α7 Nicotinic acetylcholine receptor: a key receptor in the cholinergic anti-inflammatory pathway exerting an antidepressant effect.

Depression is a common mental illness, which is related to monoamine neurotransmitters and the dysfunction of the cholinergic, immune, glutamatergic, and neuroendocrine systems. The hypothesis of monoamine neurotransmitters is one of the commonly recognized pathogenic mechanisms of depression; however, the drugs designed based on this hypothesis have not achieved good clinical results. A recent study demonstrated that depression and inflammation were strongly correlated, and the activation of alpha7 nicotinic acetylcholine receptor (α7 nAChR)-mediated cholinergic anti-inflammatory pathway (CAP) in the cholinergic system exhibited good therapeutic effects against depression. Therefore, anti-inflammation might be a potential direction for the treatment of depression. Moreover, it is also necessary to further reveal the key role of inflammation and α7 nAChR in the pathogenesis of depression. This review focused on the correlations between inflammation and depression as well-discussed the crucial role of α7 nAChR in the CAP.

Molecular mechanisms of rapid-acting antidepressants: New perspectives for developing antidepressants.

Major depressive disorder (MDD) is a chronic relapsing psychiatric disorder. Conventional antidepressants usually require several weeks of continuous administration to exert clinically significant therapeutic effects, while about two-thirds of the patients are prone to relapse of symptoms or are completely ineffective in antidepressant treatment. The recent success of the N-methyl-D-aspartic acid (NMDA) receptor antagonist ketamine as a rapid-acting antidepressant has propelled extensive research on the action mechanism of antidepressants, especially in relation to its role in synaptic targets. Studies have revealed that the mechanism of antidepressant action of ketamine is not limited to antagonism of postsynaptic NMDA receptors or GABA interneurons. Ketamine produces powerful and rapid antidepressant effects by affecting α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptors, adenosine A1 receptors, and the L-type calcium channels, among others in the synapse. More interestingly, the 5-HT2A receptor agonist psilocybin has demonstrated potential for rapid antidepressant effects in depressed mouse models and clinical studies. This article focuses on a review of new pharmacological target studies of emerging rapid-acting antidepressant drugs such as ketamine and hallucinogens (e.g., psilocybin) and briefly discusses the possible strategies for new targets of antidepressants, with a view to shed light on the direction of future antidepressant research.

Structure-Based Discovery of a Novel Allosteric Inhibitor against Human Dopamine Transporter.

Human dopamine transporter (hDAT) regulates the reuptake of extracellular dopamine (DA) and is an essential therapeutic target for central nervous system (CNS) diseases. The allosteric modulation of hDAT has been identified for decades. However, the molecular mechanism underlying the transportation is still elusive, which hinders the rational design of allosteric modulators against hDAT. Here, a systematic structure-based method was performed to explore allosteric sites on hDAT in inward-open (IO) conformation and to screen compounds with allosteric affinity. First, the model of the hDAT structure was constructed based on the recently reported Cryo-EM structure of the human serotonin transporter (hSERT) and Gaussian-accelerated molecular dynamics (GaMD) simulation was further utilized for the identification of intermediate energetic stable states of the transporter. Then, with the potential druggable allosteric site on hDAT in IO conformation, virtual screening of seven enamine chemical libraries (∼440,000 compounds) was processed, resulting in 10 compounds being purchased for in vitro assay and with Z1078601926 discovered to allosterically inhibit hDAT (IC50 = 0.527 [0.284; 0.988] µM) when nomifensine was introduced as an orthosteric ligand. Finally, the synergistic effect underlying the allosteric inhibition of hDAT by Z1078601926 and nomifensine was explored using additional GaMD simulation and postbinding free energy analysis. The hit compound discovered in this work not only provides a good starting point for lead optimization but also demonstrates the usability of the method for the structure-based discovery of novel allosteric modulators of other therapeutic targets.

Effects of almonds on ameliorating salt-induced hypertension in dahl salt-sensitive rats.

