16-Hydroxy-2-oxocleroda-3,13-dien-15,16-olide

6-Hydroxycleroda-3,13-dien-15,16-olide protects neuronal cells from lipopolysaccharide-induced neurotoxicity through the inhibition of microglia-mediated inflammation.[Pubmed:19653144]

Planta Med. 2010 Feb;76(2):120-7.

Polyalthia longifolia var. pendula is used as an antipyretic agent in indigenous systems of medicine. Microglia-mediated inflammation plays an important role in the pathway leading to neuronal cell death in a number of neurodegenerative diseases. The aim of this study was to investigate the effects of 6-hydroxycleroda-3,13-dien-15,16-olide (PL3) extracted from Polyalthia longifolia var. pendula on lipopolysaccharide(LPS)-induced inflammation in microglia-like HAPI cells and primary microglia cultures. In microglia-neuron co-cultures, LPS decreased the cell viability of neuroblastoma SH-SY5Y cells. LPS-induced cell death was attenuated by the NOS inhibitor, L-NAME, the COX-2 inhibitor, NS-398 or the NADPH oxidase inhibitor, DPI, respectively. In LPS-treated microglia cells, PL3 decreased the expression of iNOS, COX-2, gp91 (phox), and NF- kappaBp65, the degradation of I kappaB alpha, and the production of NO, PGE (2), iROS, and TNF- alpha. PL3 also enhanced the expression of HO-1, a cytoprotective and anti-inflammatory enzyme. Moreover, PL3 reduced LPS-activated microglia-induced cell death. The present results suggest that PL3 inhibits microglia-mediated inflammation and inflammation-related neuronal cell death. Therefore, PL3 has potential use for the treatment of inflammation-related neurodegenerative diseases.

16-Hydroxycleroda-3,13-dien-15,16-olide deregulates PI3K and Aurora B activities that involve in cancer cell apoptosis.[Pubmed:21530604]

Toxicology. 2011 Jul 11;285(1-2):72-80.

The PI3K-AKT pathway and Aurora kinase play essential roles in such cellular processes as cell survival, angiogenesis, and differentiation, and are usually expressed at maximum levels during cancer cell proliferation. The present study investigated the effect of the natural compound, 16-hydroxycleroda-3,13-dien-15,16-olide (PL3), on regulating the PI3K-AKT pathway and Aurora B, which led to cancer cell apoptosis. PL3 acts as a PI3K inhibitor by influencing cell survival, signaling transduction, and cell cycle progression. It was observed that PL3 targeted and induced dephosphorylation of the PI3K pathway, degradation of Aurora B and mitotic-related gene expressions, and sequentially shut down the cell cycle. This eventually resulted in cell death. As Aurora B was downregulated, spindle dysfunction and destruction of the G(2)/M phase checkpoint resulted in DNA-damaged cells undergoing apoptosis. Moreover, PL3 also resensitized T315I-mutated Bcr-ABL+ BA/F3 cells to improve the cytotoxicity of Imatinib in Imatinib-resistant cell line. Taken together, PL3 can perturb the PI3K-AKT pathway and Aurora B resulting in gene silencing and cell cycle disturbance. It was demonstrated that PL3 acted like a novel small-molecule PI3K modulator, thereby potentially contributing to cancer chemotherapy and combination medication.

16-hydroxycleroda-3,13-dien-15,16-olide regulates the expression of histone-modifying enzymes PRC2 complex and induces apoptosis in CML K562 cells.[Pubmed:21983300]

Life Sci. 2011 Dec 5;89(23-24):886-95.

AIMS: Histone modifications play central epigenetic roles in regulating the entire genome of the cell and cell proliferation. Herein, we investigated the effects of the natural compound, 16-hydroxycleroda-3,13-dien-15,16-olide (PL3), on the expressions of histone-modifying enzymes, and examined how it induces apoptosis in leukemia K562 cells. MAIN METHODS: Cell proliferation was determined by an MTT assay, and histone-modifying enzyme gene expressions were investigated by a quantitative real-time PCR. Protein expressions were analyzed by a Western blot analysis. The histone H3K27 distribution was observed with immunofluorescence staining. To verify polycomb repressive complex 2 (PRC2) complex downstream gene expressions, a gene-expression array was performed to determine gene regulations. KEY FINDINGS: PL3 induced apoptosis and modulated many histone-modifying enzymes, especially the two PRC2 components, enhancer of zeste homolog 2 (EZH2) and suppressor of zeste 12 homolog (Suz12). Genes repressed by PRC2 were shown to be reactivated by PL3. Of these, 10 genes targeted by the PRC2 complex were identified, and expressions of 10 pro-/antiapoptotic genes were significantly regulated; these effects may have contributed to PL3-induced apoptosis in K562 cells. Regulation of other histone-modifying enzymes, including Aurora B, may also be involved in cell-cycle regulation. SIGNIFICANCE: Our data suggest that the induction of apoptosis by PL3 might partly occur through both a reduction in PRC2-mediated gene silencing and the reactivation of downstream tumor suppressor gene expressions. PL3 acts as a novel small-molecule histone modulator, which can potentially contribute to cancer chemotherapy singly or as a combined medication.