Preclinical Pharmacokinetic Evaluation to Facilitate Repurposing of Tyrosine Kinase Inhibitors Nilotinib and Imatinib as Antiviral Agents

Background Several tyrosine kinase inhibitors (TKIs) developed as anti-cancer drugs, also have anti-viral activity due to their ability to disrupt productive replication and dissemination in infected cells. Consequently, such drugs are attractive candidates for “repurposing” as anti-viral agents. However, clinical evaluation of therapeutics against infectious agents associated with high mortality, but low or infrequent incidence, is often unfeasible. The United States Food and Drug Administration formulated the “Animal Rule” to facilitate use of validated animal models for conducting anti-viral efficacy studies. Methods To enable such efficacy studies of two clinically approved TKIs, nilotinib, and imatinib, we first conducted comprehensive pharmacokinetic (PK) studies in relevant rodent and non-rodent animal models. PK of these agents following intravenous and oral dosing were evaluated in C57BL/6 mice, prairie dogs, guinea pigs and Cynomolgus monkeys. Plasma samples were analyzed using an LC-MS/MS method. Secondarily, we evaluated the utility of allometry-based inter-species scaling derived from previously published data to predict the PK parameters, systemic clearance (CL) and the steady state volume of distribution (Vss) of these two drugs in prairie dogs, an animal model not tested thus far. Results Marked inter-species variability in PK parameters and resulting oral bioavailability was observed. In general, elimination half-lives of these agents in mice and guinea pigs were much shorter (1–3 h) relative to those in larger species such as prairie dogs and monkeys. The longer nilotinib elimination half-life in prairie dogs (i.v., 6.5 h and oral, 7.5 h), facilitated multiple dosing PK and safety assessment. The allometry-based predicted values of the Vss and CL were within 2.0 and 2.5-fold, respectively, of the observed values. Conclusions Our results suggest that prairie dogs and monkeys may be suitable rodent and non-rodent species to perform further efficacy testing of these TKIs against orthopoxvirus infections. The use of rodent models such as C57BL/6 mice and guinea pigs for assessing pre-clinical anti-viral efficacy of these two TKIs may be limited due to short elimination and/or low oral bioavailability. Allometry-based correlations, derived from existing literature data, may provide initial estimates, which may serve as a useful guide for pre-clinical PK studies in untested animal models

EFFECT OF SALACIA OBLONGA ROOT EXTRACT AGAINST CLINICAL ISOLATES STAPHYLOCOCCUS AUREUS

Objective: Salacia oblonga Wall. is an important medicinal plant belonging to the family Celastraceae. The study reports the effect of S. oblonga root extracts against clinical isolate Staphylococcus aureus Methods: Antibacterial activity was evaluated by agar diffusion method and assay for minimum inhibitory concentration (MIC) of extract. Further, the effect of S. oblonga extract determined by DNA fragmentation and respiratory dehydrogenase enzyme activity assays. Results: S. oblonga ethyl acetate root extract was evaluated for antibacterial activity towards clinical isolate S. aureus. Bacterial growth was determined in treated and control cells. Extract displayed good growth inhibition and MIC of the extract was 80 μg/ml. DNA fragmentation assay was carried out, this result has shown that treated bacterial cell has DNA damage compared to the control cell. Further, respiratory dehydrogenase enzyme activity was determined. In the treated cells, enzyme activity was low compared to the control cells. Conclusion: Salacia oblonga root extract inhibiting the growth of S. aureus by different modes of action

EFFECT OF SALACIA OBLONGA ROOT EXTRACT AGAINST CLINICAL ISOLATES STAPHYLOCOCCUS AUREUS

Objective: Salacia oblonga Wall. is an important medicinal plant belonging to the family Celastraceae. The study reports the effect of S. oblonga root extracts against clinical isolate Staphylococcus aureus &#x0D; Methods: Antibacterial activity was evaluated by agar diffusion method and assay for minimum inhibitory concentration (MIC) of extract. Further, the effect of S. oblonga extract determined by DNA fragmentation and respiratory dehydrogenase enzyme activity assays.&#x0D; Results: S. oblonga ethyl acetate root extract was evaluated for antibacterial activity towards clinical isolate S. aureus. Bacterial growth was determined in treated and control cells. Extract displayed good growth inhibition and MIC of the extract was 80 μg/ml. DNA fragmentation assay was carried out, this result has shown that treated bacterial cell has DNA damage compared to the control cell. Further, respiratory dehydrogenase enzyme activity was determined. In the treated cells, enzyme activity was low compared to the control cells.&#x0D; Conclusion: Salacia oblonga root extract inhibiting the growth of S. aureus by different modes of action.</jats:p

Abstract P3-03-11: Oxazine derivatives of g- and D- tocotrienols display potent anticancer effects in vivo

Abstract Breast cancer is a multi-stage process which leads to the accumulation of abnormal cells arising from excessive proliferation, lack of apoptosis or a combination of both. Natural compounds such as g-tocotrienol have been shown to selectively inhibit cancer cell growth without harming normal cell viability with little or no adverse side effects. The antiproliferative and apoptotic effects of the tocotrienol isoform, γ-tocotrienol, have been firmly established in various cancer types. However, in vivo studies have provided mixed results, attributed to γ-tocotrienol rapid clearance and low bioavailability. In order to improve anticancer potency and bioavailability in vivo, γ- and Δ-tocotrienol were chemically modified with electrophilic substitution reactions on their chromane ring using Mannich and Lederer-Manasse reactions, resulting in the synthesis of various oxazine derivatives. Several of these oxazine derivatives (compounds 26, 31, 39, 40 and 44) were found to display potent anticancer activity as compared to their parent compounds when tested on +SA mammary cancer cells grown in culture. These in vitro studies were followed up with in vivo studies to determine the anticancer effects of oxazine derivatives on the growth of mammary tumors in mice. Female syngeneic BALB/c mice, 4-6 week old were inoculated with 1×106 +SA mammary tumor cells in the left mammary pad. Once tumor size reached 5mm in diameter, animals were divided into different treatment groups and received an intra-tumoral injection injected of 0-120μg/20μl tocotrienol or its derivative every other day for 11 days. Afterwards, mice were sacrificed, tumors removed and placed in -80°C until further analysis. Results from these studies showed that tumor growth rate was significantly reduced in the oxazine derivative treated animals as compared to the vehicle-treated controls. Western blot analysis of tumor samples showed that the growth inhibitory effects of tocotrienol derivatives was also associated with a significant reduction in phosphorylated (activated) Akt and reductions in cell cycle regulatory proteins cyclin D1 and cyclin dependent kinases (CDK2, CDK4 and CDK6). In addition, oxazine derivative treatment was also associated with a large increase in CDK inhibitors p21 and p27, as compared to tumors obtained from the vehicle-treated control mice. Western blot analysis also showed that tumor from oxazine-derivative treated mice displayed a large reduction in NFκB levels and its downstream gene product COX-2. In summary, oxazine derivatives of tocotrienols display more potent anticancer activity both in vitro and in vivo, as compared to their parent compounds and suggest that these tocotrienol derivatives may provide some benefit as novel anticancer therapeutic agents. This work was supported, in part, by First Tec International Ltd. (Hong Kong), Malaysian Palm oil Council and the Louisiana Cancer Foundation. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-03-11.</jats:p