Synthesis, Biological Evaluation and Mechanism Studies of Deoxytylophorinine and Its Derivatives as Potential Anticancer Agents

Previous studies indicated that (+)-13a-(S)-Deoxytylophorinine (1) showed profound anti-cancer activities both in vitro and in vivo and could penetrate the blood brain barrier to distribute well in brain tissues. CNS toxicity, one of the main factors to hinder the development of phenanthroindolizidines, was not obviously found in 1. Based on its fascinating activities, thirty-four derivatives were designed, synthesized; their cytotoxic activities in vitro were tested to discover more excellent anticancer agents. Considering the distinctive mechanism of 1 and interesting SAR of deoxytylophorinine and its derivatives, the specific impacts of these compounds on cellular progress as cell signaling transduction pathways and cell cycle were proceeded with seven representative compounds. 1 as well as three most potent compounds, 9, 32, 33, and three less active compounds, 12, 16, 35, were selected to proform this study to have a relatively deep view of cancer cell growth-inhibitory characteristics. It was found that the expressions of phospho-Akt, Akt, phospho-ERK, and ERK in A549 cells were greater down-regulated by the potent compounds than by the less active compounds in the Western blot analysis. To the best of our knowledge, this is the first report describing phenanthroindolizidines alkaloids display influence on the crucial cell signaling proteins, ERK. Moreover, the expressions of cyclin A, cyclin D1 and CDK2 proteins depressed more dramatically when the cells were treated with 1, 9, 32, and 33. Then, these four excellent compounds were subjected to flow cytometric analysis, and an increase in S-phase was observed in A549 cells. Since the molecular level assay results of Western blot for phospho-Akt, Akt, phospho-ERK, ERK, and cyclins were relevant to the potency of compounds in cellular level, we speculated that this series of compounds exhibit anticancer activities through blocking PI3K and MAPK signaling transduction pathways and interfering with the cell cycle progression

Eremophilane Sesquiterpenes and Polyketones Produced by an Endophytic <i>Guignardia</i> Fungus from the Toxic Plant <i>Gelsemium elegans</i>

A cultured endophytic fungus, <i>Guignardia mangiferae</i>, isolated from the toxic plant <i>Gelsemium elegans</i> yielded five new sesquiterpenes (<b>1</b>–<b>5</b>), two new polyketones (<b>6</b> and <b>7</b>), and two known terpene polyketones (<b>8</b> and <b>9</b>). Their structures were elucidated using spectroscopic methods. On the basis of circular dichroism, the absolute configurations of the new compounds were determined. Compounds <b>1</b>, <b>3</b>, <b>4</b>, and <b>9</b> inhibited lipopolysaccharide-induced NO production in BV2 cells with IC₅₀ values of 15.2, 6.4, 4.2, and 4.5 μM, respectively (positive control curcumin, IC₅₀ = 3.9 μM)

Chiral Resolution and Absolute Configuration of a Pair of Rare Racemic Spirodienone Sesquineolignans from <i>Xanthium sibiricum</i>

A pair of racemic spirodienone neolignan enantiomers, (±)-sibiricumin A, were isolated from the extract of the fruits of <i>Xanthium sibiricum</i>. The resolution of (+)- and (−)-sibiricumin A was achieved by chiral HPLC. The absolute configurations of the racemes were assigned by X-ray and by electronic circular dichroism (ECD). This experiment is the first unambiguous determination of the absolute configuration of spirodienone neolignan

Effects of 1, 9, 12, 16, 32, 33, and 35 on cyclins in A549 cells.

<p>A549 cells were untreated or treated with 500 nM of 1, 9, 12, 16, 32, 33, and 35 for 24 h. Following 24 h of recovery, cell lysates were prepared and equal amounts of protein were analyzed by SDS-PAGE. Immunoblots of cellular lysates were analyzed by antibodies of CDK2, cyclin A, cyclin B1, cyclin D1, and cyclin E, with the expression of β-actin as an internal control. A. one of the selected immunoblot analysis results of CDK2, CyclinA, CyclinB1, CyclinD1, CyclinE and β-actin. B. densitometric analysis results of CDK2, CyclinA, CyclinB1, CyclinD1, and CyclinE normalized to β-actin expression. Each histogram represents the mean values ± standard deviation of three dependent experiments. (*, p<0.05 compared with control; **, p<0.01 compared with control).</p

Cytotoxic activities of deoxytylophorinine and its derivatives <i>in vitro.</i>

a<p>IC₅₀ values are the test compounds concentration (µM) that inhibited the cell growth by 50%. Data represent the mean values ± standard deviation of three dependent experiments performed in triplicate (*, p<0.05 compared with compound <b>1</b>; **, p<0.01 compared with compound <b>1</b>; ^#, p<0.05 compared with Doxorubicin; ^##, p<0.01 compared with Doxorubicin). These IC₅₀ values were all measured for 72 h treatment. IC₅₀ values for 24 h treatment were in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030342#pone.0030342.s005" target="_blank">Table S1</a>.</p

Structures of deoxytylophorinine, its intermediate and derivatives.

a<p>Compounds <b>1</b><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030342#pone.0030342-Li1" target="_blank">[36]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030342#pone.0030342-Wang2" target="_blank">[37]</a>, <b>2</b><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030342#pone.0030342-Mulchandani2" target="_blank">[35]</a>, <b>3</b><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030342#pone.0030342-Buckley1" target="_blank">[38]</a>, <b>4</b><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030342#pone.0030342-Faber1" target="_blank">[42]</a>, <b>6</b><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030342#pone.0030342-Takashi1" target="_blank">[43]</a>, <b>7</b><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030342#pone.0030342-Takashi1" target="_blank">[43]</a>, <b>9</b><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030342#pone.0030342-Mulchandani3" target="_blank">[44]</a>, and <b>33</b><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030342#pone.0030342-Wang4" target="_blank">[45]</a> are known, while others are new synthesized.</p>b<p>These compounds have been claimed in a pending patent (PCT/CN2010/070832).</p

The effects of 1, 9, 32 and 33 on cell cycle distribution in A549 cells.^a

a<p>These data indicate the percentage of cells in G₀/G₁, S, and G₂/M phases of the cell cycle. Each value is the mean ± SD of three determinations. (*, p<0.05 compared with control; **, p<0.01 compared with control).</p