Yacon has been considered to be a potent alternative food source for patients who require a dietary cure in regional area, while the leaf part has been provided and consumed as an herbal tea in local markets. We demonstrated here potent antioxidative effects of the tea leaves from yacon in different free radical assays, reducing power assay, and cellular superoxide anion radical generation assay. Results support yacon tea leaves may be a good source of natural antioxidants for preventing O2(-) radical-mediated disorders.

This study aimed to investigate the unique antioxidative effects of Japanese moringa products, herbal leaf tea and stem tea, using established free radical assays, focusing on superoxide anion (O) radical generation systems. Hot-water extracts from moringa teas resulted in different but lower scavenging activities than Trolox in four synthetic free radical models. Interestingly, these extracts further showed higher O radical scavenging effects than Trolox in the phenazine methosulfate-NADH-nitroblue tetrazolium and xanthine oxidase assay systems. Incubating human neutrophils in the presence of these tea extracts rather than Trolox effectively suppressed cellular O radical generation. Among the eight known phenolic constituents of moringa leaves, caffeic acid and chlorogenic acid may be responsible for the Ospecific radical scavenging capacity stronger than that of Trolox. These results suggest that moringa herbal teas are a good source of natural antioxidants for preventing O radical-mediated disorders. Abbreviations: O: superoxide anion; ROS: reactive oxygen species; HO: hydrogen peroxide; XOD: xanthine oxidase; DPPH: 1,1-diphenyl-2-picrylhydrazyl; ABTS: 2,2'-azinobis(2-ethylbenzothiazoline-6-sulfonic acid) cation; CPZ: chlorpromazine cation; PMS: phenazine methosulfate; NBT: nitroblue tetrazolium; PMA: phorbol 12-myristate 13-acetate.

-1-Naphthol (1-Nap) and 2-naphthol (2-Nap) are phenolic isomers that may be subjected to sulfate conjugation in vivo. Phase-II sulfate conjugation of phenolic compounds is generally thought to result in their inactivation. This study aimed to investigate the antioxidative effects of 1-NapS and 2-NapS, in comparison with their unsulfated counterparts, using established free radical scavenging assays. Based on the calculated EC 50 values, 1-NapS resulted in 5.60 to 7.35-times lower antioxidative activity than 1-Nap. In contrast, 2-NapS showed comparable activities as did the unsulfated 2-Nap. Collectively, the results obtained indicated that sulfate conjugation of the Nap isomers did not always result in the decrease of their antioxidant activity, and the antioxidant activity that remained appeared to depend on the position of sulfation.

Context: Scilla scilloides Druce (Liliaceae) is a folk medicine to treat dermal inflammation; however, the medicinal properties of this plant have not been completely established. Objective: The current study investigates the potent anti-inflammatory effects of S. scilloides bulbs for its traditional usage using lipoxygenase and hyaluronidase as the inflammation model. To gain insight into the active constituents, nine homoisoflavones (1-9) were subsequently tested. Materials and methods: Lipoxygenase and hyaluronidase inhibition of ethyl acetate extract from the bulbs of this plant within 2000 mg/mL or homoisoflavones within 1000 mM were determined by colorimetric methods. RAW264.7 cells were incubated with 10 or 50 mM homoisoflavones plus lipopolysaccharide (LPS) for 24 h. The culture media were collected and analyzed for determination of the nitric oxide (NO) level by the colorimetric Griess method to measure the extent of inflammation. Results: The extract exhibited inhibitory effects on lipoxygenase and hyaluronidase activities with IC 50 values 31.5 and 169 mg/mL, respectively. Among the nine homoisoflavones tested, four (1 and 3-5) resulted in 79.3-97.9% higher lipoxygenase inhibition than 6.7-32.7% of the others at 500 mM. Calculated IC 50 values indicated 5 as the compound responsible for strong lipoxygenase inhibition with 15.8 mM as the IC 50 value. In the hyaluronidase assay, all homoisoflavones tested at 1000 mM demonstrated 16.2-58.0% inhibition. Incubating the cells in the presence of all nine homoisoflavones tested at 50 mM significantly suppressed the NO production, downward to 1.5-66.0%, in the LPS-activated macrophage cells as a model. Discussion and conclusion: These results may indicate a potential role of S. scilloides for anti-inflammatory purposes.