Chemical Constituents and Bioactivities from the Root of Piper taiwanense

Piper taiwanense Lin & Lu (Piperaceae) is a woody climber, endemic to Taiwan, distributed in forests at low to medium altitudes throughout the island.

Previously, four new compounds and 25 known compounds, along with anti-platelet aggregation activity were reported from the stem of this species. The methanolic extract of the root of this plant showed potent antitubercular activity against Mycobacterium tuberculosis H₃₇Rv and inhibitory activities against platelet aggregation induced by collagen. The aim of this study is the isolation of chemical constituents and their bioactivities of the root of this species

The methanolic extract of root was partitioned into EtOAC and H2O-soluble layer. Bioassay-guided fractionation of the active EtOAC-soluble layer led to the isolation of eight new compounds, taiwanensols A, B (1, 2), taiwandimerols A, B (3, 4), neotaiwanensol A, B (5, 6), 1,2-diacetoxy-6- methoxy-4-allylbenzene (7), and 1-acetoxy-2-hydroxy-4-allylbenzene (8), and the last two were first isolated from nature, along with 16 known compounds. The structures of these isolates were elucidated by spectral analysis.

Among the isolates, the mixture of 8 and 2-acetoxy-1-hydroxy-4-allylbenzene (9), 1,2-dihydroxy- 4-allylbenzene (10), and 1,2-diacetoxy-4-allylbenzene (11) showed potent inhibitory activities against platelet aggregation induced by collagen, with IC₅₀ values as 1.7, 0.8, and 0.5µg/mL, respectively.

The successive isolation and bioactivity assay of the isolates are under progress.