标题：Effect of Differences Methanol Concentration and Extraction Time on the Antioxidant Capacity, Phenolics Content and Bioactive Constituents of Orthosiphon Stamineus Extracts
摘要：Bioactive compounds of Orthosiphon stamineus have been known to have the beneficial effects on health. Efficient extraction of these beneficial compounds is very important. The study was conducted to determine the efficiency of methanol as an extraction solvent for bioactive compound extraction of O. stamineus raw materials. Leaf sample was extracted in 25, 50 and 100% methanol and distilled water for 2, 4 and 8 hours at 40°C. The free radical scavenging activity (FRSA) method was used to determine antioxidant capacity and Follin-Ciocalteu method was used to determine samples total phenolic compounds. The quantification of bioactive constituents by using the high performance liquid chromatography (HPLC) and the standard markers was used for this analysis such as rosmarinic acid (RA), sinensetin (SEN) and 3-hydroxy-5,6,7,4-tetramethoxyflavone (TMF). The current research shows that the yield of RA concentration was high in 50% methanol extracts at 2, 4 and 8 h of extraction. For the FRSA result showed that methanol at 50% and 100% was the most effective concentration levels inhibition between 45-55% at 8 hours’ time extraction. For the total phenolic compound, the 50% methanol concentration in O. stamineus leaf had the highest value compared with 0%, 25% and 100% methanol concentration. But, it was observed that time extraction did not influence the TPC values for different concentrations of methanolic extracts. These indicated that time extraction had affected the total capacities of antioxidant and 50% methanolic extracts was the best concentration for indicated the TPC in the O. Storminess leaf.
