Modified ent -Abietane Diterpenoids from the Leaves of Suregada zanzibariensis .

The leaf extract of Suregada zanzibariensis gave two new modified ent -abietane diterpenoids, zanzibariolides A ( 1 ) and B ( 2 ), and two known triterpenoids, simiarenol ( 3 ) and β-amyrin ( 4 ). The structures of the isolated compounds were elucidated based on NMR and MS data analysis. Single-crystal X-ray diffraction was used to establish the absolute configurations of compounds 1 and 2 . The crude leaf extract inhibited the infectivity of herpes simplex virus 2 (HSV-2, IC 50 11.5 μg/mL) and showed toxicity on African green monkey kidney (GMK AH1) cells at CC 50 52 μg/mL. The isolated compounds 1 - 3 showed no anti-HSV-2 activity and exhibited insignificant toxicity against GMK AH1 cells at ≥100 μM.