Taxifolin stability: In silico prediction and in vitro degradation with HPLC-UV/UPLCe ESI-MS monitoring

Taxifolin has a plethora of therapeutic activities and is currently isolated from the stem bark of the tree Larix gmelinni(Dahurian larch). It is a flavonoid of high commercial interest for its use in supplements or in antioxidant-rich functional foods. However, its poor stability and low bioavailability hinder the use of flavonoid in nutritional or pharmaceutical formulations. In this work, taxifolin isolated from the seeds of Mimusops balata, was evaluated by in silico stability prediction studies and in vitro forced degradation studies(acid and alkaline hydrolysis, oxidation, visible/UV radiation, dry/humid heating) monitored by high performance liquid chromatography with ultraviolet detection(HPLC-UV) and ultrahigh performance liquid chromatography-electrospray ionization-mass spectrometry(UPLC-ESI-MS). The in silico stability prediction studies indicated the most susceptible regions in the molecule to nucleophilic and electrophilic attacks, as well as the sites susceptible to oxidation. The in vitro forced degradation tests were in agreement with the in silico stability prediction, indicating that taxifolin is extremely unstable(class 1) under alkaline hydrolysis. In addition, taxifolin thermal degradation was increased by humidity.On the other hand, with respect to photosensitivity, taxifolin can be classified as class 4(stable).Moreover, the alkaline degradation products were characterized by UPLC-ESI-MS/MS as dimers of taxifolin. These results enabled an understanding of the intrinsic lability of taxifolin, contributing to the development of stability-indicating methods, and of appropriate drug release systems, with the aims of preserving its stability and improving its bioavailability.

Electrochemical and in silico approaches for liver metabolic oxidation of antitumor-active triazoloacridinone C-1305

5-Dimethylaminopropylamino-8-hydroxytriazoloacridinone(C-1305)is a promising antitumor compound developed in our laboratory.A better understanding of its metabolic transformations is still needed to explain the multidirectional mechanism of pharmacological action of triazoloacridinone derivatives at all.Thus,the aim of the current work was to predict oxidative pathways of C-1305 that would reflect its phase I metabolism.The multi-tool analysis of C-1305 metabolism included electrochemical conversion and in silico sites of metabolism predictions in relation to liver microsomal model.In the framework of the first approach,an electrochemical cell was coupled on-line to an electrospray ionization mass spectrometer.The effluent of the electrochemical cell was also injected onto a liquid chromatography column for the separation of different products formed prior to mass spectrometry analysis.In silico studies were performed using MetaSite software.Standard microsomal incubation was employed as a reference procedure.We found that C-1305 underwent electrochemical oxidation primarily on the dialkylaminoalkylamino moiety.An unknown N-dealkylated and hydroxylated C-1305 products have been identified.The electrochemical system was also able to simulate oxygenation reactions.Similar pattern of C-1305 metabolism has been predicted using in silico approach.Both proposed strategies showed high agreement in relation to the generated metabolic products of C-1305.Thus,we conclude that they can be considered as simple alternatives to enzymatic assays,affording time and cost efficiency.

In vitro and in vivo correlation for lipid-based formulations: Current status and future perspectives

Lipid-based formulations(LBFs)have demonstrated a great potential in enhancing the oral absorption of poorly water-soluble drugs.However,construction of in vitro and in vivo correlations(IVIVCs)for LBFs is quite challenging,owing to a complex in vivo processing of these formulations.In this paper,we start with a brief introduction on the gastrointestinal digestion of lipid/LBFs and its relation to enhanced oral drug absorption;based on the concept of IVIVCs,the current status of in vitro models to establish IVIVCs for LBFs is reviewed,while future perspectives in this field are discussed.In vitro tests,which facilitate the understanding and prediction of the in vivo performance of solid dosage forms,frequently fail to mimic the in vivo processing of LBFs,leading to inconsistent results.In vitro digestion models,which more closely simulate gastrointestinal physiology,are a more promising option.Despite some successes in IVIVC modeling,the accuracy and consistency of these models are yet to be validated,particularly for human data.A reliable IVIVC model can not only reduce the risk,time,and cost of formulation development but can also contribute to the formulation design and optimization,thus promoting the clinical translation of LBFs.

Identification of Candidate Transcription Factor Binding Sites in the Cattle Genome

A resource that provides candidate transcription factor binding sites （TFBSs） does not currently exist for cattle. Such data is necessary, as predicted sites may serve as excellent starting locations for future omics studies to develop transcriptional regulation hypotheses. In order to generate this resource, we employed a phylogenetic footprinting approach--using sequence conservation across cattle, human and dog and position-specific scoring matrices to identify 379,333 putative TFBSs upstream of nearly 8000 Mammalian Gene Collection （MGC） annotated genes within the cattle genome. Comparisons of our predictions to known binding site loci within the PCKI, ACTA1 and G6PC promoter regions revealed 75% sensitivity for our method of discovery. Additionally, we intersected our predictions with known cattle SNP variants in dbSNP and on the lllumina BovineHD 770k and Bos 1 SNP chips, finding 7534, 444 and 346 overlaps, respectively. Due to our stringent filtering criteria, these results represent high quality predictions of putative TFBSs within the cattle genome. All binding site predictions are freely available at http：//bfgl. anri.barc.usda.gov/BovineTFBS/or http：//199.133.54.77/BovineTFBS.

(Q)SAR modelling of nanomaterial toxicity:A critical review

There is increasing recognition that some nanomaterials may pose a risk to human health and the environment. Moreover, the industrial use of the novel engineered nanomaterials （ENMs） increases at a higher rate than data generation for hazard assessment; consequently, many of them remain untested. The large number of nanomaterials and their variants （e.g., different sizes and coatings） requiring testing and the ethical pressure towards nonanimal testing means that in a first instance, expensive animal bioassays are precluded, and the use of（quantitative） structure-activity relationships （（Q）SARs） models as an alter- native source of （screening） hazard information should be explored. （Q）SAR modelling can be applied to contribute towards filling important knowledge gaps by making best use of existing data, prioritizing the physicochemical parameters driving toxicity, and providing practical solutions for the risk assessment problems caused by the diversity of ENMs. This paper covers the core components required for successful application of （Q）SAR methods to ENM toxicity prediction, summarizes the published nano-（Q）SAR studies, and outlines the challenges ahead for nano-（Q）SAR modelling. It provides a critical review of （1） the present availability of ENM characterization/toxicity data, （2） the characterization of nanostructures that meet the requirements for （Q）SAR analysis, （3） published nano-（Q）SAR studies and their limitations, （4） in silico tools for （Q）SAR screening of nanotoxicity, and （5） prospective directions for the development of nano-（Q）SAR models.