Antioxidant Activities of Trypsin Inhibitor, a 33 KDa Root Storage Protein of Sweet Potato (Ipomoea batatas (L.) Lam cv. Tainong 57)

Abstract

Trypsin inhibitors (TIs), root storage proteins, were purified from sweet potato (Ipomoea batatas[L.] Lam cv. Tainong 57) roots by trypsin affinity column according to the methods of Hou and Lin (Plant Sci. 1997, 126, 11-19 and Plant Sci. 1997, 128, 151-158). A single band of 33 kDa TI was obtained by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels. This purified 33 kDa TI had scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. There was positive correlation between scavenging effects against DPPH (2 to 22%) and amounts of 33 kDa TI (1.92 to 46 pmol). The scavenging activities of 33 kDa TI against DPPH were calculated from linear regression to be about one-third of those of glutathione between 5 and 80 pmol. Using electron paramagnetic resonance (EPR) spectrometry for hydroxyl radical detection, it was found that 33 kDa TI could capture hydroxyl radical, and the intensities of EPR signal were significantly decreased from 1.5 to 6 pmol of 33 kDa TI compared to those of the controls. It is suggested that 33 kDa TI, one of the sweet potato root storage proteins, may play a role as an antioxidant in roots and may be beneficial to health when it is consumed.

Purification and characterization of a trypsin inhibitor from the seeds of <italic>Artocarpus heterophyllus</italic> Lam.

“…AHLTI was a single polypeptide chain protein with the molecular mass of 28.5 kDa determined by HPLC and SDS-PAGE, which was similar to that of Kunitz-type inhibitor. Kunitz inhibitors have been purified from Crotalaria pallida seeds and sweet potato [24,25]. The amino acid of N-terminal sequence of AHLTI was DEPPSELDAS, which was submitted to the NCBI-BLAST search system for alignment analysis.…”

Protein hydrolysates obtained from Azufrado (sulphur yellow) beans (Phaseolus vulgaris): Nutritional, ACE-inhibitory and antioxidative characterization

“…Radical-scavenging activity 2.4.1. DPPH radical-scavenging activities Scavenging activity of the protein hydrolysates against DPPH radical was performed according to Hou et al (2001). Briefly, the samples were diluted in a 0.1 mol/L sodium phosphate buffer supplemented with Triton X-100 (1 g/100 ml), pH 7.…”

Expression of sweet potato cysteine protease SPCP2 altered developmental characteristics and stress responses in transgenic Arabidopsis plants

“…It contains plenty of vitamin B complex, vitamin C, b-carotenoids, multiple minerals and high potassium and calcium (Hattori et al, 1985). Several medicative effects of sweet potato trypsin inhibitor, which is the major storage root proteins, have been reported, including antioxidant activity (Hou et al, 2001, Huang et al, 2007a, 2007b, inhibition of angiotensin converting enzyme activity Huang et al, 2006), and growth inhibition and induction of apoptosis in NB4 promyelocytic leukemia cells (Huang et al, 2007c).…”