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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.
