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The present study was designed to evaluate the chemical extraction, chemical composition, and antioxidant and antibacterial properties of the total flavonoids in Willow Buds (TFW). We investigated the optimal extraction of TFW using response surface methodology (RSM). Chemical compounds were analyzed using Q-Orbitrap LC–MS/MS. The DPPH radical scavenging capacity, hydroxy radical inhibitory ability, and superoxide anion radical inhibitory ability were explored to determine the antioxidant properties of flavonoid extractions. The antibacterial effect was assessed via minimal inhibitory concentration. The results demonstrated that the optimal extraction conditions were an ethanol concentration of 50%, a time of 35 min, and a liquid/material ratio of 70:1 mL/g. Under these conditions, the yield of TFW was 7.57%. Eight flavonoids, a phenolic glycoside, and an alkaloid were enriched in the Willow Buds. The TFW exhibited significant antioxidant activity, with IC50 values of 0.18-0.24 mg/mL and antimicrobial activity against Escherichia coli, Salmonella enterica, Staphylococcus aureus, and Streptococcus pneumoniae. TFW may be explored as potential and natural compounds in food and pharmacological applications. [ABSTRACT FROM AUTHOR]

Preparation of Ag nanoparticles with high antibacterial activities and low adverse effects is urgently needed to apply to the medical and consumer products. In this study, a facile, one-step hydrothermal method has been developed to synthesize proanthocyanidins-functionalized Ag nanoparticles in aqueous solution. UV absorption spectra measurement indicated that the obtained Ag nanomaterials are mainly spherical in shape. FTIR results implied that the poly flavonoids moiety of proanthocyanidins have specific interactions with the surface of Ag nanoparticles. HR-TEM and XRD determination revealed that the Ag nanoparticles had a shell-core structure and the Ag core possessed a highly crystalline structure. Antibacterial tests demonstrated that the proanthocyanidins-functionalized-Ag nanoparticles have high bactericidal efficiency against both bacterial and fungus. Further taking into account their excellent stability, the proanthocyanidins-functionalized Ag nanoparticles in present study have the potential to be applied to the products required for the long-acting antibacterial action. [ABSTRACT FROM AUTHOR]

This study provided a facile, one-step hydrothermal method to synthesize stable Ag colloid in aqueous solution by utilizing chitosan as both reductant and stabilizer. The formation of chitosan-functionalized Ag nanoparticles was verified by UV–Vis, FTIR, TEM, AFM and XRD measurements. FTIR results revealed that the primary amine groups and amide groups of chitosan have specific interactions with the surface of Ag nanoparticles. The average diameter of the Ag nanoparticles is 10.0 ± 5.4 nm as determined by TEM. Ag nanoparticles are highly crystalline as revealed by HR-TEM and XRD measurements. The size and shape of Ag nanoparticles are also found to depend on the pH condition in the synthesis. Ag nanoparticles were the main products at pH 5.0 whereas large Ag nanotriangle and truncated triangular nanoplate were dominant at pH 4.0 in the synthesis. Due to its monodispersity and good stability, the chitosan-functionalized Ag colloid synthesized at pH 5.0 was further tested for its antibacterial activities against gram-positive bacteria, gram-negative bacteria and fungus. The results of zone of inhibition, inhibition ratio and SEM characterization revealed that chitosan-functionalized Ag nanoparticles have great bactericidal efficiency against both bacteria and fungus. [ABSTRACT FROM AUTHOR]

Abstract: Applicability of solvent-free microwave extraction (SFME) for extraction of the fruits of Schisandra chinensis essential oil was examined; the composition and antioxidant activities and antibacterial activities of the essential oil were assessed in vitro. An orthogonal experiment (L9 (3)4) was applied to optimize the extraction process. The optimum conditions were: extraction time, 45 min; microwave power, 800 W; diameter of powder particles, 0.25 mm; and proportion of water pretreatment, 30%. Under these conditions, the extraction yield was 1.75%. Thirty-five compounds, representing 91.12% of the oil, were identified, of which the major ones, ylangene (50.11%), β-himachalene (10.76%)，α-bergamotene (9.52%) and β-Chamigrene (5.41%), accounted for of 75.80% the oil. Antioxidant activity, IC50 value of the essential oil was determined as 3.87 mg/mL by DPPH assay, and the inhibition values of the essential oil at 1.8 mg/mL was 41.88% by β-Carotene–linoleic acid bleaching assay. The essential oil was screened for antibacterial activity against both Gram positive (Staphylococcus epidermidis, Staphylococcus aureus, Bacillus subtilis) and Gram negative (Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris) bacteria. The essential oil showed antibacterial effect against all the gram (+) bacteria and gram (−) bacteria tested. These results show that S. chinensis essential oil could be considered as a natural alternative to food antioxidants and preservatives. [Copyright &y& Elsevier]