China produces the greatest amount of propolis but there is still lack of basic studies on its pharmacological mechanisms. Our previous study found that ethanol extract from Chinese propolis (EECP) exerted excellent anti-inflammatory effects in vivo but mechanisms of action were elusive. To further clarify the possible mechanisms underlying the anti-inflammatory effects of Chinese propolis (poplar type), we utilized EECP to analyze its chemical composition and evaluated its potential anti-inflammatory effects in vitro . High-performance liquid chromatography (HPLC) profile indicated that EECP contained abundant flavonoids, including rutin, myricetin, quercetin, kaempferol, apigenin, pinocembrin, chrysin, and galangin. Next we found that EECP could significantly inhibit the production of NO, IL-1 β , and IL-6 in lipopolysaccharide- (LPS-) stimulated RAW 264.7 cells and suppress mRNA expression of iNOS, IL-1 β , and IL-6 in a time- and dose-dependent manner. Furthermore, we found that EECP could suppress the phosphorylation of I κ B α and AP-1 but did not affect I κ B α ’s degradation. In addition, using a reporter assay, we found that EECP could block the activation of NF- κ B in TNF- α -stimulated HEK 293T cells. Our findings give new insights for understanding the mechanisms involved in the anti-inflammatory effects by Chinese propolis and provide additional references for using propolis in alternative and complementary therapies.
In the present study, a temperature-sensitive gel composed of chitosan, carboxymethyl chitosan and glycerophosphate was prepared and loaded with chitosan microspheres encapsulating levofloxacin. The bioavailability of levofloxacin and the safety of this novel opthalmic drug delivery formulation were evaluated. Levofloxacin chitosan microspheres were prepared using the ionic gelation method, and the particle size and entrapment rate were determined. The morphology of the microspheres was observed by scanning electron microscopy. The pH and zeta potential were measured. The in vitro release of levofloxacin by the chitosan temperature-sensitive gel loaded with drug microspheres was determined using spectrophotometry. The eye retention time of the chitosan temperature-sensitive gel was calculated using a fluorescein sodium test. To assess the bioavailability and safety of the chitosan temperature-sensitive gel, a cell compatibility test, a cytotoxicity test and skin irritation test were performed. The entrapment rate of levofloxacin in the chitosan microspheres was determined to be 26.5%. The levofloxacin chitosan microspheres that were formed by chitosan and sodium tripolyphosphate were identified to be suitable for use in an ophthalmic particle dispersion system based on their physical and chemical properties. The pH of the levofloxacin chitosan microsphere suspension was 5.87±0.04, the average particle diameter was 2,452±342 nm, the polydispersity index was 0.168±0.028 and the ζ potential was 28.62±1.7 mV. The chitosan temperature-sensitive gel carrying microspheres loaded with drug prevented drug burst release at the initial stage and facilitated the slow release of the drug later on. Furthermore, this delivery system markedly prolonged the contact duration of levofloxacin with the eye. The chitosan temperature-sensitive hydrogel was safe and provided a good bioavailability of the drug. The results revealed that the chitosan temperature-sensitive gel had a cytotoxicity of grade 0, and no erythematous response was observed during the entire course of the skin irritation test. The present study provided a basis for the future development of the chitosan-based temperature-sensitive hydrogel in ophthalmic drug delivery.
As commercialisation of Brazilian green propolis is going on, quality evaluation and authenticity are important. The result demonstrated that artepillin C found by far in Brazilian green propolis by HPLC-ESI-MS/MS analysis, while a small interferent may be mistaken as artepillin C in some propolis from China. A new HPLC quality control method as artepillin C for marker was developed, which is the primary assessment criteria for quality control of Brazilian green propolis.
Veratryl alcohol (VA) is a product from the biodegradation of lignocellulosic biomass. The objective of this study was to explore the possibility whether VA could be used as the fuel of the microbial fuel cell (MFC) to generate power. Two types of MFCs, a two-chamber MFC and a single-chamber air-cathode MFC, were set up for experiments. In the two-chamber MFC, average maximum current outputs higher than 700 μA were obtained using various mixtures of glucose and VA as the fuel. The highest power density of 35.17 W m−3 was achieved using the mixture of 1000 mg L−1 glucose and 50 mg L−1 VA as the fuel. With 500 mg L−1 VA as the fuel in the MFC, we obtained an average maximum current output of 181 μA. In the single-chamber MFC, the maximum current output reached up to 178 μA with 500 mg L−1 VA in the fed-batch mode and the maximum CE reached 23.77% with 100 mg L−1 VA. At the end of all operation cycles of the MFCs, the glucose and VA were undetectable in the solution, and the removal efficiencies of COD were between 75% and 88%. The denaturing gradient gel electrophoresis profiles of 16S rRNA gene indicated that the dominant species on the anode biofilm did not change significantly with the different substrates, but the abundance of some species increased greatly. The scanning electron micrographs showed that the most abundant bacteria on the electrode were bacilli. The dominant species belonged to bacteroidetes and proteobacterium.
