研究結果發現四種水丁香屬植物並無降血壓效果，反而是兩種代用藥材－田香草(玄參科)和三肉草(三白草科)－具有顯著降血壓效果。對於田香草之分配萃取分劃，降血壓試驗顯示正丁醇層具有最大生物活性，目前正在進行本植物成分研究之中。 A Taiwan Folk-medicine named "Shui-Ding-Xiang", Genus Ludwigia, is currently used in the treatment of hypertension. The origin of these medicinal plants was identined in this study. The hypertensive effects of the crude extracts were examined on normotensive and spontaneous hypertensive rats under anesthetization. The active principles were traced by the hypotensive tests.
In this preliminary study, it was found that the most commonly employed plants, Ludwigia hyssopifolia and Ludwigia octovalvis, were practically ineffective on hypertension. In contrast, the Substituted plants for Shui-Ding-Xiang, Limnophila rugosa and Saunsrus chinensis, exhibited hypotensive effects regularly. Thus, the possible hypotensive effects of Shui-Ding-Xiang may attribute to the involvement of these two substitutive plants.