Antioxidant and antimicrobial properties of dihydroquercetin esters

Abstract Flavonoids display various beneficial biological properties, such as antioxidant activity and low cytotoxicity, which make them useful ingredients in foods, pharmaceuticals, and functional cosmetics. In particular, dihydroquercetin (DHQ) is found in various forms, and its derivatives exhibit interesting biological properties. Herein, we report the synthesis of acetylated and butyrylated dihydroquercetin derivatives and their antimicrobial and antioxidant properties. The DHQ derivatives were identified using 1H and 13C NMR spectroscopies and high-performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry. The chemical stabilities of the acetylated dihydroquercetin derivatives were found to depend on the number of acetate groups, with 3,3',4',4,7-pentaacetyldihydroquercetin found to be the most stable acetylated dihydroquercetin. Furthermore, 7,3',4'-triacetyl- dihydroquercetin exhibited potent antioxidant activity, with an IC50 of 56.67 ± 4.79 µg/mL in the 1,1-diphenyl-2-picrylhydrazyl assay, with DHQ exhibiting a value of 32.41 ± 3.35 µg/mL. The reactive-oxygen-species-scavenging activity of 7,3',4'-triacetyldihydroquercetin was highest among the esters in the ferric reducing ability of plasma assay, but lower than that of DHQ. Overall, both DHQ and 7,3',4'-triacetyldihydroquercetin exhibited antimicrobial behavior against S. aureus and P. acnes using the paper disc assay. DHQ displayed a higher antimicrobial activity, with minimum inhibitory concentrations of 625 µg/mL (P. acnes), 2,500 µg/mL (S. aureus), and 5,000 µg/mL (E. coli). DHQ and acetylated dihydroquercetins are potentially useful as complex antioxidant and antimicrobial materials

Preparation and availability analysis of glycoprotein from canola meal.

The purpose of this study is to examine the possibility of use in various fields such as cosmetics and food industry by extracting, separating, and purifying canola glycoprotein(hreinafter referred to as CNG) and comparing general characteristics and physiological activities with commercially available carrot glycoprotein(hreinafter referred to as CRG). The CNG had a protein content of 13.12%, which is higher than that of common vegetable glycoproteins, and much higher than the CRG of 2.36%. The molecular weight distribution of the CNG was 263-310 Da, which showed a lower molecular weight distribution than the 566-628 Da of the CRG. The total polyphenol content of the CNG was 29.89 mg/g, which was higher than that of the CRG measured at 1.76 mg g-1. The DPPP radical scavenging activity of CNG and carrot glycoprotein were 10.07 mg mL-1 and 7.76 mg mL-1, respectively, indicating that CNG had slightly higher electron donating ability than CRG. Total antioxidant activity of CNG was 26.84 mg AA eq/g and CRG was 10.53 mg AA eq/g.