Full biosynthetic pathway of pyrrolobenzoxazines

Pyrrolobenzoxazines are a rare terpene-amino acid family of natural products with potent biological activities. Here, we reported the full biosynthetic pathway of paeciloxazine (1), a typical pyrrolobenzoxazine, with significant insecticidal activity. Base on heterologous expression, chemical complement experiment, and in vitro biochemical assays, we demonstrated the sesquiterpene portion of 1 derived from discontinuously oxidations of amorphdiene, in which P450 monooxygenase PaxH catalyzed a cascade of hydroxylation and epoxidation, while two flavin dependent monooxygenases are involved in the transformation of the esterified tryptophan into a pyrrolobenzoxazine core. Furthermore, a total of 15 compounds were generated through heterologous expression, of which 13, 17 and 20 showed potential antiepileptic activity. This study fully elucidated the biosynthetic pathway of paeciloxazine (1) and showed the diversity and complexity of constructing natural products by organisms.