2,5-Dimethoxybenzoic acid

Screening of antimicrobial synergism between phenolic acids derivatives and UV-A light radiation.[Pubmed:33239223]

J Photochem Photobiol B. 2020 Nov 10:112081.

The objective of this study was to investigate synergistic antibacterial activity based on a combination of UV-A light and three classes of food grade compounds: benzoic acid derivatives, cinnamic acid derivatives, and gallates. By using Escherichia coli O157:H7 as the model strain, it was observed that three cinnamic acid derivatives (ferulic acid, coumaric acid, and caffeic acid) and one benzoic acid derivative (2,5-dihydroxybenzoic acid) presented strong synergistic antibacterial activity with UV-A light radiation, where 1 mM levels of these compounds plus with 15 min of UV-A light (total light dose of 6.1 cm(-2)) led to more than 7-log CFU mL(-1) of bacterial inactivation. In contrast, synergistic antibacterial activity between UV-A light and most benzoic acid derivatives (benzoic acid, gallic acid, vanillic acid, and 2,5-Dimethoxybenzoic acid) were only observed after higher concentrations of these compounds were applied (10 mM). Lastly, from the three gallates tested (methyl gallate, ethyl gallate, and propyl gallate), only propyl gallate showed strong antibacterial synergism with UV-A light, where 10 mM of propyl gallate plus 15 min of UV-A light led to approximately 6.5-log of bacterial reduction. Presence of antioxidant compounds mitigated the light-mediated antibacterial activity of gallic acid, 2,5-dihydroxybenzoic acid, and propyl gallate. Similarly, the light-mediated antibacterial activity of these compounds was significantly (P < 0.05) reduced against metabolic-inhibited bacterial cells (sodium azide pretreatment). On the other hand, the antibacterial synergism between ferulic acid and UV-A light was not affected by the presence of antioxidants or the metabolic state of the bacterial cells. Due to the increasing concerns of antimicrobial resistant (AMR) pathogens, the study also investigated the proposed synergistic treatment on AMR Salmonella. Combinations of 1 mM of ferulic acid or 1 mM of 2,5-dihydroxybenzoic acid with UV-A light radiation was able to inactivate more than 6-log of a multi-drug resistant Salmonella Typhimurium strain.

Ion Source with Laser Triangulation for Ambient Mass Spectrometry of Nonplanar Samples.[Pubmed:28976183]

Anal Chem. 2017 Nov 7;89(21):11452-11459.

The analysis of nonplanar samples in ambient mass spectrometry poses a formidable challenge. Here, an ion source equipped with laser triangulation for analyzing nonplanar surfaces was constructed. It was designed as a two-position device, where the sample height was measured using laser triangulation and the target compounds were then analyzed. Thanks to a stage movable in xyz, the ion source maintained an optimal vertical distance between the sample and the sampling capillary for each measured spot during the surface analysis. The xyz-coordinates for the movement of the sample stage were computed using the laser sensor data in such a way as to avoid direct contact of the sampling capillary and the measured surface. The ion source performance and its ability to analyze various morphologies were tested using desorption electrospray ionization with plastic objects coated by 2,5-Dimethoxybenzoic acid. The experiments showed excellent performance for nonplanar samples but also revealed some limitations especially on object edges and steep slopes. The applicability of the ion source operated in desorption electrospray ionization and desorption atmospheric pressure photoionization was examined for food and pharmaceutical samples. Chemicals on the surface of nonplanar samples were probed along a line extending across the surface of the measured objects. The device provided high-quality spectra, regardless of the sample height at the measured spot. The automatic adjustments of the sample stage in xyz proved to be beneficial for analyzing nonplanar samples and for simultaneous measurement of samples with various dimensions and shapes.