The advantages of the magnetic structure in ferromagnetic-film-coated carbon nanotube probes.

The magnetic structures of ferromagnetic-film-coated carbon nanotube (CNT) probes and conventional pyramidal probes for a magnetic force microscope (MFM) were simulated using three-dimensional micromagnetic simulation. The CNT-MFM probes with a total probe diameter less than 60 nm are almost uniformly magnetized along the longitudinal direction of the CNT, which is the ideal magnetic structure for MFM observations. On the other hand, the pyramidal probes had a vortex structure around the point tip, which suggests that they require a greater thickness of the ferromagnetic film because only part of the magnetic moment participates in the detection of the z-component of the stray field from samples. The advantages of the CNT-MFM probe are uniform magnetization along the longitudinal direction and magnetic imaging ability using a smaller coating thickness.

The gene expression profile of cardia intestinal metaplasia is similar to that of Barrett's esophagus, not gastric intestinal metaplasia.

The etiology and significance of cardia intestinal metaplasia (CIM) is disputed. CIM may represent a form of Barrett's esophagus due to reflux or could reflect generalized gastric intestinal metaplasia due to Helicobacter pylori. The aim of this study was to utilize gene expression data to compare CIM to Barrett's and gastric intestinal metaplasia. Endoscopic biopsies were classified by endoscopic and histologic criteria as CIM (n= 33), Barrett's (n= 25), or gastric intestinal metaplasia of the antrum or body (n= 18). The squamocolumnar and gastroesophageal junctions were aligned in CIM patients and patients with diffuse gastric intestinal metaplasia were excluded. H. pylori was tested for in the biopsies of all patients. After laser-capture microdissection, quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to measure the mRNA expression of a panel of nine genes that has been shown to differentiate Barrett's from other foregut mucosa. Cluster analysis with linear discriminant analysis of the expression data was used to classify each sample into groups based solely on similarity of gene expression. Cluster analysis was performed for three groups (CIM vs. Barrett's vs. gastric intestinal metaplasia) and two groups (CIM + Barrett's vs. gastric intestinal metaplasia). There was no difference in H. pylori infection among groups (P= 0.66). Clustering into three groups resulted in frequent misclassification between CIM and Barrett's while misclassification of gastric intestinal metaplasia was uncommon. The CIM and Barrett's groups were then combined for two group clustering and linear discriminant analysis correctly predicted 95% of CIM and Barrett's samples and 83% of gastric intestinal metaplasia samples based on gene expression alone. In conclusion, the gene expression profiles of CIM and Barrett's esophagus were similar in 95% of biopsies and differed significantly from that of gastric intestinal metaplasia. The indistinguishable gene expression profile of CIM and BE suggests that they may share a common etiology in the majority of patients with a similar biology, and calls into question the perception that CIM is an innocuous process.

Precise control of nanofabrication by atomic force microscopy.

With an aim of the precise control of the anodic oxidation process by atomic force microscopy, the technical improvement has been carried out based on the mechanism studies. The accuracy and reliability of the nanofabrication have been improved by the combination of ambient humidity control, improvement of instrumental performance and meniscus lifetime control. In parallel, the mechanism study has been proceeded through the detection of Faradaic current. The in situ Faradaic current detection of the nano-oxidation process can actually work as a sensitive monitor for the nano-oxidation process with a high reliability. From an engineering viewpoint with an eye to practical applications, controllable physical parameters which affect on the product size are enumerated to consider what we should do to raise the precision of nano-oxidation. Then the fast fabrication in a large area by a patchwork method, Faradaic current detection during oxidation-reduction reaction, and nanofabrication by current-control are shown as examples.

SAPPHIRE: a randomised phase II study of planned discontinuation or continuous treatment of oxaliplatin after six cycles of modified FOLFOX6 plus panitumumab in patients with colorectal cancer.

