Peroxide derivatives as SARS-CoV-2 entry inhibitors.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of the ongoing coronavirus disease 2019 (COVID-19) pandemic. Host cell invasion is mediated by the interaction of the viral spike protein (S) with human angiotensin-converting enzyme 2 (ACE2) through the receptor-binding domain (RBD). In this work, bio-layer interferometry (BLI) was used to screen a series of fifty-two peroxides, including aminoperoxides and bridged 1,2,4 - trioxolanes (ozonides), with the aim of identifying small molecules that interfere with the RBD-ACE2 interaction. We found that two compounds, compound 21 and 29, exhibit the activity to inhibit RBD-ACE2. They are further demonstrated to inhibit SARS-CoV-2 cell entry, as shown in pseudovirus assay and experiment with authentic SARS-CoV-2. A comprehensive in silico analysis was carried out to study the physicochemical and pharmacokinetic properties, revealing that both compounds have good physicochemical properties as well as good bioavailability. Our results highlight the potential of small molecules targeting RBD inhibitors as potential therapeutic drugs for COVID-19.

Anti-inflammatory effects of linalool in RAW 264.7 macrophages and lipopolysaccharide-induced lung injury model.

BACKGROUND: Inflammation, characterized by redness, swelling, pain and a sensation of heat, is one of the body's self-defense systems. Although the inflammation response has an important role in host survival, it also leads to chronic inflammatory diseases. Linalool is a natural compound of the essential oils in several aromatic plants species. It possesses anti-inflammatory, antinociceptive, and other bioactive properties. In the present study, we investigated the protective effects of linalool on inflammation in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells and an LPS-induced in vivo lung injury model. METHODS: We evaluated the effects of linalool on LPS-induced production of inflammatory mediators in Raw 264.7 murine macrophages by enzyme-linked immunosorbent assay and Western blot. To confirm the anti-inflammatory activity of linalool in vivo, we induced an acute lung injury in an LPS-induced mouse model. RESULTS: Linalool attenuated the production of LPS-induced tumor necrosis-α and interleukin-6 both in vitro and in vivo. Furthermore, phosphorylation of IκBα protein, p38, c-Jun terminal kinase, and extracellular signal-regulated kinase in LPS-stimulated RAW 264.7 cells was blocked by linalool. Our in vivo study also found that linalool attenuated lung histopathologic changes in mouse models. CONCLUSIONS: The results suggest that linalool inhibits inflammation both in vitro and in vivo, and may be a potential therapeutic candidate for the treatment of inflammatory diseases.

Protective effect of esculentoside A on lipopolysaccharide-induced acute lung injury in mice.

BACKGROUND: Esculentoside A (EsA) is a saponin isolated from the Chinese herb Phytolacca esculenta. In our study, we sought to investigate the protective effects of EsA on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice. MATERIALS AND METHODS: To determine the effects of EsA on the reduction of histopathologic changes in mice with ALI, inflammatory cell count in bronchoalveolar lavage fluid (BALF) and lung wet-to-dry weight ratio were measured in LPS-challenged mice, and lung histopathologic changes observed via paraffin section were assessed. Next, cytokine production induced by LPS in BALF was measured by enzyme-linked immunosorbent assay. To further study the mechanism of EsA protective effects on ALI, IκBa, p38, and extracellular signal receptor-activated kinase pathways were investigated in lung tissue of mice with ALI. RESULTS: In the present investigation, EsA showed marked effects by reducing inflammatory infiltration, thickening of the alveolar wall, and pulmonary congestion. Levels of tumor necrosis factor α and interleukin 6 elevated by LPS were significantly decreased in BALF in EsA-pretreated ALI model. Furthermore, EsA significantly suppressed phosphorylation of IκBa, p38, and extracellular signal receptor-activated kinase. CONCLUSIONS: Taken together, our results suggest that EsA suppressed inflammatory responses in LPS-induced ALI through inhibition of the nuclear factor kappa B and mitogen activated protein kinase signaling pathways. EsA may be a promising potential preventive agent for ALI treatment.

Attenuation of allergic airway inflammation in a murine model of asthma by Licochalcone A.

