The structure of isoflavone moiety in soybean could be altered by thermal treatment. Thus, this study analyzed the isoflavone profiles of raw soybean extract (RSe, no pretreatment), blanched soybean extract (BSe, at 85oC for 3 min), and cooked soybean extract (CSe, at 95oC for 30 min) and measured their α-glucosidase inhibitory activities. The content of malonylglucosides in RSe decreased considerably during their transformation into BSe and CSe. The total content of isoflavones in RSe and BSe was fairly similar, although there was a significant difference in the respective values for RSe and CSe. It was concluded that the cooking treatment significantly impacted soybean isoflavone content and, eventually, one-quarter of isoflavones were lost in CSe. According to authentic isoflavone tests, the inhibition of α-glucosidase by isoflavone aglycones was more effective than that of the corresponding isoflavone glucosides. The α-glucosidase inhibitions were observed in the order of BSe (70.0%), CSe (53.3%), and RSe (32.3%). However, it was challenging to identify which isoflavone derivative had contributed to the phenomenon mentioned above. Hence, the blanching of soybean seemed to be more appropriate than cooking for preparing soybean extract to inhibit α-glucosidase due to the higher loss of isoflavone during cooking.

This study investigated optimal extraction conditions for applying Capsicum annuum L. leaf as a functional food resource. Capsicum annuum L. leaf was extracted at different extraction solvents (water and 95% ethanol), extraction temperatures (80oC and 100oC), and e xtraction times ( 30, 60, and 9 0 min), a nd t he extracts were e valuated for extraction yield, luteolin content as a major flavonoid component, antioxidant activity, and α-glucosidase inhibitory activity. The extraction yield, luteolin content, DPPH and ABTS radical scavenging activities, and α-glucosidase inhibitory activity of the hot water extract were higher than those of the ethanol extract. In evaluating the extraction temperature of Capsicum annuum L. leaf, the antioxidant activities were similar, but the extraction yields, luteolin contents, and α-glucosidase inhibitory activities were higher at 100oC extraction. In evaluating the extraction time of Capsicum annuum L. leaf, extraction yield increased as the extraction time increased, but antioxidant activity and α-glucosidase inhibitory activity were the highest at 60 min of extraction. These results suggest that the optimum extraction conditions of Capsicum annuum L. leaf are hot water for 60 min at 100oC, and the extracts can be used as a functional food resource.

Coprinellus miaceus, belongs to Coprinaceae of Agaricales, Basidiomycota, has been used for an edible purposes in asian countries. This experiment was initiated to evaluate the free radical scavenging, free radical scavenging, anti-acetylcholinesterase, anti-inflammatory and α-glucosidase inhibitory activities of C. micaceus fruiting bodies extracted with methanol and hot water. In 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay, the scavenging activities of methanol and hot water extracts were lower than that of positive control, BHT. The chelating effects of methanol and hot water extracts were significantly higher than positive control, BHT at the concentrations of 0.125-2.0 mg/mL. In the reducing power assay, methanol and hot water extracts exhibited the lower activities than the positive control, BHT at the 0.125-0.2 mg/mL concentration. In the HPLC analysis of phenolic acids profile of the mushroom fruiting bodies, 4 phenolic compounds including procatechuic acid, chlorogenic acid, (-)-epicatechin, and naringin were detected. The tyrosinase inhibitory activities of methanol and hot water extracts were 91.33% and 91.99% at 2.0 mg/mL concentration, while the inhibitory activity of kojic acid, the positive control, was 99.61%. Nitric oxide (NO) production in lipopolysaccahride (LPS) activated RAW 264.7 cells were inhibited by the methanol extract in a concentration dependent manner. In the acetylcholinesterase (AChE) inhibitory activity assay, methanol and hot water extracts of the mushroom inhibited the AChE by 94.64% and 74.19%, respectively at the 1.0 mg/mL concentration, whereas galanthamine, the standard drug inhibited the AChE activity by 97.80% at the same concentration. The methanol and hot water extracts of the mushroom inhibited the α-glucosidase activity by 62.26% and 67.59%, respectively at the 2.0 mg/mL concentration, while acarbose, the positive control inhibited the α-glucosidase activity by 81.81% at the same concentration. Therefore, it is concluded that fruiting bodies of C. micaceus contained natural antioxidant, anti-inflammatory, anti-acetylcholinesterase and α-glucosidase inhibitory substances which might be used for promoting human health.

