Subcritical water extraction of horse chestnut (Aesculus hippocastanum) tree parts

Abstract

Subcritical water extraction of horse chestnut (Aesculus hippocastanum) parts, such as seeds, seed shell, bark and leaves has been performed in a batch reactor at temperatures of 150, 200 and 250°C and extraction times of 5, 15 and 30 min. The obtained extracts were analyzed by spectrophotometric methods to determine the total phenols, total carbohydrates and antioxidant activity. Furthermore, the compounds detected in the extracts, such as triterpene saponins (escins), coumarin glycosides (esculin and fraxin), phenolic compounds (chlorogenic, neochlorogenic and gallic acids) and furfurals (5-hydroxymethyfurfural, furfural, and 5-methylfufrual) were quantified using HPLC. High amount of escins was obtained in the seed extracts, while the highest amounts of esculin and fraxin were obtained in bark extracts. The total phenol content was the highest in shell and bark extracts, which implies that these extracts gave the highest antioxidant activity.

Keywords

• antioxidant activity
• extraction
• escins
• coumarin glycosides
• phenolic compounds