BACKGROUND: Fluorouracil (5-FU), leucovorin (LV) and oxaliplatin (FOLFOX) plus panitumumab therapy is a commonly used first-line chemotherapy for metastatic colorectal cancer (mCRC). However, the long-term administration of oxaliplatin is associated with peripheral neuropathy (PN). We investigated whether the planned discontinuation of oxaliplatin after FOLFOX plus panitumumab therapy can maintain efficacy and reduce PN incidence. PATIENTS AND METHODS: Chemotherapy-naive patients with RAS wild-type mCRC, aged ≥20 years, were enrolled and received six cycles of modified FOLFOX6 (mFOLFOX6) plus panitumumab as induction therapy. Patients who completed induction therapy without progression were randomised to mFOLFOX6 plus panitumumab (group A) or to 5-FU/LV plus panitumumab (group B). The primary end-point was the progression-free survival (PFS) rate at 9 months after randomisation. The secondary end-points were PFS, overall survival (OS), time to treatment failure (TTF), response rate (RR) and safety. RESULTS: In total, 164 patients were enrolled; of whom, 113 patients were then randomised (group A, n = 56; group B, n = 57). The median follow-up after randomisation was 19.6 months. The PFS rates at 9 months and median PFS were 46.4% (80% confidence interval [CI], 38.1-54.9) and 9.1 months (95% CI, 8.6-11.1) in group A, compared with 47.4% (80% CI, 39.1-55.8) and 9.3 months (95% CI, 6.0-13.0) in group B, respectively. RR, OS and TTF were also similar in both groups. Grade ≥2 PN incidence was lower in group B (9.3%) than in group A (35.7%). CONCLUSION: Planned discontinuation of oxaliplatin after six cycles of mFOLFOX6 plus panitumumab is a potential treatment option in patients with mCRC, achieving similar efficacy while reducing oxaliplatin-associated PN compared with mFOLFOX6 plus panitumumab. TRIAL REGISTRATION NUMBER: NCT02337946.

Molecular factors of 5-fluorouracil metabolism in colorectal cancer: analysis of primary tumor and lymph node metastasis.

Thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD) and thymidine phosphorylase (TP) are predictive markers for tumor response to 5-fluorouracil-based therapies. To determine whether gene expression values measured in primary cancer tissue would be useful for prediction of response of lymph node metastases, the expressions of these genes were quantitatively analyzed in 35 pairs of primary colorectal cancer (CRC) and corresponding lymph node metastases using real-time PCR. DPD and TP mRNA levels were significantly lower in the primary colorectal tumor and lymph node metastases compared with the normal adjacent stroma tissue (p<0.01), whereas TS mRNA levels were significantly higher in the primary tumor and lymph node metastases than in the normal adjacent tissue (p<0.001). Median gene expression levels of TP and TS did not differ significantly between primary colorectal tumor and corresponding lymph node metastasis but median DPD gene expression levels in the lymph node metastases were significantly higher compared to matched primary colorectal tumors (p=0.015). There was a significant correlation for DPD, TP and TS gene expression levels between primary colorectal tumor specimens and the matched lymph node metastasis. These results suggest that biopsies of the tumor of origin may be valid for determining predictive markers for chemotherapy response in patients with metastatic CRC.

NK026680, a novel compound suppressive of dendritic cell function, ameliorates mortality in acute lethal graft-versus-host reaction in mice.

A role for dendritic cells (DCs) has been emphasized in the onset of acute graft-versus-host disease (GVHD). We have made efforts to develop a new strategy for suppression of DC functions with a chemical compound in the treatment of acute GVHD. We here describe the immunological characterization of the new chemical compound NK026680. It was found that NK026680 significantly suppressed (1) expression of CD83, CD86, and major histocompatibility complex (MHC) class I and II antigens on human monocyte-derived DCs, (2) excretion of interleukin-12p40 on activation of monocyte-derived DCs, (3) allogeneic responses of human and mouse T cells and (4) mortality in mice with acute GVHD evoked across MHC class I or II. The beneficial effect of NK026680 administered orally was without any recognizable adverse effects. Early intervention in acute GVHD was required for this effect, indicating that an early event in acute GVHD is a critical target of NK026680. We propose the use of NK026680 as a prophylactic for acute GVHD.

Conformational studies and electronic structures of tamoxifen and toremifene and their allylic carbocations proposed as reactive intermediates leading to DNA adduct formation.

