Aqueous plant extracts with a high content of oleanolic and betulinic acid

Antitumoral properties of triterpene acids like betulinic acid and oleanolic acid have been shown [1, 2]. Mistletoe is composed of these triterpene acids at concentrations of 0.3–1.1g/100g dried plant material [3]. Nevertheless commercial mistletoe preparations with a drug to extract ratio of 20mg/ml contain less than 0.5µg/ml triterpene acids (rate of yield <1%), which is due to the poor aqueous solubility [4].

The aqueous solubility of triterpene acids raise with pH. Having the aim to prepare mistletoe extracts with a maximum yield of plant substances, it is inappropriate to prepare basic plant extracts because of hydrolysis.

The attempt to solve this problem was a simultaneous mixing of a high concentrated basic triterpene acid extract, a neutral mistletoe extract, and an acidic solution resulting in a neutral product (pH 7–8). It could be shown that stable preparations with more than 50µg/ml triterpene acids could be prepared, if complexation agents like oligo- or polysaccharides are present at the neutralizing step. In a first approach stability testing was performed over 6 weeks at room temperature. Further more the natural precipitation of an aqueous mistletoe extracts starts later, if it containes triterpene acids and a complexation agent. The startpoint of precipitation is directly dependend on the triterpene acid and complexation agent concentration.

In further experiments we will investigate biological activities of these triterpene rich mistletoe extracts.

[1] Eiznhamer DA, Xu ZQ. IDrugs 2004; 7(4): 359–373.

[2] Ovesna Z, Vachalkova A, Horvathova K, Tothova D. Neoplasma 2004; 51(5): 327–333.

[3] Krzaczek T. Ann Univ Mariae Curie Sklodowska 1977; 32: 125–134.

[4] Jäger S. Universität Witten/Herdecke; 2005.