Enterocin X, composed of two antibacterial peptides (X␣ and X␤), is a novel class IIb bacteriocin fromEnterococcus faecium KU-B5. When combined, X␣ and X␤ display variably enhanced or reduced antibacterial activity toward a panel of indicators compared to each peptide individually. In E. faecium strains that produce enterocins A and B, such as KU-B5, only one additional bacteriocin had previously been known.Bacteriocins are gene-encoded antibacterial peptides and proteins. Because of their natural ability to preserve food, they are of particular interest to researchers in the food industry. Bacteriocins are grouped into three main classes according to their physical properties and compositions (11,12). Of these, class IIb bacteriocins are thermostable non-lanthionine-containing two-peptide bacteriocins whose full antibacterial activity requires the interaction of two complementary peptides (8,19). Therefore, two-peptide bacteriocins are considered to function together as one antibacterial entity (14).Enterocins A and B, first discovered and identified about 12 years ago (2, 3), are frequently present in Enterococcus faecium strains from various sources (3,5,6,9,13,16). So far, no other bacteriocins have been identified in these strains, except the enterocin P-like bacteriocin from E. faecium JCM 5804 T (18). Here, we describe the characterization and genetic identification of enterocin X in E. faecium KU-B5. Enterocin X (identified after the enterocin P-like bacteriocin was discovered) is a newly found class IIb bacteriocin in E. faecium strains that produce enterocins A and B.Enterocins A and B in Enterococcus faecium KU-B5. E. faecium KU-B5, a thermotolerant lactic acid bacterium screened from sugar apples in Thailand, has the ability to multiply and express antibacterial activity across a wide range of temperatures (20 to 43°C). Bacteriocin activity was tested by the critical dilution spot-on-lawn method (21) and expressed in activity units (AU) per milliliter. The strongest antibacterial activity of E. faecium was observed when it was cultured at 37°C in de Man-Rogosa-Sharpe (MRS) broth, with a wide spectrum of targets, including Enterococcus, Lactobacillus, Lactococcus, Bacillus, and Listeria (Table 1). Since enterocins A and B are frequently found in many antibacterial E. faecium strains, we initially examined the enterocin A-and B-encoding genes in E. faecium KU-B5 by using PCR with specific primers (5Ј-TGTACGAAGTGCATTCTCAA-3Ј and 5Ј-TA TTAAAGGACCGGGATCTA-3Ј for enterocin A; 5Ј-ACT CTAAAAGGAGCGAGTTT-3Ј and 5Ј-AGAGCTGGGGA TGAAATATT-3Ј for enterocin B). As expected, these genes were detected in genomic DNA of E. faecium KU-B5. However, the pooled activities from enterocins A and B could not explain the total activities in the culture supernatant of E. faecium KU-B5, such as activity toward Bacillus circulans JCM 2504 T (Table 1). On the other hand, the gene encoding the enterocin P-like bacteriocin (18) was not detected in E. faecium KU-B5. Thus, we assumed that other bacteriocins exist in E. faecium KU-B5,...

2-Amino-1-arylidenaminoimidazoles, a novel class of orally (po) active microtubule-destabilizing anticancer agents, were synthesized. The compounds were designed from a hit compound identified in a drug discovery platform by using cancer cell-based high throughput screening assay. Selective synthesized compounds exerted cell cytotoxicity against human cancer cells. The underlying mechanisms for the anticancer activity were demonstrated as interacting with the tubulins and inhibiting microtubule assembly, leading to proliferation inhibition and apoptosis induction in the human tumor cells. Furthermore, two compounds showed in vivo anticancer activities in both po and intravenously (iv) administered routes and prolonged the life spans of murine leukemic P388 cells-inoculated mice. These new po active antimitotic anticancer agents are to be further examined in preclinical studies and developed for clinical uses.

Aims:  To characterize the novel bacteriocin produced by Enterococcus durans. Methods and Results:  Enterococcus durans QU 49 was isolated from carrot and expressed bactericidal activity over 20–43°C. Bacteriocins were purified to homogeneity using the three‐step purification method, one of which, termed durancin TW‐49M, was an enterocin B‐homologous peptide with most identical residues occurring in the N‐terminus. Durancin TW‐49M was more tolerant in acidic than in alkali. DNA sequencing analysis revealed durancin TW‐49M was translated as a prepeptide of the double‐glycine type. Durancin TW‐49M and enterocin B expressed similar antimicrobial spectra, in which no significant variation due to the diversity in their C‐termini was observed. Conclusions:  Durancin TW‐49M, a novel nonpediocin‐like class II bacteriocin, was characterized to the amino acid and genetic levels. The diverse C‐terminal parts of durancin TW‐49M and enterocin B were hardly to be suggested as the place determining the target cell specificity. Significance and Impact of the Study:  This is the first and comprehensive study of a novel bacteriocin produced by Ent. durans. The high homology at the N‐terminal halves between durancin TW‐49M and enterocin B makes them suitable to study the structure‐function relationship of bacteriocins and their immunity proteins.

BPR0C261 is a synthetic small molecule compound cytotoxic against human cancer cells and active prolonging the lifespan of leukemia mice. In the present study, we further investigated the mechanisms of its anticancer action and found that BPR0C261 inhibited microtubule polymerization through interacting with the colchicine binding sites on tubulins, disrupted microtubule arrangement and caused cell cycle arrest at G2/M phase in cancer cells. BPR0C261 also inhibited the clonogenic growths of cancer cells and showed cytotoxicity against human cervical cancer cells of multidrug‐resistant phenotype. In addition, BPR0C261 concentration‐dependently inhibited the proliferation and migration of HUVECs and disrupted the endothelial capillary‐like tube formations in HUVEC and rat aorta ring cultures. Given orally, BPR0C261 inhibited angiogenesis in s.c. implanted Matrigel plugs in mice. Notably, its IC50 values against the endothelial cell growths were approximately 10‐fold lower than those against the cancer cells. It was found orally absorbable in mice and showed a good oral bioavailability (43%) in dogs. BPR0C261 permeated through the human intestinal Caco‐2 cell monolayer, suggesting oral availability in humans. Orally absorbed BPR0C261 distributed readily into the s.c. xenografted tumors in nude mice in which the tumor tissue levels of BPR0C261 were found oral dose‐dependent. BPR0C261 showed in vivo activities against human colorectal, gastric, and nasopharyngeal tumors in nude mice. Most interestingly, the combination of BPR0C261 plus cisplatin synergistically prolonged the lifespans of mice inoculated with murine leukemia cells. Thus, BPR0C261 is a novel orally active tubulin‐binding antitumor agent with antimitotic, apoptosis‐inducing, and vasculature disrupting activities. (Cancer Sci 2011; 102: 182–191)