Synthesis and study of the biological activity of fragments of salmon calcitonin II

A number of fragments of salmon calcitonin II possessing analgesic activity of the nonopioid type have been synthesized.Institute of High-Molecular-Mass Compounds, Russian Academy of Sciences. Institute of Experimental Medicine, Russian Academy of Medical Sciences, St. Petersburg. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 126–132, January–February, 1993.     

Production of C-terminal amidated recombinant salmon calcitonin in Streptomyces lividans

Salmon calcitonin (sCT) is one of the many bioactive peptides that require C-terminal amidation for full biologic activity. To produce fully bioactive sCT in large scale, we constructed Streptomyces lividans [pMSA], an engineering Streptomyces strain. In the expression vector, glycine-extended sCT, the substrate for amidation, and rat α-amidating enzyme cDNA were cloned under the control of the strong constitutive promoter from the Streptomyces fradiae aph gene in pIJ680. Both were expressed in a secretory manner by the recombinant strain using the expression and secretion signals of melC1. Extracellularly expressed recombinant sCT was purified to near homogeneity and characterized by enzyme immunoassay, followed by direct amino-terminal sequencing. High-performance liquid chromatography, matrixassisted laser desorption ionization-time-of-flight mass spectrometry, and bioassay in vivo demonstrated purified product to be equivalent to synthetic standard. Thus, the engineered Streptomyces strain can produce bioactive, C-terminal amidated recombinant sCT in the culture supernatant directly. The ease of the recombinant process, as well as its potential for scale-up, makes it adaptable to production demands for sCT, and it may be applied to other bioactive peptides that need C-terminal amidation.     

Human calcitonin. IV. Synthesis of calcitonin M

A preliminary account is giver of the synthesis of calcitonin M (I), isolated from human C-cell tumour tissue [2] [3]. Identity of the synthetic and the natural hormone was established by thin-layer chromatography, thin-layer electrophoresis and conversion to oxidation products, as well as by reference to the pattern of tryptic degradation and by comparing the biological activity of the two hormones. The findings also afforded additional confirmation of the results of structural elucidation [1]. In the synthesis of I, use was made of methods described previously [4] for the preparation of porcine α-thyrocalcitonin, and also of a new method [5] which easily permits the formation of cyclic cystine peptides.     

Metal ions as cofactors for aggregation of therapeutic peptide salmon calcitonin

The effects of multivalent metal ions (Cu(2+)/Zn(2+)/Al(3+)) on the aggregation of salmon calcitonin (sCT)--a therapeutic peptide used worldwide in the treatment of osteoporosis and Paget's disease--have been studied in vitro using NMR (both solution state and solid state), TEM, ThT-fluorescence, and FT-IR spectroscopy. Overall, the various results indicated that the metal-ions-induced conformational transitions in the peptide--mostly toward the β-sheet--facilitate the aggregation of sCT in solution. First, the solution NMR has been used to check the interaction between the peptide and the metal ions. Following this, the formation and characterization of calcitonin aggregates has been performed using TEM, solid state NMR, and FT-IR spectroscopy. The TEM and ThT-fluorescence results revealed that the sCT peptide incubated with Cu(2+) and Zn(2+) metal ions (in aqueous environment) forms globular aggregates, while that with Al(3+) ions forms fibrils. The solid state NMR and FT-IR studies revealed the presence of a substantial amount of β-sheet content in sCT aggregates (formed in the presence of these metal ions) compared to the monomeric sCT, indicating that the metal binding is concomitant with conformational changes. The present study becomes crucial while prescribing this drug peptide under physio-pathological conditions associated with an abnormal accumulation of metal ions (Cu(2+)/Zn(2+)/Al(3+)) in the body (i.e., abnormal metal ion homeostasis).     

Synthesis of 2-ethyl-2-methyl-2,3-dihydro-1H-indole, a new insecticide exhibiting juvenile hormone activity

Catalytic hydroamination of isoprene gave N-(1,2-dimethylprop-2-en-1-yl)aniline in a preparative yield. By heating at 260°C the product was converted into 2-ethyl-2-methyl-2,3-dihydro-1H-indole, a new ecologically safe insecticide exhibiting a juvenile hormone activity. Its insecticide properties against Tenebrio Molitor L. chrysalises were estimated at 7.5 points according to the Schmialek 9-point scale.     

Synthesis of desoxyanteridiol,a lanostane analog of a fungal sex hormone

The stereoselective synthesis of a-lactone, (22R)-3-acetoxy-22-hydroxylanosta-8,24(31)-dien-32-oic acid (X), which is the first lanostane analog of the sex hormone ofAchlya aqueous fungi, was carried out by means of 1,3-dipolar addition of nitrile oxides to lanostane olefin (I) through (22R)-isoxazoline (III) as a key intermediate.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 969–972, April, 1991.     

