Biomedical subjects

F Pavanetto

Publications and source records attributed to F Pavanetto.

50 records · Page 3Linked to original sources

PubMed1977

Primary amides of bis-(2-carboxyphenyl)-disulfides with antimycotic activity.

A series of bis-amides of 2,2'-dicarboxydiphenyldisulfides with monosubstituted N-alkyl groups (substances I leads to XXVI) or N-aralkyl groups (substances XXVI leads to XLII) was prepared and examined for in vitro antifungal activity. The substances were obtained by condensing the chloride of 2,2'-dicarboxydiphenyldisulfide with suitable amines. The fungistatic activity of the products was tested in vitro against the following four strains: Candida albicans, Candida tropicalis, Saccharomyces cerevisiae, Trichophyton mentagrophytes. The results obtained summarised in Tables I and II amplify the structure-antifungal activity relationships of this class of compound. The most active compounds proved to be bis-(N-n.heptyl-2-carboxami-dophenyl)disulfide (XX) and bis-(N-beta-4Cl-phenylethyl-2-carboxamidophenyl)disulfide (XXXV).

Antifungal Agents↗

PubMed1977

[N-acylindoline with phytotoxic activity. II].

A series of N-acyl derivatives of indoline (A) was prepared and studied for phytotoxic activity. The substances studied (Tables I and II, substanes I leads to XXXVIII) were mostly new compounds and were prepared from the appropriate indoline by condensation with acid chlorides and isocyanates. The biological tests consisted in pre- and post-emergence treatment in doses of 6 kg/ha or less of six common weeds and for two substances (XVIII, XIX) of other species of agricultural importance (Table III). The results show that N-methylcarbamoyl and N-dimethylcarbamoylindolines in which the indoline nucleus bears a halogen or alkyl substituent are highly active on absorption via the roots of foliage and have a wide spectrum of action. The compounds showing the highest phytotoxic activity in both pre- and post-emergence tests were 5Cl-N-(methylcarbamoyl)indoline (XVIII), 5Cl-N-(dimethylcarbamoyl)indoline (XIX) and 2CH3-N-(methylcarbamoyl) indoline (XXXIII).

Chemical Phenomena↗

PubMed1977

[On the phytotoxicity of some N 1-phenyl-N 1- alkylureas].

A series of N1-phenyl-N1-alkylureas (E) and a series of N-carbamoyl derivatives of tetrahydroquinoline (D) were prepared and studied for phytotoxicity. The substances studied (Tables I, II, substances i leads to xxvii) were mostly new compounds and were prepared from suitable secondary amines by condensation with alkylating agents. Biological tests involved pre- and post-emergence treatment of five common weeds with doses of 6 kg/ha and lower doses (Tables i, ii). The tetrahydroquinoline derivatives (I leads to VII) proved inactive except for the N-dimethylcarbamoyl derivative (III) which on foliar absorption showed selective phytotoxicity against Vicia sativa L. Most of the members of the N1-phenyl-N1-alkylurea class (VIII leads to XXVII) did not have wide spectrum phytotoxicity. Some compounds have however interesting specificity of action against Vicia sativa L.

Alkylation↗

PubMed1976

[Phytotoxicity of hydrazones of aromatic aldehydes].

A series of hydrazones of aromatic aldehydes (B) was prepared and tested for phytotoxicity. These compounds are bioisosters of 1-aryltriazenes (A) which were found to possess interesting phytotoxic properties in a previous research. The substances studied (Tables I leads to III: compounds(I leads to CLXXX)) some of which were previously unrecorded, were prepared by the usual procedures from the required aldehyde and hydrazine derivative. The phytotoxicity of all the compounds was studied using seven representative species in both pre- and post-emergence tests at a dose of 6 kg/ha. It was found that this class of compounds shows phytotoxicity by absorption through the foliage with specificity for Amaranthus retroflexus L. The only exceptions are compounds where the aryl residue is 2,6-dichlorophenyl; these compounds show wide spectrum of phytotoxicity by absorption through the leaves.

Aldehydes↗

PubMed1976

[N-acylindoline with phytotoxic activity. I].

A series of N-acyl derivatives of indoline (A) was prepared and tested for phytotoxic activity. The substances studied (Tables I leads to III, substances I leads to XXVIII) were prepared by reaction of indoline with suitable acylating agents and were mainly new compounds. The biological tests consisted in pre- and post-emergence treatment in doses of 6 kg/ha or lower doses on five common weeds; one substance (XXV) was tested also on other species of economic importance (Table III). The results show that of the three classes studied the N-carbamoyl- and N-thiocarbamoyl derivatives of indoline have wide spectrum phytotoxic activity especialy on absorption via the foliage. The highest phytotoxic activity in both pre- and post-emergence tests was shown by N-(methylcarbamoyl)indoline (XIII) and N-(dimethylcarbamoyl(indoline (XXIII).

