Optimization of reb A extraction and application of membrane separation and other techniques to fractionate or clean up extracts of stevia rebaudiana, eleusine indica and some bracket fungi

• Main Author: Rosal, Rebecca B.
• Format: text
• Language: English
• Published: Animo Repository 2003
• Subjects: Extracts; Membrane separation; Stevia rebaudiana; Fungi; Chemistry
• Online Access: https://animorepository.dlsu.edu.ph/etd_doctoral/1207; https://animorepository.dlsu.edu.ph/context/etd_doctoral/article/2208/viewcontent/CDTG003703_P.pdf
• Institution: De La Salle University

A process for optimum extraction of the Stevia glycosides was developed. Ethanol was found to selectively extract the important non-caloric Stevia glycoside Rebaudioside A (Reb A). The plant sample was defatted with isopropyl alcohol using a modified soxhlet extraction set up. Soxhlet extraction of the Stevia samples enhanced the relatively low ethanol glycoside extract. Ultrafiltration and nanofiltraton using membranes NOVA 10K and DS-5 respectively, were established to clean up and concentrate the glycoside extract. The optimum parameters in spray drying the Stevia glycosides were established. A patent has been applied for the glycoside clean up and concentration in the United States Patenting Office. Chromatographic separation was done on the hexane and the chloroform extracts of S. rabaudiana. The GC-MS analysis of the hexane extract indicates the presence of heptacosane, hexatriacontane, 1- caryophyllene, spathulenol, phytol, m-Nitropthalic acid and β-Selinene. Stigmasterol was isolated pure from the chloroform extract of S. rebaudiana. The crude alcoholic extract of E. indica (EIA) was subjected to ultrafiltration using membranes of increasing pore size. This process efficiently separated the components of the sample. This result will be used to design a separation scheme for the physiologically active components. Separation of the ions from the rest of the extract (EIAq) components was successfully achieved by electrodialysis. This will serve as a preliminary step in the fractionation of the aqueous extract of E. indica. The quantities of Na+ and K+ ions were calculated from the atomic absorption spectrometry data. Sodium and potassium ions are present in 0.46% and 0.40% respectively, with respect to the plant sample and 0.36% and 0.32%, with respect to the freeze-dried retentate. Fractions from the hexane extract of E. indica (EIH) were found to contain campesterol, stigmasterol, sitosterol, and a series of alkanes. These compounds were inferred from their mass spectral data only. The membrane NOVA 1K has separated some of the components of the aqueous extract of P. betulinus. Polyporenic acid C was re-isolated from the chloroform extract of P. betulinus. This isolate showed hemolytic property on blood type O. The isolate obtained from the chloroform extract from F. fomentarius was identified as betulin.