CONTEXT: Licochalcone A (Lico A) is a major and biogenetically characteristic chalcone isolated from the root of Xinjiang liquorice, Glycyrrhiza inflata. OBJECTIVE: We focused on investigating whether Lico A possesses distinct anti-inflammatory activity on a non-infectious mouse model of asthma, and we aimed to elucidate its involvement with the mitogen-activated protein kinases pathway. METHODS: BALB/c mice that were sensitized and challenged to ovalbumin (OVA) were treated with Lico A (50 mg/kg) 1 h before they were challenged with OVA. RESULTS: Our study demonstrated that Lico A may effectively inhibit the increase in T-helper type 2 cytokines, such as interleukin (IL)-4, IL-5 and IL-13 in bronchoalveolar lavage fluid, and reduced serum levels of OVA-specific IgE and IgG. Furthermore, Lico A substantially inhibited OVA-induced eosinophilia in lung tissue and mucus hyper-secretion by goblet cells in the airway. Meanwhile, pretreatment with Lico A resulted in a significant reduction in mRNA expression of acidic mammalian chitinase, chitinase 3-like protein 4 (Ym2), E-selectin, Muc5ac, CCL11 and CCR3 in lung tissues and airway hyper-responsiveness to methacholine. CONCLUSIONS: These findings suggest that Lico A may effectively delay the progression of airway inflammation and could be used as a therapy for patients with allergic airway inflammation.

Liquiritigenin prevents Staphylococcus aureus-mediated lung cell injury via inhibiting the production of α-hemolysin.

Staphylococcus aureus is a significant Gram-positive bacterium that is associated with a broad spectrum of diseases ranging from minor skin infections to lethal pneumonia, endocarditis, and toxinoses. α-Hemolysin is one of the most important exotoxins that contribute to the pathogenesis of S. aureus infections. Liquiritigenin is one of the most significant active components in licorice. In this study, hemolysis, western blot, and real-time reverse transcription-PCR assays were performed to investigate the impact of liquiritigenin on the production of S. aureus α-hemolysin. The results showed that low concentrations of liquiritigenin remarkably decreased S. aureus α-hemolysin production in a dose-dependent manner. Using live/dead cell staining and lactate dehydrogenase assays, we found that liquiritigenin could protect human lung cells (A549) from α-hemolysin-mediated injury. The data indicated that this compound could potentially be useful in developing drugs aiming at staphylococcal α-hemolysin.

Adjuvant effects of salidroside from Rhodiola rosea L. on the immune responses to ovalbumin in mice.

Salidroside, a major component of Rhodiola rosea L., was evaluated for its adjuvant effects on the immune responses in mice by ovalbumin (OVA) stimulation. BALB/c mice were immunized subcutaneously with OVA 100 µg or OVA 100 µg dissolved in saline containing alum (100 µg) or salidroside (12.5, 25, or 50 µg) on Days 1 and 15. Two weeks later (Day 28), blood samples were collected to analyze OVA-specific IgG, IgG1, and IgG2b antibodies. Meanwhile, splenocytes were harvested to assess lymphocyte proliferation, cytokines (IL-2, IL-4, and IFN-γ) production, and CD4(+), CD8(+) lymphocyte subsets. The results indicated that co-administration of salidroside with OVA significantly enhanced the ConA-, LPS-, and OVA-induced splenocyte proliferation, produced more IL-2, IL-4, IFN-γ, and IgG, IgG1, and IgG2b antibody levels, and increased the percentage of CD4(+), CD8(+) lymphocyte subsets than OVA alone. Thus, salidroside possess immunological adjuvant activity by regulating humoral and cellular immune responses in mice.

(E)-N'-(2,5-Dimethoxy-benzyl-idene)-2,4-dihydroxy-benzohydrazide.

In the title compound, C(16)H(16)N(2)O(5), the dihedral angle between the two benzene rings is 4.2 (2)° and an intra-molecular O-H⋯O hydrogen bond generates an S(6) ring. In the crystal, mol-ecules are linked into layers lying parallel to the bc plane by O-H⋯O and N-H⋯O hydrogen bonds.

SIRT1 inhibition promotes atherosclerosis through impaired autophagy.

