Selective photodynamic inactivation of Helicobacter pylori by a cationic benzylidene cyclopentanone photosensitizer - an in vitro and ex vivo study.

The rise in the antibiotic resistance rate of Helicobacter pylori has led to an increasing eradication failure of this carcinogenic bacterial pathogen worldwide. This underlines the need for alternative antibacterial strategies against H. pylori infection. Antimicrobial photodynamic therapy (aPDT) is a promising non-pharmacological antibacterial technology. In this study, the selective killing activities of three benzylidene cyclopentanone (BCP) photosensitizers (Y1, P1 and P3) towards H. pylori over normal human gastric epithelial GES-1 cells were evaluated and the ex vivo photodynamic inactivation effect was preliminarily assessed on twelve H. Pylor-infected mice. Results showed that under the irradiation of 24 J/cm2 532 nm laser, Y1, P1 and P3 at 2.5 µM induced a 3-log10 reduction of H. pylori CFU (99.9% killing). Confocal images showed that P3, unlike Y1 and P1, could not be uptaken by GES-1 cells. P3 at 2.5 to 20 µM showed not significant (p > 0.05) phototoxicity to GES-1 cells, nevertheless, Y1 and P1 under the same concentrations exhibited remarkable phototoxicity to GES-1 cells. In the co-culture of H. pylori and GES-1 cells, P3 at 2.5 µM led to a complete eradication of H. pylori under the irradiation of 24 J/cm2 532 nm laser. While for the GES-1 cells, no significant (p > 0.05) phototoxicity was observed under the same aPDT dosage. The ex vivo experiments showed that P3 mediated aPDT resulted in 82.4% to 100% reduction of H. pylori CFU without damaging the gastric mucosa. To sum up, P3 is a promising anti-H. pylori photosensitizer with the ability to selectively photo-inactivate H. pylori while sparing normal gastric tissues.

A simplified fabric phase sorptive extraction method for the determination of amphetamine drugs in water samples using liquid chromatography-mass spectrometry.

Fabric phase sorptive extraction (FPSE) can directly extract the target analytes and simultaneously determine many similar substances from complicated sample matrices. Also, it has very high chemical stability. Therefore, we used fabric phase sorptive extraction to analyze three amphetamine drugs (amphetamine (AM), methamphetamine (MAM), and 3,4-methylenedioxymethamphetamine (MDMA)) in water. This was coupled with ultrahigh-performance liquid chromatography and tandem mass spectrometry. The effects of different sorbent chemistries such as sorption time, ratios of back-extraction solvents, back-extraction time, and the salt effect on the extraction efficiency were studied; the optimum operation conditions were determined. Medium polarity polar polymer-coated FPSE media were created using short-chain poly (tetrahydrofuran) (PTHF). This is the most efficient extraction media for the analytes of interest. Under the optimized conditions, the linear range of the three amphetamine drugs were 0.1-150.0 (AM, MAM) and 0.5-200 ng mL-1 (MDMA). The correlation coefficients (γ) were 0.9947 (AM), 0.9925 (MAM), and 0.9918 (MDMA). The detection limits (LOD) were 0.025 ng mL-1 for AM, 0.029 ng mL-1 for MAM, and 0.01 ng mL-1 for MDMA. The corresponding limit of quantification values (LOQ) were 0.083 ng mL-1, 0.097 ng mL-1, and 0.031 ng mL-1, respectively. The recoveries were 73.4-91.6%, 82.6-95.4%, and 92.7-95.3%, respectively, and the relative standard deviations (RSD) were 1.65-6.88%, 1.38-6.11%, and 1.58-7.34%, respectively. Moreover, our method can be successfully applied for the analysis of amphetamines in wastewater samples, and at the same time, lays the foundation for the future detection of such substances.

In vitro photodynamic inactivation effects of benzylidene cyclopentanone photosensitizers on clinical fluconazole-resistant Candida albicans.

BACKGROUND: The incidence of Candida infections has increased for various reasons, including, the more frequent use of immunosuppresants or broad-spectrum antibiotics. Photodynamic inactivation (PDI) is a promising approach for treating localized Candida infections. METHODS: The PDI efficacies of three benzylidene cyclopentanone-based (BCB) photosensitizers (PSs: P1, P2 and Y1) against three fluconazole-resistant C. albicans (cal-1, cal-2, and cal-3) and one control C. albicans (ATCC 90028), respectively, were evaluated using an established plate dilution method. The binding of PSs to C. albicans was determined by fluorescence spectroscopy. The mechanism of antifungal PDI was investigated using confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM). RESULTS: Three BCB PSs all bound rapidly to C. albicans. After incubation with PSs for 30 min and irradiation with a 532 nm laser for 10 min (40 mW cm-2, 24 J cm-2), the fungicidal activity was achieved as 7.5 µM for P1 and P2, and 25 µM for Y1. CLSM confirmed that P1 and Y1 were located in intracellular components, including mitochondria, while P2 bound to the protoplast exterior and failed to enter the cells. TEM revealed the damage of mitochondria ultrastructures after P1- or Y1-mediated PDI, consistenting with the CLSM results. However, most cells became edematous, enlarged or deformation after P2-mediated PDI. CONCLUSIONS: The three BCB PSs all have remarkable PDI effects on C. albicans. The best effect is obtained by P1, which has one cationic charge with a proper lipophilicity. The respective subcellular localization of the three PSs led to different PDI mechanisms.