2.5. Reactive oxygen species production assay
2.5.1. Preparation of P. acnes culture supernatant
P. acnes was cultivated in BHI and glucose with and without plant extracts (100 μg/ml) for 72 h at 37 °C in
anaerobic conditions. The supernatant was harvested, filtered through a 0.22 μm-pore size filter and stored at −20 °C
until use.
2.5.2. Nitroblue tetrazolium dye (NBT) reduction test
The NBT test was performed according to the method of Park et al [12]. The test was aimed to determine ROS
activity. Briefly, the 500 μl of venous blood of healthy volunteers, 50 μl of stimulants and positive or negative controls
(Culture supernatant-P. acnes with and without extracts and zymosan and culture media) were added and the solutions