Minor Nortriterpenoids from the Twigs and Leaves of Rhododendron latoucheae

Abstract

A hyphenated NMR technique (analytical HPLC with a DAD connected to MS, SPE, and NMR) has proven effective for the full structural analysis and identification of minor natural products in complex mixtures. Application of this hyphenated technique to the CH₂Cl₂-soluble fraction of Rhododendron latoucheae led to the identification of 15 new minor ursane-type 28-nortriterpenoids (1-15). Compounds 1 and 12 inhibited HSV-1 with IC₅₀ values of 6.4 and 0.4 μM, respectively.