Development and validation of a sensitive UPLC-MS/MS analytical method for GFH009 in rat plasma and its application to toxicokinetics studies.

GFH009 is a potent, highly selective, small molecule that targets and inhibits the activity of the CDK9/cyclin T1 regulatory complex of P-TEFb. This study aimed to develop and validate a highly selective and sensitive ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for precise quantification of GFH009 in rat plasma. This method was subsequently employed for conducting toxicokinetic studies of GFH009 in rats. Plasma was prepared using a simple protein precipitation method by acetonitrile. Chromatographic separation of the analytes was achieved on a BEH C18 analytical column with a rapid 3.0 min run time and a flow rate of 0.5 ml/min. The calibration curves for plasma samples exhibited excellent linearity over a wide concentration range of 1.0-1,000 ng/ml for GFH009. Intra- and inter-day accuracies were within 92.7-105.7%, and precisions were no more than 6.7%. Furthermore, the analyte demonstrated stability under four different storage conditions, with variations of <15.0%. This study pioneers a methodological innovation by introducing a highly reliable, specific and sensitive analytical method for GFH009 in rat plasma. The successful application of this method in toxicokinetic studies further underscores its significance, offering valuable insights for the methodology of clinical pharmacokinetic research.

Synthesis and in vitro and in vivo biological evaluation of novel derivatives of flexicaulin A as antiproliferative agents.

As our research focuses on anticancer drugs, a series of novel derivatives of flexicaulin A (FA), an ent-kaurene diterpene, condensed with an aromatic ring were synthesized, and their antiproliferative activities against four human cancer cell lines (TE-1, EC109, MCF-7, and MGC-803) were evaluated. The activities of most of the new compounds were better than those of FA. Compound 2y exhibited the best activity with an IC50 value reaching 0.13 µM against oesophageal cancer cells (EC109 cells). The IC50 values for 2y in normal cells (GES-1 cells and HUVECs) were 0.52 µM and 0.49 µM, respectively. Subsequent mechanistic investigations found that compound 2y can inhibit the proliferation of cancer cells and cell cloning. In addition, 2y could reduce the mitochondrial membrane potential, increase the apoptosis rate, and increase the ROS level in EC109 cells. Moreover, 2y can upregulate the expression of ROS/JNK pathway-related proteins (p-ASK1, p-MKK4, p-JNK, and p-Cjun (ser63)) and pro-apoptotic proteins (Bax, Bad, and Bim). In vivo experiments showed that 2y can inhibit tumour growth in nude mice. The mechanism involves an increase in protein expression in the ROS pathway, leading to changes in apoptosis-related proteins. In addition, compound 2y shows low toxicity. These results indicate that compound 2y holds promising potential as an antiproliferative agent.

[Study on safety of apnea test in clinical determination of brain death].

OBJECTIVE: To determine the occurrence of severe complications such as hypotension, pulmonary artery hypertension as well as hypercapnia during apnea test in the affirmation of brain death and to investigate the possible effective prophylactic interventions. METHODS: Conventional apnea test was performed in 15 clinically suspected brain death patients. Stable circulation was achieved by adjusting preload only (n=4) or combined with titrating norepinephrine (NE, n=11). Blood gas was respectively analyzed before apnea test, 10 minutes after 100% fraction of oxygen (FiO(2)) ventilation, at each 2-minute interval after disconnecting ventilator and 5 minutes after reventilation. Hemodynamic parameters and dosage of NE were recorded at the same time points. Plasma concentration of lactate was measured before and at the end of apnea test. RESULTS: Spontaneous breath occurred in 1 case among 15 suspected brain death patients. Partial pressure of carbon dioxide (PaCO(2)) reached higher than 60 mm Hg (1 mm Hg=0.133 kPa) within 8 minutes in positive apnea test patients (P<0.01). pH significantly decreased (P<0.05), but partial pressure of oxygen (PaO(2)) maintained higher than 100 mm Hg during the test. Heart rate (HR) and mean artery pressure (MAP) slightly lowered (P>0.05), but pulmonary artery pressure (PAP) markedly elevated (P<0.05) at the end of the test in comparison with their base lines. On the other hand, HR and MAP increased in the negative apnea test case after ventilator disconnection. Severe arrhythmia events did not occur in all the cases. There was no change in the dosage of NE infusion, the range of which was 0.10-0.60 microg.kg(-1).min(-1) with the mean level of (0.23+/-0.17) microg.kg(-1).min(-1). The trend of HR, MAP, PAP and pulmonary arterial wedge pressure (PAWP) alterations was the same in patients no matter whether or not NE was used. HR, MAP and PAWP lowered, while PAP enhanced. Plasma lactate level was not significantly altered at the end of the test compared with the base line (from (1.41+/-0.05) mmol/L to (1.47+/-0.07) mmol/L). CONCLUSION: Adequate oxygenation could be maintained during conventional apnea test. The risk of inducing severe hypotension is low in non brain death patients. Based on adequate preload, low dose of NE infusion could prevent patients with high risk circulation instability from severe hypotension.