Compounds

Dichloroacetic acid (Merck KGaA) was used to prepare a 1 M stock solution of DCA every four weeks and stored at 4°C. Different concentrations and dilution series from 0.1–20 mM DCA were prepared immediately before each experiment. The purchased dichloroacetic acid solution is given with a specific concentration of 1.547 g/mL. For the preparation of a 1 M DCA stock solution, 0.827 mL of the dichloroacetic acid stock solution was diluted in 2 mL distilled water. Subsequently, the pH was adjusted to pH 7 by titration with sodium hydroxide. The solution was filled up with distilled water to a final volume of 10 mL. Afterwards, the obtained DCA stock solution was sterile filtrated and stored at 4°C.

Metformin solution was always freshly prepared on the day of application. To prepare a 100 mM stock solution, 82.8 mg metformin hydrochloride (BIOMOL GmbH, Hamburg, Germany) were dissolved in 5 mL cell culture medium and sterile filtrated as well.