Optimization of Rutaecarpine as ABCA1 Up-Regulator for Treating Atherosclerosis

Computational Docking as a Tool in Guiding the Drug Design of Rutaecarpine Derivatives as Potential SARS-CoV-2 Inhibitors

COVID-19 continues to spread around the world. This is mainly because new variants of the SARS-CoV-2 virus emerge due to genomic mutations, evade the immune system and result in the effectiveness of current therapeutics being reduced. We previously established a series of detection platforms, comprising computational docking analysis, S-protein-based ELISA, pseudovirus entry, and 3CL protease activity assays, which allow us to screen a large library of phytochemicals from natural products and to determine their potential in blocking the entry of SARS-CoV-2. In this new screen, rutaecarpine (an alkaloid from Evodia rutaecarpa) was identified as exhibiting anti-SARS-CoV-2 activity. Therefore, we conducted multiple rounds of structure-activity-relationship (SAR) studies around this phytochemical and generated several rutaecarpine analogs that were subjected to in vitro evaluations. Among these derivatives, RU-75 and RU-184 displayed remarkable inhibitory activity when tested in the 3CL protease assay, S-protein-based ELISA, and pseudovirus entry assay (for both wild-type and omicron variants), and they attenuated the inflammatory response induced by SARS-CoV-2. Interestingly, RU-75 and RU-184 both appeared to be more potent than rutaecarpine itself, and this suggests that they might be considered as lead candidates for future pharmacological elaboration.

Protein-enriched extracts from housefly (Musca domestica) maggots alleviates atherosclerosis in apolipoprotein E-deficient mice by promoting bile acid production and consequent cholesterol consumption

Currently, atherosclerosis control is important to prevent future heart attacks or strokes. Protein-enriched extract (PE) from housefly maggots (Musca domestica) can inhibit the development of atherosclerosis partially through its antioxidant effects. Whether PE exerts other anti-atherosclerosis functions remains unclear. Here, PE was found to simultaneously promote cholesterol metabolism effects in apolipoprotein E knockout (ApoE^-/- ) mice. Bile acid synthesis plays a key role in regulating cholesterol homeostasis in atherosclerosis. Whether PE alleviates atherosclerosis by promoting bile acid production and consequent cholesterol consumption was further explored. First, 8-week-old male ApoE^-/- mice were recruited and fed on a cholesterol-enriched diet. After 8 weeks, these mice were divided into three groups and received gavage administration of PE, simvastatin, and saline for another 8 weeks. Atherosclerosis severity was then assessed. Real-time quantitative polymerase chain reaction and western blot were employed to determine the expression of hepatic ATP-binding cassette transporter A1 (ABCA1), liver X receptor α (LXRα), and peroxisome proliferator-activated receptor-γ (PPAR-γ). Serum levels of high-density lipoprotein-cholesterol (HDL), low-density lipoprotein-cholesterol (LDL), and total cholesterol (TC) were determined by enzyme-linked immunoassay. Results revealed that PE reversed the formation of atherosclerotic lesion; increased the expression of PPAR-γ, LXRα, and ABCA1; increased the amount of bile flow and total bile acid; reduced the serum level of LDL and TC; and increased the level of HDL. In conclusion, enhancement on bile acid production and consequent cholesterol consumption may partially contribute to the anti-atherosclerotic effects of PE. The reversal of PPARγ-LXRα-ABCA1 signaling pathway may be involved in this process.

Synthesis of Spiroindolenine-3,3'-pyrrolo[2,1-b]quinazolinones through Gold(I)-Catalyzed Dearomative Cyclization of N-Alkynyl Quinazolinone-Tethered Indoles

A variety of functionalized spiroindolenine-3,3'-pyrrolo[2,1-b]quinazolinones were prepared in good to excellent yields through a gold(I)-catalyzed dearomative cyclization of N-alkynyl quinazolinone-tethered C2-substituted indoles. The reaction features broad substrate scope, good functional...

