Plants\nUtilize a Protection/Deprotection Strategy\nin Limonoid Biosynthesis: A “Missing Link” Carboxylesterase\nBoosts Yields and Provides Insights into Furan Formation

The furan ring is\na defining feature of limonoids, a class of\nhighly rearranged and bioactive plant tetranortriterpenoids. We recently\nreported an apparent complete biosynthetic pathway to these important\nnatural furanoids. Herein, we disclose the subsequent discovery of\na yield-boosting “missing link” carboxylesterase that\nselectively deprotects a late-stage intermediate, so triggering more\nefficient furan biosynthesis. This has allowed, for the first time,\nthe isolation and structural elucidation of unknown intermediates,\nrefining our understanding of furan formation in limonoid biosynthesis.