Dimethyl thiourea

From January 2017 to December 2020, 1,200 nonrepetitive K. pneumoniae strains were isolated from clinical samples of inpatients and outpatients from the Anhui Center for Surveillance of Bacterial Resistance with qualified data (44 (link)). These strains were identified using a matrix-assisted laser desorption–ionization time of flight mass spectrometry (MALDI-TOF MS) automated microbiology system (Bioyong, China) (45 (link)). All isolates were stored in Muller-Hinton broth (MHB; Sigma-Aldrich, USA) with 50% glycerol in cryovials for stock at −80°C and grown on Muller-Hinton agar (MHA; Sigma-Aldrich) at 37°C. K. pneumoniae ATCC 43816, ATCC 13883, ATCC 700603, and ATCC BAA-1705, A. baumannii ATCC 17978 and ATCC 19606, E. coli ATCC 25922 and BW 25113, and P. aeruginosa MPAO1 and CMCC 10104 were the wild-type standard strains.
All the antibiotics, Ga(NO₃)₃ · xH₂O, gallium maltolate, dimethyl thiourea, and ascorbic acid, were obtained from Sigma-Aldrich (St. Louis, MO, USA). All prepared solutions were stored at −20°C for up to 1 month.
Wild-type female C57BL/6 mice (8 weeks, 16 to 20 g) were purchased from the Experimental Animal Center of the Anhui Province (Hefei, China). All experiments involving mice were approved by the Institutional Animal Care and Use Committee of Anhui Medical University (approval no. LLSC20190253).

All reagents used were of analytical grade. Sodium pyruvate, dimethyl thiourea (DMTU), nordihydroguaiaretic acid (NDGA), ascorbic acid, histidine, xylenol orange (FOX), 2,2-diphenyl-1-picrylhydrazyl (DPPH), dimethylsulfoxide (DMSO), N,N-dimethyl-4-nitrosoaniline (DMNA), catalase, xanthine, xanthine oxidase, nitroblue tetrazolium (NBT), dL-penicillamine 2-thiobarbituric acid (TBA), α-tocopherol, Folin and Ciocalteu's phenol reagent, 3,5-di-tert-4-butylhydroxytoluene (BHT), and 5-fluoro-2′-deoxyuridine were purchased from Sigma-Aldrich (Toluca, Mexico, or Sigma, St. Louis, MO). Absolute ethanol, hydrogen peroxide (H₂O₂), sulfuric acid (H₂SO₄), methanol, ethylenediaminetetraacetic acid disodium salt (EDTA), NaCl, KH₂PO₄, NaHPO₄·7H₂O, NaOH, and H₂SO₄ were purchased from Merck-Mexico. Sodium hypochlorite (NaOCl) was purchased from Hycel (Mexico City, Mexico).

Kaempferol, quercetin, rutin, astragalin, isoquercitrin, and quercitrin standards, as well as PTZ, tween 80, and diazepam, were purchased from Sigma (Sigma-Aldrich Co., St Louis, MO, USA). Extracts were resuspended in saline solution (s.s. 0.9%, NaCl) alone or in 0.2% tween 80 in s.s. Control animals received the same volume of the vehicle via the same administration route. PTZ and flavonoids were dissolved in s.s. and diazepam in 0.2% tween 80 in s.s. Drugs were freshly prepared on the day of the experiments. All treatments were injected using an intraperitoneal (i.p.) administration within a volume of 10 mL/kg body weight.
For antioxidant analysis, reagents were used as follows: dimethyl thiourea (DMTU), nordihydroguaiaretic acid (NDGA), ascorbic acid, histidine, xylenol orange, ammonium iron (II) sulfate hexahydrate, N,N-dimethyl-4-nitrosoaniline (DMNA), catalase, xanthine, xanthine oxidase, nitroblue tetrazolium (NBT), deoxyribose, and butylated hydroxytoluene (BHT) were from Sigma Aldrich (St. Louis, MO, USA); potassium persulfate and sodium carbonate (Na₂CO₃) were from Mallinckrodt (Paris, KY, USA). Absolute ethanol, hydrogen peroxide (H₂O₂), sulfuric acid (H₂SO₄), methanol, ethylenediaminetetracetic acid disodium salt (EDTA), and sodium hypochlorite (NaOCl) were from JT Baker (Mexico City, Mexico). All other chemicals were reagent grade and commercially available.