Acylation↗

PubMed1976

[Phytotoxic activity of triazene derivatives. VI. 1-aryl-3-arylalkyl-3-alkyltriazene derivatives].

A series of of 1-aryl-3-arylalkyl-3-alkyltriazenes (B) was prepared and studied for phytotoxic activity. The previously unknown substances [Table I: substances (I leads to XVI)] were prepared by condensation of the appropriate diazonium salt with the required secondary amine in an alkaline medium and were tested against five representative plant species in both pre- and post-emergence tests at a dose of 6 kg/ha. All the substances studied were inactive in pre-emergence tests. However most of the compounds showed phytotoxic activity by absorption through the foliage. This activity was not very pronounced and always lower than triazene analogs previously studied (type A compounds) which have no aralkyl residue on nitrogen 3.

Herbicides↗

PubMedDate not supplied

Evaluation of enzyme stability during preparation of polylactide-co-glycolide microspheres.

This work was aimed at studying enzyme prolidase stability and its interactions with the reagents and the process conditions involved in preparation, by an emulsification process, of prolidase loaded poly(lactide-co-glycolide) (PLGA) microparticulate systems. Enzyme stability was tested with respect to contact with methylene chloride, ethyl acetate, PLGA polymers, and several agents used as emulsifiers such as polyvinyl alcohol (PVA), polyvinyl pyrolidone (PVP), carboxymethyl cellulose (CMC) and sodium oleate (NaOl). Enzyme stability to temperature and mechanical stirring was also evaluated. Prolidase-loaded PLGA microspheres were prepared and evaluated in terms of protein activity. The results obtained showed that the prolidase-loaded PLGA microspheres can be prepared only upon enzyme stabilization by addition of both BSA and MnCl(2) into its TRIS solution. Methylene chloride was the suitable organic solvent to be used in the double emulsion process, together with PVA as dispersing agent in the outer aqueous phase. Low temperatures during the emulsification step and very short process times are recommended, in order to maintain enzyme activity at its maximum. In these conditions spherical microspheres were obtained, releasing active prolidase for up to 15 days.

Animals↗

PubMedDate not supplied

Boron-loaded liposomes in the treatment of hepatic metastases: preliminary investigation by autoradiography analysis.

Boronophenylalanine (BPA)-loaded conventional and stabilized liposomes were prepared by the reversed phase evaporation method to treat liver metastases by boron neutron capture therapy. Conventional vesicles were composed of phosphatidylcholine and cholesterol, molar ratio 1:1. To obtain stealth liposomes, GM1 or PEG were included in the lipidic bilayer at a concentration of 6.67 or 5 mol%, respectively. Large unilamellar vesicles were formulated encapsulating BPA in the liposome aqueous compartment as a complex with fructose; BPA free base also was embedded into the lipidic bilayer. In vivo experiments were carried out after intravenous injection of liposome suspensions in BD-IX strain rats in which liver metastases had been induced. Alpha particle spectroscopy associated with histological analysis was performed to visualize boron spatial distribution in liver. Simultaneously, tissue boron concentrations were determined using inductively coupled plasma-mass spectroscopy. Results showed that PEG-modified liposomes accumulated boron in therapeutic concentrations (> 30 micrograms boron/g tissue) in metastatic tissue. The PEG-liposomes could be further explored in enhancing boron delivery to tumor cells.

Animals↗

PubMedDate not supplied

Use of polylactic acid for the preparation of microparticulate drug delivery systems.

This report reviews the development of particulate drug delivery systems technology based on polylactic acid (PLA). The following methods used to produce PLA microparticles are considered: emulsion solvent evaporation, emulsion solvent extraction, interfacial phase deposition, spray coating, and the melting method. The different preparation processes and parameters used, the characteristics of microparticles obtained and those parameters affecting the characteristics of these systems, are discussed.

Chemistry, Pharmaceutical↗

PubMedDate not supplied

Evaluation of spray drying as a method for polylactide and polylactide-co-glycolide microsphere preparation.