BACKGROUND: Excessive dietary salt intake is related to an increased risk of hypertension. Dietary functional foods probably could help to improve salt-induced hypertension. In this study, Dahl salt-sensitive (DSS) rats were used to investigate their metabolic differences from those of salt-resistant SS.13BN rats and determine whether dietary protein-rich almonds could ameliorate salt-induced elevation of blood pressure in DSS rats. RESULTS: After high-salt intake, the systolic blood pressure and mean arterial pressure of the DSS rats increased dramatically. Metabolomics analysis indicated abnormal amino acid metabolism in their kidneys. Their renal nitric oxide (NO) content and nitric oxide synthase activity decreased significantly after high-salt diet. Oxidative stress also occurred in DSS rats. After the DSS rats received almond supplementation, the levels of various amino acids in their kidney increased, and renal arginine and NO contents were upregulated. Their renal hydrogen peroxide and malonaldehyde levels decreased, whereas renal catalase, superoxide dismutase and glutathione peroxidase activities and glutathione levels increased. CONCLUSION: The renal abnormal amino acid metabolism of DSS rats contributed to the impaired NO production in response to high-salt intake. Together with salt-induced oxidative stress, high-salt diet intake ultimately led to an increase in the blood pressure of DSS rats. Protein-rich almond supplementation might prevent the development of salt-induced hypertension by restoring arginine and NO regeneration and alleviating salt-induced oxidative stress. © 2021 Society of Chemical Industry.

Solid lipid nanoparticle as an effective drug delivery system of a novel curcumin derivative: formulation, release in vitro and pharmacokinetics in vivo.

CONTEXT: Curcumin (Cur) has a short duration of action which limits its therapeutic efficacy. Carbonic acid 17-(1,5-dimethyl-hexyl)-10,13-dimethyl-2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthren-3-yl ester 4-[7-(4-hydroxy-3-methoxy-phenyl)-3,5-dioxo-hepta-1,6-dienyl]-2-methoxy-phenyl ester (CUD), as a small molecule derivative of Cur with superior stability, has been developed in our laboratory. OBJECTIVE: CUD-loaded solid lipid nanoparticles (CUD-SLN) were prepared to prolong the duration of the drug action of Cur. MATERIALS AND METHODS: CUD-SLN were prepared with Poloxamer 188 (F68) and hydrogenated soybean phospholipids (HSPC) as carriers, and the prescription was optimized. The in vitro release of CUD and CUD-SLN was investigated. CUD-SLN (5 mg/kg) was injected into Sprague Dawley (SD) rats to investigate its pharmacokinetic behaviour. RESULTS: CUD-SLN features high entrapment efficiency (96.8 ± 0.4%), uniform particle size (113.0 ± 0.8 nm), polydispersity index (PDI) (0.177 ± 0.007) and an appropriate drug loading capacity (6.2 ± 0.1%). Optimized CUD-SLN exhibited sustained release of CUD for about 48 h. Moreover, the results of the pharmacokinetic studies showed that, compared to Cur, CUD-SLN had a considerably prolonged half-life of 14.7 h, slowed its metabolism in vivo by 35.6-fold, and had an improved area under the curve (AUC0-t) of 37.0-fold. CONCLUSIONS: CUD-SLN is a promising preparation for the development of a small molecule derivative of Cur.

High-salt diet affects amino acid metabolism in plasma and muscle of Dahl salt-sensitive rats.

Genetic background and high-salt diet are considered key factors contributing to the development of hypertension and its associated metabolic disorders. Metabolomics is an emerging powerful tool to analyze the low-molecular weight metabolites in plasma and tissue. This study integrated metabolomics and correlation network analysis to investigate the metabolic profiles of plasma and muscle of Dahl salt-sensitive (SS) rats and SS.13BN rats (control) under normal and high-salt diet. The hub metabolites, which could play important roles in the metabolic changes, were identified by correlation network analysis. The results of the network analysis were further confirmed by pathway analysis and enzyme activity analysis. The results indicated a higher amino acid levels in both plasma and muscle of SS rats fed with high-salt diet. Alanine was found as a hub metabolite with the highest score of three centrality indices and also as the significant differential metabolite in plasma of SS rats after high-salt diet. Valine and lysine were found as hub metabolites and differential metabolites in muscle of SS rats after high-salt diet. Amino acid levels increased in both plasma and muscle of SS rats fed with a high salt diet. Moreover, alanine in plasma and valine and lysine in muscle as hub metabolites could play important roles in the response to high-salt diet.