Influence of the mobile phase on salmon calcitonin analysis by reversed-phase liquid chromatography

The retention properties of calcitonins on a reversed-phase column are examined using salmon calcitonin as the model compound. The effect of the concentration of organic modifier, buffer strength, pH of the mobile phase, and ion-pair reagent are studied. In the absence of an ionic modifier in the eluent the calcitonin peak shapes are not symmetrical. The addition of 0.1% trifluoroacetic acid (TFA), however, results in good peak characteristics without the need to add nonvolatile salts. The retention of the calcitonins was found to be very sensitive to the concentration of the organic modifier (acetonitrile) present in the mobile phase. A change of pH between 2 and 5 has only a slight effect of the k' of salmon calcitonin, but the k' increases significantly at higher pH values. The addition of a phosphate buffer to the mobile phase and an increase in the buffer concentration (0-0.2 M) causes a decrease in the retention of salmon calcitonin. Evidence shows that reproducible, quantitatively measurable data can be obtained using reversed-phase chromatography if the ion-pairing reagent and organic modifier concentrations are carefully controlled. The system also shows a good selectivity for the calcitonin series. Therefore, both highly selective methods (qualitative) as well as quantitative methods for analytical, pharmaceutical, and manufacturing use can be developed by adjusting the high-performance liquid chromatography (HPLC) conditions as discussed.     

Synthesis of a new chemically stable prostacyclin analogue with high and long-lasting activity

The chemically stable prostacyclin analogue (Z)-4,5-didehydroisocarbacyclin analogue (6) has been synthesized. Compound 6 given intravenously or orally is very potent in inhibiting platelet aggregation.     

Synthesis of silenosterone, an insect-molting hormone

Silenosterone is synthesized in five steps: acetylation of 2-desoxy-α-ecdysone (1), saponification of 2-desoxy-α-ecdysone-3,22-diacetate (2) to the 22-monoacetate (3), and oxidation of the latter to a ketone (4) and its base hydrolysis (5). The structures of the compounds are confirmed by PMR, IR spectroscopy, and mass spectrometry. Academician S. Yu. Yunusov Institute of the Chemistry of Plant Substances. Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (99871) 120 64 75. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 767–770, November–December, 1999.     

Synthesis and biological activity of a stereoisomeric mixture of the mating hormone of Phytophthora

The first synthesis of a stereoisomeric mixture of hormone α1, the mating hormone of Phytophthora, was achieved, and the synthetic mixture was confirmed to be hormonally active.     

Synthesis of tritiated antiviral isoxazoles at high specific activity

The tritiation of WIN 51711 and several structural analogues is described.     

Synthesis of a heptapeptide with sequence 17–23 of human calcitonin

Two schemes for the synthesis of a peptide with sequence 17–23 of human calcitonin with the minimum protection of the lateral functions of the amino acids are proposed.     

Nasal absorption and pharmacokinetic disposition of salmon calcitonin modified with low molecular weight polyethylene glycol

This study was performed to examine the absorption potential of polyethylene glycol (PEG)-modified salmon calcitonin (sCT) in rats administered via the nasal route. Previous studies have used relatively high molecular weight polyethylene glycols (e.g., > or =5000 daltons) for PEG-modification of sCT to provide increased metabolic stability and biological half-life. Unlike these studies, the present study utilized a low molecular weight succinimidyl-propionated monomethoxy-poly(ethylene glycol) (MW 2000). It was hypothesized that the potential for membrane transport would not be significantly altered due to a relatively small increase in the molecular size while the metabolic stability would be enhanced due to resistance to proteolytic degradation. After PEG-modification of sCT, the mono-PEG positional isomer (mono-PEG2k-sCT) was separated from di-PEG2k-sCT, tri-PEG2k-sCT, and unmodified sCT by size exclusion chromatography. The mono-PEG2k-sCT and unmodified sCT were radioiodinated, and the resulting 125I-sCT and 125I-mono-PEG2k-sCT were separated from free iodine by RP HPLC and confirmed by MALDI-TOF MS. The 125I-sCT and 125I-mono-PEG2k-sCT were administered to rats via the nasal route, and serial blood, tissue, and urine samples were taken for up to 36 h for the determination of radioactivity. Mono-PEG2k-sCT exhibited significantly increased AUC (20,638 vs. 3,650 ng.min/ml), tmax (520 vs. 77 min), and t1/2,lambdaz (923 vs. 199 min) compared with unmodified sCT. This study demonstrates that mono-PEG2k-sCT is absorbed systemically when given by the intranasal route, exhibiting altered absorption kinetics compared with unmodified sCT.     

Synthesis, modeling, and anti-tubulin activity of a D-seco paclitaxel analogue

[reaction: see text] We have previously described a model of paclitaxel-microtubule binding that led to the prediction that analogues of paclitaxel lacking any D ring could stabilize microtubules as well as paclitaxel if the substituent present at C4 did not have unfavorable steric interactions with the binding pocket. We report the synthesis of a 4-methyl paclitaxel analogue, compound 1, which bears this prediction out. Compound 1 is as potent as paclitaxel at microtubule stabilization in vitro; however, it has only about one-four-hundredth the cytotoxicity of paclitaxel.     

Synthesis of compounds with juvenile hormone activity—XVII : A stereoselective synthesis of dl-C17-Cecropia juvenile hormone

A stereoselective synthesis of the title compound (2) was accomplished using a coupling reaction of a C₆-unit (4) with a C₁₀-unit (8) as the key-step.