Angiotensin-converting enzyme inhibitory activity of Viscum triflorum is host plant-dependent

Objective: The in vitro angiotensin-converting enzyme (ACE) inhibitory activity of extracts of V. triflorum and the corresponding host plant species were examined to evaluate the use as a remedy against hypertension, and to investigate whether the host plants have an influence on the activity. Materials and methods: Aqueous, ethanol and acetone extracts of 24 leaf samples of V. triflorum and the corresponding host plants, representing 10 plant species, were prepared. The ACE inhibitory activities of the extracts were measured by HPLC using dansyltriglycine as substrate. Results and conclusion: Water extracts of Viscum samples from only two of the 10 host plants, namely Acacia heterophylla Willd. (Fabaceae) and Sophora denudata Bory (Fabaceae), showed significant inhibitory activity, >= a parts per thousand yen50% inhibition in a concentration of 0.33 mg crude plant extract in 1 mL test solution. From the two mentioned host plant species activity was only detected in the water extract from one of the six samples of A. heterophylla. Three host species showed pronounced activity without any detection of activity in the samples of V. triflorum. The results support the traditional use provided that V. triflorum is collected from A. heterophylla or S. denudata.