammation and dysfunction as well as vascular lesion.

Antiproliferative and Antimigration Activities of Beauvericin Isolated from Isaria sp. on Pancreatic Cancer Cells.

This study describes the antiproliferative and antimigration effects of beauvericin from a culture broth of Isaria sp. in human pancreatic cancer cells (PANC-1). Activity-guided fractionation of the EtOAc extract of cultured broth of Isaria sp. RD055140 afforded beauvericin (1), a new isariotin derivative, 7-O-methylisariotin C (2), together with the known isariotin analogs, TK-57-164A (3) and B (4). As a result of the measurement of the cell viability, 1 inhibited cell growth (IC50 = 4.8 µM) of PANC-1 cells. Furthermore, 1 was found to inhibit the migration activity of PANC-1 cells by upregulating the expression of the E-cadherin gene and reducing N-cadherin and Snail genes in a dose-dependent manner (0.1-1 µM). These activities of 1 had lower concentrations than the cytotoxic activity. These findings suggest that 1 can be used as an anticancer agent against human pancreatic carcinoma.

Levistilide A reverses rat hepatic fibrosis by suppressing angiotensin II­induced hepatic stellate cells activation.

The renin angiotensin system (RAS) serves an important role in the development of hepatic fibrosis. Therefore, the present study investigated the effect of levistilide A (Lev A) on hepatic fibrosis via regulation of RAS. The effects of Lev A on the proliferation and activation of hepatic stellate cells (HSCs) were measured using a 5­ethynyl­2'­deoxyuridine assay, western blot analysis and immunofluorescence. The in vivo anti­hepatic fibrosis effect of Lev A was examined using a CCL4­induced rat fibrosis model. Lev A significantly prohibited angiotensin (Ang) II­induced proliferation of HSCs, and overexpression of smooth muscle α­actin (α­SMA) and F­actin in HSCs. Lev A partly reversed Ang II­induced angiotensin type 1 receptor (AT1R) upregulation and ERK and c­Jun phosphorylation. In CCL4­induced hepatic fibrosis rats, Lev A treatment significantly decreased the expression of collagen, α­SMA and hydroxyproline in rat liver, and improved liver functions. Lev A treatment also significantly inhibited the CCL4­induced increase in plasma Ang II, and upregulation of AT1R and phosphorylated ERK in rat liver. In conclusion, Lev A is a potential agent for the treatment of hepatic fibrosis by suppressing Ang II/AT1R/ERK/c­Jun activation in HSCs.

Securinine suppresses osteoclastogenesis and ameliorates inflammatory bone loss.

Securinine (Sec) is a naturally derived compound separated from the roots of Securinega suffruticosa, which has long been used as a herbal medicine. Sec is widely known as a GABA receptor antagonist, it is also known as an innate immune cell agonist and has been reported to increase macrophage activity and promote monocyte maturation. On the basis of these studies, we investigated the effect of Sec on osteoclast differentiation and bone resorbing function. We have found that Sec inhibits RANKL-induced osteoclast differentiation, fusion, actin ring formation, and bone resorbing function by the inhibition of gene expression associated with each stage. Moreover, Sec significantly suppressed osteoclastogenesis by decreasing the phosphorylation of p38, Akt, JNK, IκB, and PLCγ2, in pathways involved in early osteoclastogenesis as well as through the subsequent suppression of c-Fos and NFATc1. Finally, Sec effectively protected bone loss induced by the excessive inflammatory responses and activity of osteoclasts in vivo by a micro-CT and histological analysis. In conclusion, our findings suggest that Sec may be a promising drug for bone metabolic diseases such as osteoporosis, which is associated with the excessive activity of osteoclasts.

Structure-Based Design of Highly Potent HIV-1 Protease Inhibitors Containing New Tricyclic Ring P2-Ligands: Design, Synthesis, Biological, and X-ray Structural Studies.