Background: The plant Aster koraiensis has long been used as an ingredient in folk medicine. It has been reported that Aster koraiensis extract (AKE) prevents the progression of diabetes-induced retinopathy and nephropathy. However, although these beneficial effects of AKE on diabetes complications have been identified, the antidiabetic effects of AKE have not yet been completely investigated and quantified. In the present study, the glucose-lowering and antioxidant effects of aqueous and ethanolic AKEs were evaluated. Methods and Results: The glucose-lowering effects of aqueous and ethanolic (30%−, 50%−, and 80%-ethanol) AKEs were investigated via α-glucosidase inhibitory assays. The mode of inhibition by AKEs on α-glucosidase was identified through kinetic analysis. The total antioxidant capacity of each of the 4 AKEs was evaluated by assessing their conversion rate of Cu2+ to Cu+. The content of chlorogenic acid and 3,5-di-O-caffeoylquinic acid, the bioactive compounds in AKE, in each extract were analyzed by high performance liquid chromatography (HPLC). The AKEs showed potent α-glucosidase inhibitory activity with mixed inhibition mode, and significant antioxidant capacity. Conclusions: These results of this study suggested that the AKEs tested had α-glucosidase inhibitory and antioxidant effects. Among the extracts, the 80% ethanol extract showed the most significant α-glucosidase inhibitory activity, with a half maximal inhibitory concentration (IC50 value) of 1.65 ± 0.36㎎/㎖ and a half maximal effective concentration (EC50 value) for its antioxidant activity of 0.42 ± 0.10㎎/㎖. It can therefore be used as a source of therapeutic agents to treat diabetes patients.

Background: Invasion of these invasive plants in the ecosystem threatens the habitat of endemic species, reduces biodiversity, and causes a disturbance in the ecological system. Hypochaeris radicata L. (Asteraceae), the most invasive plant in Korea, particularly in Jeju Island, invades farmlands, and autochthonous forests, resulting in the establishment of monocultures and modification of the ecosystem structure. Methods and Results: In this study was, we evaluated the biological activity of 70% ethanolic extracts from different parts of Hypochaeris radicata L. The biological activities of 70% ethanolic extracts of different parts, such as flower, leaf, stem, and root, of H. radicata were investigated. The total polyphenol content was highest in flower extracts (50.82 ± 3.16 ㎎ · GAE/g). In addition, the highest flavonoid content was observed in flower extract (15.19 ± 2.03㎎ · QE/g). The flower extract of H. radicata exhibited stronger DPPH radical-scavenging activities, ABTS radical scavenging activities, and reducing power than the other parts. The flower extract of H. radicata was observed to have the highest tyrosinase and α-glucosidase inhibitory activities. Conclusions: The flower extracts of H. radicata exhibited remarkable antioxidant activity as well as tyrosinase and α-glucosidase inhibitory effects. These activities might be related to the phenolic compounds present in the H. radicata flower extract.

Background: The biological activities of Tradescantia pallida grown in Korea have not been well determined, thus the aim of this study was to investigate the possibility of using it as a medicinal plant. Methods and Results: To investigate the antioxidant activity, α-glucosidase inhibitory effect and antimicrobial activity of T. pallida, we performed the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity and reducing power assay. This assay for T. pallida leaf extract showed the highest antioxidant activity for the ethyl acetate fraction (RC50= 14.55 ± 0.16㎍/㎖ and Abs = 0.613 at 300㎍). Further, the ethyl acetate fraction exhibited higher α-glucosidase inhibitory effect with an IC50 value of 14.1 ± 0.1㎍/㎖ and showed antimicrobial activity against gram positive bacteria (minimum inhibitory concentration = 1,000㎍/㎖). Conclusions: The ethyl acetate fraction of the crude methanol extract of T. pallida showed remarkable antioxidant activity, α-glucosidase inhibitory effects and antimicrobial activity. These activities might be related to the flavonoid content in the T. pallida leaf extract.

Maesa japonica (Thunb.) is an evergreen shrub belonged to the Myrsinaceae family, which was discovered in2006 in South Korea. And, its biological functions have not been well studied. In this study, we determined the antioxidantactivities, α-glucosidase inhibitory effects and antimicrobial activities of methanol extract and the solvent fractions of M.japonica leaves and twigs. The highest antioxidant activity obtained by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scav-enging assay and reducing power assay was found in the ethylacetate fraction of twigs methanol extract, which contained thehighest level of total phenolic compounds compared to the other fractions. In addition, ethylacetate fraction of twigs extractexhibited higher inhibitory activities against α-glucosidase (IC50=0.8㎍/㎖) compared to the IC50 of the buthanol fraction(IC50=16㎍/㎖) of leaves extract. It showed antimicrobial activities against Bacillus atrophaeus and Bacillus subtilis subsp.Spizizenii. Although the data is too limited, the current study is the first report on biological functions of M. japonica.

We studied the total polyphenol content, DPPH radical scavenging activity, hydroxyl radical scavenging activity and α-glucosidase inhibition of water extracts from 17 medicinal plants. Total polyphenol contents ranged from 10.0 (Coix lachryma-jobi L, CL) ~ 279.7 (Perilla sikokiana, PS)mg/g. The water extract from medicinal plants were evaluated for its free radical scavenging activities and compared with a commercial antioxidant, ascorbic acid. DPPH radical scavenging activity of Pyrus pyrifolia (PP), Chamaecyparis obtusa L. (COL), Chamaecyparis obtusa F. (COF), and PS were higher than positive control. Higher hydroxyl radical scavenging activity were shown in Acanthopanax senticosus (AS) and Cordyceps militaris (CM) than the other plants. The highest anti-α-glucosidase activity was observed in Cornus officinalis (CO) and Paeonia suffruticosa Andrews (PSA) water extracts. PSA showed not only the higher DPPH radical scavenging activity but also the anti-α-glucosidase activity. The results of our study that PP, COL, COF, PS, AS, CM, CO and PSA could be potential candidates for natural antioxidants.