Bioassay guided fractionation against a-glucosidase and separation of the ethanolic extract of Pasania formosana leaf by chromatographic methods led to the isolation of a novel secocycloartane triterpene. This compound, named pasasecocycloartenoic acid, was elucidated as 21,24(R)-epoxy-25-hydroty-3;4- secocycloart-4(28)-en-3-oic acid through analysis of 1D and 2D NMR spectra and on the basis of HRESIMS data. The compound showed weak activity against α-glucosidase, but its poor solubility hampered the bioassay.