Functional Analysis of a Methyltransferase Involved in Anthocyanin Biosynthesis from Blueberries (Vaccinium corymbosum)

Anthocyanins are natural water-soluble pigments that widely exist in plants, with various biological activities, including antioxidant, anti-obesity, and anti-diabetic activities. Currently, monomeric anthocyanins are mainly obtained through natural sources, which limits their availability. In the biosynthesis of anthocyanins, anthocyanin methyltransferases are recognized to play important roles in the water solubility and structural stability of anthocyanins. Blueberries are a rich source of anthocyanins with more than 30 chemical structures. However, the enzymes that were responsible for the methylation of anthocyanidin cores in blueberries had not been reported. Here, blueberries (Vaccinium corymbosum) have been selected as the candidate for characterization of the key enzyme. Phylogenic analysis, enzymatic activity assay, homology modeling, molecular simulation, protein expression and purification assay, site-directed mutation, isothermal titration calorimetry assay, and enzyme kinetic assay were used to identify the enzymatic function and molecular mechanism of VcOMT, which was responsible for the methylation of anthocyanidin cores. VcOMT could use delphinidin as a substrate but not cyanidin, petunidin, anthocyanins, flavonols, and flavonol glycosides. Ile191 and Glu198 were both identified as important amino acid residues for the binding interactions of anthocyanidins with VcOMT

Mild and Regioselective <i>N</i>‑Alkylation of 2‑Pyridones in Water

A mild and regioselective <i>N</i>-alkylation reaction of 2-pyridones in water has been developed. Tween 20 (2% w/w) was added to create a micellar system for improved solubility of starting materials, which leads to enhanced reaction rates. The protocol demonstrated a wide substrate scope with good isolated yields (40–94%) for all of the 24 examples evaluated. High regioselectivity favoring <i>N</i>-alkylation over <i>O</i>-alkylation was observed for benzyl halides (>5:1), primary alkyl halides (>6:1), and bulky and less reactive secondary alkyl halides (>2.4:1)

Demographic and characteristic data of smoker and nonsmoker participants.

<p>* The number of participants for smoker's QSU scores was 19. The data of three smokers were removed as they were not included in further GBC analysis.</p><p>Abbreviation: QSU, Questionnaire of Smoking Urges; SOA, State of Abstinence; SOS, State of Satisfaction.</p

Regions of lower global brain connectivity for smokers under the state of satisfaction.

<p>Regions of lower global brain connectivity for smokers under the state of satisfaction.</p

The effect of chronic cigarette smoking on GMV.

<p>Smokers showed higher GMV in the angular gyrus and inferior parietal lobule (A) and lower GMV in the insula, thalamus, and medial frontal cortex (B) compared with nonsmokers. GMV in the medial frontal cortex (B, region with yellow circle) was significantly negatively correlated with the history of smoking after controlling for age, education, and whole-brain volume (C). The results are shown with p<0.05 and corrected for multiple comparisons with the AlphaSim correction.</p

Regions of higher GBC in smokers under the SOA condition.

<p>Compared with that of nonsmokers, the GBC of smoker under the SOA condition was higher in the insula (A) and superior frontal gyrus (B). The GBC of the superior frontal gyrus was negatively correlated with the QUS-brief scores (C). The results are shown with p<0.01 and corrected for multiple comparisons with the AlphaSim correction.</p

Differences in gray matter volumes between smokers and nonsmokers.

<p>Differences in gray matter volumes between smokers and nonsmokers.</p

Regions of decreased GBC in smokers after acute cigarette smoking.

<p>Smokers showed decreased GBC the in bilateral insula (A) and regions of the DMN (B), including the middle frontal cortex, precuneus, bilateral angular gyrus, and bilateral inferior parietal lobule. The results are shown with p<0.01 and corrected for multiple comparisons with the AlphaSim correction.</p

Regions of correlation between rGMV and EFT score

<div><p>(<b><i>p</i> < 0.05, corrected for FDR)</b>. </p> <p>(A) The left IPL in which variability in rGMV exhibited significant positive correlation with EFT score (n=286) is superimposed on a standard T1-weighted template brain in MNI stereotactic space. (B) A scatterplot between left IPL volume and EFT score adjusted for age, gender, and total gray matter volume is shown for illustration purpose only.</p></div

ALFF was positively correlated with individual EFT score.

<p>In the left panel, results are shown with p < 0.0005 uncorrected for visualization purposes. (A) Coronal view. Regions of significant correlation are shown in the left IPL; (B) Sagittal view. Regions of significant correlation are shown in the mPFC. The right panel shows corresponding scatterplots of the relationship between the EFT score and ALFF values of the significant cluster in the region of the left panel. The scatterplots adjusted for age, gender, CRT score are shown for illustration purpose only.</p