Brønsted acid-induced transannulation of the phytochemical zerumbone.

The sesquiterpene zerumbone was treated with HCl in ethyl acetate under the light-protected condition, and the time-dependent conversions were analyzed by gas chromatography. Nine products were isolated, and their structures were revealed by several NMR measurements such as 1H NMR, 13C{1H} NMR, distortionless enhancement by polarization transfer (DEPT)-135, 1H-1H correlation spectroscopy (COSY), 1H-13C heteronuclear multiple quantum coherence (HMQC), and 1H-13C heteronuclear multiple bond coherence (HMBC). The X-ray crystallography determined the stereochemistries of the three products and the two derivatives. After all, this acidic reaction was found to provide the (2Z,6E,10E)-isomer, the two HCl adducts, the two 7,6-bicyclic compounds, the valence isomers cycloheptatriene and norcaradiene, and the two dihydronaphthalenes. Based on the product analyses of the reactions from the isolated intermediates as well as the mechanistic considerations, these products were arranged into two paths: one of the paths ended in the two dihydronaphthalenes the same as previously reported under the Lewis acid condition; the other ended in the 7,6-bicyclic compound, the epimer of which was known. In addition, density functional theory (DFT) calculations indicated that the (2Z,6E,10E)-isomer was more stable than the (2E,6E,10Z)-isomer as well as that the activation energy for the isomerization at the C2-C3 double bond decreased to half by protonation. The closely examined reaction mechanisms under the simple acidic condition were established upon the intensive characterization of the intermediates and products, and these findings would add to the attractive value of zerumbone and would help understand the unknown biosynthetic pathway around sesquiterpenoids.

[Establishment of Simple and Quick Method to Confirm the Heating History of Milk and Dairy Products].

In Japan, the import quarantine procedure for dairy products was newly introduced in November 2017. The treatment such as 15 sec heating at 72℃ is required for virus inactivation when importing milk or dairy products from the area which is not free from foot and mouth disease. Moreover, the heating history of imported items is also inspected as import quality procedures. The IDF 63 method is known as one of the methods to confirm the heating history of milk by checking the alkaline phosphatase (ALP) activity. However, this procedure is complicated for daily quarantine inspection. Therefore, we attempted the ALP activity measurement based on the amount of fluorescent substance produced by the enzymatic reaction. Milk and dairy products derived from cow, sheep, and goat were tested after various heat treatment conditions. The ALP of heat-treated milk and dairy products derived from these species above were confirmed to be inactivated under substantially the same heat treatment for 15 sec at 72℃. The measurement method established in this study is simpler, faster, and requires smaller amount of sample compared to other methods. Additionally, the method was also applicable to confirm the heating history of various dairy products by making them into suspension.

Remarkable Potential of Zerumbone to Generate a Library with Six Natural Product-like Skeletons by Natural Material-Related Diversity-Oriented Synthesis.

Diversity-oriented synthesis (DOS) is an effective strategy for the quick creation of diverse and high three-dimensional compounds from simple starting materials. The selection of a starting material is the key to constructing useful, chemically diverse compound libraries for the development of new drugs. Here, we report a novel, general, and facile strategy for the creation of diverse compounds with high structural diversity from readily available natural products, such as zerumbone, as the synthetic starting material. Zerumbone is the major component of the essential oil from wild ginger, Zingiber zerumbet Smith. It is noteworthy that zerumbone has a powerful latent reactivity, partly because of its three double bonds, two conjugated and one isolated, and a double conjugated carbonyl group in an 11-membered ring structure. In fact, zerumbone has been shown to be a successful example of natural material-related DOS (NMRDOS). We will report that zerumbone can be converted in one chemical step from four zerumbone derivatives into rare and markedly different scaffolds by transannulation.

Homologous Expression and Characterization of Gassericin T and Gassericin S, a Novel Class IIb Bacteriocin Produced by Lactobacillus gasseri LA327.

