New ent-Kaurane and cleistanthane diterpenoids with potential cytotoxicity from Phyllanthus acidus (L.) Skeels.

Six diterpenoids including three ent -kauranes (1 – 2 , 4) and three cleistanthanes (3 , 5 – 6) were isolated from the roots and stems of Phyllanthus acidus (L.) Skeels. Of them, (16 S)- ent -16,17,18-tri-hydroxy-19-nor-kaur-4-en-3-one (1), phyllanthone A (2), and 6-hydroxycleistanthol (3) are new compounds, while the ent -kaurane diterpenoids were reported from the titled plant for the first time. Their structures were elucidated on the basis of the extensive spectroscopic analyses. Compounds 2 and 4 – 6 displayed cytotoxic potential with IC 50 values ranging from 1.96 to 29.15 μM. They also showed moderate anti-inflammatory activities (IC 50 = 6.30–12.05 μM). Particularly, the new ent -kaurane 2 displayed cytotoxic potential against HL-60 (IC 50 = 2.00 μM) and MCF-7 (IC 50 = 3.55 μM) cells, and anti-inflammatory activity (IC 50 = 6.47 μM). [Display omitted] [ABSTRACT FROM AUTHOR]