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Item The Passiflora tripartita (Banana Passion) Fruit: A Source of Bioactive Flavonoid C-Glycosides Isolated by HSCCC and Characterized by HPLC-DAD-ESI/MS/MSAutores: Simirgiotis, M.J.; Schmeda-Hirschmann, G.; Borquez, J.; Kennelly, E.J.The banana passion fruit (Passiflora tripartita Breiter, Passifloraceae) known as "tumbo" is very appreciated in tropical and subtropical countries of South America. Methanolic extracts from peel and the fruit juice of P. tripartita growing in Chile were analyzed for antioxidant capacity as well as for flavonoid and phenolic content. A chromatographic method was developed for the rapid identification of the main phenolics in the samples by HPLC-DAD and HPLC-MS. The fast fingerprint analysis allowed the detection of eighteen flavonoid C-glycosides and four flavonoid O-glycoside derivatives which were characterized by UV spectra and ESI-MS-MS analysis. Several of the C-glycosides detected are structurally related to the orientin derivative 4'-methoxy-luteolin-8-C-(6 '' acetyl)-beta-D-glucopyranoside (31), fully elucidated by spectroscopic methods. The antioxidant derivative 31 along with schaftoside, vicenin II, orientin and vitexin were isolated from the fruit extract by high-speed countercurrent chromatography (HSCCC). A suitable method for the preparative isolation of flavonol C-glycosides from "tumbo" extracts by HSCCC is reported. The pulp of the fruits showed good antioxidant capacity (12.89 +/- 0.02 mu g/mL in the DPPH assay). The peel presented the highest content of flavonoids (56.03 +/- 4.34 mg quercetin/100 g dry weight) which is related to the highest antioxidant power (10.41 +/- 0.01 mu g/mL in the DPPH assay).Item Free radical scavengers and antioxidants from lemongrass (Cymbopogon citratus (DC.) Stapf.)Autores: Cheel, J.; Theoduloz, C.; Rodriguez, J.; Schmeda-Hirschmann, G.Methanol, MeOH/water extracts, infusion, and decoction of Cymbopogon citratus were assessed for free radical scavenging effects measured by the bleaching of the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical, scavenging of the superoxide anion, and inhibition of the enzyme xanthine oxidase (XO) and lipid peroxidation in human erythrocytes. The extracts presented effect in the DPPH and superoxide anion assay, with values ranging between 40 and 68% and 15-32% at 33 and 50 mu g/mL, respectively, inhibited lipid peroxidation in erythrocytes by 19-71% at 500 mu g/mL and were inactive toward the XO at 50 mu g/mL. Isoorientin, isoscoparin, swertiajaponin, isoorientin 2"-O-rhamnoside, orientin, chlorogenic acid, and caffeic acid were isolated and identified by spectroscopic methods. Isoorientin and orientin presented similar activities toward the DPPH (IC50: 9-10 mu M) and inhibited lipid peroxidation by 70% at 100 gamma g/mL. Caffeic and chlorogenic acid were active superoxide anion scavengers with IC50 values of 68.8 and 54.2 mu M, respectively, and a strong effect toward DPPH. Caffeic acid inhibited lipid peroxidation by 85% at 100 mu g/mLItem Free radical scavengers and antioxidants from Baccharis grisebachiiAutores: Tapia, A.; Rodriguez, J.; Theoduloz, C.; Lopez, S.; Feresin, G.E.; Schmeda-Hirschmann, G.The exudate and seriated extracts from the aerial parts of Baccharis grisebachii (Asteraceae) which is recommended as a digestive and to relieve gastric ulcers in Argentina, showed activity as free radical scavengers and inhibited lipoperoxidation in erythrocytes. Assay-guided isolation led to seven p-coumaric acid derivatives and six flavonoids as the main active constituents of the crude drug. The activity towards the superoxide anion was mainly due to the flavonoid constituents. 5,7,4'-Trihydroxy-6-methoxyflavone and quercetin presented high activity (64 and 79%) even at 12.5 mug/ml. The xanthine oxidase inhibitory effect of the extracts can be related with the p-coumaric acid derivatives drupanin, 4-acetyl-3,5-diprenylcinnamic acid and trans-ferulic acid O-hexan-3-onyl-ether which showed IC50 values in the range 28-40 mug/ml. Both p-coumaric acid derivatives and flavonoids inhibited lipoperoxidation in erythrocytes. The highest activity was found for the p-coumaric acid derivatives 4-acetyl-3-prenyl-ethoxycinnamate, 3-prenyl-4-(4'-hydroxydihydrocinnamoyloxy)-cinnamate and trans-ferulic acid O-hexan-3-onyI-ether (69-82%) and the flavonoids 5,7,4'-trihydroxy-6-methoxyflavone, quercetin, 5,7,4'-trihydroxy-6,3'-dimethoxyflavone and 5,7,4'-trihydroxy-6,8-dimethoxyflavone (64-84%) at 100 mug/ml.
