Buformin hydrochloride

Ipratropium bromide, IBC, IBC-d6, l-noradrenaline, ritodrine hydrochloride, sumatriptan-d6, thiamine-d3 hydrochloride, and trospium chloride were obtained from Santa Cruz Biotechnology. Ranitidine-d6 and trospium-d8 were obtained from Toronto Research Chemicals, ASP⁺ was obtained from Life Technologies, and buformin hydrochloride was obtained from Wako Chemicals. Radiolabeled MPP⁺ (N-[methyl-³H], 80 Ci/mmol) and TEA⁺ ([ethyl-1-¹⁴C]; 55 mCi/mol) were obtained from Hartmann Analytic. All other compounds tested as substrates were obtained from Sigma–Aldrich. All chemicals used in this study were purchased from commercial sources and had purities of 97% or higher.
Dulbecco's modified Eagle's medium, Hank's buffered salt solution (HBSS), and additives used for cell culturing were obtained from Life Technologies. Poly-d-lysine (1–5 kDa), Hepes, bicinchoninic acid, and copper sulfate pentahydrate were obtained from Sigma–Aldrich. Twelve-well plates were obtained from Starlab, and tissue culture flasks were from Sarstedt. Acetonitrile and methanol in LC–MS/MS grade were obtained from LGC Standards, and formic acid (LC–MS/MS grade) and sodium chloride were obtained from Merck. SDS (UltraPure) was obtained from AppliChem.

Ipratropium bromide and trospium chloride were obtained from Santa Cruz Biotechnology (Heidelberg, Germany). Trospium-d8 was obtained from Toronto Research Chemicals (TRC, Toronto, ON, Canada). Buformin hydrochloride was obtained from Wako Chemicals (Neuss, Germany). Fenoterol hydrochloride, fenoterol-d6, metformin hydrochloride, butylscopolamine bromide, and atropine were obtained from Sigma-Aldrich (Taufkirchen, Germany).
Dulbecco’s Modified Eagle Medium (DMEM), Hank’s Buffered Salt Solution (HBSS), and additives used for cell culturing were obtained from Life Technologies (Darmstadt, Germany). Poly-d-lysine (1-5 kDa), 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid (HEPES), bicinchoninic acid, and copper sulfate pentahydrate were obtained from Sigma Aldrich. Twelve-well plates were obtained from Starlab (Hamburg, Germany) and tissue culture flasks from Sarstedt (Nümbrecht, Germany). Acetonitrile and methanol in LC-MS/MS grade were obtained from LGC Standards (Wesel, Germany), formic acid (LC-MS/MS grade) and sodium chloride were obtained from Merck (Darmstadt, Germany). Sodium dodecylsulfate (SDS, ultrapure) was obtained from AppliChem (Darmstadt, Germany).

Chemicals and reagents used were procured from the following sources: graphene nanoplatelet, metformin hydrochloride (97%), phenformin hydrochloride (97%), propranolol hydrochloride (99%), triethylamine, sodium monophosphate were purchased from Sigma Aldrich (Steinheim, Germany); zeolite Linde Type L (LTL) (Tosoh Corporation, Japan); buformin hydrochloride (95%) was from Wako Pure Chemicals Industries (Osaka, Japan); HPLC grade methanol (MeOH) and acetonitrile (ACN), and sodium chloride were from Quality Reagent Chemicals (QReC, Auckland, New Zealand). HPLC grade tetrahydrofuran (THF) (>99.9%), 2-propanol (IPA), dichloromethane (DCM) sodium hydroxide, orthophosphoric acid were obtained from Merck (Darmstadt, Germany). Toluene and acetic acid (99.8%) were purchased from HmbG Chemicals (Hamburg, Germany). Ultrapure water (resistivity, 18.2 MΩ cm⁻¹) was produced from Millipore water (Molsheim, France) purification system and was used throughout. Polypropylene (PP) sheet membrane (Accurel 2E HF (R/P), 166 μm thickness, 0.2 μm pore size) was purchased from Membrana (Wuppertal, Germany).