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    Item type:Publication,
    Isolation and characterization of anti-inflammatory peptides derived from trypsin hydrolysis of microalgae protein (Synechococcus sp. VDW)
    (2019-10-02)
    Suttisuwan, Rutairat
    ;
    Phunpruch, Saranya
    ;
    Saisavoey, Tanatorn
    ;
    Sangtanoo, Papassara
    ;
    Thongchul, Nuttha
    The Synechococcus sp. VDW peptides were prepared by trypsin digestion, which was then purified by ultrafiltration with molecular weight cut off membranes of 10, 5 and 3 kDa. Among the fractions, the MW <3 kDa fraction exhibited high levels of inhibitory activity toward the NO radical scavenging activities with IC<inf>50</inf> values of 34.51 ± 9.8 μg/mL. The MW <3 kDa fraction was purified by reversed-phase HPLC to yield four fractions. The 30–40 min sub-fraction with maximum NO radical scavenging activity (77.50 ± 0.55%) was selected for further analysis by Q-TOF ESI mass spectrometry. Five isolated peptides with amino acid sequences of AILQSYSAGKTK; 1,265.69 Da, ALNKTHLIQTK; 1,265.74 Da, LLVHAPVK; 875.55 Da, IPDAHPVK; 875.48 Da, and VVVLRDGAVQQLGTPR; 1,706.97 Da were identified. The MW <3 kDa fraction showed no cytotoxicity toward RAW264.7 macrophage cells. Quantitative RT-PCR results showed that the MW <3 kDa fraction reduced gene expression of pro-inflammatory cytokines iNOS, TNF-α, COX-2, and IL-6. The peptides isolated from the MW <3 kDa fractions represent potential model peptides to develop natural anti-inflammation food-grade ingredients, drugs, and cosmetic products.
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    Item type:Publication,
    Free radical scavenging properties and induction of apoptotic effects of fa fraction obtained after proteolysis of bioactive peptides from microalgae synechococcus sp. VDW
    (2019-01-01)
    Suttisuwan, Rutairat
    ;
    Phunpruch, Saranya
    ;
    Saisavoey, Tanatorn
    ;
    Sangtanoo, Papassara
    ;
    Thongchul, Nuttha
    This study aims to determine the antioxidant activity of bioactive peptides derived from Synechococcus sp. VDW cells cultured for 21 days. Synechococcus sp. VDW protein hydrolysates were prepared with trypsin and purified by ultrafiltration with molecular mass cut-off membranes of 10, 5 and 3 kDa. The M<3 kDa (FA) fraction had the highest 2,2'-azino- bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities, with IC50 values of (11.5±0.3) and (13.6±0.2) μg/ mL, respectively. The FA fraction was separated by reversed phase HPLC to yield four subfractions (F1-4). The F4 subfraction showed the highest maximum ABTS radical scavenging activity (3.55±0.61) % and it was selected for further analysis by electrospray ionisation quadrupole time-of-flight mass spectrometry (ESI-Q-TOF-MS/MS) based on de novo peptide sequencing. Five antioxidant peptides were identified, of which AILESYSAGKTK had the highest ABTS radical scavenging activity. Furthermore, the FA fraction showed high cytotoxic activities against human cancer-derived cell lines, especially the colon cancer cell line (SW620) with an IC50 value of (106.6±21.5) μg/mL, but not the untransformed Wi38 cell line. The FA fraction activated the apoptotic pathway in SW620 cells after treatment for 24, 48 and 72 h, with the highest activities of caspases-3, -8 and -9 being observed after treatment for 72 h. These findings suggested that microalgae Synechococcus sp. VDW may be used to develop natural anticancer drugs.