Effect of Extraction Temperature on Stability of Major Polyphenols and Antioxidant Activity of<i>Orthosiphon stamineus</i>Leaf

Abstract

The effect of extraction temperature on the stability of polyphenols and free radical scavenging activity of Orthosiphon stamineus leaf extract was investigated. Sinensetin (SEN) and rosmarinic acid (RA) were selected as flavonoid and non-flavonoid polyphenolic markers of the extract, respectively. The levels of the markers were significantly (p < 0.5) higher at the extraction temperature of 40°C. However, decrease in marker concentration was observed from extraction temperature of 60°C and above. The extracts at lower temperature exhibited significant (p < 0.5) free radical–scavenging activity compared to extracts at elevated temperature owing to their degradation.