Lactobacillus gasseri LA327, isolated from the large intestine tissue in humans, is a bacteriocinogenic strain with two kinds of class IIb bacteriocin structural genes, i.e., those for gassericin T (GT) and acidocin LF221A (Acd LF221A). In this study, DNA sequencing of the genes for GT and Acd LF221A from L. gasseri LA327 revealed that the amino acid sequences for GT corresponded with those for GT genes, except for GatK (histidine kinase). However, Acd LF221A genes had analogues which differed in at least one amino acid residue, to encode a class IIb bacteriocin designated gassericin S (GS). The LA327 strain retained antimicrobial activity after the deletion of the GT structural genes (gatAX); however, both GS and GT activities were lost by deletion of the putative ABC transporter gene (gatT). This indicates that the LA327 strain produces GS and GT and that GS secretion is performed via GT genes with the inclusion of gatT Homologous expression using deletion mutants of GS and GT, each containing a single peptide, elucidated that GS (GasAX) and GT (GatAX) showed synergistic activity as class IIb bacteriocins and that no synergistic activity was observed between GS and GT peptides. The molecular mass of GS was estimated to be theoretical ca. 5,400 Da by in situ activity assay after SDS-PAGE, clarifying that GS was actually expressed as an active class IIb bacteriocin. Furthermore, the stability of expressed GS to pH, heat, and protease was determined.IMPORTANCE Bacteriocins are regarded as potential alternatives for antibiotics in the absence of highly resistant bacteria. In particular, two-peptide (class IIb) bacteriocins exhibit the maximum activity through the synergy of two components, and their antimicrobial spectra are known to be relatively wide. However, there are few reports of synergistic activity of class IIb bacteriocins determined by isolation and purification of individual peptides. Our results clarified the interaction of each class IIb component peptide for GT and GS via the construction of homologous mutants, which were not dependent on the purification. These data may contribute to understanding the mechanisms of action by which class IIb bacteriocins exhibit wide antibacterial spectra.

Auto-oxidation products of epigallocatechin gallate activate TRPA1 and TRPV1 in sensory neurons.

The sensation of astringency is elicited by catechins and their polymers in wine and tea. It has been considered that catechins in green tea are unstable and auto-oxidized to induce more astringent taste. Here, we examined how mammalian transient receptor potential V1 (TRPV1) and TRPA1, which are nociceptive sensors, are activated by green tea catechins during the auto-oxidation process. Neither TRPV1 nor TRPA1 could be activated by any of the freshly prepared catechin. When one of the major catechin, epigallocatechin gallate (EGCG), was preincubated for 3h in Hank's balanced salt solution, it significantly activated both TRP channels expressed in HEK293 cells. Even after incubation, other catechins showed much less effects. Results suggest that only oxidative products of EGCG activate both TRPV1 and TRPA1. Dorsal root ganglion (DRG) sensory neurons were also activated by the incubated EGCG through TRPV1 and TRPA1 channels. Liquid chromatography-mass spectrometry revealed that theasinensins A and D are formed during incubation of EGCG. We found that purified theasinensin A activates both TRPV1 and TRPA1, and that it stimulates DRG neurons through TRPV1 and TRPA1 channels. Results suggested a possibility that TRPV1 and TRPA1 channels are involved in the sense of astringent taste of green tea.

Nattokinase, a Subtilisin-like Alkaline-Serine Protease, Reduces Mutacin Activity by Inactivating the Competence-Stimulating Peptide in Streptococcus mutans.

Streptococcus mutans is a major cariogenic organism because of its ability to form biofilms on tooth surfaces. Bacteriocins produced by S. mutans (known as mutacins) are indirect pathogenic factors that play a role in the persistence of this microbe in the oral environment. Nattokinase, a subtilisin-like alkaline serine protease, potently inhibits biofilm formation without affecting S. mutans growth. However, effective strategies utilizing nattokinase to control mutacin production by S. mutans are lacking. In this study, we evaluated the effect of nattokinase on mutacin activity in 46 strains of S. mutans with different mutacin genotypes isolated from the dental plaques of pediatric patients with caries. Nattokinase reduced the activity of mutacin against oral streptococci at a concentration of 1 mg/mL in all clinical isolates. Furthermore, nattokinase reduced the expression of non-lantibiotic mutacin structural genes (nlmABCD) and inactivated the extracellular competence-stimulating peptide involved in comDE activation, which regulates non-lantibiotic mutacin gene expression. These results suggest that nattokinase may reduce the virulence of S. mutans and could potentially be used as a new caries-preventive agent as an alternative to conventional drug treatments.

Advanced application of bovine intestinal epithelial cell line for evaluating regulatory effect of lactobacilli against heat-killed enterotoxigenic Escherichia coli-mediated inflammation.

