Two new triterpenoid lactones have been isolated from the resin of Bur
sera delpechiana and their structures assigned as 3 beta-acetoxy-11 al
pha, 12 alpha-epoxyurs-28,13-olide and 3 beta-acetoxy-12 beta-hydroxyu
rs-28,13-olide respectively on the basis of their spectroscopic proper
ties and chemical evidence.