Antioxidant and anti-diabetic effects of Ixeris strigosa extract / 한국영양학회지

Purpose@#Ixeris strigosa (IS) is a perennial plant that commonly grows in meadows. The leaves and roots of IS have been used in medicine as a sedative. This study evaluated the antioxidant and carbohydrate-digestive-enzyme inhibitory effects of IS to determine its potential as an essential antioxidant and glycemic inhibitor for type 2 diabetics. @*Methods@#The antioxidative and α-amylase and α-glucosidase inhibitory activities were examined using the water extracts (ISW), ethanol extracts (ISE), and solvent fractions from IS. The antioxidative activities were measured using in vitro methods by measuring the 1,1-diphenyl-2-picrylhydrazyl and 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical scavenging activity. @*Results@#Investigations of the total polyphenol, flavonoid content, in vitro antioxidant activity, and α-amylase and α-glucosidase inhibitory activities of the IS extract showed that the ISE had higher total phenolic and flavonoid contents than the ISW, as well as high antioxidant activity. The ethanolic extracts of IS (70%) had an α-amylase inhibitory activity of 78.55%. The ethyl acetate fraction (90.56%) showed higher α-glucosidase inhibitory activity than the positive control, acarbose (83.01%). @*Conclusion@#Among the ISE fractions, the ethyl acetate and butanol fractions showed the best digestive enzyme inhibitory activity. Moreover, the antioxidant activity of the extract and the carbohydrate, α-amylase, and α-glucosidase inhibitory effects showed a stronger correlation with the total phenol and flavonoid contents compared to the ISW. As a result, the antioxidant and digestive enzyme inhibitory activities of high ISE are due to the phenolic compounds, particularly the flavonoid compounds. Therefore, ethyl acetate and butanol fractions of the 70% ethanol extract are excellent anti-diabetic functional materials.

Comparison of whitening effect of Rubus coreanus fruit according to maturity / 한국영양학회지

Purpose@#The Rubus coreanus fruit (RF) is an important traditional medicinal herb having antioxidant, anti-inflammatory, and immunoregulatory properties. These activities are known to change dramatically, depending on maturity of the RF. It is presumed that change of functional components, such as flavonoids, tannins, phenolic acids, triterpenoids and organic acids in RF, affect the various bioactivities. This study aimed to confirm changes in the anti-melanogenic effects of RF based on maturity, and to identify the bioactive compounds responsible. @*Methods@#The cell viability of mature RF (MRF) and immature RF (IRF) extracts was investigated using B16F10 cells. To compare the anti-melanogenic effect of MRF and IRF extracts, we first assessed the melanin content. High-performance liquid chromatography analysis was performed to evaluate changes in the level of ellagic acid according to maturity of the RF. In addition, tyrosinase inhibitory activity of both extracts was examined. @*Results@#MRF and IRF extracts (50–200 μg/mL) do not affect the cell viability of B16F10 melanoma cells. IRF extract more effectively inhibited melanin synthesis than MRF extract. The content of ellagic acid in IRF extract was higher than that obtained in MRF extract. Furthermore, greater inhibition of tyrosinase activity was observed after exposure to IRF extract than MRF extract. A positive correlation was determined between ellagic acid content and tyrosinase inhibitory activity, and a negative correlation was obtained between ellagic acid content and melanin content. Taken together, our results indicate that ellagic acid is one of the major bioactive compounds of RF that imparts a whitening effect. @*Conclusion@#Our results indicate that ellagic acid in MRF and IRF extracts affect the anti-melanogenesis effect through inhibition of tyrosinase activity. Therefore, the ellagic acid rich IRF has greater potential for application as a natural and functional cosmetic material.

Changes in the constituents and UV-photoprotective activity of Astragalus membranaceus caused by roasting / 한국영양학회지

PURPOSE: Astragalus membranaceus (AM) is an important traditional medicinal herb. Pharmacological research has indicated that AM has various physiological activities such as antioxidant, anti-inflammatory, immunoregulatory, anticancer, hypolipidemic, antihyperglycemic, and hepatoprotective activities. The bioactive substances responsible for the physiological activities in AM, including many antioxidant substances, change during the roasting process. This study investigated and compared the changes in the antioxidant constituents of AM caused by roasting. METHODS: DPPH (1,1-diphenyl-2-picryl hydrazyl) and ABTS⁺ (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt) radical scavenging activities and their total phenolic content (TPC) were measured. High-performance liquid chromatography (HPLC) analysis was performed to confirm any changes in the isoflavonoids of roasted AM (R-AM),. The cell viability of UVB-induced HDF (Human dermal fibroblast) cells treated with AM and R-AM extracts was investigated. The comet assay was used to examine the inhibitory effects of R-AM extracts on DNA damage caused by oxidative stress. RESULTS: The DPPH and ABTS⁺ radical scavenging activities were 564.6±20.9 and 108.2±3.1 (IC₅₀ value) respectively, from the 2R-AM. The total phenol content was 47.80±1.40 mg GAE/g from the 1R-AM. The values of calycosin and formononetin, which are the known isoflavonoid constituents of AM, were 778.58±2.72 and 726.80±3.45 µg/g respectively, from the 2R-AM. Treatment of the HDF cells with R-AM (50 ~ 200 µg/mL) did not affect the cell viability. Furthermore, the R-AM extracts effectively protected against UVB-induced DNA damage. CONCLUSION: The findings of this study indicate that R-AM increases its isoflavonoid constituents and protects against UVB-induced DNA damage in HDF cells.

Anti-oxidant and anti-adipocyte differentiation of Aster glehni and Aster yomena / 한국영양학회지

PURPOSE: Aster glehnii (AG) and Aster yomena (AY) are medicinal plants that belong to the family Compositea and grow widely in Korea. Plants in the genus Aster have been used to treat snakebite wounds or bruises in oriental medicine. This study compared the effects of anti-oxidants and anti-adipocyte differentiation according to the species (the aerial parts of AG and AY). METHODS: AG and AY were extracted using 70% ethanol (−E) and water (−W) at room temperature. The anti-oxidant activities were measured by total phenol contents (TPC), total flavonoid contents (TFC), DPPH and ABTS+ assay. In addition, correlation analysis was performed for the anti-oxidant compounds and effect. The level of anti-adipocyte differentiation was assessed using an oil red O assay on pre-adipocytes. RESULTS: AG-W showed higher TPC (6.92 µg/mL) and AG-E presented higher TFC (8.22 µg/mL) than the other extracts. Furthermore, AG-E exhibited higher radical scavenging activity in the DPPH and ABTS+ assay (IC50: 104.88 and 30.06 µg/mL). In the cytotoxicity assay, AG and AY extracts at concentrations less than 100µg/mL were non toxic. AG-W reduced the lipid accumulation of 3T3-L1 cells significantly after differentiation (70.49%) compared to the other extracts. CONCLUSION: These results show that the water extract of AG has anti-oxidant effects and reduces the differentiation of 3T3-L1 cells. Therefore, AG has utility as a functional food material for its anti-oxidant activities and ability to prevent lipid accumulation.