Search

Engineering the microbial production of secondary metabolites is limited by the known reactions of correctly annotated enzymes. Therefore, the machine learning discovery of specialized enzymes offers great potential to expand the range of biosynthesis pathways. Benzylisoquinoline alkaloid production is a model example of metabolic engineering with potential to revolutionize the paradigm of sustainable biomanufacturing. Existing bacterial studies utilize a norlaudanosoline pathway, whereas plants contain a more stable norcoclaurine pathway, which is exploited in yeast. However, committed aromatic precursors are still produced using microbial enzymes that remain elusive in plants, and additional downstream missing links remain hidden within highly duplicated plant gene families. In the current study, machine learning is applied to predict and select plant missing link enzymes from homologous candidate sequences. Metabolomics-based characterization of the selected sequences reveals potential aromatic acetaldehyde synthases and phenylpyruvate decarboxylases in reconstructed plant gene-only benzylisoquinoline alkaloid pathways from tyrosine. Synergistic application of the aryl acetaldehyde producing enzymes results in enhanced benzylisoquinoline alkaloid production through hybrid norcoclaurine and norlaudanosoline pathways. Producing plant secondary metabolites by microbes is limited by the known enzymatic reactions. Here, the authors apply machine learning to predict missing link enzymes of benzylisoquinoline alkaloid (BIA) biosynthesis in Papaver somniferum, and validate the specialized activities through heterologous production. [ABSTRACT FROM AUTHOR]

A high-performance liquid chromatography method for the analysis of gizzerosine in fishmeal was developed. The method was performed using an ODS column (250 × 4.6 mm) and achieved a gizzerosine total analysis time of approximately 35 min. Gizzerosine was extracted from fishmeal with a 0.1-N HCl solution, diazotized with sulfanilic acid (Pauly's reagent), and successfully separated from other reagent-positive components in fishmeal extracts. Using this method, the calibration curve of standard gizzerosine was estimated to be within the range of 1 to 250 mg/l (r2 = 0.9942). The coefficient of variation (relative standard deviation) of gizzerosine derivatization was 0.27%. The mean recovery was 96.2% with addition of 0.1, 1, 5, 10, and 15 μg/100 g of gizzerosine in fishmeal. Moreover, the limit of detection for spiked feed blanks, based on a S/N of 3, was 0.61 mg/kg. This method was also efficient in detection of the wavelength of the analyte derivatives as well as in clean sample preparation. Therefore, this method could be used to analyze gizzerosine in fishmeal. [ABSTRACT FROM AUTHOR]

A taxane with an amino-side chain on C-5 was identified for the first time from rooted cuttings of the Canadian yew, Taxus canadensis. The structure was characterized as 2α,10β,13α-triacetoxy-5α-[3'-(N-formyl-Nmethylamino)-3'-phenylpropanoyloxy]taxa-4(20),12-dien-9α-ol (1) on the basis of 1D and 2D NMR data and HR-FAB-MS analyses. The spectra revealed that in CDCl solution 1 was composed of two rotamers ( 1a and 1b) in a ratio of approximately 1:1. [ABSTRACT FROM AUTHOR]

A new natural product, 8,8'-bi-3- O-methylquercetin ( 9), and eight known flavonoids were isolated from the flowers of Achillea millefolium. Their structures were established on the basis of spectral evidence. All the spectral data of these compounds were reassigned after interpretation of their 2D NMR spectroscopic data. Compounds 2, 5, and 7 exhibited antiproliferative activity against human breast cancer cell line MCF7WT. In addition, 2 and 5 showed antiproliferative activity against human prostatic cancer cell line PC-3, while the other compounds did not show inhibitory effects in two human tumor cell lines tested. [ABSTRACT FROM AUTHOR]

