Amino acids imprinted ZIF-8s for the highly efficient and selective adsorption of antioxidant peptides from silkworm pupa protein.

Antioxidant peptides from edible protein sources have attracted great attention due to their high activity, easy adsorption and low toxicity. The purpose of this study was to develop a new MOF material with specific recognition and capture ability to achieve the aim of highly efficient and selective antioxidant peptides from silkworm pupa protein hydrolysate-N (SPPH-N). Firstly, Histidine (His) widely presented in antioxidant peptides was used to in-suit construct the modified ZIF-8 material (ZIF-His) with imprinted defective mesopores, based on "molecular imprinting strategy". Then, it was applied to extract antioxidant peptides from SPPH-N. ZIF-His exhibited high adsorption uptake for antioxidant peptides and especially presented specific adsorption property for peptides contained His, tryptophan, phenylalanine and tyrosine. Three peptides with the highest antioxidant activity (FKVPNMY, AVNMVPFPR and VNMVPFPR) from ZIF-His eluent were identified by Nano-LC-MS/MS. These peptides were synthesized and presented the excellent free radicals scavenging activity and the Ferric reducing power.

Accurate prediction for adsorption rate of peptides with high ACE-inhibitory activity from sericin hydrolysate on thiophene hypercross-linked polymer using CoMSIA in 3D-QSAR model.

Efficient screening of angiotensin converting enzyme inhibitory (ACE-I) peptides from agricultural or edible sources attract increasing attention. However, their purification process from the complex natural system is still semi-empirical or even uncontrollable, which has seriously reduced their screening efficiency. Herein, inspired by the prediction of ACE-I activity, 3D-QSAR was proposed to predict the adsorption performance of peptides from sericin hydrolysate (SH) having high ACE-I activity on porous hypercross-linked polymers according to their molecular structures. Thiophene hypercross-linked polymer (T-HCP) possessing better screening capacity for ACE-I peptides was chosen as our research object in this work. The sequence and relative adsorption rate of 101 peptides in SH were analyzed by LC-MS and was used as a database to construct the relationship of peptide's chemical structure and adsorption performance on T-HCP by Comparative molecular similarity indices analysis (CoMSIA) from 3D-QSAR. Optimum CoMSIA revealed that enhanced interaction of hydrophobicity and H-bond between T-HCP and the peptide was conducive to increase the adsorption performance of di- to hexa- peptides. Based on these relationships, the adsorption capability of 24 designed peptides with distinguished hydrophobic and H-bond fields was predicted on T-HCP by using optimum CoMSIA and the results of half of these were verified, which showed high consistency with their predicted adsorption rate. Interestingly, these peptides having higher adsorption capacities on T-HCP also possessed higher ACE-I activity. This can be attributed to the high concentration of aromatic surface with π-π interaction and weak-polar CSC group with H-bond interaction on T-HCP material, which is ideal for the selective adsorption of peptides with higher ACE-I activity from SH. This study provides important theoretical guidance for the industrial screening of bio-functional peptides from complex protein mixtures.

Chemotherapeutic agent CPT-11 eliminates peritoneal resident macrophages by inducing apoptosis.

CPT-11 (Irinotecan) is a first-line chemotherapeutic agent in clinic, but it may induce side effects including diarrhea and enteritis in patients. The underlying mechanism of CPT-11's intestinal toxicity is unclear. Peritoneal resident macrophages have been reported to be important for the maintenance of intestinal homeostasis. In this study, we evaluated the cytotoxic effects of CPT-11 on mouse peritoneal resident macrophages. CPT-11 was administered intraperitoneally to mice and their peritoneal exudate cells were isolated for evaluation. CPT-11 treatment strikingly decreased the ratio of F4/80(hi)MHCII(low) large peritoneal macrophages (LPMs), which are regarded as prenatally-originated peritoneal resident macrophages. Consistent with this, the transcription factor GATA6 specifically expressed in LPMs was barely detectable in the macrophages from CPT-11-treated mice, indicative of elimination of LPMs. Such elimination of LPMs was at least partly due to CPT-induced apoptosis in macrophages, because inhibition of apoptosis by caspase-3 inhibitor z-DEVD-fmk significantly diminished the loss of GATA6(+) LPMs. As GATA6 is a transcription factor that controls expression of multiple genes regulating peritoneal B-1 cell development and translocation, elimination of GATA6(+) LPMs led to a great reduction in B-1 cells in the peritoneal cavity after CPT-11 treatment. These results indicated that CPT-11-induced apoptosis contributed to the elimination of peritoneal resident macrophages, which might in turn impair the function of peritoneal B-1 cells in maintaining intestinal homeostasis. Our findings may at least partly explain why CPT-11 treatment in cancer patients induces diarrhea and enteritis, which may provide a novel avenue to prevent such side effects.