Melatonin derivatives combat with inflammation-related cancer by targeting the Main Culprit STAT3

The combination between two well-studied bioactive compounds melatonin and salicylic acid with proper modifications unexpectedly creates a sharp pair of "scissors" cutting off the vicious connection between inflammation and cancer by targeting a key contributor Signal Transducers and Activators of Transcription 3 (STAT3) in the two pathological processes. A representative compound P-3 with IC₅₀ values on each tested cell line ranging from 7.37 to 18.62 μM among the designed melatonin derivatives is equipped with the ability of curbing inflammation-promoting cancer by down-regulating the expression, activation and nuclear translocation of STAT3, breaking the feedforward loop of STAT3 activation by decreasing the expression of pro-tumorigenic cytokines, and inducing cell apoptosis through ROS triggered Cyto-c/Caspase-3 pathway. This study suggests that the melatonin derivative P-3 is likely to become a promising chemical structure for developing the novel anti-cancer agents taking effect through hindering the mutual-promoting processes between inflammation and cancer.

Analysis of Low Molecular Weight Substances and Related Processes Influencing Cellular Cholesterol Efflux

Cholesterol efflux is the key process protecting the vascular system from the development of atherosclerotic lesions. Various extracellular and intracellular events affect the ability of the cell to efflux excess cholesterol. To explore the possible pathways and processes that promote or inhibit cholesterol efflux, we applied a combined cheminformatic and bioinformatic approach. We performed a comprehensive analysis of published data on the various substances influencing cholesterol efflux and found 153 low molecular weight substances that are included in the Chemical Entities of Biological Interest (ChEBI) database. Pathway enrichment was performed for substances identified within the Reactome database, and 45 substances were selected in 93 significant pathways. The most common pathways included the energy-dependent processes related to active cholesterol transport from the cell, lipoprotein metabolism and lipid transport, and signaling pathways. The activators and inhibitors of cholesterol efflux were non-uniformly distributed among the different pathways: the substances influencing ‘biological oxidations’ activate cholesterol efflux and the substances influencing ‘Signaling by GPCR and PTK6’ inhibit efflux. This analysis may be used in the search and design of efflux effectors for therapies targeting structural and functional high-density lipoprotein deficiency.

Identification of N-benzothiazolyl-2-benzenesulfonamides as novel ABCA1 expression upregulators

ATP binding cassette transporter A1 (ABCA1) is a critical transporter that mediates cellular cholesterol efflux from macrophages to apolipoprotein A-I (ApoA-I). Therefore, increasing the expression level of ABCA1 is anti-atherogenic and ABCA1 expression upregulators have become novel choices for atherosclerosis treatment. In this study, a series of N-benzothiazolyl-2-benzenesulfonamides, based on the structure of WY06 discovered in our laboratory, were designed and synthesized as novel ABCA1 expression upregulators. Based on an in vitro ABCA1 upregulatory cell model, ABCA1 upregulation of target compounds was evaluated. Compounds 6c, 6d, and 6i have good upregulated ABCA1 expression activities, with EC₅₀ values of 0.97, 0.37, and 0.41 μM, respectively. A preliminary structure-activity relationship is summarized. Replacing the methoxy group on the benzothiazole moiety of WY06 with a fluorine or chlorine atom and exchanging the ester group with a cyano group resulted in more potent ABCA1 upregulating activity. Moreover, compound 6i increased ABCA1 mRNA and protein expression and significantly promoted cholesterol efflux in RAW264.7 cells. In conclusion, N-benzothiazolyl-2-benzenesulfonamides were identified as novel ABCA1 expression upregulators.

