The purpose of this study was to investigate total polyphenols, total flavonoid, and DPPH radical scavenging activity in 26 species of Korean natural plants and 14 species of medicinal plant extracts. The plant containing the highest total polyphenols and total flavonoids were Plantago asiatica, and Lespedeza cuneata G. Don, respectively. The content of polyphenols and flavonoids in natural plants was the highest in Lespedeza cuneata G. Don, which also demonstrated high DPPH radical scavenging activity. In medicinal plant extract, Saururus chinensis (Lour.) Baill and Artemisiae Asiaticae Herba had the highest level of total polyphenols (194.60 and 203.92 mg/g extract, respectively) and DPPH radical scavenging activity. Diospyros kaki Thunb and Dryopteris crassirhizoma did not contain high levels of total polyphenols (112.98, 121.46 mg/g extract, respectively) and flavonoids (46.10, 58.69 mg/g extract respectively), but DPPH radical scavenging activity was relatively high. Further study regarding plants that exhibit higher total polyphenols, total flavonoid, and DPPH radical scavenging activity is needed.
Radical scavenging effect and protective activity against oxidative stress of Acer okamotoanum were investigated. A. okamotoanum was extracted with methanol (MeOH) and then fractionated with n-BuOH, ethyl acetate (EtOAc), methylene chloride and n-hexane fractions. The MeOH extract and fractions showed strong 1,1-diphenyl-2-picrylhydrazyl and superoxide radical scavenging activity. Among the MeOH extract and fractions, the EtOAc fraction showed the strongest radical scavenging activity. In addition, total phenolic and flavonoid contents of EtOAc fraction was higher than other extract and fractions. Furthermore, we investigated the neuroprotective effect of the MeOH extract and fractions from A. okamotoanum against oxidative stress under cellular system using C6 glial cell. The C6 glial cells showed a decrease in cell viability and high production of reactive oxygen species (ROS) by the treatment of amyloid beta [25][26][27][28][29][30][31][32][33][34][35] (Aβ 25-35 ). However, with the treatment of the MeOH extract and fractions, it significantly increased the cell viability and inhibited the overproduction of ROS by Aβ 25-35 . In particular, the EtOAc fraction led to significantly increase the cell viability and decrease the generation of ROS against oxidative stress by Aβ 25-35. The current study indicated that A. okamotoanum demonstrated antioxidative and neuroprotective effects. In particular, the EtOAc fraction which attributed a strong protective activity against oxidative stress.
Antioxidative, immunostimulating, and antihypertensive activities of hot water extracts of fermented Hizikia fusiformis were evaluated. Fermentation with lactic acid bacteria generally increased the biological activities of H. fusiformis. Fermentation with isolated Weissella sp. SH-1 resulted in 13.83-62.15% DPPH radical scavenging activity and 34.90-59.25% SOD-like activity. The maximal inhibition of ACE was 82.25%, and the maximal reduction in NO production was 46.53%. Fermentation with Lactobacillus casei resulted in 11.98-72.84% DPPH radical scavenging activity and 14.17-33.62% of SOD-like activity. The maximal inhibition of ACE was 73.31%, and the maximal reduction in NO production was 65.20%. These results hint at the applicability of fermentation with lactic acid bacteria to improve the diverse biological activities of H. fusiformis and to develop functional materials or foods.
Physicochemical changes in persimmon were examined during natural organic acid fermentation. Major organic acids in raw persimmon juices were lactic acid (980 mg%) and acetic acid (245 mg%). The content of acetic acid was continuously increased during the whole period of fermentation up to 3 years. Glucose was the dominant free sugar, but the content was decreased after 20 days of fermentation. Most of the glucose was converted to ethanol until 40 days after initiation of acid fermentation. L-and a values of Hunter's color in fermented persimmon juice, which was naturally exuded from persimmon fruit as fermentation continued, increased gradually, while b value decreased. Acetic acid (1584 mg%) was the most abundant organic acid followed by lactic acid (712 mg%) and citric acid (48 mg%) in a persimmon fruit juice after completion of 3 year fermentation. A minute amount of residual free sugars, mainly glucose, even after 3 years of fermentation may cause changes in quality characteristics while storage for edible use.
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