Toremifene, a compound which differs from tamoxifen by the substitution of a chlorine atom for a hydrogen atom in the ethyl group, is significantly less potent than tamoxifen in causing DNA adduct formation in rats. To examine the relationship of the DNA adduct-forming ability of these compounds with their physicochemical properties such as stable conformation and chemical reactivity, we carried out molecular mechanics, molecular dynamics, and quantum mechanics calculations for the two compounds. For tamoxifen, six stable conformers were identified by conformational search with CFF91 force field. Molecular dynamics simulations showed that these were often interconverted within 1.0 ns. On the other hand, although the conformation of stable conformers and dynamical behavior of toremifene were almost the same as those of tamoxifen, a few conformations were slightly different from those of tamoxifen owing to the effect of the chlorine atom at chloroethyl group. In addition, the stability of the allylic carbocation, which had been proposed as the reactive intermediate leading to DNA adduct formation, was calculated with both semiempirical and density functional methods. Results showed that the carbocation intermediate of toremifene was less stable than that of tamoxifen by 4-5 kcal/mol, suggesting that toremifene was less frequently activated to the intermediate than tamoxifen. Furthermore, the carbocation intermediates of two other tamoxifen derivatives, 4-iodotamoxifen and droxifene, which show no DNA adduct-forming ability, were also less stable compared with that of tamoxifen. These calculated results suggest a close relation between the stability of the proposed carbocation intermediate and DNA adduct-forming ability.

Woodfruticosin (woodfordin C), a new inhibitor of DNA topoisomerase II. Experimental antitumor activity.

Woodfruticosin (woodfordin C) (WFC), a new inhibitor of DNA topoisomerase II (topo-II), was isolated from methanol extract of Woodfordia fruticosa Kurz (Lythraceae) and studied for in vitro and in vivo antitumor activities in comparison with Adriamycin (ADR) and etoposide (ETP), well known inhibitors of topo-II. The inhibitory activity against DNA topo-II shown by WFC was much stronger than that shown by ETP or ADR. WFC inhibited strongly intracellular DNA synthesis but not RNA and protein synthesis. On the other hand, WFC had a weaker growth inhibitory activity against various human tumor cells than ETP or ADR, but it showed remarkable activity against PC-1 cells and moderate activity against MKN45 and KB cells. Furthermore, WFC had in vivo growth inhibitory activity against s.c. inoculated colon38. These results indicate that the mechanism by which WFC exhibits antitumor activity may be through inhibition of topo-II.

Changes in intratumoral thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) mRNA expression in colorectal and gastric cancer during continuous tegafur infusion.

Thymidylate synthase (TS) is the target enzyme of 5-fluorouracil (5-FU), and dihydropyrimidine dehydrogenase (DPD) is the key enzyme in the 5-FU catabolic pathway. We wanted to determine whether the TS and DPD mRNA expression levels of gastric and colorectal cancer patients would be affected by tegafur (futrafur:FT)-based chemotherapy and whether changes in their expression might be responsible for patient outcome. Thirty-five patients with resectable advanced primary gastric cancer and 36 patients with resectable advanced primary colorectal cancer were the subjects of this study. They all underwent neoadjuvant chemotherapy with protracted infusion of FT alone or FT plus low doses of cisplatin. The TS and DPD mRNA expression levels of endoscopic biopsy specimens before chemotherapy and surgical specimens after chemotherapy were measured by TaqMan reverse transcription-PCR assay using glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as the internal standard. There was a significant difference in the DPD mRNA levels during chemotherapy in the colorectal cancers. Although the TS and DPD levels were unrelated to any conventional histopathological grade factors, colorectal cancer patients whose surgical specimens contained lower TS and DPD mRNA levels had longer disease-free intervals. The results of this study suggest that FT may affect DPD mRNA expression in colorectal cancer patients, that TS/DPD expression can be regarded as an independent prognostic factor, and that colorectal cancer patients with low TS and low DPD mRNA are candidates for FT-based adjuvant chemotherapy. In addition, quantitative analysis of the change in TS/DPD mRNA in surgical specimens during FT-based chemotherapy might be a more accurate means of predicting the post-operative disease-free interval of colorectal cancer patients than analysis of endoscopic specimens before chemotherapy. There also seems to be a relation between regulation of TS and DPD during FT chemotherapy. Elucidation of the mechanisms regulating TS and DPD mRNA expression might make it possible to predict sensitivity and/or toxicity to FT.

Mechanism of association of a specific aldehyde inhibitor, leupeptin, with bovine trypsin.

