Effects of drying techniques on composition of biomarker compounds (Sinensetin and rosmarinic acid) and antioxidant capacity of Misai Kucing leaves

Abstract

Orthosiphon staminues or misai kucing is one of the recommended herbal species in Malaysia. This study was conducted to determine the effect of drying techniques on antioxidant capacity and composition of biomarkers compounds of misai kucing leaves. Misai kucing leaves samples were subjected into three different drying techniques, namely sun drying, ambient temperature drying and oven drying at 50 oC until the samples weight become constant. Then, the samples were extracted with methanol in shaking water bath. The total phenolic compounds were evaluated by using Folin-Ciocalteu method and the antioxidant activity was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity assay and were analyzed by using UV/VIS Spectrophotometer. The biomarker compounds were determined by using High Performance Liquid Chromatography (HPLC). The results of the experiments showed differences in values on concentration of total phenolic compounds, free radical scavenging activity and concentration of rosmarinic and sinensetin acid when treatment of different drying techniques were applied. In conclusion, for different drying techniques, ambient drying techniques obtained the highest concentration of total phenolic compound, free radical scavenging activity, concentration of rosmarinic acid and sinensetin. For total weight loss, ambient temperature drying obtained the highest amount of free radical scavenging activity, sun drying obtained the highest concentration of sinensetin and oven drying obtained highest concentration of total phenolic compound.