Search

The palladium-catalyzed alternating copolymerization of fluoroalkenes, represented as CH2=CH-CH2-CnF(sub 2n+1), with CO is performed using (R,S)-BINAOHOS as ligand. NMR studies suggest that the much higher reactivity with (R,S)-BINAPHOS than that with the conventional ligand DPPP can be attributed to the unique 1,2-insertion of the fluoroalkene into acylpalladium species.

Food additives, such as hypochlorous acid water, sodium metabisulfite, and sodium sulfite, strongly affect the chemical and biological properties of vitamin B 12 (cyanocobalamin) in aqueous solution. When cyanocobalamin (10 μmol/L) was treated with these compounds, hypochlorous acid water (an effective chlorine concentration of 30 ppm) rapidly reacted with cyanocobalamin. The maximum absorptions at 361 and 550 nm completely disappeared by 1 h, and vitamin B 12 activity was lost. There were no significant changes observed in the absorption spectra of cyanocobalamin for 0.01% (w/v) sodium metabisulfite; however, a small amount of the reaction product was formed within 48 h, which was subsequently identified as sulfitocobalamin through high-performance liquid chromatography. Similar results were shown for sodium sulfite. The effects of these food additives on the vitamin B 12 content of red shrimp and beef meats were determined, revealing no significant difference in vitamin B 12 content of shrimp and beef meats with or without the treatment even in hypochlorous acid water. The results suggest that these food additives could not react with food vitamin B 12 in food, as most of this vitamin present in food is its protein-bound form rather than the free form., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

To investigate the effects of processing Chinese quince fruit on the denaturation of phenolics and their food functions, fruit phenolic extracts were heated together with organic acid for up to 12 h. Chinese quince phenolic (mostly procyanidins) solution subjected to heat treatment changed from almost colorless, pale yellow, to a reddish color. Before heat treatment, the absorption spectra of polymeric procyanidins were observed only around 280 nm; after heat treatment, absorption occurred between 400 and 600 nm, which is related to the reddish color appearance. Thioacidolysis of denatured reddish phenolics showed that (-)-epicatechin subunits decreased during heat treatment and, in contrast, cyanidin increased. In addition, novel substances that could not be degraded by thioacidolysis were formed. Meanwhile, antioxidant activities, assessed by linoleic acid peroxidation, 1,1-diphenyl-2-picrylhydrazyl (DPPH), Folin-Ciocalteu, and FRAP methods, increased during heat treatment. The antiinfluenza viral activity of denatured reddish phenolics was inferior to that of intact fruit phenolics; however, they retained moderate activity. These results indicate that red coloration of fruit products of Chinese quince was mainly due to the spectral (i.e. structural) changes of procyanidins accompanied with formation of cyanidin. Increasing the length of heat treatment increased the antioxidant capacity of phenolics, and the resultant reddish phenolics retained moderate antiinfluenza viral activity.

The vitamin B12 concentration of the dried cells of Aphanizomenon flos-aquae was determined by both microbiological method with Lactobacillus delbrueckeii ATCC7830 and chemiluminescence method with intrinsic factor. The Aphanizomenon cells contained 616.3 +/- 30.3 micro g (n = 4) of vitamin B12 per 100 g of the dried cells by the microbiological method. The values determined with the chemiluminescence method, however, were only about 5.3% of the values determined by the microbiological method. A corrinoid-compound was purified from the dried cells and characterized. The purified corrinoid-compound was identified as pseudovitamin B12 (an inactive corrinoid-compound for humans) by silica gel 60 TLC, C18 reversed-phase HPLC, ultraviolet-visible spectroscopy, and 1H NMR spectroscopy. The results suggest that the Aphanizomenon cells are not suitable for use as a vitamin B12 source, especially in vegans.

Vitamin B(12) content of an algal health food, Chlorella tablets (Chlorella sp.), was determined by both Lactobacillus leichmannii ATCC 7830 microbiological and intrinsic factor-chemiluminescence methods. The values of 200.9-211.6 microg/100 g dry weight determined by the chemiluminescence method were similar to the values (201.3-285.7 microg/100 g dry weight) determined by the microbiological method. A corrinoid compound was purified to homogeneity from the Chlorella tablets and characterized. The purified corrinoid compound was identified as vitamin B12, on the basis of silica gel 60 TLC, C18 reversed-phase HPLC, 1H NMR spectroscopy, and UV-Vis spectroscopy.