BACKGROUND: Previously, a bovine intestinal epithelial cell line (BIE cells) was successfully established. This work hypothesized that BIE cells are useful in vitro model system for the study of interactions of microbial- or pathogen-associated molecular patterns (MAMPs or PAMPs) with bovine intestinal epithelial cells and for the selection of immunoregulatory lactic acid bacteria (LAB). RESULTS: All toll-like receptor (TLR) genes were expressed in BIE cells, being TLR4 one of the most strongly expressed. We demonstrated that heat-stable PAMPs of enterotoxigenic Escherichia coli (ETEC) significantly enhanced the production of IL-6, IL-8, IL-1α and MCP-1 in BIE cells by activating both NF-κB and MAPK pathways. We evaluated the capacity of several lactobacilli strains to modulate heat-stable ETEC PAMPs-mediated inflammatory response in BIE cells. Among these strains evaluated, Lactobacillus casei OLL2768 attenuated heat-stable ETEC PAMPs-induced pro-inflammatory response by inhibiting NF-κB and p38 signaling pathways in BIE cells. Moreover, L. casei OLL2768 negatively regulated TLR4 signaling in BIE cells by up-regulating Toll interacting protein (Tollip) and B-cell lymphoma 3-encoded protein (Bcl-3). CONCLUSIONS: BIE cells are suitable for the selection of immunoregulatory LAB and for studying the mechanisms involved in the protective activity of immunobiotics against pathogen-induced inflammatory damage. In addition, we showed that L. casei OLL2768 functionally modulate the bovine intestinal epithelium by attenuating heat-stable ETEC PAMPs-induced inflammation. Therefore L. casei OLL2768 is a good candidate for in vivo studying the protective effect of LAB against intestinal inflammatory damage induced by ETEC infection or heat-stable ETEC PAMPs challenge in the bovine host.

Dorsamin-A's, glycerolipids carrying a dehydrophenylalanine ester moiety from the seed-eating larvae of the bruchid beetle Bruchidius dorsalis.

Using a TLC autographic assay for radical-scavenging activity with the ABTS radical, the presence of lipophilic antioxidants in the larvae of the wild bruchid seed beetle Bruchidius dorsalis was detected. Assay-guided fractionation of the CHCl3-soluble fraction of the larvae resulted in the isolation of new glycerolipids, designated dorsamin-A763, -A737, -A765, -A739, and -A767, comprising 1,2-diacyl-sn-glycero-3-dehydrophenylalanine ester structural units. The ABTS radical scavenging activity of the dorsamin-A's was comparable with or stronger than that of Trolox.

Evaluation of oxygen-containing pentadentate ligands with pyridine/quinoline/isoquinoline binding sites via the structural and electrochemical properties of mononuclear copper(II) complexes.

Eighteen mononuclear copper(II) complexes with oxygen-containing N4O1 pentadentate ligands were prepared. The ligand library consists of 2-aminoethanol derivatives ((Ar1CH2)(Ar2CH2)NCH2CH2OCH2Ar3) bearing three nitrogen-containing heteroaromatics (Ars) including pyridine, quinoline and isoquinoline via a methylene linker. Systematic replacements of pyridine binding sites with quinolines and isoquinolines reveal the general trends in the perturbation of bond distances and angles, the redox potential and the absorption maximum wavelength of the copper(II) complexes, depending on the position and number of (iso)quinoline heteroaromatics. The small effect on the redox potentials resulting from quinoline substitution at the Ar3 position (near oxygen) of the ligand comes from the steric hindrance of the peri hydrogen atom in the quinoline moiety at this position, which removes the counter anion to enhance the coordination of quinoline nitrogen and ether oxygen atoms to the metal centre. In the absorption spectra of copper(II) complexes in the d-d transition region, the quinoline substitution at this site (Ar3) exhibits an opposite effect to those at the Ar1 and Ar2 sites. The electronic and steric contributions of the heteroaromatic binding sites to the ligand properties are comprehensively discussed.

Immunobiotic Lactobacillus jensenii elicits anti-inflammatory activity in porcine intestinal epithelial cells by modulating negative regulators of the Toll-like receptor signaling pathway.

