Initial Screening of 10 Plant Essential Oils in Vitro Antibacterial Activity Against Blueberry Pathogens

In order to develop natural antistaling agent for blueberries preservation,the antibacterial activities of 10 kinds of plant essential oils were analyzed by oxford-cup test and tube dilution method,and their inhibitory abilities to two kinds of representative Gram bacteria which are Escherichia coli and Staphylococcus aureus,and three kinds of harmful fungi in blueberries,involving Alternaria alternata,Penicillium digitatum and Botrytis cinerea,were tested.The results showed that 7 kinds of essential oils can inhibit the three fungi,among which cinnamon oil,clove oil,anise oil and thyme oil have strong fungi static efficacy.Cinnamon oil and thyme oil can effectively inhibit the Gram-positive bacterium(Staphylococcus aureus);cinnamon oil and masson pine oil are strongly inhibitory to Gram-negative bacterium(E.coli).Cinnamon oil has broad-spectrum ability to inhibit fungi,Gram-negative and positive bacteria,with a minimum inhibitory concentration(MIC)ranging from 0.0391 to 0.1560 L/mL.With strong inhibition effects on fungi,cinnamon oil can be used as a compound base oil and mixed with other essential oils to retain the freshness of blueberries,thus achieving better antibacterial and anti-corrosion effects.

In Vitro Anti-Bacterial and Anti-Fungal Activities of Extracts from Different Parts of 7 Zingiberaceae Plants

This study aimed to explore the anti-bacterial and anti-fungal activities of extracts from different parts of plants in the Zingiberaceae family.The inhibitory rate,minimum inhibitory concentration(MIC),and minimum bactericidal concentration(MBC)of leaf and stem,and root and rhizome extracts from Alpinia katsumadai Hayata,Alpinia oxyphylla Miq×Alpinia henryi K.Schumann,Alpinia oblongifolia Hayata,Alpinia nigra(Gaertn.)Burtt,Amomum villosum Lour,Alpinia zerumbet(Pers.)Burtt.et Smith and Alpinia oxyphylla Miq were determined using the fungus cake method and double dilution method.The seven Zingiberaceae plants exhibited characteristic antibacterial activities against pathogenic bacteria and fungi.At a 1.5 mg mL^(−1),A.zerumbet root and rhizome extracts exhibited strong inhibitory activity against S.aureus and E.coli,with 83.23%and 79.62%,respectively.In addition,A.zerumbet leaf and stem extracts had an inhibitory rate of 90.85%against P.aeruginosa.At the same concentration,the leaf and stem,root and rhizome extracts of A.katsumadai had the best anti-bacterial effect against F.oxysporum,with inhibition rates of 84.46%and 84.73%,respectively.Moreover,A.katsumadai and A.zerumbet leaf and stem extracts had the most significant antibacterial effect against S.aureus,with a MIC of 0.063 mg mL^(−1).Thus,both A.katsumadai and A.zerumbet extracts had significant antibacterial activity.In addition,by comparing the inhibitory effect of extracts from different parts,it was found that the inhibitory rate and average inhibitory rate of extracts from leaf and stem were higher than those from root and rhizome.The chemical constituents of A.katsumadai and A.zerumbet,determined by the high-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS),revealed that citric acid(CA),alpinetin,and pinocembrin(PNCB)were the functional constituents yielding the antibacterial activity.Overall,A.katsumadai and A.zerumbet have the potential to be developed as new plant fungicides and bactericides.

In vitro prebiotic effects of seaweed polysaccharides

Although prebiotic activities of alginate and agar oligosaccharides isolated from seaweeds have been reported, it remains unknown whether seaweed polysaccharides have prebiotic activity. In this study, we isolated polysaccharides from four species of seaweeds, such as Grateloupia fi licina(GFP), Eucheuma spinosum(ESP), Ulva pertusa(UPP), and A scophyllum nodosum(ANP), and characterized their structures and prebiotic ef fects in vitro. The results showed that these polysaccharides were dif ferent in total sugar and sulfate contents as well as monosaccharide composition. GFP and ESP significantly promoted bifi dobacterium proliferation and 0.1% ESP and 0.4% GFP resulted in the highest proliferation rates of beneficial bacteria, whereas UPP and ANP inhibited the growth of beneficial bacteria at all tested concentrations(0.1%–0.5%). The different behaviors of the four seaweed-originated polysaccharides might be refl ected by differences in monosaccharide composition and structure. Therefore, polysaccharides isolated from GFP and ESP could be utilized as prebiotics. However, more studies must be carried out in vivo.

Formulation optimization and in vitro antibacterial ability investigation of azithromycin loaded FDKP microspheres dry powder inhalation

Azithromycin loaded fumaryl diketopiperazine(FDKP)dry powder inhalation was designed and prepared for the treatment of community-acquired pneumonia.The solubility of FDKP and stability of azithromycin solution was investigated.Formulation of azithromycin loaded FDKP microparticle was investigated and optimized by the single factor experiment.High-pressure homogenization and spray drying conditions were also optimized to prepare the particles by spray drying azithromycin dissolved FDKP microparticle suspension at pH 4.5.The in vitro antibacterial efficiency and in vitro dispersion performance was also investigated to confirm the antibacterial efficiency,dispersion and deposition behavers.FDKP/azithromycin mass ratio(3:2)was the optimized formulation of azithromycin loaded FDKP microparticle with the maximal drug loading efficiency.High-pressure homogenization and spray drying conditions were also optimized.The in vitro antibacterial results indicated that only with the antibiotic concentration higher than mutant prevention concentration could totally inhibit the reproduction of bacteria.In vitro dispersion performance of azithromycin loaded FDKP microparticles(AZM@FDKP-MPs)also shows remarkable improvement of dispersion and deposition behavers of AZM.AZM@FDKP-MPs dry powder inhalation as a targeting delivery route has better potential for lung infection treatment.