Subcritical water extraction of bioactive compounds from Orostachys japonicus A. Berger (Crassulaceae).

Subcritical-water extraction is an ecofriendly method for extracting antioxidant compounds only using water. The Subcritical-water extraction was employed for the extraction of bioactive compounds from Orostachys japonicus known as rock pine by investigating the use of various temperatures (110-260 °C) and extraction times (5-20 min). The Subcritical-water extraction condition at 220 °C for 15 min; the total phenolics content (39.9 ± 4.1 mg/g), flavonoids content (11.4 ± 0.6 mg/g), and antioxidant activities (90.3 ± 2.2%, 96.0 ± 2.9%, and 662.4 ± 17.2 mg/g) of Subcritical-water extract were higher under this condition than for extraction with either methanol or ethanol. Triterpene saponins were observed only in subcritical-water extraction condition at 220 °C for 15 min. Further, some of its phenolic constituents; gallic acid, quercetin, and kaempferol were quantified by high performance liquid chromatography. Subcritical-water extraction is an effective method for extracting valuable bioactive compounds from Orostachys japonicus.

Conversion of 6-gingerol to 6-shogaol in ginger (Zingiber officinale) pulp and peel during subcritical water extraction.

Subcritical water extraction is an eco-friendly method for the extraction of less polar compounds without the use of organic solvents. This study determined the extraction conditions that maximize the contents of 6-gingerol and 6-shogaol obtained from ginger pulp and peel. The highest yields of 6-gingerol (0.68 ±â€¯0.08 mg/g), and 6-shogaol (0.39 ±â€¯0.03 mg/g) were obtained from ginger pulp at the extraction conditions of 130 °C/25 min, and 190 °C/15 min. 6-Shogaol content increased with the increasing extraction temperature and extraction time due to the conversion of 6-gingerol to 6-shogaol by thermal cracking. The antioxidant activity of ginger extracts were increased depending on the increasing of 6-shogaol content.