Pitfalls in testing saponins for their anti-angiogenic activity: comparison of test systems

Angiogenesis is a major component in the progression of various diseases such as cancer, psoriasis and rheumatoid arthritis. Besides their virucidal, haemolytic and molluscicidal activity, the saponins of M. lanceolata, displayed anti-angiogenic activity in the chick chorioallantoic membrane (CAM) assay [1,2]. This latter activity was further investigated in an ex-vivo test.

The growth of the microvessels in the rat aorta ring assay was compared with the sprouting in the human placental vein assay during 20 days, while different concentrations of serum were added to the test. In both ex-vivo assays suramin was tested as positive control. A mixture of maesasaponins and several individual saponins were tested in the rat aorta ring assay (10–100µg/mL).

Based on the growth curves, the tests with suramin in both ex-vivo assays and literature the rat aorta ring assay was chosen as most preferable ex-vivo test for angiogenesis.

Although the tested maesasaponins showed anti-angiogenic activity in the CAM assay at a concentration of 1–10µg/mL, assay activity was only found at 25–50µg/mL in the rat aorta ring assay. This could be due to the concentration locally obtained with the pellets used in the CAM assay or the influence of a non specific inflammatory reaction in the in-vivo test which is not present in the ex-vivo test.

References: [1] Apers, S. et al. (1998)J. Nat. Prod. 61:585–590.

[2] Apers, S. et al. (2002)J. Pharm. Belg. 57:47–49.