The complete plastid genome provides insight into maternal plastid inheritance mode of the living fossil plant Ginkgo biloba.

In the current research, we focus on uniparental inheritance of chloroplast genome of the living fossil plant, Ginkgo biloba L., one of the gymnosperms, using genomic data.•Our results provide strong genomic evidence to support plastid maternal inheritance mode of G. biloba, which is different from most other gymnosperms.•The combination of manually genetic crosses and genomic data is proved to be an efficient way to investigate the inheritance mode of chloroplasts genome in land plants.•The current research also provides a case study for further research of plastid inheritance in gymnosperms using genomic techniques, which will contribute to a better understanding of cytologically uniparental inheritance mode and evolutionary mechanism of plastids in both gymnosperms and angiosperms.

The complete chloroplast genome of Aristolochia hainanensis Merr. (Aristolochiaceae).

Aristolochia hainanensis Merr. 1922, a well-known Chinese medicinal plant, is distributed in Hainan Province and Guangxi Province, China. In the current study, we sequenced the complete chloroplast genome of A. hainanensis. The complete plastome genome was 159,764 bp in length, with a GC content of 38.8%, showing a typical quadripartite organization. The genome contained a large single-copy (LSC) of 89,134 bp, a small single-copy (SSC) of 19,306 bp, and a pair of inverted repeats (IRs) of 25,662 bp. A total of 113 genes were annotated, including 79 protein-coding genes, 30 tRNAs, and four rRNAs. The trnK-UUU gene contained the longest intron (2644 bp). The topology of the maximum-likelihood tree supported a close relationship between A. hainanensis and A. kwangsiensis.

Solution degradant of mirabegron extended release tablets resulting from a Strecker-like reaction between mirabegron, minute amounts of hydrogen cyanide in acetonitrile, and formaldehyde in PEG during sample preparation.

During the related substances testing of mirabegron extended release tablets, an unknown peak was observed in HPLC chromatograms in a level exceeding the identification threshold. By using a strategy that combines LC-PDA/UV-MSn with mechanism-based stress studies, the unknown peak was rapidly identified as cyanomethyl mirabegron, a solution degradant that is caused by a Strecker-like reaction between the API, formaldehyde (an impurity in PEG), and HCN (an impurity in HPLC grade acetonitrile). The mechanism of the solution degradation chemistry was verified by stressing mirabegron with formaldehyde and trimethylsilyl cyanide (TMSCN, a synthetic reagent that generates HCN upon contact with water), in which the secondary amine group of mirabegron first reacts with formaldehyde to form the iminium ion intermediate; the latter then undergoes a nucleophilic attack by cyanide to yield the cyanomethyl mirabegron. The structure of the impurity was further confirmed through the synthesis of the impurity and subsequent structure characterization by 1D and 2D NMR. Due to the ubiquitous presence of formaldehyde in pharmaceutical excipients (e.g., PEG and polysorbate) and trace amount of HCN in HPLC grade acetonitrile, this type of solution degradation would likely occur in sample preparations of pharmaceutical finished products containing APIs with primary and secondary amine moieties. In a GMP environment, such an event may trigger undesirable out-of-specification (OOS) investigations; the results of this paper should help resolve such OOS investigations or even prevent these events from happening in the first place.

"Ghost peak" of clofazimine: A solution degradation product of clofazimine via nucleophilic substitution by nitrite leaching from certain glass HPLC vials.

Analytical solutions of clofazimine drug substance stored in glass HPLC vials were found to undergo degradation at room temperature occasionally. At the time of each sample preparation, it was unpredictable if a particular solution would undergo such solution degradation. Once the degradation peak was observed in a particular vial, typically within 24h, it would keep growing until reaching a total yield of approximately 2%. By using a strategy that combines LC-PDA/UV-MSn with mechanism-based stress studies, followed by preparative HPLC separation and subsequent structure characterization by 1D and 2D NMR, the unknown peak was identified as a clofazimine nitrite ester. It apparently results from nucleophilic substitution of clofazimine by residual nitrite leaching out of the inner surface of the glass HPLC vials used in the sample preparation. Overall, the percentage of the sample solutions that underwent solution degradation is approximately ∼10% to 15%, when the sample solutions were stored in glass HPLC vials at room temperature. Over the period of the analytical method development, it was found that the occurrence of the degradation can be suppressed when the solutions were stored under refrigerated condition (2 - 8°C) or when the samples were prepared in less acidic diluents.

An aptamer based surface plasmon resonance biosensor for the detection of ochratoxin A in wine and peanut oil.

Ochratoxin A (OTA), as a kind of chlorophenolic mycotoxin, exist widely in plant origin food and is harmful to human. Herein, a surface plasmon resonance (SPR) biosensor using an anti-OTA aptamer immobilized sensor chip was developed to measure ochratoxin A (OTA) quantificationally through a straightforward direct binding assay. The streptavidin protein as a crosslinker was immobilized onto the surface of a sensor chip and the biotin-aptamer was captured through streptavidin-biotin interaction. The biosensor exhibited a detection range from 0.094 to 100ng/mL (linear range from 0.094 to 10ng/mL) of OTA with a lower detection limit of 0.005ng/mL. Detection of OTA in wine and peanut oil was further performed in the SPR biosensor using simple liquid-liquid extraction for sample pretreatments. Recoveries of ochratoxin A from spiked samples ranged from 86.9% to 116.5% and coefficients of variation (CVs) ranged from 0.2% to 6.9%. The developed methods in our studies showed good analytical performances with limits of detection much lower than the maximum residue limit, as well as a good reproducibility and stability.