Different organics have different effects on the power generation of microbial fuel cell. A packing-type MFC was constructed to investigate organic matter degradation and power generation. Experiments were conducted using an initial pyridine concentration of 500 mg/L with different glucose concentrations (500, 250, and 100 mg/L) as the MFC fuel. Results showed that maximum voltages decreased with the decrease of concentration of glucose and the maximum voltage was 623 mV. The cycle time were 49.5, 25.7, 25.2 h respectively. Correspondingly, the maximal volumetric power densities were 48.5, 36.2, 15.2 W/m3. Pyridine removal rate reached 95% within 24 h using MFC, which was not affected by concentration of glucose. Power generation using glucose was not affected in the presence of high concentration of pyridine. However, the phenomenon of electricity production was not obvious when using 500 mg/L pyridine as sole fuel. The results clearly demonstrated the feasibility of using the MFC to generate electricity when using pyridine and glucose mixture as fuel and simultaneously enhanced pyridine degradation.
Propolis is a honeybee product with broad clinical applications. Current literature describes that propolis is collected from plant resins. From a systematic database search, 241 compounds were identified in propolis for the first time between 2000 and 2012; and they belong to such diverse chemical classes as flavonoids, phenylpropanoids, terpenenes, stilbenes, lignans, coumarins, and their prenylated derivatives, showing a pattern consistent with around 300 previously reported compounds. The chemical characteristics of propolis are linked to the diversity of geographical location, plant sources and bee species.
Honey is a sweet substance laboriously collected and crafted from nectar by bees, and since ancient times, it has been deeply cherished by humans for its unique flavor and nutritional value. Litchi honey stands out among various types of honey with its unique flavor and sweet taste, and it is particularly favored by consumers. In accordance with the testing methodologies specified in relevant Chinese national standards, we conducted an exhaustive analysis of the physicochemical properties of six litchi honey samples in Southern China. The results showed that the moisture content fell within a range of 17.18% to 22.7%, while the electrical conductivity remained below 0.28 mS/cm, and amylase activity surpassed 7.7 mL/(g·h). The fructose content varied from 36.5% to 39.6%, with glucose content ranging between 30.57% and 37.63%. The combined total of these two monosaccharides was found to be within the spectrum of 69.63% to 77.23%, and sucrose content was recorded between 0.59% and 1.15%. The F/G was between 1.05 and 1.28, the proportion of fructose in reducing sugars ranged from 51.28% to 56.22%, and the maltose content was between 1.09% and 1.51%. The HMF content was measured between 1.04 and 3.49 mg/kg. Moreover, the presence of C-4 plant sugars was absent in all tested honey samples. These results definitively demonstrate that the physicochemical attributes of all litchi honey samples align with the standards set forth by Chinese national regulations and international authorities such as CODEX. During our in-depth examination of volatile constituents, we identified 26 common compounds, with trans-linalool oxide, linalool, lilac aldehyde B, lilac aldehyde D, α-terpineol, and cedrol emerging as pivotal in crafting the unique flavor and aroma profile of litchi honey. Additionally, the detection of methyl cyclosiloxane in litchi honey has garnered our attention, necessitating a comprehensive investigation into the honey production process. In conclusion, this study not only establishes a robust scientific basis for the quality assurance and product development of litchi honey but also provides valuable reference information for consumers in their selection of honey products.
Insect herbivory poses a major threat to maize. Benzoxazinoids are important anti-insect secondary metabolites in maize, whose biosynthetic pathway has been extensively studied. However, yet little is known about how benzoxazinoids are regulated in maize, partly due to lack of mutant resources and recalcitrance to genetic transformation. Transient systems based on mesophyll- or cultured cell-derived protoplasts have been exploited in several plant species and have become a powerful tool for rapid or high-throughput assays of gene functions. Nevertheless, these systems have not been exploited to study the regulation of secondary metabolites.A protocol for isolation of protoplasts from etiolated maize seedlings and efficient transfection was optimized. Furthermore, a 10-min-run-time and highly sensitive HPLC-MS method was established to rapidly detect and quantify maize benzoxazinoids. Coupling maize protoplast transfection and HPLC-MS, we screened a few genes potentially regulating benzoxazinoid biosynthesis using overexpression or silencing by artificial microRNA technology.Combining the power of maize protoplast transfection and HPLC-MS analysis, this method allows rapid screening for the regulatory and biosynthetic genes of maize benzoxazinoids in protoplasts, before the candidates are selected for in planta functional analyses. This method can also be applied to study the biosynthesis and regulation of other secondary metabolites in maize and secondary metabolites in other plant species, including those not amenable to transformation.
Abstract Dehydrochlorination of 3-chloro-2- or -3-alkenoyltrimethylsilanes with DBU affords the parent 2,3-butadienoyltrimethylsilane, as well as 4-monoalkyl- and 4,4-dialkyl homologues.
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