Isolation and identification of antioxidative phenolic acids and flavonoid glycosides from Camellia japonica flowers

Abstract

The ethyl acetate (EtOAc) layer of the hot water extracts of Camellia japonica flowers was found to have higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity than the other solvent layers. Nine phenolic compounds were isolated and purified from the EtOAc layer by Sephadex LH-20 column chromatography and octadecyl silane-high performance liquid chromatography using a guided DPPH radical-scavenging assay. The isolated compounds were identified as 3,4,5-trihydroxybenzoic acid (1), 3,4-dihydroxybenzoic acid (2), 4-hydroxybenzoic acid (3) (8), and kaempferol 3-O--D-glucopyranoside (9), based on mass spectrometry and nuclear magnetic resonance. Four compounds (6-9) had been previously identified in the leaves of this plant, but other compounds (1-5) were newly isolated from this plant. Their DPPH radical-scavenging activities based on the 50% scavenging concentration decreased in the following order: 4 = 5 (4.7 M) > 1 (9.8 M) > 6 = 7 (8.2 M) > -tocopherol (24.7 M) > ascorbic acid (25.1 M) > 2 (35.6 M) > 3 = 8 = 9 (> 250 M). Quercetin glycosides (6, 7), gallic acid (1) and its glucosides (4, 5) showed higher DPPH radical-scavenging activities than other compounds. These results indicate that the antioxidant effect of C. japonica flowers may be attributable to quercetin glycosides and gallic acid derivatives. These isolated compounds will be useful in basic studies of plant physiology, food manufacturing, and biological function of C. japonica flowers.

Investigation of Livistona decipiens Leaf Methanol Extract and Evaluation of Antioxidant, Antimicrobial and Cytotoxic Activities

“…Research Article / JAPR ISSN: 2357-0539 (Online) Ibrahim et al, 2018, 2 (4), 256-268 Based on its chromatographic properties, 1 H NMR and 13 C NMR, compound 5 was expected to be kaempferol 3-O-glucoside structure 24 . This expectation was supported by 1 H NMR spectrum showing an A2X2 spin coupling system of two ortho-doublets, each integrated for two Protons at δ ppm 7.67 (2H, d, J = 8.47 Hz, H-2′/6′) and 6.94 (2H, d, J = 8.69Hz, H-3′/5′) indicated 4′-hydroxyl.…”

“…Moreover, the O-glycoside moiety in the structures was confirmed as 3-O-glucopyranoside depending on the characteristic down field location of C-1′′ at 102.27 δ ppm with respect to those of C-glycosides. The assignment of all other 13 C NMR resonances of compound 5 was achieved by comparison with the corresponding data of structural related compounds 24,25 . According to the above discussed data compound 5 was confirmed as 6-(O-methyl)-kaempferol-3-Oglucopyranoside, which was isolated for the first time from L. decipiens.…”

Structural elucidation of four flavonoid glycosides from Barringtonia acutangula

“…From all the above evidence, compound 2 was identified as quercetin 3-O-α-L-arabinopyran-osyl-(1 2)-β-Dgalactopyranoside. [5] Similarly, detailed analysis of the 1D and 2D NMR data as well as comparison of them with the literature values led to identification of compounds 3 and 4 as kaempferol 3-O-β-D-galactopyranoside [7,8] and quercetin-3-O--D-galactopyranoside. [9]…”

Cosmetic Functional Ingredients from Botanical Sources for Anti-Pollution Skincare Products

“…The ethanol extract of C. japonica flowers exhibits antioxidant properties by scavenging ROS (superoxide and hydroxyl radicals) in a free-cell system and in human HaCaT keratinocytes; moreover, it is able to increase the protein expression of the antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase [108]. The ROS scavenging effect and the induction of antioxidant enzymes of C. japonica extract may be associated with the presence of antioxidant phenolic compounds such as quercetin and kaempferol glycosides [108,113]. In a study on the anti-aging properties of C. japonica flower extract in an ex vivo model, it has been shown that it reduces piknotic nuclei and it prevents the detachment of the dermo-epidermal junction induced by pollutants such as heavy metals and hydrocarbons; moreover, it also induces an increase of collagen I and a decrease of MMP-1 [114].…”