Batatasenol, a Major Triterpenol from Sweet Potato Skins

Abstract

Sweet potatoes (the tuber of Ipomoea batatas) are a major food crop globally. The sweet potato weevil (Cylas formicarius elegantulus) is a serious pest of this important crop. The triterpenol, boehmerol, has previously been found in the skin of the tuber where, as its acetate ester, it has been shown to signal oviposition by the weevil. A new triterpenol, batatasenol, was identified in two varieties of sweet potatoes, ‘Covington’ and ‘Purple Stokes’. In the ‘Covington’ variety, batatasenol was practically the only triterpenol present in the skins. In the ‘Purple Stokes’ variety, batatasenol was present along with boehmerol and several minor triterpenols. Based on the structures of the co-occurring compounds, it is proposed that their biosynthesis involves an epoxysqualene cyclase which can carry out both all-chair and B-boat cyclizations.