ra-vii and Leukemia-P388

Penta-N-methyl and hexa-N-methyl analogues of RA-VII, an antitumor bicyclic hexapeptide of plant origin, were prepared. In the former, the nitrogens of d-Ala-1 and Ala-4 and in the latter, those of d-Ala-1, Ala-2, and Ala-4 were methylated under the phase-transfer catalysis conditions. Their solution structures were established by NOESY experiments and the crystal structures by X-ray crystallography. Those two methylated analogues showed much weaker cytotoxicity against P-388 leukemia cells than the parent RA-VII.

Topics: Animals; Antineoplastic Agents, Phytogenic; Crystallography, X-Ray; Humans; Leukemia P388; Mice; Molecular Conformation; Oligopeptides; Peptides, Cyclic; Rubia

Several aromatic ring substituent modified RA derivatives were prepared from RA-VII (1), RA-V (8) and RA-II (11), and evaluated for cytotoxicity against P388 leukemia and KB cells. In terms of IC50 values, the C zeta methoxyl group of Tyr-3 greatly influenced the activities, while the substituents at the C zeta position of Tyr-6 were less important. One of the derivatives, Tyr-6-C zeta-deoxyRA-V (9, P388, IC50, 0.0025 micrograms/ml) was nearly as active as RA-VII (1, 0.0013 micrograms/ml), and also expressed promising anti-P388 in vivo activity (test/control = 171%, at 25 mg/kg).

Topics: Animals; Antineoplastic Agents, Phytogenic; Cell Survival; Female; Humans; KB Cells; Leukemia P388; Mice; Mice, Inbred Strains; Peptides, Cyclic; Plants, Medicinal

A number of RA-VII derivatives having various amino acids including proline (6), pipecolic acid (11), norvaline (12), ornithine (14), aspartic acid (15) and methionine (20) in place of Ala2 have been synthesized from RA-X methyl ester (3) and evaluated for cytotoxicity to P388 leukemia and KB cells in vitro. Comparison of the cytotoxicity of these compounds suggests that the polarity and the length of the 2nd amino acid residue affect the activity. An NMR study revealed that, in solution, 6 and 11 are locked in one conformational state, corresponding to conformer A of RA-VII.

Topics: Animals; Antineoplastic Agents; Cell Survival; Humans; KB Cells; Leukemia P388; Magnetic Resonance Spectroscopy; Mice; Mice, Inbred Strains; Molecular Conformation; Peptides, Cyclic; Tumor Cells, Cultured

Nine daily intravenous (iv) injections of RA-700 (an antitumor cyclic hexapeptide) at doses of 2 to 6 mg/kg/day caused increases of WBC counts at 4-6 days after treatment in normal C57BL/6 X DBA/2 (BDF1) mice. The percentages of neutrophils and lymphocytes were modified. There was a decrease of colony-forming units in culture (CFUc) in bone marrow to 40% of the control value on day 1 but CFUc rapidly returned to normal values on day 3. The colony-forming units in spleen (CFUs) in bone marrow decreased during treatment. On the other hand, CFUc and CFUs in spleen were increased from the initiation of treatment to the time prior to the increase of WBC count. Spleen weight increased after treatment, and histologically, increases of immature and also mature granulocytes and megakaryocytes were observed. However, RA-700 did not stimulate the progress of hematoprogenitors in vitro. The results indicated that RA-700 stimulates the progress of hematoprogenitors in the spleen, but this effect is probably indirect.

Topics: Animals; Antineoplastic Agents, Phytogenic; Bone Marrow; Colony-Forming Units Assay; Female; Hematopoietic Stem Cells; Leukemia P388; Leukocytosis; Lymphocytes; Mice; Mice, Inbred C57BL; Mice, Inbred DBA; Neutrophils; Peptides, Cyclic; Spleen

The antitumor activity of a newly obtained cyclic hexapeptide, RA-700, from Rubiae Radix was studied using several murine experimental tumor systems. In P388 leukemia (inoculated intraperitoneally (i.p.), administered i.p.: i.p.-i.p.) the maximal increase in life span (ILSmax) resulting from an administration of RA-700 (4 mg/kg/d for 9 d) was 134% and the therapeutic ratio was 400. These values indicate that RA-700 has higher anti-tumor activity and broader active dose range than that of mitomycin C (MMC, 1 mg/kg/d for 9 d) which was used as a positive control. In the study of the treatment schedules on P388, RA-700 had the highest activity by consecutive injections. In MOPC-104E mouse plasmacytoma system (i.p.-i.p.), ILSmax of RA-700 (2.5 mg/kg/d for 9 d) was 84%. In a solid tumor, colon adenocarcinoma 38 (subcutaneously (s.c.)-intravenously (i.v.], RA-700 (4 mg/kg/d for 11 d) showed complete cures (8/8) compared to MMC (0.5 mg/kg/d for 11 d) which showed one cure out of 8 animals. In the study of a model of the inhibition of lymph node metastasis using P388 leukemia, the administration of RA-700 at more than 2.5 mg/kg/d i.v. for 7 d resulted in the survival of all animals (5/5) for over 60 d. In the amputation system of the same metastasis model at a dose of 4 mg/kg/d i.v. for 7 d, 3 animals out of 5 survived over 60 d.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Antineoplastic Agents, Phytogenic; Doxorubicin; Drug Evaluation, Preclinical; Female; Leukemia P388; Male; Mice; Mice, Inbred C57BL; Mice, Inbred ICR; Mice, Inbred Strains; Mitomycin; Mitomycins; Neoplasm Metastasis; Neoplasms, Experimental; Peptides, Cyclic; Plants, Medicinal

Alkylehter and ester derivatives of the antitumor cyclic hexapeptide RA-V obtained from the roots of Rubia cordifolia (Rubiaceae) were synthesized and bioassayed for activity against cultured tumor cells. RA-V and its n-hexylether showed significant effects against human nasopharynx carcinoma (KB), P388 lymphocytic leukemia and MM2 mammary carcinoma cells. The activity values (log 1/IC50) of ether derivatives of RA-V gave an upward parabolic or bilinear relationship when plotted against log P (P: partition coefficient determined with the 1-octanol/water system) as the carbon number of the side chain at the phenol moiety of RA-V was increased, the optimum log P values being in the range from 3.5 to 4.9. The ester derivatives showed a similar relationship, the optimum log P values being 6.3-6.7, which is higher than that of the ether derivatives. The lethal effect of RA-V on KB cells was clearly different from that of mitomycin C, and RA-V was concluded to be a "time-dependent drug" like vinblastine.

Topics: Animals; Antineoplastic Agents; Cell Division; Cell Line; Cell Survival; Humans; Kinetics; Leukemia P388; Mammary Neoplasms, Experimental; Mice; Mouth Neoplasms; Nasopharyngeal Neoplasms; Peptides, Cyclic; Plants, Medicinal; Structure-Activity Relationship