Cargo-Free Nanomedicine with pH Sensitivity for Codelivery of DOX Conjugated Prodrug with SN38 To Synergistically Eradicate Breast Cancer Stem Cells.

As a result of their ability to transform into bulk cancer cells and their resistance to radiotherapy and chemotherapy, cancer stem cells (CSCs) are currently considered as a major obstacle for cancer treatment. Application of multiple drugs using nanocarriers is a promising approach to simultaneously eliminate noncancer stem cells (non-CSCs) and CSCs. Herein, to employ the advantages of nanomedicine while avoiding new excipients, pH-responsive prodrug (PEG-CH═N-DOX) was employed as the surfactant to fabricate cargo-free nanomedicine for codelivery of DOX conjugated prodrug with SN38 to synergistically eradicate breast cancer stem cells (bCSCs) and non-bCSCs. Through the intermolecular interaction between DOX and SN38, PEG-CH═N-DOX and SN38 were assembled together to form a stable nanomedicine. This nanomedicine not only dramatically enhanced drug accumulation efficiency at the tumor site but also effectively eliminated bCSCs and non-bCSCs, which resulted in achieving a superior in vivo tumor inhibition activity. Additionally, the biosafety of this nanomedicine was systematically studied through immunohistochemistry, blood biochemistry assay, blood routine examination, and metabolomics. The results revealed that this nanomedicine significantly reduced the adverse effects of DOX and SN38. Therefore, this simple yet efficient nanomedicine provided a promising strategy for future clinical applications.

Combined metabolomic and correlation networks analyses reveal fumarase insufficiency altered amino acid metabolism.

Fumarase catalyzes the interconversion of fumarate and l-malate in the tricarboxylic acid cycle. Fumarase insufficiencies were associated with increased levels of fumarate, decreased levels of malate and exacerbated salt-induced hypertension. To gain insights into the metabolism profiles induced by fumarase insufficiency and identify key regulatory metabolites, we applied a GC-MS based metabolomics platform coupled with a network approach to analyze fumarase insufficient human umbilical vein endothelial cells (HUVEC) and negative controls. A total of 24 altered metabolites involved in seven metabolic pathways were identified as significantly altered, and enriched for the biological module of amino acids metabolism. In addition, Pearson correlation network analysis revealed that fumaric acid, l-malic acid, l-aspartic acid, glycine and l-glutamic acid were hub metabolites according to Pagerank based on their three centrality indices. Alanine aminotransferase and glutamate dehydrogenase activities increased significantly in fumarase deficiency HUVEC. These results confirmed that fumarase insufficiency altered amino acid metabolism. The combination of metabolomics and network methods would provide another perspective on expounding the molecular mechanism at metabolomics level.

DTNPD: A comprehensive database of drugs and targets for neurological and psychiatric disorders.

In response to the shortcomings in data quality and coverage for neurological and psychiatric disorders (NPDs) in existing comprehensive databases, this paper introduces the DTNPD database, specifically designed for NPDs. DTNPD contains detailed information on 30 NPDs types, 1847 drugs, 514 drug targets, 64 drug combinations, and 61 potential target combinations, forming a network with 2389 drug-target associations. The database is user-friendly, offering open access and downloadable data, which is crucial for network pharmacology studies. The key strength of DTNPD lies in its robust networks of drug and target combinations, as well as drug-target networks, facilitating research and development in the field of NPDs. The development of the DTNPD database marks a significant milestone in understanding and treating NPDs. For accessing the DTNPD database, the primary URL is http://dtnpd.cnsdrug.com, complemented by a mirror site available at http://dtnpd.lyhbio.com.

Zein-Based Triple-Drug Nanoparticles to Promote Anti-Inflammatory Responses for Nerve Regeneration after Spinal Cord Injury.

