101,921 research outputs found
1:2 Inclusion complex progesterone/HPBCD studied by Raman and NMR spectroscopy
No full textComplexes between Progesterone (P) and β-cyclodextrin (BCD) to obtain water soluble formulations are widely known; since hydroxypropyl β-cyclodextrin (HPBCD) displays higher water solubility (48% p/v), we started experiments to achieve a better solubilization of the hormone, to obtain up to 50 mg/ml progesterone concentration in physiological solution, to formulate a suitable dosage form for progesterone therapy.
We developed a production process in which the residual BCD (commercial HPBCD contains up to 0.8 % of unreacted material) is preliminarly separated by the formation of a poorly soluble complex. The stoichiometry and stability constant of the desired soluble complex were calculated by phase/solubility study. DSC and X-Ray analysis confirmed the absence of crystalline P in the final freeze-dried powder. The structural evaluation by spectroscopic analysis (Raman, FTIR and NMR) confirms the presence of an inclusion complex with a stoichiometry guest/host 1:2. The Raman spectrum of P shows tree sharp signals at 1616, 1664 and 1669 cm-1 due to the two carbonyls in position 3 and 20 of the steroid structure. HPBCD alone does not show signals in the considered area. P/HPBCD complex show a broad main signal at 1657 cm-1with a minor signal at 1691 cm-1 This change in the spectrum indicates the inclusion of the progesterone involving both rings A and D of the steroid structure. This idea was also confirmed by FT-IR spectroscopy (right).
NMR experiment shows shifts of signals attributed to P protons 4, 18,19 and 21 indicating again a involvement of rings A and D in the inclusion complex (left)
Multiple interactions of HIV-1 Tat protein with size-defined heparin oligosaccharides
No full textTat protein, a transactivating factor of the human immunodeficiency virus type I, acts also as an extracellular molecule. Heparin affects the bioavailability and biological activity of extracellular Tat (Rusnati, M., Coltrini, D., Oreste, P., Zoppetti, G., Albini, A., Noonan, D., D'Adda di Fagagna, F., Giacca, M., and Presta, M. (1997) J. Biol. Chem. 272, 11313-11320). Here, a series of homogeneously sized, (3)H-labeled heparin fragments were evaluated for their capacity to bind to free glutathione S-transferase (GST)-Tat protein and to immobilized GST-Tat. Hexasaccharides represent the minimum sized heparin fragments able to interact with GST-Tat at physiological ionic strength. Also, the affinity of binding increases with increasing the molecular size of the oligosaccharides, with large fragments (>/=18 saccharides) approaching the affinity of full-size heparin. 6-Mer heparin binds GST-Tat with a dissociation constant (K(d)) equal to 0.7 +/- 0.4 microM and a molar oligosaccharide:GST-Tat ratio of about 1:1. Interaction of GST-Tat with 22-mer or full-size heparin is consistent instead with two-component binding. At subsaturating concentrations, a single molecule of heparin interacts with 4-6 molecules of GST-Tat with high affinity (K(d) values in the nanomolar range of concentration); at saturating concentrations, heparin binds GST-Tat with lower affinity (K(d) values in the micromolar range of concentration) and a molar oligosaccharide:GST-Tat ratio of about 1:1. In agreement with the binding data, a positive correlation exists between the size of heparin oligosaccharides and their capacity to inhibit cell internalization, long terminal repeat-transactivating activity of extracellular Tat in HL3T1 cells, and its mitogenic activity in murine adenocarcinoma T53 Tat-less cells. The data demonstrate that the modality of heparin-Tat interaction is strongly affected by the size of the saccharide chain. The possibility of establishing multiple interactions increases the affinity of large heparin fragments for Tat protein and the capacity of the glycosaminoglycan to modulate the biological activity of extracellular Tat
Screening of Spotlight CSK images for large area monitoring and detection of infrastructures
No full textThis paper presents an automatic pre-screening algorithm of SAR images of huge size (more than 20;000x20;000 pixels), which is capable to identifying extended infrastructures in an effective and computationally efficient way. The algorithm is tested on true one-look Cosmo-SkyMed SAR image data for target detection purposes on an airport scenario. Both visual and objective results are presented to show the potentials of the proposed method
New injectable formulation containing water soluble Progesterone-Hydroxypropyl-beta-cyclodextrin complex
No full textProgesterone (P) is a natural hormone used as a drug to control reproductive function and for postmenopausal therapy. Oral and vaginal routes display low bioavailability and, in addition, oral route has a limited usefulness, because of P short half-life and extensive degradation after absorption. Therefore the injection route should be the preferred choice, since the oily solution and the aqueous suspension allow only intramuscolar administration. This encourages the research of new injectable pharmaceutical form with increase of the patient compliance. Water-soluble P formulations represent a suitable solution, because they could be administered also by subcutaneous route, therefore allowing auto medication and less pain during the treatment is expected.
Pitha et al. described the use of Cyclodextrins to increase the water solubility of Progesterone (P), through the formation of an inclusion complex to obtain a water soluble formulation (1). Also other authors, using different physico-chemical methods (2, 3, 4), reported experimental evidences of the inclusion complex formation between P and b-cyclodextrin and derivatives. Among the cyclodextrins tested hydroxypropyl-b-cyclodextrin (HPBCD) is a suitable choice for formulations containing therapeutic concentration of P. The therapeutic dosage of P by injection varies from 5 to 200 mg. as a function of the specific pathology (5). HPBCD, displaying high water solubility (48% p/v), allows solubilisation of large quantity of P. Considering the formation of a 1:2 complex, it is possible to obtain solutions up to 50 mg/ml P, which is a considerable dosage in the progesterone therapy. In the development of P/HPBCD complex we observed the formation of a light precipitate under stability ICH conditions. Choi et al (4) and also by Pitha et al (1) noticed the precipitate formation, but its chemical structure was not elucidated.
