The subcritical water (SCW) extraction of Chaga mushroom (CM) was carried out at various temperatures (50, 100, 150, 200, 250, and 300°C) and times (10, 30, and 60 min), and then antioxidant activities of the SCW extracts were evaluated by determining 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, reducing power (RP), superoxide dismutase (SOD)-like activity, and total phenol content (TPC). The DPPH and ABTS radical scavenging activities, and the SOD-like activity of the extracts increased with elevated temperatures and times.
For example, DPPH and ABTS radical scavenging activities, and SOD-like activity of the extracts at 250°C for 60 min were 72.5, 97.8, and 92.3%, respectively, while those at 50°C for 60 min were 63.2, 14.4, and 22.6%, respectively.
However, the activities decreased at 300°C. The highest TPC and RP were found at 250°C for 30 min with values of 10.724 mg/mL and 1.063 optical density, respectively. These results indicate that SCW extraction was significantly effective on the increase of antioxidant activity of the CM.
Source: Antioxidant Activity of Subcritical Water Extracts from Chaga Mushroom (Inonotus obliquus) Journal: Separation Science and Technology Volume 45, Issue 2, January 2010, pages 198-203 Hye-Kyung Seoa & Seung-Cheol Leea*