蝶啶是一种在生物体内的化合物，与单麸胺酸组合之后会成为叶酸。蝶啶属于杂环化合物，且拥有许多取代作用后的变异产物，例如在生物体内有重要作用的蝶呤（pterins）和黄素（flavins）。

Pteridine is an aromatic chemical compound composed of fused pyrimidine and pyrazine rings. A pteridine is also a group of heterocyclic compounds containing a wide variety of substitutions on this structure. Pterins and flavins are classes of substituted pteridines that have important biological activity.