Pimpinelol, a novel atypical Sesquiterpene lactone from Pimpinella haussknechtii fruits with evaluation of endoplasmic reticulum stress in breast cancer cells.

Pimpinella haussknechtii is an annual native plant grows in west of Iran. Phytochemical study of the fruits of P. haussknechtii led to the isolation of a novel irregular sesquiterpene lactone with a new skeletone and oxidation pattern named: pimpinelol. The structure of the isolated compound was elucidated by extensive spectroscopic methods. Cytotoxic activity of Pimpinelol was evaluated using standard MTT assay against breast cancer cells. Induced endoplasmic reticulum stress and related gene expressions were evaluated with fluorescence microscopy analysis and real time PCR, respectively. These findings confirmed that Pimpinelol concentrations dependently increased protein aggregation and the mRNA expression of ATF-4, CHOP, GADD34 and TRIB3 in MCF-7 breast cancer cell line. According to the obtain results, we demonstrated for the first time that Pimpinelol decreased breast cancer cell viability by inducing ER stress.