Sukweenadi J, Yunita O, Setiawan F, Kartini, Siagian MT, Danduru AP, Avanti C. 2020. Antioxidant Activity Screening of Seven Indonesian Herbal Extract. Biodiversitas 21: 2062-2067. Kumis kucing ...(Orthosiphon stamineus), pegagan (Centella asiatica), seledri (Apium graveolens), kunyit (Curcuma domestica), temulawak (Curcuma xanthorrhiza), tempuyung (Sonchus arvensis) and meniran (Phyllanthus niruri) are herbs that commonly used in the Indonesia folk medicine. The constituents that responsible for several important biological activities are phenolic and flavonoid compounds which also possess antioxidant activity. Antioxidant activity of those seven Indonesian herbal extracts was evaluated using DPPH, ABTS and FRAP methods. The extraction was done with the reflux method by using 80% ethanol as a solvent. The total phenol and total flavonoids from each herbal extract were measured using Folin–Ciocalteu reagent and spectrophotometry. Antioxidant activity results by DPPH method on O. stamineus, C. asiatica, A. graveolens, C. domestica, C. xanthorrhiza, S. arvensis, and P. niruri showed IC50 value at 132; ND; 2221; 361; 538; 1118; and 102 ppm, respectively. Results from ABTS method, showed IC50 value at 22; 1199; 169; 100; 82; 143; and 20 ppm respectively. While results from the FRAP method showed that the ethanolic extract of P. niruri at a concentration of 20 ppm possesses the strongest antioxidant activity (17.41 ppm AEAC/ppm extract). The content of total phenolic compounds are 22.50; 0.67; 2.16; 11.40; 7.80; 7.22; and 2.62% GAE, while the total flavonoid compounds were 19.88; 6.67; 4.06; 71.02; 34.62; 3.78; and 8.34% QE, respectively. It can be concluded that ethanolic extract of P. niruri and O. stamineus obtain the highest antioxidant activity based on DPPH, ABTS and FRAP method.
How GPCRs and G proteins interact is important for their biologic functions and their functions as pharmacologic targets. It is still an open question whether receptors and G proteins are ...preassembled in a complex or interact only after receptor activation. We compared the propensity of the two Gs‐coupled serotonin (5‐HT) receptors 5‐HT4 and 5‐HT7 to associate with G protein prior to agonist activation. Combining receptor‐immobilized fluorescence recovery after photobleaching and fluorescence resonance energy transfer methodologies, we observed that 5‐HT7 receptors markedly reduced the diffusion of both Gα and Gβγ at the cell surface, which indicated 5‐HT7 receptor preassociation with Gs. This is in sharp contrast to the 5‐HT4 receptor for which the diffusion of Gαβγ was not modified, and agonist activation brought together the receptor and Gγ, which is consistent with interaction by collision coupling. Agonist activation of 5‐HT7 dissociated Gγ from the receptor, whereas Gαs underwent a rapid conformational change with respect to both Gγ and the receptor, followed by a slower dissociation of Gγ from both Gαs and the receptor. Taken together, these data demonstrate a different propensity among receptors to preassociate with G protein in the absence of ligand and reveals a rapid conformational change in Gαs upon activation by the receptor.—Andressen, K. W., Ulsund, A. H., Krobert, K. A., Lohse, M. J., Bünemannn M., Levy, F. O. Related GPCRs couple differently to Gs: preassociation between G protein and 5‐HT7 serotonin receptor reveals movement of Gαs upon receptor activation. FASEB J. 32, 1059–1069 (2018). www.fasebj.org
Aqueous extracts of 30 plants were investigated for their antioxidant properties using DPPH and ABTS radical scavenging capacity assay, oxygen radical absorbance capacity (ORAC) assay, superoxide ...dismutase (SOD) assay, and ferric reducing antioxidant potential (FRAP) assay. Total phenolic content was also determined by the Folin−Ciocalteu method. Antioxidant properties and total phenolic content differed significantly among selected plants. It was found that oak (Quercus robur), pine (Pinus maritima), and cinnamon (Cinnamomum zeylanicum) aqueous extracts possessed the highest antioxidant capacities in most of the methods used, and thus could be potential rich sources of natural antioxidants. These extracts presented the highest phenolic content (300−400 mg GAE/g). Mate (Ilex paraguariensis) and clove (Eugenia caryophyllus clovis) aqueous extracts also showed strong antioxidant properties and a high phenolic content (about 200 mg GAE/g). A significant relationship between antioxidant capacity and total phenolic content was found, indicating that phenolic compounds are the major contributors to the antioxidant properties of these plants.
•Antioxidant properties of catechins and other antioxidants were compared.•Catechins were most reactive in ABTS and FRAP assays.•Flavonoids effectively protected against SIN-1, AAPH and NaOCl ...reactions.•Catechins best protected against AAPH- and NaOCl-induced hemolysis.•Catechins most effectively inhibited intracellular H2DCF oxidation by AAPH.
Antioxidant properties of five catechins and five other flavonoids were compared with several other natural and synthetic compounds and related to glutathione and ascorbate as key endogenous antioxidants in several in vitro tests and assays involving erythrocytes. Catechins showed the highest ABTS-scavenging capacity, the highest stoichiometry of Fe3+ reduction in the FRAP assay and belonged to the most efficient compounds in protection against SIN-1 induced oxidation of dihydrorhodamine 123, AAPH-induced fluorescein bleaching and hypochlorite-induced fluorescein bleaching. Glutathione and ascorbate were less effective. (+)-catechin and (−)-epicatechin were the most effective compounds in protection against AAPH-induced erythrocyte hemolysis while (−)-epicatechin gallate, (−)-epigallocatechin gallate and (−)-epigallocatechin protected at lowest concentrations against hypochlorite-induced hemolysis. Catechins (−)-epigallocatechin gallate and (−)-epicatechin gallate) were most efficient in the inhibition of AAPH-induced oxidation of 2′7′-dichlorodihydroflurescein contained inside erythrocytes. Excellent antioxidant properties of catechins and other flavonoids make them ideal candidates for nanoformulations to be used in antioxidant therapy.
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•Microwave-assisted extraction is used to extract polyphenols from white button mushrooms.•RSM was combined with different parameters at which extraction was carried out.•The study ...investigated optimal conditions for the extraction of bioactive compounds.•White button mushroom is a good source of polyphenols and antioxidants.
Response surface methodology (RSM) was used to optimize the microwave-assisted extraction (MAE) of phenols from white button mushrooms (Agaricus bisporus). The total phenolic content (TPC), total flavonoid content (TFC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, and ferric reducing antioxidant power (FRAP) assays of white button mushrooms were optimized using three extraction parameters: ethanol concentration (10–90 %), extraction time (1–30 min), and solvent-to-solid ratio (5–20 mL of ethanol/water (80:20, v/v) solvent added to fixed amount of 0.2 g of sample for extraction). The ideal conditions for TPC were 58 % ethanol concentration, 16 min of extraction duration, and a solvent-to-solids ratio of 12.9 mL/0.2 g. 56 % ethanol concentration, an extraction period of 18 min, and a solvent-to-solid ratio of 12 mL/0.2 g were the ideal TFC conditions. Furthermore, the optimal conditions for maximum antioxidant activity also revealed the significant effect of independent variables. The experimental values of the responses were correlated with the predicted response values, which suggested the efficiency of MAE for extracting polyphenols from white button mushrooms. White button mushroom is an excellent antioxidant source, and conditions to extract phytochemicals have been optimized using RSM.
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