Design, synthesis and bioactivity study of N-salicyloyl tryptamine derivatives as multifunctional agents for the treatment of neuroinflammation

Because of the complex etiology in neuroinflammatory process, the design of multifunctional agents is a potent strategy to cure neuroinflammatory diseases including AD and PD. Herein, based on the combination principles, 23 of N-salicyloyl tryptamine derivatives as multifunctional agents were designed and their new application for anti-neuroinflammation was disclosed. In cyclooxygenase assay, two compounds 3 and 16 displayed extremely preferable COX-2 inhibition than N-salicyloyl tryptamine. In LPS-induced C6 and BV2 cell models, some compounds decreased the production of proinflammatory mediators NO, PGE₂, TNF-α, iNOS, COX-2 and ROS, while increased the production of IL-10. Among them, compound 3 and 16 showed approximately six-fold better inhibition on nitric oxide production than N-salicyloyl tryptamine in C6. Besides, compounds 3, 13 and 16 attenuated the activation of BV2 and C6 cells. More importantly, in vivo, compounds 3 and 16 reduced GFAP and Iba-1 levels in the hippocampus, and displayed neuroprotection in Nissl staining. Besides, both compounds 3 and 16 had high safety (LD₅₀ > 1000 mg/kg). Longer plasma half-life of compounds 3 and 16 than melatonin supported combination strategy. All these results demonstrated that N-salicyloyl tryptamine derivatives are potential anti-neuroinflammation agents for the treatment of neurodegenerative disorder.

Electrosynthesis of polycyclic quinazolinones and rutaecarpine from isatoic anhydrides and cyclic amines

A direct decarboxylative cyclization between readily available isatoic anhydrides and cyclic amines was established to construct polycyclic fused quinazolinones employing electrochemical methods. This procedure was performed in an undivided cell without the use of a transition-metal-catalyst and external oxidant. A broad scope of polycyclic fused quinazolinones were obtained in moderate to good yields. Additionally, rutaecarpine was also prepared through our method in one step in good yield.

Polycyclic quinazolinones and rutaecarpine were synthesized from isatoic anhydrides and cyclic amines through an electrochemical method without an external oxidant and transition-metal-catalyst.

TFA/TBHP-promoted oxidative cyclisation for the construction of tetracyclic quinazolinones and rutaecarpine

An efficient TFA/TBHP-promoted oxidative cyclisation of readily available isatins with 1,2,3,4-tetrahydroisoquinolines has been firstly developed. The potential utility of this strategy was demonstrated by one-step synthesis of a natural alkaloid Rutaecarpin.

Targeting Foam Cell Formation in Atherosclerosis: Therapeutic Potential of Natural Products

Foam cell formation and further accumulation in the subendothelial space of the vascular wall is a hallmark of atherosclerotic lesions. Targeting foam cell formation in the atherosclerotic lesions can be a promising approach to treat and prevent atherosclerosis. The formation of foam cells is determined by the balanced effects of three major interrelated biologic processes, including lipid uptake, cholesterol esterification, and cholesterol efflux. Natural products are a promising source for new lead structures. Multiple natural products and pharmaceutical agents can inhibit foam cell formation and thus exhibit antiatherosclerotic capacity by suppressing lipid uptake, cholesterol esterification, and/or promoting cholesterol ester hydrolysis and cholesterol efflux. This review summarizes recent findings on these three biologic processes and natural products with demonstrated potential to target such processes. Discussed also are potential future directions for studying the mechanisms of foam cell formation and the development of foam cell-targeted therapeutic strategies.

Catalyst-free cyclization of anthranils and cyclic amines: one-step synthesis of rutaecarpine

An efficient synthesis of a variety of quinazolinone derivatives via a direct cyclization reaction between commercially available anthranils and cyclic amines is described. The developed transformation proceeds with the merits of high step- and atom-efficiency, a broad substrate scope, and good to excellent yields, without additional catalysts, and offers a practical way for the preparation of rutaecarpine and its derivatives with structural diversity.

Bioprospection of anti-inflammatory phytochemicals suggests rutaecarpine and quinine as promising 15-lipoxygenase inhibitors

