Extraction and scale-up of rosmarinic acid from Orthosiphon stamineus
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Date
2016
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Publisher
Universiti Teknologi Malaysia
Abstract
Orthosiphon stamineus and its extract have been developed into various kinds of herbal products. However, there is no standard guideline to prepare the products for quality assurance. Therefore, this study focused on the optimization, kinetic studies and scale-up of rosmarinic acid extraction from O. stamineus. The extraction was optimized in a laboratory scale reflux extractor (100 mL) using a response surface methodology (central composite design). The optimum conditions were 70% v/v concentration of ethanol, 9.14:1 ratio of solvent-to-solid loading, extraction temperature at 56.53 °C for 3 hours. The yield of crude extract and rosmarinic acid content under the optimal conditions were 10.05% and 44.79 mg/g, respectively. The results were close to the predicted values (10.31% and 41.15 mg/g). The extraction was then carried out in a preparative scale extractor (2.5 L) to investigate the kinetic profile of rosmarinic acid extraction. A first order kinetic model gave the best fit for the experimental data. The yield of the crude extract and rosmarinic acid content for the preparative scale extraction were 9.28% and 39.76 mg/g, respectively, which was less than 1% of the reduction compared to the performance of laboratory scale reactors. The kinetic model was then applied in the scaled-up extraction (10 L) based on constant power dissipation. The experimental data fitted well to the kinetic equation with R2 value of 0.90. The crude extract was fractionated by using solid phase extraction (SPE) method. The results showed that the content of rosmarinic acid was increased from 4.0 to 6.7% w/w after fractionation by SPE. The O. stamineus fraction (IC50, 37.3-45.1 µg/ml) showed higher antioxidant activity than crude extract (IC50, 58.85±7.1 µg/ml) due to high content of rosmarinic acid in the fraction. In summary, the processing technology of O. stamineus extract with high rosmarinic acid (6.7%) was established based on the reflux system, followed by SPE clean-up process.
Description
Thesis (PhD. (Bioprocess Engineering))
Keywords
Extraction (Chemistry), Lamiaceae, Herb products