Antibacterial novel phenolic diterpenes from Podocarpus macrophyllus D. Don

Two new sempervirol type diterpenes, inumakiols A, B, and six new totarol type diterpenes, inumakiols C-H, were isolated from a methanolic extract of bark of Podocarpus macrophyllus (Podocarpaceae), along with one known abietane, two known totarol type diterpenes, and one known totarol type diterpene dimer. The structures of the new compounds were elucidated by the spectroscopic methods. Some of them possessed antibacterial activity against oral pathogenic microorganisms with minimum inhibitory concentration (MIC) values ranging from 3.1 to 25 ppm.