Defects in autophagy contribute to neurological deficits and motor dysfunction after spinal cord injury. Here a nanosystem is developed to deliver autophagy-promoting, anti-inflammatory drugs to nerve cells in the injured spinal cord. Celastrol, metformin, and everolimus as the mTOR inhibitor are combined into the zein-based nanoparticles, aiming to solubilize the drugs and prolong their circulation. The nanoparticles are internalized by BV2 microglia and SH-SY5Y neuron-like cells in culture; they inhibit the secretion of inflammatory factors by BV2 cells after insult with lipopolysaccharide, and they protect SH-SY5Y cells from the toxicity of H2O2. In a rat model of spinal cord injury, the nanoparticles mitigate inflammation and promote spinal cord repair. In the in vitro and in vivo experiments, the complete nanoparticles function better than the free drugs or nanoparticles containing only one or two drugs. These results suggest that the triple-drug nanoparticles show promise for treating spinal cord injury.

Preliminary Investigation Into the Antidepressant Effects of a Novel Curcumin Analogue (CACN136) In Vitro and In Vivo.

The aim of this study was to develop a novel antidepressant with high activity. Based on the findings of molecular docking, eight novel curcumin analogues were evaluated in vitro to check for antidepressant efficacy. Among them, CACN136 had the strongest antidepressant effect. Firstly, CACN136 had a stronger 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) radical ion scavenging ability (IC50: 17.500 ± 0.267 µg/mL) compared to ascorbic acid (IC50: 38.858 ± 0.263 µg/mL) and curcumin (27.189 ± 0.192 µg/mL). Secondly, only CACN136 demonstrated clear protective effects on cells damaged by glutamate and oxidative stress at all concentrations. Finally, only CACN136 showed ASP + inhibition and was more effective than fluoxetine hydrochloride (FLU) at low concentrations. To further confirm the antidepressant effect of CACN136 in vivo, the CUMS model was established. Following 28 days of oral administration of CUMS mice, CACN136 increased the central area residence time in the open-field test, significantly increased the sucrose preference rate in the sucrose preference test (P < 0.001) and significantly reduced the immobility period in the tail suspension test (P < 0.0001), all of which were more effective than those of FLU. Subsequent research indicated that the antidepressant properties of CACN136 were linked to a decrease in the metabolism of 5-HT and the modulation of oxidative stress levels in vivo. In particular, the activation of the Keap1-Nrf2/BDNF-TrkB signaling pathway by CACN136 resulted in elevated levels of antioxidant enzymes, enhancing the antioxidant capability in mice subjected to CUMS. In conclusion, CACN136 has the potential to treat depression and could be an effective antidepressant.

Synthesis and biological evaluation of substituted acetamide derivatives as potential butyrylcholinestrase inhibitors.

Alzheimer's disease (AD) is the most common type of age-related dementia. Inhibition of butyrylcholinesterase (BChE) emerge as an effective therapeutic target for AD. A series of new substituted acetamide derivatives were designed, synthesized and evaluated for their ability to inhibit BChE. The bioassay results revealed that several compounds displayed attractive inhibition against BChE). Among them, compound 8c exhibited the highest BChE inhibition with IC50 values of 3.94 µM. Lineweaver Burk plot indicated that 8c acted as a mixed-type BChE inhibitor. In addition, docking studies confirmed the results obtained through in vitro experiments, and showed that 8c bound to the catalytic anionic site (CAS) and peripheral anionic site (PAS) of BChE active site. Meanwhile, its ADME parameters were approximated using in silico method. Molecular dynamics simulation studies on the complex of 8c-BChE were performed, RMSD, RMSF, Rg, SASA, and the number of hydrogen bonds were calculated as well. These results implied that 8c could serve as appropriate lead molecule for the development of BChE inhibitor.

Multi-state Model-Based Identification of Cryptic Allosteric Sites on Human Serotonin Transporter.

