Optizen 3220uv spectrophotometer

To remove extracellular acetonesoluble phenolics, the lichen thalli were washed several times with acetone (approximately 25 mL/g) and then air-dried. The samples were subsequently ground in a cold mortar with liquid nitrogen until a very fine powder was obtained. Next, 100 mg of this powder was amended with ascorbic acid, polyvinylpolypyrrolidone (PVPP), and 1 mL of extracting solution (1 : 10 weight : volume) containing 5 mM ethylenediaminetetraacetic acid (EDTA), 2 mM phenylmethylsulfonyl fluoride (PMSF), and a protease inhibitor cocktail (Roche Applied Science, Indianapolis, IN, USA) at concentrations recommended by the manufacturer. Extraction was then conducted by stirring the samples at 180 rpm and 15℃ for 2 hr. The samples were subsequently centrifuged at 10,000×g for 30 min, after which the pellet was discarded and the supernatant was centrifuged again if necessary. Finally, the absorbance of the supernatant was measured at 280 nm and 320 nm using an Optizen 3220UV spectrophotometer (Mecasys Co., Daejeon, Korea).