Diterpenes from Grangea maderaspatana.

Phytochemical investigation of the ethanolic extract of Grangea maderaspatana led to isolation of gramaderins A-D, together with thirteen known compounds. All isolates were assayed for their anti-inflammatory activities. Consequently, 5,7-dihydroxy-3,6,3',4',5'-pentamethoxyflavone and 5,3'-dihydroxy-3,6,7,4',5'-pentamethoxyflavone showed significant bioactivities by inhibiting superoxide anion generation. 8-Acetoxy-pentadeca-1,9Z,14-trien-4,6-diyne-3-ol also demonstrated potent inhibition on elastase release. The gramaderins A/C (β-alkyl linked γ-lactone) and gramaderins B/D (α-alkyl linked γ-lactone) co-exist in this plant material, of which the latter derivatives are few in nature. Gramaderins C/D possess a special linear dilactone diterpene skeleton, which never been reported.