Serotonin transporter (SERT) plays a fundamental role in taking the synaptic cleft serotonin back to the presynaptic neuron. The discovery of allosteric SERT modulators represents the next-generation medication for psychiatric disorders such as depression. Here, based on the cryo-EM structures of ibogaine in complex with SERT in distinct conformations, the multiple functional structures of the transporter bound to serotonin, including outward-open (OOholo), outward-occluded (OCholo), and inward-open (IOholo and IOholo'), were carefully characterized by induced-fit docking Gaussian-accelerated molecular dynamics (IFD-GaMD) simulation and the free-energy landscape analysis. Further MM/GBSA binding free energy, per-residue contribution, and molecular interaction fingerprint calculations revealed the interaction variations of serotonin with SERT in functional structures, which confirmed the allostery of SERT during serotonin reuptake. Moreover, five unique cryptic allosteric sites, which are druggable and capable of targeting by small molecules, were identified on the characterized multistate structures. These results provide structural and energetic information for the molecular mechanism of serotonin reuptake and will provide opportunities for the development of novel therapeutics based on the identified new allosteric sites on SERT.

Biomineral-binding liposomes with dual antibacterial effects for preventing and treating dental caries.

Dental caries is a chronic oral disease that results from the demineralization of dental hard tissues caused by the long-term interaction of various pathogenic factors in the human oral cavity. Although magnolol (Mag) and fluconazole (FLC) have shown promising antibacterial activity against Candida albicans (C. albicans) and Streptococcus mutans (S. mutans), their clinical application is limited due to hydrophobicity. In this study, we constructed biomineral-binding liposomes co-loaded with Mag and FLC (PPi-Mag/FLC-LPs) to overcome the hydrophobicity and achieve a dual antibacterial activity in the acidic microenvironment of caries. PPi-Mag/FLC-LPs were characterized by laser particle size analysis, transmission electron microscopy, and high-performance liquid chromatography (HPLC). The ability of PPi-Mag/FLC-LPs to bind hydroxyapatite was assessed in vitro using fluorescence microscopy and HPLC, while the antibacterial activity was examined by measuring drug effects on the acidogenicity, acid resistance, biofilm formation and survival of C. albicans and S. mutans. The pharmacodynamics of PPi-Mag/FLC-LPs was also evaluated in vivo in a rat model of dental caries. Mag and FLC were released rapidly from PPi-Mag/FLC-LPs in a pH-sensitive manner, and they bound effectively to hydroxyapatite, leading to a better antibacterial effect on C. albicans and S. mutans compared to free drugs or liposomes loaded with a single drug. PPi-Mag/FLC-LPs improved the medicinal properties of Mag and FLC and provided a rapid, pH-sensitive release of both drugs in vitro. PPi-Mag/FLC-LPs displayed good antibacterial activity in vivo, showing promise as a dual-drug delivery system for the prevention and treatment of caries.

Nanoparticles that target the mitochondria of tumor cells to restore oxygen supply for photodynamic therapy: Design and preclinical validation against breast cancer.

Photodynamic therapy, in which photosensitizers locally generate cytotoxic reactive oxygen species, can treat tumor tissue with minimal effects on surrounding normal tissue, but it can be ineffective because of the anoxic tumor microenvironment. Here we developed a strategy to inactivate the mitochondria of tumor cells in order to ensure adequate local oxygen concentrations for photodynamic therapy. We conjugated the photosensitizer 5-aminolevulinic acid to the lipophilic cation triphenylphosphine, which targets mitochondria. Then we packaged the conjugate into nanoparticles that were based on biocompatible bovine serum albumin and coated with folic acid in order to target the abundant folate receptors on the tumor surface. In studies in cell culture and BALB/c mice bearing MCF-7 xenografts, we found that the nanoparticles helped solubilize the cation-photosensitizer conjugate, prolong its circulation, and enhance its photodynamic antitumor effects. We confirmed the ability of the nanoparticles to target tumor cells and their mitochondria using confocal laser microscopy and in vivo assays of pharmacokinetics, pharmacodynamics, and tissue distribution. Our results not only identify a novel nanoparticle system for treating cancer, but they demonstrate the feasibility of enhancing photodynamic therapy by reducing oxygen consumption within tumors.

Long-Circulating Lipid Nanospheres Loaded with Flurbiprofen Axetil for Targeted Rheumatoid Arthritis Treatment.