We established a simple, rapid method for gizzerosine analysis in fish meal. Gizzerosine was extracted from fish meal with 0.1 N HCl solution. Samples and standard gizzerosine solutions were absorbed onto a paper disc, which was then set on electrophoresis paper for 18 min, and the paper was dried. Gizzerosine was visualized with Pauly's reagent, and the intensity of the colored spots was digitized and calculated by image processing method software. We achieved successful separation of gizzerosine from other Pauly's reagent-positive components in fish meal extracts. The linearity of gizzerosine estimation using this method was within the range 30-1000 ng ( R = 0.99). Gizzerosine was satisfactorily detected and completely separated from histamine and other Pauly's reagent-positive compounds. This method does not require expensive instruments or tedious pretreatment to eliminate interfering compounds, such as histamine or histidine. It also uses less reagent compared with high-performance liquid chromatography. Moreover, it is a simple, rapid, sensitive, and reproducible method. It is suitable for monitoring gizzerosine in fish meal products that contain as little as 10 ppm gizzerosine. [ABSTRACT FROM AUTHOR]

A new taxane, 2 α,5 α,10 β-triacetoxy-4 β,20-epoxytax-11-ene-1 β,7 β,9 α,13 α-tetraol (1), was isolated from the rooted cuttings of the Canadian yew, Taxus canadensis. [ABSTRACT FROM AUTHOR]

Arteminal, a novel eudesmane sesquiterpenoid, was isolated from the whole plant of Artemisia frigida. The structure was characterized on the basis of spectroscopic methods. [ABSTRACT FROM AUTHOR]

A novel isocomene sesquiterpenoid, 11-hydroxyisocom-2-en-5-one, was isolated from the roots of Echinops spinosissimus subsp. spinosus Greuter. The structure was characterized on the basis of NMR spectroscopic methods, including H-H COSY, HMBC, HSQC, and NOESY experiments. [ABSTRACT FROM AUTHOR]

A novel germacrane sesquiterpenolide was isolated from the whole plant of Artemisia frigida. The structure was characterized as 1α,3α-dihydroxy-7β,11αH-germacra-4Z,10(14)-dien-12,6α-olide ( 1) on the basis of spectroscopic methods. [ABSTRACT FROM AUTHOR]

In the original version of this Article, the abbreviation of 3,4-dihydroxyphenylacetaldehyde synthase presented in the first paragraph of the Discussion section was given incorrectly as DYPAA. The correct abbreviation for this enzyme is DHPAAS. This error has been corrected in both the PDF and HTML versions of the Article. [ABSTRACT FROM AUTHOR]

Development of novel influenza neuraminidase inhibitors is critical for preparedness against influenza outbreaks. Knowledge of the neuraminidase enzymatic mechanism and transition-state analogue, 2-deoxy-2,3-didehydro-N-acetylneuraminic acid, contributed to the development of the first generation anti-neuraminidase drugs, zanamivir and oseltamivir. However, lack of evidence regarding influenza neuraminidase key catalytic residues has limited strategies for novel neuraminidase inhibitor design. Here, we confirm that influenza neuraminidase conserved Tyr406 is the key catalytic residue that may function as a nucleophile; thus, mechanism-based covalent inhibition of influenza neuraminidase was conceived. Crystallographic studies reveal that 2?,3ax-difluoro-N-acetylneuraminic acid forms a covalent bond with influenza neuraminidase Tyr406 and the compound was found to possess potent anti-influenza activity against both influenza A and B viruses. Our results address many unanswered questions about the influenza neuraminidase catalytic mechanism and demonstrate that covalent inhibition of influenza neuraminidase is a promising and novel strategy for the development of next-generation influenza drugs. [ABSTRACT FROM AUTHOR]

A new taxane, 2 α,5 α,10 β-triacetoxy-4 β,20-epoxytax-11-ene-1 β,7 β,9 α,13 α-tetraol (1), was isolated from the rooted cuttings of the Canadian yew, Taxus canadensis. [ABSTRACT FROM AUTHOR]

Arteminal, a novel eudesmane sesquiterpenoid, was isolated from the whole plant of Artemisia frigida. The structure was characterized on the basis of spectroscopic methods. [ABSTRACT FROM AUTHOR]