Parthenolide

Parthenolide (PTL), a well-known sesquiterpene lactone of natural origin with α,β-unsaturated carbonyl structure, has proven to show promising anti-cancer properties. In this report, anti-proliferative potential of two synthetic methyleneisoxazolidin-5-ones, MZ-6 and MZ-14, with the same structural motif, has been investigated in human hepatoma HepG2 cells. The effects on apoptosis induction and DNA damage were evaluated. All compounds decreased the number of live cells and increased the number of late apoptotic cells. However, only MZ-14 was able to induce DNA damage. Both synthetic compounds increased intracellular reactive oxygen species (ROS) generation and mitochondrial membrane potential changes at the same level as PTL. Additionally, cell survival was analyzed after a combined treatment, in which HepG2 cells were preincubated for 24 h with MZ-6, MZ-14 or PTL and irradiated with different doses of X-rays. The inhibition of cell survival was assessed by the clonogenic assay.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy that preferentially affects children and adolescents. Over 50% of human T-ALLs possess activating mutations of Notch1. The clerodane diterpene casearin J (CJ) is a natural product that inhibits the sarcoendoplasmatic reticulum calcium ATPase (SERCA) pump and induces cell death in leukemia cells, but the molecular mechanism of cytotoxicity remains poorly understood. Here we show that owing to SERCA pump inhibition, CJ induces depletion of the endoplasmic reticulum calcium pools, oxidative stress, and apoptosis via the intrinsic signaling pathway. Moreover, Notch1 signaling is reduced in T-ALL cells with auto-activating mutations in the HD-domain of Notch1, but not in cells that do not depend on Notch1 signaling. CJ also provoked a slight activation of NF-κB, and consistent with this notion a combined treatment of CJ and the NF-κB inhibitor parthenolide (Pt) led to a remarkable synergistic cell death in T-ALL cells.

The title compound, C19H22N2O3, {systematic name (1aR,4E,7aS,8E,10aS,10bR)-1a,5-dimethyl-8-[(pyrimidin-5-yl)-methylid-ene]-2,3,6,7,7a,8,10a,10b-octa-hydro-oxireno[2',3':9,10]cyclo-deca-[1,2-b]furan-9(1aH)-one} was obtained from the reaction of parthenolide [systematic name (1aR,7aS,10aS,10bR,E)-1a,5-dimethyl-8-methyl-ene-2,3,6,7,7a,8,10a,10b-octa-hydro-oxireno[2',3':9,10]cyclodeca-[1,2-b]furan-9(1aH)-one] with 5-bromo-pyrimidine under Heck reaction conditions, and was identified as an E isomer. The mol-ecule possesses ten-, five- (lactone) and three-membered (epoxide) rings with a pyrimidine group as a substituent. The ten-membered ring displays an approximate chair-chair conformation, while the lactone ring shows a flattened envelope-type conformation. The dihedral angle between the pyrimidine moiety and the lactone ring system is 29.43 (7)°.

BACKGROUND: Parthenolide (PN) has been reported to inhibit proliferation and induces apoptosis in a variety of cancer cells with different mechanisms. Nevertheless, to the best of our knowledge, its relative anticancer activity at lower doses has not been reported in HaCaT immortalized keratinocytes and A375 melanoma cells.