Commercial baker’s yeast was washed by repeated
centrifugation (4 200 r/min, 5 min) in distilled water until the
supernatant fluids were clear and a 10% (v/v) suspension
was prepared in distilled water. Various concentrations of
extracts (1-5 mg) were added to 1 mL of glucose solution
(5-25 mmol/L) and incubated together for 10 min at 37 °C. The
reaction was started by adding 100 µL of yeast suspension,
vortexed and further incubated at 37 °C for 60 min. After
60 min, the tubes were centrifuged (3 800 r/min, 5 min) and