Background: Flurbiprofen axetil (FA) is a non-steroidal anti-inflammatory drug with good analgesic and anti-inflammatory effects. However, it suffers from poor solubility, short circulation time, and off-target binding profile, which significantly limit its clinical application. Here, we loaded FA into stealth lipid microspheres modified with the arginine-glycine-aspartic acid (RGD) peptide (cRGD-FA-SLM), and examined the therapeutic potential of the resulting platform for the treatment of rheumatoid arthritis (RA). Methods: cRGD-FA-SLM was prepared by high pressure homogenization, and its toxicity and uptake by macrophages were examined using cultures of RAW264.7 cells. Hemolysis and hepatotoxicity tests were performed to assess the safety of the developed platform, while its pharmacokinetics, biodistribution, and therapeutic efficacy were investigated in a collagen-induced arthritis rat model. Results: cRGD-FA-SLM showed homogeneous spherical morphology and efficient encapsulation of FA. The developed platform was non-toxic to normal macrophages and was selectively internalized by lipopolysaccharide-activated macrophages in vitro, while it distributed mainly to arthritic joints and significantly prolonged FA in circulation in vivo. cRGD-FA-SLM also significantly reduced the expression of prostaglandin E2 and alleviated joint edema and bone erosion, showing prolonged analgesic effects in arthritic rats. Conclusion: cRGD-FA-SLM shows good inflammation-targeting ability and prolongs drug circulation in vivo, suggesting promise as an anti-inflammatory and analgesic agent for targeted RA treatment.

Preparation and Evaluation of Curcumin Derivatives Nanoemulsion Based on Turmeric Extract and Its Antidepressant Effect.

Purpose: The early stage of this study verified that a turmeric extract (TUR) including 59% curcumin (CU), 22% demethoxycurcumin (DMC), and 18% bisdemethoxycurcumin (BDMC), could enhance the stability of CU and had greater antidepressant potential in vitro. The objective of the study was to develop a nano-delivery system containing TUR (TUR-NE) to improve the pharmacokinetic behavior of TUR and enhance its antidepressant effect. Methods: The antidepressant potential of TUR was explored using ABTS, oxidative stress-induced cell injury, and a high-throughput screening model. TUR-NE was fabricated, optimized and characterized. The pharmacokinetic behaviors of TUR-NE were evaluated following oral administration to normal rats. The antidepressant effect of TUR-NE was assessed within chronic unpredictable mild stress model (CUMS) mice. The behavioral and biochemical indexes of mice were conducted. Results: The results depicted that TUR had 3.18 and 1.62 times higher antioxidant capacity than ascorbic acid and CU, respectively. The inhibition effect of TUR on ASP+ transport was significantly enhanced compared with fluoxetine and CU. TUR-NE displayed a particle size of 116.0 ± 0.31 nm, polydispersity index value of 0.121 ± 0.007, an encapsulation rate of 98.45%, and good release and stability in cold storage. The results of pharmacokinetics indicated the AUC(0-t) of TUR-NE was 8.436 and 4.495 times higher than that of CU and TUR, while the Cmax was 9.012 and 5.452 times higher than that of CU and TUR, respectively. The pharmacodynamic study confirmed that the superior antidepressant effect of TUR-NE by significantly improving the depressant-like behaviors and elevating the content of 5-hydroxytryptamine in plasma and brain in CUMS mice. TUR-NE showed good safety with repeated administration. Conclusion: TUR-NE, which had small and uniform particle size, enhanced the bioavailability and antidepressant effect of TUR. It could be a promising novel oral preparation against depression.

Biological evaluation, molecular modeling and dynamics simulation of phenanthrenes isolated from Bletilla striata as butyrylcholinesterase inhibitors.

