New isobenzofurans and anti-inflammatory constituents from the root of Pittosporum illicioides var. illicioides

Pittosporum illicioides var. illicioides (Pittosporaceae) is an evergreen shrub that grows in medium-to-high altitude forests throughout China and Taiwan. Carotenoids [1], sesquiterpene glycosides [2], triterpenoid saponins [3], and their derivatives are widely distributed in plants of the genus Pittosporum. Many of these compounds exhibit diverse biological activities, including cytotoxic [2] and antimicrobial [4] activities. However, the chemical constituents and biological activities of this plant have never been studied. In our studies on the anti-inflammatory constituents of Formosan plants, many species have been screened for in vitro anti-inflammatory activity, and P. illicioides var. illicioides has been found to be one of the active species. Phytochemical investigation of the roots of this plant has led to the isolation of five new isobenzofurans, pittosphthalide A (1), pittosphthalide B (2), pittosphthalide C (3), pittosphthalide D (4), and pittosphthalide E (5), along with eight known compounds. The structural elucidation of these new compounds and the anti-inflammatory properties of the isolated compounds are described herein. Among the isolated compounds, 1, 3, 4, and 5 exhibited potent inhibition (IC₅₀≤6.21µM) on superoxide anion generation by human neutrophils in response to formyl-L-methionyl-L-leucyl-L-phenylalanine/cytochalasin B (FMLP/CB).

Acknowledgements: This work was supported by grant from the National Science Council of the Republic of China.

References: 1. Fujiwara, Y., et al. (2001) Chem. Pharm. Bull. 9:985–987. 2. Eparvier, V. et al. (2007) Phytochemistry 68: 604–608. 3. Abdel Gawad, M. M. et al. (2000)J. Drug Res. 23:1–10. 4. Ramanandraibe, V. et al. (2000)J. Essent. Oil Res. 12: 650–652.