Leupeptin (acyl peptidyl-L-argininal) is a potent inhibitor of trypsin and related proteases. We analyzed the association of leupeptim with bovine trypsin kinetically, assuming that it proceeds by a pathway which involves two steps: E + I in equilibrium K1 Complex I k-2 in equilibrium k+2 Complex II. The observed dissociation constant (K1) for the first step was 1.24 X 10(-3) M (at pH 8.2 15 degrees C) and the two first-order rate constants (k+2 and k-2) were 166 s-1 and 1.75 X 10(-3.s-1, respectively (at pH 8.2, 15 degrees C). The dissociation constant (Kd) for the whole process was calculated from these parameters to be 1.34 X 10(-8) M. This value is compatible with that determined directly by an independent static method (2.36 X 10(-8) M). We also measured Kd for the leupeptine complex of anhydrotrypsin, a trypsin derivative in which the active-site hydroxyl group is missing. The observed value was about 5 orders of magnitude larger than Kd and was rather similar to K1 in native trypsin. A elupeptin isomer which contains a D-argininal residue did not show strong affinity towards trypsin. These findings suggest that complex II consists of a covalent hemiacetal adduct formed between the serine hydroxyl group in the enzyme active site and the aldehyde group in the inhibitor. The pH dependencies of the dissociation constant and other parameters show that deprotonation of the charge-relay sustem in the active site is important for the formation and stabilization of complex II.

Correction of amino acid sequence of phospholipase A2 I from the venom of Laticauda semifasciata (Erabu sea snake).

The amino acid sequence of phospholipase A2 I from the venom of the sea snake Laticauda semifasciata was reinvestigated. The previously reported sequence at positions 70-80 was corrected to Asp-Cys-Ser-Thr-Glu-Glu-Pro-Asn-Cys-Ser-Thr. The positions of half-cystine residues in the corrected sequence agree with most other phospholipases A2.

Tumor cell permeability to peplomycin.

The uptake of [3H]peplomycin-Cu(II) ([3H]PEP-Cu(II)) into various tumor cell lines was studied. The time course of [3H]PEP-Cu(II) uptake into AH66, AH66F, Ehrlich and P388 cells was biphasic. The first phase of uptake was completed within 5 minutes. The second, slower phase, of uptake into AH66, AH66F and Ehrlich cells increased linearly with incubation time, but that into P388 cells reached a plateau level. In L1210 cells, only the first rapid uptake was observed. The lower uptake into P388 and L1210 cells during the second phase may be related to their insensitivity to PEP. However, the uptake into AH66F cells was higher than that into AH66 cells, although AH66F cells were less sensitive to PEP than AH66 cells. Deamide PEP was detected in intact cells which had taken up [3H]PEP-Cu(II) during 4 hours. This confirmed that PEP-Cu(II) was transported into the cell, the copper removed and PEP metabolized to deamide PEP. [3H]PEP-Cu(II) uptake into AH66 and AH66F cells increased in proportion to the extracellular concentration of drug up to at least 200 micrograms/ml, suggesting that uptake was not mediated by a carrier system. Metabolic inhibitors such as NaN3 and 2,4-dinitrophenol enhanced [3H]PEP-Cu(II) uptake, but did not influence efflux. Uptake was also enhanced by membrane modifiers such as dibucaine and chlorpromazine which increase the fluidity of lipid membranes. The results suggest that PEP-Cu(II) was taken up into tumor cells by passive diffusion, controlled by an energy-dependent cell membrane barrier.

DNA cleavage activity of liblomycin (NK313), a novel analog of bleomycin.

Liblomycin (NK313), a novel analog of bleomycin and peplomycin (PEP), produced acid soluble DNA, base propenals and nucleo bases from isolated DNA. This was similar to the action of PEP. However, the DNA cleavage activity of NK313 was 1/2-1/10 of that of PEP in the absence of reducing agents. In the presence of reducing agents such as 2-mercaptoethanol and ascorbic acid, the activity of NK313 was stimulated more strongly than PEP. NK313 was also different from PEP in the formation and decomposition of active intermediates. This result suggested that differences in DNA cleavage activity between NK313 and PEP may be due to the different properties of their active intermediates. NK313 released preferentially pyrimidine bases from DNA, and the molar ratio of the released pyrimidine bases to the total of the released bases was little affected by the concentration of NK313 relative to DNA. In contrast, the ratio of the released purine bases by PEP increased with the concentration of PEP relative to DNA. NK313 induced double strand cleavage on pBR322 DNA as efficiently as did PEP. The major cleavage sites of NK313 on pBR322 DNA were similar to those of PEP. However, certain minor cleavage sites of NK313 were specific for NK313. Increase of PEP concentration led to increased degradation of DNA fragments; this was not the case with NK313. These results indicate that the cleavage sites of NK313 were similar to, but more limited than those for PEP.

