Ultrasonic-assisted preparation of eucalyptus oil nanoemulsion: Process optimization, in vitro digestive stability, and anti-Escherichia coli activity.

Eucalyptus oil (EO) is a natural and effective antimicrobial agent; however, it has disadvantages such as poor water solubility and instability. The aim of this study was to investigate the effect of process vessels and preparation process parameters on the particle size of the emulsion droplets using ultrasonic technique and response surface methodology to prepare eucalyptus oil nanoemulsion (EONE). The optimal sonication process parameters in conical centrifuge tubes were confirmed: sonication distance of 0.9 cm, sonication amplitude of 18%, and sonication time of 2 min. Under these conditions, the particle size of EONE was 18.96 ± 4.66 nm, the polydispersity index was 0.39 ± 0.09, and the zeta potential was -31.17 ± 2.15 mV. In addition, the changes in particle size, potential, micromorphology, and anti-Escherichia coli activity of EONE during digestion were investigated by in vitro simulated digestion. The emulsion was stable in simulated salivary fluid, tended to aggregate in simulated gastric fluid, and increased in particle size and potential value in simulated intestinal fluid. EONE showed higher anti-E. coli activity than EO by simulated digestion. These results provide a useful reference for the in vivo antimicrobial application of the essential oil.

Ultrasound-Assisted Preparation of Exopolysaccharide/Nystatin Nanoemulsion for Treatment of Vulvovaginal Candidiasis.

PURPOSE: As one of the classic anti-Canidia albicans (CA) and vulvovaginal candidiasis (VVC) drugs, nystatin (NYS) is limited by poor water solubility and easy aggregation. Traditional NYS vaginal delivery formulations do not fully adapt to the specific environment of the vaginal cavity. The use of exopolysaccharides (EPS) has great application potential in emulsifiers, but its use has not been reported in nanoemulsions. In this work, an EPS/NYS nanoemulsion (ENNE) was developed to improve the activities of NYS against CA and VVC. METHODS: The ENNE was prepared by ultrasonic method using EPS as an emulsifier, liquid paraffin oil as an oil phase, PEG400 as a co-emulsifier, and NYS as the loaded drug. ENNE preparation was optimized by response surface method. After optimization, in vitro and in vivo analysis of the anti-CA activity; animal experiments; staining with propidium iodide (PI), periodic acid-schiff (PAS), and hematoxylin-eosin (H&E); and cytokine experiments were performed to investigate the therapeutic ability against VVC. RESULTS: The optimal formulation and preparation parameters of ENNE were determined as follows: EPS content of 1.5%, PEG400 content of 3.2%, NYS content of 700 µg/mL, paraffin oil content of 5.0%, ultrasonic time of 15 min, and ultrasonic amplitude of 35%. The ENNE showed an encapsulated structure with an average particle size of 131.1 ± 4.32 nm. ENNE exhibited high storage and pH stability, as well as slow release. The minimum inhibitory concentration (MIC) of ENNE against CA was only 0.125 µg/mL and the inhibition zone was 19.0 ± 0.5 mm, for greatly improved anti-CA effect. The prepared ENNE destroyed the membrane of CA cells, and exhibited good anti-CA effect in vivo and therapeutic ability against VVC. CONCLUSION: The results of this study will promote the application of EPS in nanotechnology, which should lead to new and effective local drug formulations for treating VVC.

Preparation of Calcipotriol Emulsion Using Bacterial Exopolysaccharides as Emulsifier for Percutaneous Treatment of Psoriasis Vulgaris.

An exopolysaccharides/calcipotriol (EPS/CPT) emulsion was prepared using bacterial EPS as emulsifier, sunflower oil as an oil phase and CPT as the loaded drug, and the effect of this emulsion on psoriasis vulgaris treatment was evaluated. An EPS composed of mannose (70.56%) and glucose (29.44%) was obtained from the marine mangrove bacteria Bacillus amyloliquefaciens ZWJ (Zhu Wenjing) strain. The EPS has significant emulsifying activity at the concentration of 1.5%. The prepared EPS/CPT emulsion has small and stable particle size, with a drug content of 0.00492%, and good spreading properties. The in vitro drug release results revealed that the emulsion showed a certain sustained release effect. In vitro and in vivo animal experiments show that the EPS/CPT emulsion can effectively treat psoriasis vulgaris by increasing the accumulation of CPT in psoriatic skin lesions and reducing the levels of inflammatory cells and inflammatory factors (TNF and IL6). Additionally, it has a certain effect on reducing the side effects associated with CPT. This study lays a foundation for the research of EPS in the topical application of medical materials and treatment of psoriasis.

Exopolysaccharide from Bacillus vallismortis WF4 as an emulsifier for antifungal and antipruritic peppermint oil emulsion.

The paper aims to study emulsifying capacities of bacterial exopolysaccharides (EPS) on essential oils (EOs), and the antifungal and antipruritic properties of the emulsion. A marine bacterium Bacillus vallismortis was identified and named the WF4 strain. The molecular weight of the EPS was 3.83 × 105 Da. The composition of monosaccharide was mannose/glucose/xylose/arabinose (51.77%:20.82%:13.28%:14.13%). Rheology study shows shear thinning characteristics. EPS had significant emulsifying activity to EOs at 1.0% (w/v). The prepared EPS-peppermint oil (EPS-PO) emulsion was an O/W emulsion with an average particle size of 16.3 µm and was stable. The antifungal activity results showed that the minimum inhibitory concentration (MIC) of the EPS-PO emulsion was 4.0 mg/mL, and the pure PO was 16.0 mg/mL, indicating that the emulsion of PO could enhance the antifungal ability. Moreover, propidium iodide (PI) staining and Scanning electron microscopy (SEM) observation showed that the EPS-PO emulsion damaged the membrane of Candida albicans (CA). The anti-itching test showed that the EPS-PO emulsion could significantly increase the itch threshold of guinea pigs to phosphate histamine and reduce the number of scratching incidents. This study laid the foundation for the application of EPS as an emulsifier and highlighted the application prospects of EPS in topical emulsion.

Physical and chemical properties, percutaneous absorption-promoting effects of exopolysaccharide produced by Bacillus atrophaeus WYZ strain.

A high yield of exopolysaccharides bacteria isolated from mangrove system was identified as Bacillus atrophaeus by 16S rDNA and named as WYZ strain. An exopolysaccharide (BPS) was obtained from this strain after purification with a yield of about 0.58 g/L. Then some physical and chemical properties of BPS, such as weight average molecular weight (Mw), monosaccharide composition, intrinsic viscosity and water retention capacity were studied. The microstructure (SEM) showed that BPS was porous wound three-dimensional spider web structure. Using BPS as transdermal absorption enhancer, and lidocaine as a test drug, in vitro and local anesthesia in live animals experiments were conducted to explore that the BPS promote lidocaine transdermal absorption and mechanism. In conclusion, the BPS had good water retention capacity and transdermal absorption promoting effect, all of these indicated that BPS has great potential in the field of biomaterials.