Diterpenoids from the aerial parts of Plectranthus ornatus

Phytochemical investigation of a hexane extract of the aerial parts of Plectranthus ornatus yielded three new neoclerodane diterpenoids (1-3), two labdane diterpenes (4 and 5) obtained for the first time as natural products, and several previously known substances. The structures and relative stereochemistry of 1-5 were established mainly on the basis of NMR spectroscopic studies and by comparison with related compounds.