Polylactide and polylactide-co-glycolide microspheres containing a lipophilic model drug (vitamin D3) were prepared by spray drying. The purpose of this work is to evaluate the efficacy of spray drying as a method for microsphere preparation. The study was carried out on five different polymers of lactide class: poly-L-lactide 57000 MW, poly-D,L-lactide 209,000 MW, 109,000 MW, 16,000 MW, and polylactide-co-glycolide 22,000 MW. The process conditions were experimentally assessed for each polymer used. The microspheres obtained were characterized for their shape, size and drug content, and the influence of the polymer on microsphere characteristics was evaluated. Results show that polymer type, polymer molecular weight and its concentration in the spraying solution greatly affect microsphere characteristics. In vitro dissolution tests performed with the rotating bottle method resulted in different release profiles depending on type of polymer and on microsphere morphology.

Biocompatible Materials↗

PubMedDate not supplied

Spray-dried albumin microspheres for the intra-articular delivery of dexamethasone.

This work deals with the preparation of corticosteroid-loaded albumin microspheres designed for intra-articular administration. Dexamethasone was chosen as the model drug and bovine serum albumin was used as the biodegradable, natural polymer. Albumin microspheres were produced by spray drying, a 'one-step' technique seldom used in the preparation of microparticulate drug delivery systems with particle sizes < 10 microns. The effects of both polymer/drug ratio used in the formulations and the different heat-stabilization conditions were evaluated on morphology, size, solubility characteristics, drug loading and 'in vitro' drug release of the microparticles.

Dexamethasone↗

PubMedDate not supplied

Evaluation of process parameters involved in chitosan microsphere preparation by the o/w/o multiple emulsion method.

Chitosans are interesting biopolymers largely studied for applications in the medical and pharmaceutical fields. In this work, an o/w/o multiple emulsion technique was used for the preparation of hydrophobic drug loaded microspheres. Moreover, the influence of critical variables (concentration of acetic acid in the polymer solution and drug-polymer ratio) on microsphere morphology and drug content was evaluated. Two chitosans of different molecular weights and deacetylation degree were employed; ketoprofen, a non-steroidal anti- inflammatory drug, was chosen as the hydrophobic model drug. The multiple emulsion method produced well-formed microspheres with good yields. Acetic acid concentration in the polymeric solutions influenced particle size and drug content of the microspheres. The highest drug encapsulation efficiencies were obtained for the lowest theoretical drug/chitosan ratio.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMedDate not supplied

Liposomes containing boronophenylalanine for boron neutron capture therapy.

In the present work, liposomes loaded with Boronophenylalanine (BPA), with or without stabilization, were formulated for the application in boron neutron capture therapy. BPA was encapsulated into liposomes as a complex with fructose, but also as a free drug in two different pH buffers. The influence of critical variables (cholesterol content, drug:lipid molar ratio, osmotic stress of liposomes containing hyperosmotic drug solution) on liposome morphology and drug content was evaluated. The drug content and dissolution profile of different BPA loaded liposomes were also studied. The physical stability of liposomes in terms of changes in the size distribution in different osmotic pressure buffers and the chemical oxidation of phospholipids during storing conditions were investigated. The encapsulation efficiencies of all formulations were always satisfactory, being between 20-48%; even when the liposomes were exposed to high osmotic stress, the particle size was below 200 nm. The BPA-fructose complex loaded liposomes showed a slower drug release profile.

Boron Compounds↗

PubMedDate not supplied

Evaluation of the influence of open and closed-ampoule technologies on particulate matter in small-volume parenterals.

SVP in glass ampoules are manufactured using two main different technological production processes: the open-ampoule process (O) and the closed-ampoule process (C). In principle, the open-ampoule production technology should lead to better controlled production process. To test this hypothesis and quantify the possible qualitative differences in the manufactured ampoules, a suitable experimental design was set up. The two ampoule production processes have been compared on the basis of the visible particulate burden. Two batches of ampoules filled with water for injections were produced for each type of process, following conventional industrial procedures. Two samples of 20,000 units were taken from each batch and inspected with different automatic inspection systems: two Brevetti CEA machines (S1, S2--light scattering) and two EISAI machines (S3, S4--light absorbtion). The comparison between the processes was based on the rejection percentage. On both inspection machines the open-ampoule production samples present rejection percentages (ranging from 0.154% to 1.248% rejection percentages) which, on average, are lower than those detected in closed-ampoule production (ranging from 1.434% to 3.86% rejection percentages). The difference between the two processes is even more marked if we also consider the data obtained using inspection machines S3 and S4. The substantial differences in performance of the four inspection machines stress the need to provide for adequate validation procedures.

Drug Contamination↗