Advances in the study of silica nanoparticles in lung diseases.

Silicon dioxide nanoparticles (SiNPs) are one of the major forms of silicon dioxide and are composed of the most-abundant compounds on earth. Based on their excellent properties, SiNPs are widely used in food production, synthetic processes, medical diagnostics, drug delivery, and other fields. The mass production and wide application of SiNPs increases the risk of human exposure to SiNPs. In the workplace and environment, SiNPs mainly enter the human body through the respiratory tract and reach the lungs; therefore, the lungs are the most important and most toxicologically affected target organ of SiNPs. An increasing number of studies have shown that SiNP exposure can cause severe lung toxicity. However, studies on the toxicity of SiNPs in ex vivo and in vivo settings are still in the exploratory phase. The molecular mechanisms underlying the lung toxicity of SiNPs are varied and not yet fully understood. As a result, this review summarizes the possible mechanisms of SiNP-induced lung toxicity, such as oxidative stress, endoplasmic reticulum stress, mitochondrial damage, and cell death. Moreover, this study provides a summary of the progression of diseases caused by SiNPs, thereby establishing a theoretical basis for future studies on the mechanisms of SiNP-induced lung toxicity.

Antibacterial Mesoporous Silica Granules Containing a Stable N-Halamine Moiety.

High-efficacy and regenerable antimicrobial silica granules were prepared via oxa-Michael addition between poly(vinyl alcohol) (PVA) and methylene-bis-acrylamide (MBA) under the catalysis of sodium carbonate in an aqueous solution. Diluted water glass was added, and the solution pH was adjusted to about 7 to precipitate PVA-MBA modified mesoporous silica (PVA-MBA@SiO2) granules. N-Halamine-grafted silica (PVA-MBA-Cl@SiO2) granules were achieved by adding diluted sodium hypochlorite solution. It was found that a BET surface area of about 380 m2 g-1 for PVA-MBA@SiO2 granules and a Cl+% of about 3.80% for PVA-MBA-Cl@SiO2 granules could be achieved under optimized preparation conditions. Antimicrobial tests showed that the as-prepared antimicrobial silica granules were capable of about a 6-log inactivation of Staphylococcus aureus and Escherichia coli O157:H7 within 10 min of contact. Furthermore, the as-prepared antimicrobial silica granules can be recycled many times due to the excellent regenerability of their N-halamine functional groups and can be saved for a long time. With the above-mentioned advantages, the granules have potential applications in water disinfection.

(±)-Sarcanan A, a pair of new enantiomeric dihydrobenzofuran neolignans from the aerial parts of Sarcandra glabra.

(+)-Sarcanan A (1a) and (-)-Sarcanan A (1b), a pair of new dihydrobenzofuran neolignan enantiomers, together with six known compounds (2-7), were isolated from the aerial parts of Sarcandra glabra. Their structures were elucidated by spectroscopic analysis, and the absolute configurations of 1a and 1b were determined by analyses of the electronic circular dichroism (ECD) data. All compounds were evaluated for their inhibitory effects on the nitric oxide (NO) production induced by lipopolysaccharide (LPS) in RAW264.7 cells, and compounds 2-4 exhibited moderate inhibition against NO production.

Bioinformatics-Guided Identification of Ethyl Acetate Extract of Citri Reticulatae Pericarpium as a Functional Food Ingredient with Anti-Inflammatory Potential.