The effect of Lactobacillus jensenii TL2937 on the inflammatory immune response triggered by enterotoxigenic Escherichia coli (ETEC) and lipopolysaccharide (LPS) in a porcine intestinal epitheliocyte cell line (PIE cells) was evaluated. Challenges with ETEC or LPS elicited Toll-like receptor 4 (TLR4)-mediated inflammatory responses in cultured PIE cells, indicating that our cell line may be useful for studying inflammation in the guts of weaning piglets. In addition, we demonstrated that L. jensenii TL2937 attenuated the expression of proinflammatory cytokines and chemokines caused by ETEC or LPS challenge by downregulating TLR4-dependent nuclear factorκB (NF-κB) and mitogen-activated protein kinase (MAPK) activation. Furthermore, we demonstrated that L. jensenii TL2937 stimulation of PIE cells upregulated three negative regulators of TLRs: A20, Bcl-3, and MKP-1, deepening the understanding of an immunobiotic mechanism of action. L. jensenii TL2937-mediated induction of negative regulators of TLRs would have a substantial physiological impact on homeostasis in PIE cells, because excessive TLR inflammatory signaling would be downregulated. These results indicated that PIE cells can be used to study the mechanisms involved in the protective activity of immunobiotics against intestinal inflammatory damage and may provide useful information for the development of new immunologically functional feeds that help to prevent inflammatory intestinal disorders, including weaning-associated intestinal inflammation.

An adhesin-like protein, Lam29, from Lactobacillus mucosae ME-340 binds to histone H3 and blood group antigens in human colonic mucus.

A cell-surface 29-kDa protein (Lam29, cysteine-binding protein of the ABC transporter) from Lactobacillus mucosae ME-340 showed an adhesin-like property for human ABO blood group antigens expressed on the gastrointestinal mucosa. In addition, here we report that Lam29 also bound to an 18-kDa protein on human colonic mucus. By ligand blot assay and N-terminal amino acid sequence of the protein, it was identified as human histone H3. By ligand blot and microplate binding assays with recombinant histone H3, binding between Lam29 and histone H3 was confirmed. The adhesion of ME-340 cells to histone H3 was significantly inhibited by 26% after the addition of 2.5 mg/mL Lam29 as compared to the absence of Lam29 (p<0.01). By GHCl extraction and transcription attenuation of ME-340 cells, binding reduction of ME340 cells against histone H3 was detected at 12% and 13% respectively, as compared to control cells by the BIACORE assay (p<0.01). These data indicate that Lam29 shows multiple binding activities to blood group antigens and histone H3 in human colonic mucus. This is the first report to indicate that lactobacilli expressing Lam29 adhere to histone H3 on gastrointestinal mucosa.

Immunobiotic lactic acid bacteria beneficially regulate immune response triggered by poly(I:C) in porcine intestinal epithelial cells.

This study analyzed the functional expression of TLR3 in various gastrointestinal tissues from adult swine and shows that TLR3 is expressed preferentially in intestinal epithelial cells (IEC), CD172a(+)CD11R1(high) and CD4(+) cells from ileal Peyer's patches. We characterized the inflammatory immune response triggered by TLR3 activation in a clonal porcine intestinal epitheliocyte cell line (PIE cells) and in PIE-immune cell co-cultures, and demonstrated that these systems are valuable tools to study in vitro the immune response triggered by TLR3 on IEC and the interaction between IEC and immune cells. In addition, we selected an immunobiotic lactic acid bacteria strain, Lactobacillus casei MEP221106, able to beneficially regulate the anti-viral immune response triggered by poly(I:C) stimulation in PIE cells. Moreover, we deepened our understanding of the possible mechanisms of immunobiotic action by demonstrating that L. casei MEP221106 modulates the interaction between IEC and immune cells during the generation of a TLR3-mediated immune response.

Conjugative plasmid from Lactobacillus gasseri LA39 that carries genes for production of and immunity to the circular bacteriocin gassericin A.

Gassericin A is a circular bacteriocin produced by Lactobacillus gasseri strain LA39. We found a 33,333-bp plasmid, designated pLgLA39, in this strain. pLgLA39 contained 44 open reading frames, including seven genes related to gassericin A production/immunity (gaa), as well as genes for replication, plasmid maintenance, and conjugative transfer. pLgLA39 was transferred from LA39 to the type strain of L. gasseri (JCM 1131) by filter mating. The transconjugant exhibited >30-fold-higher more resistance to gassericin A and produced antibacterial activity. Lactobacillus reuteri LA6, the producer of reutericin 6, was proved to harbor a plasmid indistinguishable from pLgLA39 and carrying seven genes 100% identical to gaa. This suggests that pLgLA39 might have been transferred naturally between L. gasseri LA39 and L. reuteri LA6. The seven gaa genes of pLgLA39 were cloned into a plasmid vector to construct pGAA. JCM 1131(T) transformed with pGAA expressed antibacterial activity and resistance to gassericin A. pGAA was segregationally more stable than a pGAA derivative plasmid from which gaaA was deleted and even was more stable than the vector. This suggests the occurrence of postsegregational host killing by the gaa genes. pLgLA39 carried a pemIK homolog, and segregational stabilization of a plasmid by the pLgLA39-type pemIK genes was also confirmed. Thus, pLgLA39 was proved to carry the genes for at least two plasmid maintenance mechanisms, i.e., gaa and pemIK. Plasmids containing a repA gene similar to pLgLA39 repA were distributed in several L. gasseri strains.

