Vitepyrroloids A–D, 2-Cyanopyrrole-Containing Labdane Diterpenoid Alkaloids from the Leaves of Vitex trifolia

Vitepyrroloids A–D (1–4), four new 2-cyano-substituted pyrrole-ring-containing labdane diterpenoids, were isolated from the leaves of Vitex trifolia. Their structures were elucidated based on spectroscopic data analysis. The absolute configuration of compound 1 was determined by X-ray diffraction. Compounds 1–4 are unprecedented labdane diterpenoids featuring a 2-cyano-substituted pyrrole ring. Compound 1 showed cytotoxic activity against a human nasopharyngeal carcinoma cell line (CNE1) with an IC50 value of 8.7 μM.