Effect of Drying Methods on Metabolites Composition of Misai Kucing (Orthosiphon stamineus) Leaves

In this research the effects of different drying methods on the capacity of antioxidant, total phenolic and biomarker compounds concentrations of Orthosiphon stamineus leaves were studied. The biomarker compounds of the leaves studied were sinensetin (SEN) and rosmarinic acid (RA). Three different drying methods adopted were an oven at 40oC, under the shade, and under the direct sunlight. Initial moisture content of the leaves was determined as 76.6% (w.b). The total antioxidant activity of the dried leaves extract was not significantly affected by the drying methods (P>0.05). However, the total phenolic content (TPC), sinensetin and rosmarinic acid content in the dried leaves extracts were significantly affected by the drying methods (P<0.05). The sinensetin was detected in samples dried in an oven (0.197 mg/g) and was not detected in leaves dried under the shade or open sunlight. In contrast, the rosmarinic acid was only detected in samples dried under the shade (0.303 mg/g).