DNA sequencing and homologous expression of a small peptide conferring immunity to gassericin A, a circular bacteriocin produced by Lactobacillus gasseri LA39.

Gassericin A, produced by Lactobacillus gasseri LA39, is a hydrophobic circular bacteriocin. The DNA region surrounding the gassericin A structural gene, gaaA, was sequenced, and seven open reading frames (ORFs) of 3.5 kbp (gaaBCADITE) were found with possible functions in gassericin A production, secretion, and immunity. The deduced products of the five consecutive ORFs gaaADITE have homology to those of genes involved in butyrivibriocin AR10 production, although the genetic arrangements are different in the two circular bacteriocin genes. GaaI is a small, positively charged hydrophobic peptide of 53 amino acids containing a putative transmembrane segment. Heterologous expression and homologous expression of GaaI in Lactococcus lactis subsp. cremoris MG1363 and L. gasseri JCM1131(T), respectively, were studied. GaaI-expressing strains exhibited at least sevenfold-higher resistance to gassericin A than corresponding control strains, indicating that gaaI encodes an immunity peptide for gassericin A. Comparison of GaaI to peptides with similar characteristics found in the circular bacteriocin gene loci is discussed.

Utilization of the porcine system to study lymphotoxin-beta regulation in intestinal lymphoid tissue.

Lymphotoxin-beta (LT-beta) has been suggested to be a regulator of secondary lymphoid structure development. In the present study, we isolated porcine LT-beta (poLT-beta) from adult swine spleens. The open reading frame encoded a predicted 246-amino acid polypeptide exhibiting higher similarity to the human than the mouse LT-beta protein. Expression of LT-beta mRNA in various swine tissues was analyzed by real-time PCR, and it was found to be higher in the ileal Peyer's patches (Pps) of adults than in newborns. In addition, ligand stimulation of toll-like receptors 2, 4, and 9, which are activated by bacterial components, increased LT-beta expression only in neonatal ileal Pps. These results suggest that colonization by commensal bacteria may affect the maturation of neonatal ileal Pps by the induction of LT-beta via toll-like receptors. LT-beta may therefore be useful for studying the development of the intestinal immune system at parturition in both swine and humans.

Molecular cloning and functional characterization of porcine nucleotide-binding oligomerization domain-2 (NOD2).

The nucleotide-oligomerization domain (NOD) 2 is an important molecule involved in host defense. In this study, we report the cloning and characterization of porcine NOD2 (poNOD2) cDNA. The open reading frame of poNOD2 contains 3042 bp which encode 1013 amino acid residues. The putative poNOD2 protein shares higher level of homology with human counterpart (81.6% amino acid identity) than the mouse protein (76.6% amino acid identity). In order to determine the function of poNOD2, we established human embryonic kidney (HEK) 293 cells transfected to express poNOD2 cDNA. We found that poNOD2 was expressed not only in the cytoplasm but also in the inner side of the plasma membrane of HEK293 cells. HEK293 cells expressing poNOD2 responded to muramyl dipeptide (MDP) by activation of the nuclear factor kappa B (NF-kappaB). Quantitative real-time PCR revealed that poNOD2 mRNA was expressed by a number of tissues isolated from adult and newborn swine such as esophagus, duodenum, jejunum, ileum, ileal Peyer's patches (Pps), colon, spleen, and mesenteric lymph nodes (MLNs). In the newborn swine, the expression of poNOD2 mRNA was detected at higher levels in MLNs and spleen as compared to other tissues. In the adult swine, the highest expression was observed in ileal Pps. Furthermore, Toll-like receptor (TLR) and NOD2 ligands as well as immunobiotic lactic acid bacteria (LAB) enhanced the expression of NOD2 in gut-associated lymphoid tissues (GALT) in adult and newborn swine. Our results implicate NOD2 as an important immunoregulator in the swine intestinal immunity.

