The objectives of present study were to characterize the peptides which were isolated from Korean fermented soybean paste, chungkukjang, and to determine their antioxidant activities. Four fractions were collected from the methanol extract of chungkukjang by using a recycling preparative HPLC. Among fractions, Fr-2 was identified to be highly potent free radical scavenging activity in the assay of 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and nitroblue tetrazolium(NBT)-reduction inhibition. Base on antioxidant effects, fraction Fr-2 was employed for the refraction with a prep-column and separated into five fractions of which two fractions were identified to have higher antioxidant activity. To confirm the amino acid constituents of antioxidant fractions Fr-2-2 and Fr-2-3 were analyzed, and eight kinds of amino acids such as aspartic acid, threonine, serine, glutamic acid, glycine, lysine, histidine, and arginine were identified as the constituent amino acids. Antioxidant activities of the separated peptides were further assessed cell viability with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl terazolium bromide (MTT), and fluorescence-activated cell sorting (FACS) analysis of H4IIE cells treated with hydrogen peroxide (H2O2). Chungkukjang peptides have shown their ability to protect H4IIE rat hepatoma cells against H2O2- induced oxidative stress by concentration and time-dependent manner. Therefore, These results indicated that fermented soybean paste chungkukjang will be promoted the antioxidant and radical scavenging activities, and beneficial for health. The antioxidant peptide fractions Fr-2-2 and Fr-2-3 were denominated as P-NICS-1 and P-NICS-2, respectively. However, further studies were required to clarify their amino acid sequences and molecular properties, and physiological significances.

Soyasaponins A1 , DDMP-conjugated group B soyasaponins αg~;and~;βg , non-DDMP counterpart soyasaponin I, II+III, and DDMP moiety were quantified in the large-, midium-, and small-seed soybean varieties. Protein contents were ranged from 38.1% to 41.8%, and oil contents were ranged from 15.5% to 18.9%, respectively. Oil contents in the large-seed varieties were significantly higher than those of medium- and small-seed varieties. Among detected soyasaponin peaks, βg was a major soyasaponin in DDMP-conjugated group B soyasaponins followed by soyasaponin I, DDMP moiety and A1 . Soyasaponin concentration among different seed size soybean varieties. The soyasaponin concentration of mediumseed (4014.5~mug/g ) was slightly higher than those of largeseed (3755.0~mug/g ) and small-seed varieties (3620.3~mug/g ), however, the differences was statistically not significant. The composition rates of soyasaponins in the large-size seeds were 9.4% of soyasaponin A1 , 26.5% of DDMP-conjugated soyasaponins, 49.9% of non-DDMP counterpart soyasaponins, and 14.2% of DDMP moiety, respectively. Similar results were observed in the composition ratios of middle- and small-size seeds. Oil content and C:N ratio showed the significant positive correlations with total soyasaponin concentration, while the 100-seed weight, fiber, and ash contents showed the negative correlations with total soyasaponin but statistically not significant. It was noted that protein contents didn't have any relationship with group A, group B, DDMP moiety, and total soyasaponin. This fact suggested that protein contents are not affects the variation of soyasaponin concentration.

The 117 soybean cultivars were collected from nine provinces in Korea, and various seed quality traits along with isoflavone contents were evaluated to elucidate their relationship. The 100-seed weight of the black soybean (31.2 g) was significantly higher (p<0.05) than yellow soybeans (28.6 g). The composition of genistein, daidzein, and glycitein accounted for 75.8, 22.8, and 1.4 % of total isoflavone in yellow soybean cultivars, while their compositions in black soybeans were 58.5, 39.7, and 1.8%, respectively. The mean contents of total isoflavone in yellow and black soybean were l,561.6~mug~;g-1~;and~;l,018.3~mug~;g-1 . The isofalvone content showed significant variation among cultivars when classified by the seed size. In the yellow soybeans, total isoflavone content was higher in small size soybean cultivars (1,776.0~mug~;g-1) and medium size soybean cultivars (1,714.3~mug~;g-1) compared to large size ones (1,518.5~mug~;g-1) . Genistein content was proved as the major factor determining the relationship between isoflavone content and 100-seed weights (r =-0.206*). Daidzein and glycitein, however, showed no significant relationship with the 100-seed weights. Isoflavone content was not significantly correlated with color parameters L (lightness) and a (redness) values, but color parameter b (yellowness) was positively correlated with glycitein (r=0.264*) in the yellow soybeans, while its negative correlation between daidzein (r=-0.245*) and total isoflavone (r=-0.256*) were observed in black soybeans. However, these findings suggested that the seed color value may not serve as an effective parameter for estimating the isoflavone intensity of the soybeans. Variation of protein and lipid contents between yellow soybeans (n=58) and black soybeans (n=59) was relatively stable, however, protein and lipid contents have no significant relationship with isoflavone content.