Flavonoids from Machilus japonica Stems and Their Inhibitory Effects on LDL Oxidation

Abstract

Stems of Machilus japonica were extracted with 80% aqueous methanol (MeOH) and the concentrated extract was successively extracted with ethyl acetate (EtOAc), normal butanol (n-BuOH), and water. Six flavonoids were isolated from the EtOAc fraction: (+)-taxifolin, afzelin, (−)-epicatechin, 5,3'-di-O-methyl-(−)-epicatechin, 5,7,3'-tri-O-methyl-(−)-epicatechin, and 5,7-di-O-methyl-3',4'-methylenedioxyflavan-3-ol. The chemical structures were identified using spectroscopic data including NMR, mass spectrometry and infrared spectroscopy. This is the first report of isolation of these six compounds from M. japonica. The compounds were evaluated for their diphenyl picryl hydrazinyl scavenging activity and inhibitory effects on low-density lipoprotein oxidation. Compounds 1 and 3–6 exhibited DPPH antioxidant activity equivalent with that of ascorbic acid, with half maximal inhibitory concentration (IC50) values of 0.16, 0.21, 0.17, 0.15 and 0.07 mM, respectively. The activity of compound 1 was similar to the positive control butylated hydroxytoluene, which had an IC50 value of 1.9 µM, while compounds 3 and 5 showed little activity. Compounds 1, 3, and 5 exhibited LDL antioxidant activity with IC50 values of 2.8, 7.1, and 4.6 µM, respectively.

Biologically Active Compounds in Stizolophus balsamita Inflorescences: Isolation, Phytochemical Characterization and Effects on the Skin Biophysical Parameters

“…The NMR assignments of proton and carbon signals were verified by HSQC, HMBC and NOESY spectra ( Table 1 ; Figures S7–S9 ). From those data, compound 7 was identified as 5,7,3′,4′-tetrahydroxydihydroflavonol ( Figure 1 ) or dihydroquercetin, known by the trivial name—taxifolin [ 36 ].…”

Chemical Constituents of Muehlenbeckia tamnifolia (Kunth) Meisn (Polygonaceae) and Its In Vitro α-Amilase and α-Glucosidase Inhibitory Activities

“…Other CH aromatic carbon atoms are represented by signals at 131.9 (positions 2′ and 6′), 116.5 (positions 3′ and 5′), 100.1 and 94.9 ppm. The rhamnose moiety anomeric carbon atom corresponds to the signal at 103.5 ppm [22,23].…”

Chemical Characterization of the Hydroethanolic Extract of the Inner Stem Bark of Dilodendron bipinnatum. Comparative Cytotoxic Evaluation and Anti-inflammatory Potential of a Simple Mixture of its Isolates 3-O-β-Glucopyranosyl-β-sitosterol and 3-O-β-Glucopyranosyl-stigmasterol

“…13 C-and 1 H-NMR analysis (Figures S5-S6) allowed the elucidation of the structures of compounds 4 and 5; these are supported by the literature data [6,7]. Compound 6 was identified as epicatechin, after IR, 1 H-and 13 C-NMR (Figure S7) analyses [12]. Animals: Male Swiss mice (25-30 g) were used.…”