Cell surface glyceraldehyde-3-phosphate dehydrogenase (GAPDH) of Lactobacillus plantarum LA 318 recognizes human A and B blood group antigens.

Lactobacillus plantarum LA 318 is a potential probiotic strain isolated from normal human intestinal tissue that shows high adhesion to human colonic mucin mediated by the bacterial cell surface glyceraldehyde-3-phosphate dehydrogenase (GAPDH). We report the adhesion mechanism of the lactobacilli is in part due to GAPDH binding to human ABO-type blood group antigens expressed on human colonic mucin (HCM). After periodate oxidation of HCM, adhesion of L. plantarum LA 318 bacterial cells significantly decreased compared to normal HCM. A BIACORE binding assay of GAPDH to blood group antigens was then performed. High binding was observed to A and B group antigens, while binding to H group antigen was lower (P<0.01). No interaction was observed between GAPDH and various monosaccharides. Furthermore, GAPDH binding to the B-trisaccharide biotinyl polymer (BP)-probe [Galalpha1-3 (Fucalpha1-2) Gal-] was significantly higher as compared to B-disaccharide, Lewis D-trisaccharide, 3-fucosyl-N-acetylglucosamine and alpha-N-acetylneuraminic acid BP-probes. The data suggests the trisaccharide structure is important in binding to the blood group antigens. The binding of GAPDH to HCM significantly decreased after incubation with NAD+. This suggests that the NAD binding domain on GAPDH may be related to binding to HCM.

Identification of five phospho-beta-glycosidases from Lactobacillus gasseri ATCC33323T cultured in lactose medium.

Lactobacillus gasseri ATCC33323(T) has seven putative phospho-beta-glycosidase genes. Using column chromatography, we found that this strain cultured in lactose medium expresses five phospho-beta-glycosidases (LacG1, LacG2, Pbg1, Pbg2, and Pbg3), where these gene expressions can be suppressed by glucose. To our knowledge, this is the first report indicating that five glycosidases are induced from a single bacterial strain using a single carbon source, lactose.

Molecular cloning of porcine RP105/MD-1 involved in recognition of extracellular phosphopolysaccharides from Lactococcus lactis ssp. cremoris.

In this study, we cloned the cDNAs encoding porcine RP105 (poRP105) and porcine MD-1 (poMD-1) from Peyer's patches of adult swine. The complete open reading frames of poRP105 and poMD-1 contain 1986 and 480bp and encode 661 and 159 amino acid residues, respectively. These two proteins were more similar to the human (77.6% and 76.5% amino acid identity) than the mouse counterparts (70.0% and 71.1% amino acid identity). The results of several experiments in cells cotransfected with poRP105 and poMD-1 indicated both lipopolysaccharide and extracellular phosphopolysaccharide from Lactococcus lactis subsp. cremoris (Lc.cremoris) strongly activate nuclear factor-kappaB and induce the expression of various cytokines via RP105. These effects were mediated by phosphatidylinositol 3-kinase and Bruton's tyrosine kinase. Thus, we identified extracellular polysaccharide from Lc.cremoris as an active substance that can induce immune activation via RP105 and MD-1.

Enzymatic digestion of the milk protein beta-casein releases potent chemotactic peptide(s) for monocytes and macrophages.

Proteins in the milk release biologically active peptides upon enzymatic digestion. In the present study, we report the identification of novel monocyte/macrophage chemotactic peptides derived from enzymatically digested bovine beta-casein, a casein family member that is a major constituent of milk. Beta-casein fragments generated by actinase E showed potent chemotactic activity for human and mouse monocytes/macrophages, but not neutrophils, T lymphocytes or dendritic cells. The fragment-induced migration of human monocytes was inhibited by pertussis toxin and was not desensitized by a variety of known chemoattractants, suggesting that the digests activate a unique G protein-coupled receptor(s). The digests were further fractionated and purified to yield 3 small peptides. One peptide Q1 designated as "beta-casochemotide-1" with the amino acid sequence of YPVEP (f114-118 of beta-casein) induced high levels of macrophage chemotaxis. It also promoted calcium mobilization in macrophages, another indication of cell activation. Our study suggests that biologically active peptides released by actinase-digested milk beta-casein may promote innate host immune responses by inducing macrophage migration and activation.