An active intermediate formed in the reaction of bleomycin-Fe(II) complex with oxygen.

The base-release activity of oxygen adduct of bleomycin-Fe(II) complex [BLM-Fe(II)] from DNA decreased with a half-life of 5.2 minutes, when incubated at 0 degrees C in 0.05 M Tris-HCl buffer at pH 7.8 in the absence of DNA. Under the same condition, however, visible and ESR spectra showed that the adduct was immediately converted into the ferric complex. The ESR study further indicated the simultaneous formation of two kinds of the low-spin BLM-Fe(III) complex. One of them disappeared in parallel with the decrease of the base-release activity and transformed into the other. The latter Fe(III) complex was stable but inactive. However, by addition of hydrogen peroxide to the latter, the former was regenerated and the base-release activity appeared. Oxygen concentration measurements by oxygraph showed that one mole of BLM-Fe(II) consumed approximately 0.5 mole of molecular oxygen instantly, but did not any more thereafter in the absence of a reducing agent. While in the presence of 2-mercaptoethanol, the oxygen consumption proceeded biphasically, and equimolar oxygen was consumed by BLM-Fe(II) in the first rapid reaction. These results suggest that oxygen adduct of BLM-Fe(II) is reduced by one electron transfer from an external electron donor and the resulting BLM-Fe(III)-O2H- [or its deprotonated form: BLM-Fe(III)-O2(2)-] shows the activity to break DNA accompanying the base-release.

Biological activity of the main metabolites of ubenimex in humans.

The biological activity of the two main metabolites of ubenimex in humans, (-)-N-[(2S,3R)-3-amino-2-hydroxy-4-(4'-hydroxy)phenylbutyryl]-L-leucine (OH-ubenimex) and (2S,3R)-3-amino-2-hydroxy-4-phenylbutyric acid [2S,3R)-AHPA) was examined. OH-Ubenimex was almost identical in inhibitory activity against mouse peritoneal resident macrophage aminopeptidases (APases) and the growth of IMC carcinoma in mice to ubenimex. In contrast, the inhibition of; mouse spleen cell APase activities in vitro, blastogenesis of mouse T and B cells in vitro, delayed cutaneous hypersensitivity in mice, and the growth of C1498 leukemia and HeLa S3 cells in vitro was weaker than ubenimex. Macrophage APase activity was only slightly inhibited by (2S,3R)-AHPA which also had practically no activity in the other biological assays.

Kinetics of the reaction of bleomycin-Fe(II)-O2 complex with DNA.

The kinetics of the reaction of BLM-Fe(II)-O2 with DNA in the absence or presence of 2-mercaptoethanol (2-ME) were studied. The total number of bases released by BLM-Fe(II)-O2 in the presence of 2-ME increased about 6.5 times more than that in the absence of 2-ME in the reaction of 6 hours at 37 degrees C. The molar ratios of the released bases ware little affected by the reaction time, temperature or 2-ME. Among the four bases, thymine was preferentially released. On the basis of a reaction scheme of BLM-Fe(II)-O2 with DNA, the equations were derived by the steady-state method. In the absence of 2-ME, the release of bases from DNA was dependent on the concentration of BLM-Fe(II)-O2, but independent of the concentration of DNA. In the presence of 2-ME, a biphasic reaction was observed; the first one is due to BLM-Fe(II) which originally existed and the second one is due to BLM-Fe(II) produced by the reduction of BLM-Fe(III) with 2-ME. In the second reaction, the rate of the release of bases from DNA was proportional to the concentration of BLM-Fe(II) and 2-ME, but inversely proportional to the concentration of DNA. The rate-determining step in the reaction of BLM-Fe(II)-O2 with DNA in the presence of 2-ME was found to be the reduction of BLM-Fe(III) to BLM-Fe(II). By these kinetic studies, the reaction of BLM-Fe(II)-O2 with DNA in the presence of 2-ME was elucidated to proceed in a catalytic fashion. Furthermore, the maximum number of bases released by BLM from DNA was one base per twelve to thirteen bases.

Cell killing mode of liblomycin (NK313), a novel dose-survival relationship different from bleomycins.

