Monday, May 5, 2008
9-30

Extraction and Identification of Julibroside Saponins from the bark of Albizia julibrissin

Abigail S. Engelberth1, D. J. Carrier2, and E.C. Clausen1. (1) Chemical Engineering, University of Arkansas, 3202 Bell Engineering Center, Fayetteville, AR 72701, (2) Biological and Agricultural Engineering, University of Arkansas, 203 Engineering Hall, Fayetteville, AR 72701

Value-added products may be found in a number of biomass feedstocks used in the production of energy. One such product, saponins, can be found in the bark of Albizia julibrissin (mimosa), a leguminous species that has a forage yield of 4.5 tons/acre·yr. Saponins are a natural detergent and can be found in a variety of plants, ranging from Yucca schildigera in Mexico to Panax ginseng in China. Saponins contain both a water-soluble and a fat-soluble component. Saponins have been shown to have antiprotozal activity in ruminals and to reduce blood cholesterol levels in mammals. Triterpenoidal saponins are known to be present in Albizia julibrissin, aptly called julibrosides, and have previously been extracted from the plant material with methanol and other organic solvents. They were then separated by RP-HPLC and finally analyzed by mass spectrometry. Unfortunately, julibrosides are not available commercially as reference compounds. Hence, the objective of this paper is to present results from the extraction of saponins from mimosa bark in order to secure reference material. Centrifugal partition chromatography (CPC), a unique separations tool based on the principles of countercurrent chromatography, is used to separate and purify the extracted saponins. In the future, pressurized hot water will be used to extract saponins, in a green manner, from Albizia biomass prior to conversion to a liquid fuel.