In this study, the antioxidant activities of fractions (methanol, hexane, methylene chloride, butanol, ethyl acetate and water) of Solanum nigrum L. extract was investigated. The contents of total phenolic compounds of each fractions of methanol, butanol, methylene chloride, ethyl acetate, hexane and water are 4.41±0.23%, 5.57±0.35%, 9.89±0.19%, 9.86±0.19%, 1.89±0.04%, and 3.18±0.06%, respectively. For assay of antioxidant activity, 1,1-diphenyl-2-picryhydrazyl (DPPH) radical scavenging activity, reducing power and nitrite scavenging activity are evaluated. In DPPH radical scavenging activity, the highest effect was obtained from the fraction of ethyl acetate. Reducing power is ordered as ethyl acetate > methylene chloride > methanol. In nitrite scavenging activity, the highest activity was 5.5% (butanol fraction), whereas hexane fraction did not detected. Overall, antioxidant activities are closely related the content of phenolic compound in extracts of S. nigrum L.

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For accurate analysis of low molecular peptides using SELDI-TOF MS (surface enhanced laser desorption/ ionization time of flight mass spectrometry), the optimized analytical conditions should be established for a specific biological sample. This study was conducted to optimize SELDI-TOF MS analytical conditions for profiling low molecular peptide below 10 kDa presented in sorghum seeds. Analytical conditions were as follows; (1) protein chips: CM10 (weak cation exchanger) and Q10 (strong anion exchanger), (2) dilution factors of binding buffer: 1/2, 1/5, 1/10, 1/20, 1/50, 1/100, and 1/200, (3) the stringency of Q10 binding buffer: 10 mM and 100 mM, and (4) protein extraction buffers: sodium borate, sodium borate + acetone, phenol, and TCA buffers. Optimum dilution factors were selected as 1/20 and 1/50 in both protein chips, CM10 and Q10. Low stringency of Q10 binding buffer (10mM) detected more peptide peaks than high stringency (100 mM). Selected protein extraction buffers of sorghum seed for SELDI-TOF MS analysis was the sodium borate buffer in the range of 2~10 kDa, while the phenol buffer was more suitable in the range of 10~20 kDa.