This work describes a method to obtain a P/HPBCD without insoluble particles, the physico-chemical characterization of the precipitate and of the purified inclusion complex
ATR/Raman and fractal characterization of HPBCD/progesterone complex solid particles
No full textPURPOSE: Characterization of hydroxypropyl-beta-cyclodextrin/progesterone (HPBCD/P) complex solid particles obtained from an aqueous solution, by three different technological processes, with the aim of preparing ready-to-dissolve powders for injectable as well as solid oral formulations in progestinic therapy. METHODS: HPBCD/P complex in the 2:1 molar ratio was prepared in aqueous solution and obtained as dry solid particles by freeze-drying, by spray-drying and by fluid-bed evaporation of the solvent. The particles were characterized by mu-FT-IR, mu-Raman and X-ray spectroscopy, by thermal analysis (differential scanning calorimetry-DSC and thermogravimetry-TGA), by Karl Fischer (KF) titration, by image and fractal analysis and by BET specific surface area analysis. The structure of the complex was also defined by comparison of FT-IR and Raman spectra of progesterone with those of pregnenolone and testosterone, structurally related. Dissolution tests were also performed. RESULTS: Powders of the complex obtained by the three different methods are different in size and shape. Particles obtained by freeze-drying are flat and angular, irregularly shaped without any relation to known geometrical solid figures. Particles obtained by spray-drying are spherically shaped and display a very small size (5-10 microm), with evident deformations and depression of the external surface, due to the rapid evaporation of the solvent. Particles obtained by fluid bed technique have intermediate sizes, display a tri-dimensional structure and irregular surface, with small and rounded protuberances. Fractal dimension of the particle contour was found close to one unit for the microspheres obtained by spray-drying. FT-IR and Raman spectra confirm the occurrence of the complexation by the shift of representative bands of the two carbonyl groups in positions 3 and 20 of the complexed progesterone. X-ray diffractograms indicate the amorphous nature of all the types of particles, also suggested by the absence of any melting peak of the drug in DSC thermograms. The samples contain different amounts of humidity: particles obtained by fluid-bed method demonstrated non-porous in BET analysis. Dissolution of different types of particles is complete after 3 min and only negligible differences could be appreciated among the three powders. CONCLUSIONS: - mu-FT-IR, mu-Raman and X-ray spectroscopy, and the dissolution test did not reveal defined differences among the three different types of particles, confirming occurrence of the complex in the solid state. The spherical shape, the very small size and the low value of the contour fractal dimension allows better technological performance of the particles obtained by spray-drying: this drying process appears the most promising one to prepare dry particles of the HPBCD/P complex, in view of its formulation in the fast preparation of extemporaneous injectable solutions and solid oral formulations intended for sublingual delivery
Biotechnological engineering of heparin/heparan sulphate: a novel area of multi-target drug discovery.
No full textPer un rinnovamento europeo della cultura e della scienza a Bergamo: Gianantonio Tadini e la Fisica
No full textThe interaction of basic fibroblast growth factor (bFGF) with heparan sulfate proteoglycans: biochemical bases and biological implications
No full textStructure and conformation of polyalcohols and polyacids obtained from periodate oxyamylose and oxycellulose
No full textDifferent effects of mucosal, beef lung, and chemically modified heparin on selected biological properties of basic fibroblast growth factor
No full textHeparins from bovine mucosa and lung, and chemically modified heparins were assayed for their capacity to: (i) protect human recombinant basic fibroblast growth factor (bFGF) from tryptic cleavage; (ii) prevent 125I-bFGF binding to heparan sulphate proteoglycans present in the extracellular matrix and on the cell surface of fetal bovine aortic endothelial GM 7373 cell cultures; (iii) affect 125I-bFGF binding to high-affinity tyrosine kinase FGF receptors present on the cell membrane of GM 7373 cells; (iv) inhibit the mitogenic activity exerted by bFGF in the same cells. The results demonstrate that the potency shown by mucosal heparins in the different assays is a direct function of size, very-low-molecular-mass heparin (2.0 kDa) being significantly less effective on a molar basis than unfractionated heparin (13.6 kDa). Increased flexibility of the backbone structure, as observed in reduced/oxidized heparins of different size, does not affect the capacity of the polysaccharide to interact with bFGF. In contrast, selective 2-O-desulphation, but not 6-O-desulphation, drastically reduced the capacity of heparin to protect bFGF from proteolytic cleavage, to affect its interaction with low- and high-affinity sites, and to inhibit its mitogenic activity. Two preparations of bovine lung heparin, differing in molecular mass, were as effective as mucosal heparin in the bFGF-tryptic-digestion assay and the endothelial-cell proteoglycan-binding assay, but they were highly inefficient at inhibiting the capacity of bFGF to interact with its tyrosine kinase receptors. Bovine lung heparins were also less effective than mucosal heparin as bFGF antagonists in GM 7373-cell-proliferation assays. N-Desulphated/N-acetylated bovine lung heparin retained only a significant capacity to protect bFGF from tryptic cleavage. The results demonstrate that different chemical features of the heparin molecule, including decrease in molecular mass, selective desulphation, disaccharide composition and clustering, affect differently the capacity of the glycosaminoglycan to interact with bFGF and to influence its biological behaviour in different assays in vitro and in endothelial cell cultures. Our findings should aid the design of synthetic oligosaccharides aimed at improving the bioavailability of bFGF when administered in vivo as a therapeutic agent
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