As part of our continuous studies on natural cholinesterase inhibitors from plant kingdom, the 95% ethanol extract from tubers of Bletilla striata showed promising butyrylcholinesterase (BChE) inhibition (IC50 = 8.6 µg/mL). The extracts with different polarities (petroleum ether, ethyl acetate, n-butanol, and water) were prepared and evaluated for their inhibition of cholinesterases. The most active ethyl acetate extract was subjected to a bioassay-guided isolation and afforded twenty-two bibenzyls and phenanthrenes (1-22). All isolates were further evaluated for their BChE inhibition activity, and five phenanthrenes presented promising capacity (IC50 < 10 µM). Further kinetic studies indicated their modes of inhibition. Compounds 6, 8, and 14 were found to be mixed-type inhibitors, while compounds 10 and 12 could be classified as non-competitive inhibitors. The potential interaction mechanism of them with BChE was demonstrated by molecular docking and molecular dynamics simulation, showing that they could interact with catalytic active site and peripheral anionic site of BChE. These natural phenanthrenes provide new scaffold for the further design and optimization, with the aim to discover new selective BChE inhibitors for the treatment of AD.

Absolute bioavailability, dose proportionality, and tissue distribution of rotundic acid in rats based on validated LC-QqQ-MS/MS method.

Rotundic acid (RA), an ursane-type pentacyclic triterpene acid isolated from the dried barks of Ilex rotunda Thunb. (Aquifoliaceae), possesses diverse bioactivities. To further study its pharmacokinetics, a simple and sensitive liquid chromatography with triple quadrupole mass spectrometry (LC-QqQ-MS/MS) method was developed and validated to quantify RA concentration in rat plasma and tissue using etofesalamide as an internal standard (IS). Plasma and tissue samples were subjected to one-step protein precipitation. Chromatographic separation was achieved on a ZORBAX Eclipse XDB-C18 column (4.6 mm × 50 mm, 5 µm) under gradient conditions with eluents of methanol:acetonitrile (1:1, V/V) and 5 mM ammonium formate:methanol (9:1, V/V) at 0.5 mL/min. Multiple reaction monitoring transitions were performed at m/z 487.30 → 437.30 for RA and m/z 256.10 → 227.10 for IS in the negative mode. The developed LC-QqQ-MS/MS method exhibited good linearity (2-500 ng/mL) and was fully validated in accordance with U.S. Food and Drug Administration bioanalytical guidelines. Dose proportionality and bioavailability in rats were determined by comparing pharmacokinetic data after single oral (10, 20, and 40 mg/kg) and intravenous (10 mg/kg) administration of RA. Tissue distribution was studied following oral administration at 20 mg/kg. The results showed that the absolute bioavailability of RA after administration at different doses ranged from 16.1% to 19.4%. RA showed good dose proportionality over a dose range of 10-40 mg/kg. RA was rapidly absorbed in a dose-dependent manner and highly distributed in the liver. In conclusion, this study is the first to systematically elucidate the absorption and distribution characteristics of RA in rats, which can provide additional information for further development and evaluation of RA in drug metabolism and pharmacokinetic studies.

Anti-lung cancer effect of paclitaxel solid lipid nanoparticles delivery system with curcumin as co-loading partner in vitro and in vivo.

The main aim of this study was to improve the therapeutic potential of a paclitaxel (PTX) and curcumin (CU) combination regimen using solid lipid nanoparticles (SLNs). PTX and CU were successfully co-encapsulated at a predetermined ratio in SLNs (PC-SLNs) with high encapsulation efficiency (CU: 97.6%, PTX: 95.8%), appropriate particle size (121.8 ± 1.69 nm), small PDI (0.267 ± 0.023), and negative zeta potential (-30.4 ± 1.25 mV). Compared with PTX or the combination of CU and PTX (CU + PTX), PC-SLNs can greatly reduce the dose of PTX while still achieving the same therapeutic effect on four cancer cell lines, among which the inhibitory effect on A549 lung cancer cells was the strongest. PC-SLNs improved the area under the curve (CU: 1.40-fold; PTX: 2.88-fold), prolonged the residence time (CU: 6.94-fold; PTX: 2.51-fold), and increased the half-life (CU: 5.62-fold; PTX: 6.46-fold), achieving long circulation. PC-SLNs were used to treat lung cancer in a nude mouse xenograft tumor model and the tumor suppression rate reached 78.42%, while those of PTX and (CU + PTX) were 40.53% and 51.56%, respectively. As PC-SLNs can prevent P-glycoprotein efflux, reverse MDR and downregulate the NF-κB pathway. PC-SLNs are a potential antineoplastic agent that is more effective and less toxic in treating lung cancer.