A new jujubogenin saponin was isolated from the stems of Colubrina retusa and identified as jujubogenin 3-O-alpha-L-arabinofuranosyl (1-->2)-[3-O-(trans)-p-coumaroyl-beta-D-glucopyranosyl (1-->3)]-alpha-L-arabinopyranoside (4) on the basis of chemical and spectroscopic data. The antimycobacterial activity expressed as minimum inhibitory concentration (MIC) for compound 4 was 10 microg/mL.