Exploring the novel antioxidant peptides in low-salt dry-cured ham: Preparation, purification, identification and molecular docking.

Dry-cured ham is important source of bioactive peptides. In this study, the antioxidant activities of peptides and components from low and fully salted dry-cured hams were compared by peptidomics. And novel antioxidant peptides were identified and characterized. The results showed that the peptides (<3 KDa) extracted from low-salt dry-cured ham had higher antioxidant activity. Therefore, the antioxidant peptides in low-salt dry-cured ham were further characterized and the mechanism of their antioxidant activity was investigated. From the five candidate peptides selected, we found DWPDARGIWHND (DD12) to be highly stable, non-sensitizing, and non-toxic with the highest free radical scavenging activity. Molecular docking predicted that DD12 interacted with Keap1 through hydrogen-bond formation and hydrophobic interactions, suggesting that DD12 had good cellular antioxidant activity. DD12 peptide can bind to DPPH• and ABTS•+, resulting in strong free radical scavenging activity. Our findings support the development and application of natural antioxidant peptides in dry-cured ham.

Correction to: Bioactive compounds and antioxidant activities of Quercus salicina Blume extract.

[This corrects the article DOI: 10.1007/s10068-020-00755-1.].

Bioactive compounds and antioxidant activities of Quercus salicina Blume extract.

Quercus salicina Blume (QS) is an oak species that is indigenous to Japan and Korea. Historically, extracts of leaves, stems, barks and buds from the QS tree had been extensively utilized as herbal medicines. As rich sources of natural antioxidants, QS extracts could prevent oxidative stress and the occurrence of related neurodegenerative diseases. In pharmaceutical applications, decoction or infusion of comminuted QS powder is prepared as an herbal tea for oral use. Various extraction methods and extracting mediums showed the potential antioxidant activities of QS extracts, as well as the different types and levels of bioactive compounds found in them. Due to their functional properties and possibly low-level of cytotoxicity, the potential application of QS extracts as a novel food ingredient could be considered. In this review paper, a brief overview about QS extracts and their bioactive components, antioxidant activities, toxicity and technological applications is described based on previous works.

Quantitative proteomic analysis reveals that Luks-PV exerts antitumor activity by regulating the key proteins and metabolic pathways in HepG2 cells.

Hepatocellular carcinoma (HCC) is a complicated and poor prognosis cancer, necessitating the development of a potential treatment strategy. In this study, we initially revealed that LukS-PV belonged to leukocidin family performs an anti-HCC action. Then, we used liquid chromatography-mass spectrometry (LC/MS) to compare protein expression profiles of the LukS-PV-treated human HCC cell lines HepG2 and the control cells. GO annotations and Kyoto Encyclopedia of Genes and Genomes pathway analysis were carried out of differential expression followed by protein-protein interactome, to explore the underlying cancer suppressor mechanisms of LukS-PV for human HCC. A total of 88 upregulated proteins and 46 downregulated proteins were identified. The top 10 proteins identified by the MCC method are FN1, APP, TIMP1, nucleobindin-1, GOLM1, APLP2, CYR61, CD63, ENG, and CD9. Our observation on protein expression indicated that LukS-PV produces a signature affecting central carbon metabolism in cancer, galactose metabolism, and fructose and mannose metabolism pathways. The results give a functional effects and molecular mechanism insight, following LukS-PV treatment.

LukS-PV induces apoptosis in acute myeloid leukemia cells mediated by C5a receptor.

LukS-PV is one of the two components of Panton-Valentine leucocidin (PVL). Our previous study showed that LukS-PV can induce apoptosis in human acute myeloid leukemia (AML) THP-1 and HL-60 cells. C5aR (C5a receptor) is the receptor for PVL, but whether C5aR plays a key role in LukS-PV induced apoptosis is unclear. The aim of this study was to establish whether C5aR plays a physiological role in apoptosis of leukemia cells induced by LukS-PV. We investigated the role of C5aR in leukemia cell apoptosis induced by LukS-PV by pretreatment of THP-1 and HL-60 cells with C5aR antagonist and transfection to knockdown C5aR in THP-1 cells or overexpress C5aR in Jurkat cells before treatment with LukS-PV. Cell apoptosis was analyzed by staining with Annexin V/propidium iodide or Annexin V-PE/7-AAD. Mitochondrial membrane potential (MMP) was determined using JC-1 dye. The expression of apoptosis-associated genes and proteins was identified by qRT-polymerase chain reaction and Western blotting analysis, respectively. As the C5aR antagonist concentration increased, the rate of apoptosis induced by LukS-PV decreased, the MMP increased, and expression of pro-apoptotic Bax and Bak genes and proteins was downregulated while that of anti-apoptotic Bcl-2 and Bcl-x genes and proteins was upregulated. Knockdown of C5aR also decreased LukS-PV-induced THP-1 cell apoptosis. LukS-PV did not induce apoptosis of Jurkat cells, which have no endogenous C5aR expression; however, LukS-PV did induce apoptosis in Jurkat cells after overexpression of C5aR. Correspondingly, the MMP decreased and Bax and Bak were upregulated while Bcl-2 and Bcl-x were downregulated. LukS-PV can induce apoptosis in AML cells by targeting C5aR. C5aR may be a potential therapeutic target for AML and LukS-PV is a candidate targeted drug for the treatment of AML.

Interleukin-21 up-regulates interleukin-21R expression and interferon gamma production by CD8+ cells in SHIV-infected macaques.

Interleukin-21 (IL-21) is produced primarily by CD4+ T cells and regulates immunity against human/simian immunodeficiency virus (HIV/SIV) infection. Activated CD8+ cells and their secreted interferon-gamma (IFN-γ) are crucial for the control of acute HIV/SIV infection. However, whether IL-21 can regulate IFN-γ production by CD8+ cells remains controversial. Rhesus macaques (RMs, n = 8) were infected with SHIV and the levels of plasma IL-21, IFN-γ and the frequency of peripheral blood activated T cells were measured longitudinally. Following infection with SHIV, the levels of plasma IL-21 and IFN-γ increased, peaked at 17 days postinfection and declined later. Furthermore, IL-21 induced IL-21 receptor (IL-21R) and IFN-γ, perforin, but not granmyze B, expression in CD8+ cells from four selected SHIV-infected RMs. The regulatory effect of IL-21 on CD8+ cell function appeared to be associated with increased levels of STAT3, but not STAT5, phosphorylation in CD8+ cells from SHIV-infected RMs. In parallel, treatment with soluble IL-21R/Fc, an inhibitor of IL-21-induced activation of JAK1/3 and STAT3, abrogated IL-21-induced STAT3 activation and IFN-γ production in CD8+ cells from SHIV-infected RMs in vitro. Our data indicated that IL-21 was a positive regulator of IFN-γ-secreting CD8+ cells and increased the STAT3 phosphorylation, regulating T-cell immunity against acute SHIV infection in RMs. Our findings may provide a new basis for the development of immunotherapies for the control of SHIV/HIV infection.