Liblomycin (NK313) is a novel derivative of bleomycin (BLM) and peplomycin (PEP). The cell kill kinetics of NK313 on rat ascites hepatoma AH66 were compared with those of PEP. NK313 induced intracellular DNA cleavage and arrested cell cycle progression at the G2 phase similarly to PEP. The cytocidal effect of NK313, however, was found to be different from that of PEP as described below: 1) The dose-survival curve for cells exposed to PEP for 1 hour was upward concave, whereas in case of NK313, the survival curve was linear. PEP was more effective to AH66 than NK313 at lower concentration, but at higher concentration, NK313 was much more effective. 2) The time-survival curve for cells treated with either NK313 or PEP was biphasic. NK313, however, did not induce temporary resistance of AH66 cells to NK313, while PEP induced resistance to PEP. 3) NK313 was effective against the cells which became temporarily resistant to PEP by the treatment of PEP. These differences suggest that NK313 might be of value to treat PEP-insensitive tumor cells.

Action of ubenimex on aminopeptidase activities in spleen cells and peritoneal macrophages from mice.

The action of ubenimex on aminopeptidase (APase) activity was studied in intact spleen cells and peritoneal macrophages from mice. Ubenimex strongly inhibited hydrolyzing activities against arginine-beta-naphtylamide (Arg-NA), Lys-NA and Pro-NA in both cells. Inhibition of hydrolysis of Leu-NA, Met-NA and Ala-NA was relatively small or not observed. When both cells were incubated in HANKS' solution, hydrolyzing activities against Arg-NA, Lys-NA and Pro-NA were released to the medium, while Leu-NA and Met-NA-hydrolyzing activities were mostly bound. In addition, the Leu-NA-hydrolyzing activity in the spleen cells was kinetically studied. The Arg-NA and Leu-NA-hydrolyzing activities in four fractions prepared from the homogenate of spleen cells were also studied kinetically. From these studies it was suggested that ubenimex inhibits aminopeptidase B and a Pro-NA-hydrolyzing enzyme more effectively than Leu-APase in intact spleen cells and peritoneal macrophages from mice.

The antiproliferative action of deoxyspergualin is different from that induced by amine oxidase.

The amine oxidase activities contained in calf serum and human serum were detected at levels of 90.8 and less than 0.1 nmol O2/minute/ml serum, respectively, by measuring oxygen consumption coupled with spermidine oxidation. Deoxyspergualin (NKT-01) and spergualin (SGL) containing spermidine in their structure were also oxidized in calf serum at the rate of 3.6 and 11.6 nmol O2/minute/ml serum, respectively. To investigate whether amine oxidase is essential for NKT-01 and SGL to exhibit their antiproliferative activities or not, the in vitro activities of NKT-01, SGL and polyamines against L1210 cells were examined in the presence of calf or human serum. Polyamines exhibited antiproliferative activity only in the presence of calf serum, while NKT-01 and SGL inhibited cell growth in the presence of both calf and human serum. In the presence of calf serum the activity of NKT-01 was inhibited by aminoguanidine, an amine oxidase inhibitor. Aminoguanidine did not inhibit the activity of NKT-01 in the presence of human serum. The activity of NKT-01 was shown at much lower concentrations in the presence of human serum than that in the presence of calf serum, and was strongly dependent on incubation time. The in vivo activities of NKT-01, SGL and SGL derivatives correlated with their in vitro activities in the presence of human serum. These results suggest that the in vivo antitumor activities of NKT-01, SGL and SGL derivatives may be attributed to a mechanism different from those of amine oxidase-oxidized product and represent a novel growth inhibitory action.

Biological studies on the degradation products of 3-[(S)-1'-phenylethylamino]propylaminobleomycin: a novel analog (pepleomycin).

Pepleomycin (PEP), 3-[(S)-1'-phenylethylamino]propylaminobleomycin has potent activity and is less pulmonary toxic than bleomycin (BLM). Biological activity and toxicity of the following degradation products of PEP have been studied in detail: the product of carbamoyl migration (ISO), the product of decarbamylation (DC), the product of ring closure of the side chain on the pyrimidine moiety (RC), the depyruvamide product (DP) and the product of an enzymatic inactivation (DA). These degradation products showed much lower activity than PEP in vitro: antimicrobial and anti-HeLa activities, inhibition of DNA synthesis in AH66 cells and the DNA strand cleavage. Acute toxicity and pulmonary toxicity were tested in mice. Results indicated much lower acute toxicity corresponding to the decreased in vitro activity when compared to PEP. DP and RC did not cause lung fibrosis in mice, while ISO and DC showed 1/2.6 and 1/5.7 degree of pulmonary toxicity, respectively, in comparison with PEP.