We describe here design, synthesis, and biological evaluation of a series of highly potent HIV-1 protease inhibitors containing stereochemically defined and unprecedented tricyclic furanofuran derivatives as P2 ligands in combination with a variety of sulfonamide derivatives as P2' ligands. These inhibitors were designed to enhance the ligand-backbone binding and van der Waals interactions in the protease active site. A number of inhibitors containing the new P2 ligand, an aminobenzothiazole as the P2' ligand and a difluorophenylmethyl as the P1 ligand, displayed very potent enzyme inhibitory potency and also showed excellent antiviral activity against a panel of highly multidrug-resistant HIV-1 variants. The tricyclic P2 ligand has been synthesized efficiently in an optically active form using enzymatic desymmetrization of meso-1,2-(dihydroxymethyl)cyclohex-4-ene as the key step. We determined high-resolution X-ray structures of inhibitor-bound HIV-1 protease. These structures revealed extensive interactions with the backbone atoms of HIV-1 protease and provided molecular insights into the binding properties of these new inhibitors.

Biosynthetically Inspired Syntheses of Secu'amamine A and Fluvirosaones A and B.

Presented here is a concise synthesis of secu'amamine A, and fluvirosaones A and B from readily available allosecurinine and viroallosecurinine. The key C2-enamine derivative of (viro)allosecurinine, the presumed biosynthetic precursors of these natural products, was accessed, for the first time, by a VO(acac)2 -mediated regioselective Polonovski reaction. Formal hydration and 1,2-amine shift of this pluripotent enamine compound afforded secu'amamine A. Formal oxidative [3+2] cycloaddition reaction between this enamine and TMS-substituted methallyl iodide reagent paved the way to the precursors of fluvirosaones A and B. The relative stereochemistry at the C2 position of these advanced intermediates governs the fate of 1,2-amine shift leading to fluvirosaones A and B. The syntheses of potential biosynthetic precursors and investigations of their chemical reactivities have provided insights regarding the biogenesis of these natural products.

Bridged α-helix mimetic small molecules.

Herein, we report a strategy for generating conformationally restricted α-helix mimetic small molecules by introducing covalent bridges that limit rotation about the central axis of α-helix mimetics. We demonstrate that the bridged α-helix mimetics have enhanced binding affinity and specificity to the target protein due to the restricted conformation as well as extra interaction of the bridge with the protein surface.

Novel virosecurinine bivalent mimetics as potent reversal agents against P-glycoprotein-mediated multidrug resistance.

Multidrug resistance (MDR) is a main cause of chemotherapy failure and patient death. This situation usually involves a glycoprotein (P-gp) mediated drug efflux, resulting in a low cellular drug concentration and insensitivity. Here we report the design, synthesis and evaluation of novel (+/-)-securinine bivalents as P-gp inhibitors in vitro and in vivo. MTT assays reflected that bivalent mimetics of securinine particularly the virosecurinine bivalent mimetic 8C showed promissing MDR reversal potential in both P-gp highly expressed cell line HepG2/DOX and MCF-7/ADM. At a 10 µM concentration, 8C can entirely reverse the resistance of HepG2/DOX to doxorubicin (DOX), and is more effective than the positive control verapamil (VRP). Fluorescence, flow cytometry, and DOX efflux assays demonstrated that 8C can facilitate the accumulation and diminish the efflux of intracellular DOX. Molecular docking analysis and western blot assays indicated that 8C accomplished this by competitively inhibiting the activity of P-gp rather than by affecting its expression. Compound 8C was also observed to reverse drug resistance effectively in xenograft models when combined with DOX. This study lays a foundation for the discovery of (+/-)-securinine ramifications as P-gp inhibitors and provides a promising lead compound 8C as a P-gp mediated MDR reversal agent.

Synthesis of the Tetracyclic Cores of the Integrastatins, Epicoccolide A and Epicocconigrone A.

The integrastatins, epicoccolide A and epicoccongirone A, are natural products containing a unique [6.6.6.6]-tetracyclic core framework that exhibit a broad spectrum of biological activities. A synthesis of the common core of epicoccolide A and epicocconigrone A has been achieved using an umpolung alkylation-lactonization to assemble an isochromanone from which the bridged 1,3-dioxane was readily assembled. A different strategy was required to access the core on the integrastatins; an initial aryllithium addition to an aldehyde, followed by oxidation and treatment of the masked dihydroxyketone with acid gave the desired core structure.