Optimization of application schedule of camphecene, a novel anti-influenza compound, based on its pharmacokinetic characteristics.

Due to high variability and rapid life cycle, influenza virus is able to develop drug resistance against direct-acting antivirals. Development of novel virus-in113039hibiting drugs is therefore important goal. Previously, we identified camphor derivative, camphecene, as an effective anti-influenza compound. In the present study, we optimize the regimen of its application to avoid high sub-toxic concentrations. The protective activity of camphecene was assessed on the model of lethal pneumonia of mice caused by influenza viruses. Camphecene was administered either once a day or four times a day, alone or in combination with Tamiflu. Mortality and viral titer in the lungs were studied. Pharmacokinetics of camphecene was studied in rabbits. We have demonstrated that camphecene, being used every 6 h at a dose of 7.5 mg/kg/day, results in antiviral effect that was statistically equal to the effect of 100 mg/kg/day once a day, that is, the same effect was achieved by 13 times lower daily dose of the drug. This effect was manifested in decrease of mortality and decrease of virus' titer in the lungs. The studies of pharmacokinetics of camphecene have demonstrated that it does not accumulate in blood plasma and that its m ultiple applications with dosage interval of 65 min are safe. In addition, the results of the study demonstrate also that camphecene possesses additive effect with Tamiflu, allowing to decrease the dose of the latter. The results suggest that due to safety and efficacy, camphecene can be further developed as potential anti-influenza remedy.

Development and validation of an LC-MS/MS method for the quantitative analysis of the anti-influenza agent camphecene in rat plasma and its application to study the blood-to-plasma distribution of the agent.

A method of quantitative determination of camphecene, a new anti-influenza agent, in rat blood plasma based on LC-MS/MS was developed, validated and used to study the distribution of the agent between blood cells and blood plasma. The method was validated according to FDA and EMA recommendations in terms of selectivity, linearity, accuracy, precision, recovery, stability and carry-over. Plasma samples were precipitated with methanol followed by the addition of a methanolic solution of 2-adamantylamine hydrochloride (internal standard). HPLC analysis was performed on a reversed-phase column; the total time of analysis was 11 min, including column equilibration. MS/MS detection was performed on a 3200 QTRAP triple quadrupole mass spectrometer in multiple reaction monitoring (MRM) mode. Transitions 196.4 → 122.2/153.3 and 152.2 → 93.1/107.2 were monitored for camphecene and the internal standard, respectively. The calibration curve was built in the concentration range of 10-5000 ng/ml. The intra-day and inter-day accuracy and precision, carry-over and recovery were within the acceptable limits. It was found that, after spiking blood with camphecene and separating plasma, the concentration of the substance in the latter was close to its initial concentration in the blood. This property of the substance may be useful for clinical trials of the agent. It has also been established that the process of camphecene distribution (adsorption) between blood cells and blood plasma is reversible, and the amount of adsorbed substance is linearly dependent on its initial concentration in the blood for a wide range of concentrations, temperatures and hematocrit values.

Mitochondria-targeted betulinic and ursolic acid derivatives: synthesis and anticancer activity.

A series of new betulinic and ursolic acid conjugates with a lipophilic triphenylphosphonium cation, meant to enhance the bioavailability and mitochondriotropic action of natural triterpenes, have been synthesized. The in vitro experiments on three human cancer cell lines (MCF-7, HCT-116 and TET21N) revealed that all the obtained triphenylphosphonium triterpene acid derivatives not only showed higher cytotoxicity as compared to betulinic acid but were also markedly superior in triggering mitochondria-dependent apoptosis, as assessed using a range of apoptosis markers such as cytochrome c release, stimulation of caspase-3 activity, and cleavage of poly(ADP-ribose) polymerase, which is one of the targets of caspase 3. The IC50 was much lower for all triphenylphosphonium derivatives when compared to betulinic acid. Out of the tested group of conjugates, the most potent toxicity was exhibited by the betulinic acid conjugate 9 (for 9, the IC50 values against MCF-7 and TET21N cells were 0.70 µM and 0.74 µM; for betulinic acid (BA), IC50 > 25 µM against MCF-7 cells).