15-Lipoxygenase (15-LOX) belongs to the family of nonheme iron containing enzymes that catalyzes the peroxidation of polyunsaturated fatty acids (PUFAs) to generate eicosanoids that play an important role in signaling pathways. The role of 15-LOX has been demonstrated in atherosclerosis as well as other inflammatory diseases. In the present study, drug-like compounds were first screened from a set of anti-inflammatory phytochemicals based on Lipinski's rule of five (ROF) and in silico toxicity filters. Two lead compounds-quinine (QUIN) and rutaecarpine (RUT) were shortlisted by analyzing molecular interactions and binding energies of the filtered compounds with the target using molecular docking. Molecular dynamics simulation studies indicate stable trajectories of apo_15-LOX and docked complexes (15-LOX_QUIN and 15-LOX_RUT). In vitro 15-LOX inhibition studies shows that both QUIN and RUT have lower inhibitory concentration (IC₅₀ ) value than the control (quercetin). Both QUIN and RUT exhibit moderate antioxidant activities. The cell viability study of these compounds suggests no significant toxicity in HEK-293 cell lines. Further, QUIN and RUT both did not show any inhibition against selected Gram-positive and Gram-negative bacterial species. Thus, based on our present findings, rutaecarpine and quinine may be suggested as promising 15-LOX inhibitor for the prevention of the atherosclerosis development.

Rational Design of a New Class of Toll-Like Receptor 4 (TLR4) Tryptamine Related Agonists by Means of the Structure- and Ligand-Based Virtual Screening for Vaccine Adjuvant Discovery

In order to identify novel lead structures for human toll-like receptor 4 (hTLR4) modulation virtual high throughput screening by a peta-flops-scale supercomputer has been performed. Based on the in silico studies, a series of 12 compounds related to tryptamine was rationally designed to retain suitable molecular geometry for interaction with the hTLR4 binding site as well as to satisfy general principles of drug-likeness. The proposed compounds were synthesized, and tested by in vitro and ex vivo experiments, which revealed that several of them are capable to stimulate hTLR4 in vitro up to 25% activity of Monophosphoryl lipid A. The specific affinity of the in vitro most potent substance was confirmed by surface plasmon resonance direct-binding experiments. Moreover, two compounds from the series show also significant ability to elicit production of interleukin 6.

Copper-catalyzed C–O bond cleavage and cyclization: synthesis of indazolo[3,2-b]quinazolinones

Cu-catalyzed sequential inert C–O bond cleavage followed by intramolecular C–N bond formation for the synthesis of indazolo[3,2-b]quinazolinones.

Progress in Studies on Rutaecarpine. II.--Synthesis and Structure-Biological Activity Relationships

Rutaecarpine is a pentacyclic indolopyridoquinazolinone alkaloid found in Evodia rutaecarpa and other related herbs. It has a variety of intriguing biological properties, which continue to attract the academic and industrial interest. Studies on rutaecarpine have included isolation from new natural sources, development of new synthetic methods for its total synthesis, the discovery of new biological activities, metabolism, toxicology, and establishment of analytical methods for determining rutaecarpine content. The present review focuses on the synthesis, biological activities, and structure-activity relationships of rutaecarpine derivatives, with respect to their antiplatelet, vasodilatory, cytotoxic, and anticholinesterase activities.

High-density lipoprotein-based drug discovery for treatment of atherosclerosis

INTRODUCTION

Although there has been great progress achieved by the use of intensive statin therapy, the burden of atherosclerotic cardiovascular disease (CVD) remains high. This has initiated the search for novel high-density lipoprotein (HDL)-based therapeutics. Recent years have witnessed a shift from traditional raising HDL-C levels to enhancing HDL functionality, in which the process of reverse cholesterol transport (RCT) has acquired much attention.

AREAS COVERED

In this review, the authors describe the key factors involved in RCT process for potential drug targets to reduce the CVD risk. Furthermore, the review provides a summary of the effective screening methods that have been developed to target RCT and their applications. This review also introduces some new strategies currently being clinically developed, which have the potential to improve HDL function in the RCT process.

EXPERT OPINION

It is rational that the functionality of HDL is more important than the plasma HDL-C level in the evaluation of pharmacological treatment in atherosclerosis. HDL-based strategies designed to promote macrophage RCT are a major area of current drug discovery and development for atherosclerotic diseases. A better understanding of the functionality of HDL and its relationship with atherosclerosis will expand our knowledge of the role of HDL in lipid metabolism, holding promise for a future successful HDL-based therapy.