Flavonol glycosides from the aerial parts ofAceriphyllum rossii and their antioxidant activities

Abstract

The methanol extract obtained from the aerial parts of Aceriphyllum rossii (Saxifragaceae) was fractionated into ethyl acetate (EtOAc), n-BuOH and H2O layers through solvent fractionation. Repeated silica gel column chromatography of EtOAc and n-BuOH layers afforded six flavonol glycosides. They were identified as kaempferol 3-O-beta-D-glucopyranoside (astragalin, 1), quercetin 3-O-beta-D-glucopyranoside (isoquercitrin, 2), kaempferol 3-O-alpha-L-rhamnopyranosyl (1-->6)-beta-D-glucopyranoside (3), quercetin 3-O-alpha-L-rhamnopyranosyl (1-->6)-beta-D-glucopyranoside (rutin, 4), kaempferol 3-O-[alpha-L-rhamnopyranosyl (1-->4)-alpha-L-rhamnopyranosyl (1-->6)-beta-D-glucopyranoside] (5) and quercetin 3-O-[alpha-L-rhamnopyranosyl (1-->4)-alpha-L-rhamnopyranosyl (1-->6)-beta-D-glucopyranoside] (6) on the basis of several spectral data. The antioxidant activity of the six compounds was investigated using two free radicals such as the ABTS free radical and superoxide anion radical. Compound 1 exhibited the highest antioxidant activity in the ABTS [2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)] radical scavenging method. 100 mg/L of compound 1 was equivalent to 72.1+/-1.4 mg/L of vitamin C, and those of compounds 3 and 5 were equivalent to 62.7+/-0.5 mg/L and 54.3+/-1.3 mg/L of vitamin C, respectively. And in the superoxide anion radical scavenging method, compound 5 exhibited the highest activity with an IC50 value of 17.6+/-0.3 microM. In addition, some physical and spectral data of the flavonoids were confirmed.

Chemical Constituents, Antischistosomal and Antioxidant Activities of the Methanolic Extract of Azadirachta indica

“…Also, two anomeric carbon signals appeared at δ 101.70 and 101.12 ppm. The glycosylation at C-3 was confirmed by presence of signal at 133.59 ppm and downfield signal of C-2 at 156.84 ppm (25,24) . The interglycosidic (1→6) linkage was also confirmed by the downfield shift of C-6 of the glucose moiety by δ 67.25 ppm relative to an unsubstituted glucose moiety (C-6 at δ 61.21 ppm) (25,22,24) .…”

“…The glycosylation at C-3 was confirmed by presence of signal at 133.59 ppm and downfield signal of C-2 at 156.84 ppm (25,24) . The interglycosidic (1→6) linkage was also confirmed by the downfield shift of C-6 of the glucose moiety by δ 67.25 ppm relative to an unsubstituted glucose moiety (C-6 at δ 61.21 ppm) (25,22,24) . The sugar moiety and the aglycone were resulting from acid hydrolysis which identified as kaempferol, L-rhamnose and D-glucose by CO-TLC with authentic samples.…”

“…Two doublets which one of them appeared at δ 6.90 (2H, d, J= 8.85 Hz, H-3', H-5') whereas the other δ at 7.99 (2H, d, J= 8.90 Hz, H-2', H-6') indicated the presence of 4'-hydroxylation of the B-ring. In addition, two anomeric protons were assigned at δ 5.32 (1H, d, J= 7.5 Hz, H-1'') and 4.39 (1H, d, J= 1.25 Hz, H-1''') and one methyl protons at δ 1.03 (3H, d, J= 6.07 Hz) ppm of the rhamnose unit (22,24,25) . This was confirmed by presence of characteristic signals of kaempferol aglycone in 13 C-NMR as shown in Table 1, where the chemical shift of C-2 was observed downfield at δ 156.84 ppm as compared with kaempferol which appeared at 146.80 ppm indicating 3-O-glycosylation (22,24) .…”

“…The presence of 7-OH group was indicated by the bathochromic shift (17 nm) with NaOAc (band II). The bathochromic shift (27 nm) band I with NaOAc/H 3 BO 3 suggested the presence of O-dihydroxy groups in B-ring (25)(26)(27)(28)(29)(30) . In ppm.…”

Protective Effect of <i>Alpina nigra</i> Leaves Extract in Mouse Liver Injury Induced by Carbon Tetrachloride

“…India, the abode of Ayurvedic system of medicine, assigns much importance to the pharmacological aspects of many plants. Hepatoprotective effect of some plants like Spirulina maxima [5], Eclipta alba [6], Boehmeria nivea [7], Cichorium intybus [8], Picrorhiza kurroa [9], Maydis stigma (10), Gmelina arborea Roxb. (11) and Manilkara zapota [12] etc.…”