The BH3-mimetic gossypol and noncytotoxic doses of valproic acid induce apoptosis by suppressing cyclin-A2/Akt/FOXO3a signaling.

Previously we reported that valproic acid (VPA) acts in synergy with GOS to enhance cell death in human DU145 cells. However, the underlying mechanism remains elusive. In this study, we observed that such synergistic cytotoxicity of GOS and VPA could be extended to human A375, HeLa, and PC-3 cancer cells. GOS and VPA co-treatment induced robust apoptosis as evidenced by caspase-8/-9/-3 activation, PARP cleavage, and nuclear fragmentation. GOS and VPA also markedly decreased cyclin A2 protein expression. Owing to the reduction of cyclin A2, Akt signaling was suppressed, leading to dephosphorylation of FOXO3a. Consequently, FOXO3a was activated and the expression of its target genes, including pro-apoptotic FasL and Bim, was upregulated. Supporting this, FOXO3a knockdown attenuated FasL and Bim upregulation and apoptosis induction in GOS+VPA-treated cells. Furthermore, blocking proteasome activity by MG132 prevented the downregulation of cyclin A2, dephosphorylation of Akt and FOXO3a, and induction of apoptosis in cells co-treated with GOS and VPA. In mouse model, GOS and VPA combination significantly inhibited the growth of A375 melanoma xenografts. Our findings indicate that GOS and VPA co-treatment induces apoptosis in human cancer cells by suppressing the cyclin-A2/Akt/FOXO3a pathway.

Piperine metabolically regulates peritoneal resident macrophages to potentiate their functions against bacterial infection.

Pepper, a daily-used seasoning for promoting appetite, is widely used in folk medicine for treating gastrointestinal diseases. Piperine is the major alkaloid in pepper and possesses a wide range of pharmacological activities. However, the mechanism for linking metabolic and medicinal activities of piperine remains unknown. Here we report that piperine robustly boosts mTORC1 activity by recruiting more system L1 amino acid transporter (SLC7A5/SLC3A2) to the cell membrane, thus promoting amino acid metabolism. Piperine-induced increase of mTORC1 activity in resident peritoneal macrophages (pMΦs) is correlated with enhanced production of IL-6 and TNF-α upon LPS stimulation. Such an enhancement of cytokine production could be abrogated by inhibitors of the mTOR signaling pathway, indicating mTOR's action in this process. Moreover, piperine treatment protected resident pMΦs from bacterium-induced apoptosis and disappearance, and increased their bacterial phagocytic ability. Consequently, piperine administration conferred mice resistance against bacterial infection and even sepsis. Our data highlight that piperine has the capacity to metabolically reprogram peritoneal resident macrophages to fortify their innate functions against bacterial infection.

Treatment with sodium benzoate leads to malformation of zebrafish larvae.

Sodium benzoate (SB) is a commonly used food preservative and anti-microbial agent in many foods from soup to cereals. However, little is known about the SB-induced toxicity and teratogenicity during early embryonic development. Here, we used zebrafish as a model to test the toxicity and teratogenicity because of their transparent eggs; therefore, the organogenesis of zebrafish embryos is easy to observe. After low dosages of SB (1-1000 ppm) treatment, the zebrafish embryos exhibited a 100% survival rate. As the exposure dosages increased, the survival rates decreased. No embryos survived after treatment with 2000 ppm SB. The 50% lethal dose (LD(50)) of zebrafish is found to be in the range of 1400-1500 ppm. Gut abnormalities, malformation of pronephros, defective hatching gland and edema in pericardial sac were observed after treatment with SB. Compared to untreated littermates (vehicle-treated control), SB-treated embryos exhibited significantly reduced tactile sensitivity frequencies of touch-induced movement (vehicle-treated control: 27.60+/-1.98 v.s. 1000 ppm SB: 7.89+/-5.28; N=30). Subtle changes are easily observed by staining with specific monoclonal antibodies F59, Znp1 and alpha6F to detect morphology changes in muscle fibers, motor axons and pronephros, respectively. Our data showed that the treatment of SB led to misalignment of muscle fibers, motor neuron innervations, excess acetyl-choline receptor cluster and defective pronephric tubes. On the basis of these observations, we suggest that sodium benzoate is able to induce neurotoxicity and nephrotoxicity of zebrafish larvae.