无色花青素（英语：Leucocyanidin，亦称为无色氰定）是一种与无色花色素有关的无色的化学物质。可经由(+)二氢槲皮素被硼氢化钠还原而合成。

无色花青素加氧酶将无色花青素、2-酮戊二酸与O₂转化为产物：顺式二氢槲皮素、反式二氢槲皮素（紫杉叶素）、琥珀酸、CO₂与H₂O。

无色花色素还原酶将(2R,3S)-儿茶素、NADP与H₂O转化为产物2,3-反式-3,4-顺式-无色花青素、NADPH与H。现已在葡萄果实以及葡萄藤叶子中研究过这种酶的基因表达。也在紫花苜蓿、百脉根、大百脉根、Hedysarum sulfurescens与刺槐这些蔬菜类的叶、花以及种子中测量出它的酶活。

Leucocyanidin is a colorless chemical compound related to leucoanthocyanidins. Leucoyanidin can be found in Aesculus hippocastanum (Horse chestnut), Anacardium occidentale (Cashew, acajou), Arachis hypogaea (Earth Nut), Areca catechu (Areca nut), Asimina triloba (American custardapple), Cerasus vulgaris (Cherry), Cinnamomum camphora (Camphor), Erythroxylon coca (coca), Gleditsia triacanthos (Honey locust), Hamamelis virginiana (American Witch Hazel), Hippophae rhamnoides (Hippophae berry Sanddorn), Hordeum vulgare (Barley), Humulus lupulus (bine), Hypericum perforatum (perikon Amber), Laurus nobilis, Magnolia denudata (Hsin-I Yulan-Magnolie), Malva silvestris (Blue mallow), Musa acuminata × balbisiana (Banana), Nelumbo nucifera (Baladi bean), Pinus strobus (Eastern white pine), Prunus serotina ssp. serotina (black cherry), Psidium guajava (Common guava), Quercus alba (White oak), Quercus robur (Common oak), Rumex hymenosepalus (Arizona dock), Schinus terebinthifolius (Brazilian pepper tree), Terminalia arjuna (arjun), Terminalia catappa (Indian almond), Theobroma cacao (Cacao), Drimia maritima (Sea Squill), Vicia faba (bell-bean), Vitis vinifera (Common Grape Vine), Zea Mays (Corn, mais), Ziziphus jujuba (jujube, Chinese date).