Citri Reticulatae Pericarpium (CRP) is one of the most commonly used food supplements and folk medicines worldwide, and possesses cardiovascular, digestive, and respiratory protective effects partially through its antioxidant and anti-inflammatory functions. The unique aromatic flavor and mild side effects make CRP a promising candidate for the development of anti-inflammatory functional food. However, recent studies show that the crude alcoholic extract and some isolated compounds of CRP show compromised anti-inflammatory activity, which became the main factor hindering its further development. To identify the bioactive compounds with anti-inflammatory potential, and improve the anti-inflammatory effects of the extract, a bioinformatics-guided extraction protocol was employed in this study. The potential bioactive candidates were identified by combing network pharmacology analysis, molecular docking, principal components analysis, k-means clustering, and in vitro testing of reference compounds. Our results demonstrated that 66 compounds in CRP could be grouped into four clusters according to their docking score profile against 24 receptors, while the cluster containing flavonoids and phenols might possess a more promising anti-inflammatory function. In addition, in vitro anti-inflammatory tests of the seven reference compounds demonstrated that hesperitin, naringenin, and gardenin B, which were grouped into a cluster containing flavonoids and phenols, significantly decreased LPS-induced NO, TNF-α, and IL-6 production of macrophages. While the compounds outside of that cluster, such as neohesperidin, naringin, hesperidin, and sinensetin showed little effect on alleviating LPS-induced NO and proinflammatory cytokine production. Based on the chemical properties of selected compounds, ethyl acetate (EtOAc) was selected as the solvent for extraction, because of its promising solubility of flavonoids and phenols. Furthermore, the ethanol alcoholic extract was used as a reference. The chemical profiling of EtOAc and crude alcoholic extract by HPLC/MS/MS also demonstrated the decreased abundance of flavonoid glycosides in EtOAc extract but increased abundance of phenols, phenolic acid, and aglycones. In accordance with the prediction, the EtOAc extract of CRP, but not the crude alcoholic extract, significantly decreased the NO, IL-6, and TNF-α production. Taken together, the results suggested selective extraction of phenols and flavonoids rich extract was able to increase the anti-inflammatory potential of CRP partially because of the synergistic effects between flavonoids, phenols, and enriched polymethoxyflavones. Our study might pave the road for the development of ethyl acetate extract of CRP as a novel functional food with anti-inflammatory function.

Antibacterial Activity of the Essential Oil From Litsea cubeba Against Cutibacterium acnes and the Investigations of Its Potential Mechanism by Gas Chromatography-Mass Spectrometry Metabolomics.

Cutibacterium acnes (C. acnes) is an anaerobic Gram-positive bacterium generally considered as a human skin commensal, but is also involved in different infections, such as acne and surgical infections. Although there are a variety of treatments, the side effects and the problem of bacterial drug resistance still limit their clinical usage. In this study, we found that essential oil (EO) distilled from fresh mature Litsea cubeba possessed promising antibacterial activity against C. acnes. In order to elucidate its potential mechanism, bacteriostatic activity test, Live/Dead kit assay, scanning electron microscope (SEM), transmission electron microscope (TEM), and metabolomics were employed. In addition, the content of adenosine triphosphate (ATP) in bacterium and the activities of key enzymes involved in critical metabolic pathways were detected using a variety of biochemical assays. The results showed that EO exhibited significant antibacterial activity against C. acnes at a minimum inhibitory concentration (MIC) of 400 µg/mL and a minimum bactericidal concentration (MBC) of 800 µg/mL, and EO could destroy C. acnes morphology and inhibit its growth. Moreover, results from our study showed that EO had a significant effect on the C. acnes normal metabolism. In total, 86 metabolites were altered, and 34 metabolic pathways related to the carbohydrate metabolism, energy metabolism, amino acid metabolism, as well as cell wall and cell membrane synthesis were perturbed after EO administration. The synthesis of ATP in bacterial cells was also severely inhibited, and the activities of key enzymes of the glycolysis and Wood-Werkman cycle were significantly affected (Pyruvate Carboxylase, Malate Dehydrogenase and Pyruvate kinase activities were decreased, and Hexokinase was increased). Taken together, these results illustrated that the bacteriostatic effect of EO against C. acnes by breaking the bacterial cell morphology and perturbing cell metabolism, including inhibition of key enzyme activity and ATP synthesis. The results from our study may shed new light on the discovery of novel drugs with more robust efficacy.

Porous antimicrobial starch particles containing N-halamine functional groups.

The porous antimicrobial starch particles containing N-Halamine functional groups (PST-MBA-Cl particles) were synthesized by a crosslinking polymerization between starch (ST) and N, N'-methylenebisacrylamide (MBA), and then a chlorination of amide groups of MBA. The synthetic process used only water as the solvent and was environmentally friendly. The results showed that under the optimal preparation conditions, the as-synthesized PST-MBA-Cl particles could have a Cl+% of 8.60 %. Antimicrobial tests showed that PST-MBA-Cl particles had very powerful antimicrobial efficacy against both Staphylococcus aureus and Escherichia coli and could completely kill Staphylococcus aureus with a concentration of 2.1 × 106 CFU/mL and Escherichia coli with a concentration of 5.6 × 106 CFU/mL within a contact time of one minute. Furthermore, the N-Halamine functional groups of PST-MBA-Cl particles also showed excellent stability under storage and reproducibility. Therefore, the as-synthesized PST-MBA-Cl particles will have potential applications in water disinfection.