SIRT1, a highly conserved NAD+-dependent protein deacetylase, plays a pivotal role in the pathogenesis and therapy of atherosclerosis (AS). The aim of this study is to investigate the potential effects of SIRT1 on AS in ApoE-/- mice and the underlying mechanisms of autophagy in an ox-LDL-stimulated human monocyte cell line, THP-1. In vivo, the accelerated atherosclerotic progression of mice was established by carotid collar placement; then, mice were treated for 4 weeks with a SIRT1-specific inhibitor, EX-527. The atherosclerotic lesion size of EX-527-treated mice was greatly increased compared to that of the mice in the control group. Immunostaining protocols confirmed that the inhibition of SIRT1 during plaque initiation and progression enhanced the extent of intraplaque macrophage infiltration and impaired the autophagy process. In vitro cultured THP-1 macrophages exposed to ox-LDL were utilized to study the link between the SIRT1 function, autophagy flux, pro-inflammatory cytokine secretion, and foam cell formation using different methods. Our data showed that ox-LDL markedly suppressed SIRT1 protein expression and the autophagy level, while it elevated the MCP-1 production and lipid uptake. Additionally, the application of the SIRT1 inhibitor EX-527 or SIRT1 siRNA further attenuated ox-LDL-induced autophagy inhibition. In conclusion, our results show that the inhibition of SIRT1 promoted atherosclerotic plaque development in ApoE-/- mice by increasing the MCP-1 expression and macrophage accumulation. In particular, we demonstrate that blocking SIRT1 can exacerbate the acetylation of key autophagy machinery, the Atg5 protein, which further regulates the THP-1 macrophage-derived foam cell formation that is triggered by ox-LDL.

Cordycepin alleviates airway hyperreactivity in a murine model of asthma by attenuating the inflammatory process.

Cordycepin (Cor), which is a naturally occurring nucleoside derivative isolated from Cordyceps militaris, has been shown to exert excellent antiinflammatory activity in a murine model of acute lung injury. Thus, this study aimed to evaluate the antiasthmatic activity of Cor (10, 20, and 40 mg/kg) and to investigate the possible underlying molecular mechanisms. We found that Cor attenuated airway hyperresponsiveness, mucus hypersecretion, and ovalbumin (Ova)-specific immunoglobulin (Ig) E, and alleviated lung inflammation with decreased eosinophils and macrophages in the bronchoalveolar lavage (BAL) fluid. Notably, Cor reduced the upregulation of eotaxin, intercellular cell adhesion molecule-1 (ICAM-1), IL-4, IL-5, and IL-13 in the BAL fluid. Furthermore, Cor markedly blocked p38-MAPK and nuclear factor-kappaB (NF-κB) signalling pathway activation in the Ova-driven asthmatic mice. In conclusion, this study demonstrated that some of the antiasthmatic benefits of Cor attributable to diets and/or tonics may result from reductions in inflammatory processes and that these antiasthmatic properties involve the inhibition of Th2-type responses through the suppression of the p38-MAPK and NF-κB signalling pathways.

Geniposide inhibits airway inflammation and hyperresponsiveness in a mouse model of asthma.

Our group recently reported the strong anti-inflammatory effects of geniposide (Gen), a bioactive iridoid glucoside derived from gardenia jasminoides, in a mouse acute lung injury model. Herein, we hypothesized that Gen might also have potential therapeutic benefits in treatment of asthma, which was tested in a mouse model of ovalbumin (Ova)-induced allergic airway inflammation. Ova-sensitized and -challenged BALB/c mice, as compared with control animals, displayed airway hyperresponsiveness (AHR), bronchoalveolar lavage eosinophilia, mucus hypersecretion, and increased T help 2 (Th2)-associated cytokine and chemokine amounts, as well as serum Ova-specific immunoglobulin E (IgE) level. Being compared with the Ova-induced hallmarks of asthma, intraperitoneal Gen treatment prevented eosinophilic pulmonary infiltration, attenuated the increases in interleukin (IL)-4, IL-5, and IL-13, and reduced eotaxin and vascular cell adhesion molecule 1 (VCAM-1) expression. Also, Gen significantly ameliorated the Ova-driven airway hyperresponsiveness, mucus hypersecretion, and allergen-specific IgE level, which are the cardinal pathophysiological symptoms in allergic airway diseases. In addition, the efficacy of Gen was comparable to that of dexamethasone (Dex), a currently available anti-asthmatic drug. Collectively, our findings reveal that the development of immunoregulatory strategies based on Gen may be considered as an effective adjuvant therapy for allergic asthma.