Star-Shaped Poly(furfuryl glycidyl ether)-Block-Poly(glyceryl glycerol ether) as an Efficient Agent for the Enhancement of Nifuratel Solubility and for the Formation of Injectable and Self-Healable Hydrogel Platforms for the Gynaecological Therapies

In this paper, we present novel well-defined unimolecular micelles constructed a on poly(furfuryl glycidyl ether) core and highly hydrophilic poly(glyceryl glycerol ether) shell, PFGE-b-PGGE. The copolymer was synthesized via anionic ring-opening polymerization of furfuryl glycidyl ether and (1,2-isopropylidene glyceryl) glycidyl ether, respectively. MTT assay revealed that the copolymer is non-cytotoxic against human cervical cancer endothelial (HeLa) cells. The copolymer thanks to furan moieties in its core is capable of encapsulation of nifuratel, a hydrophobic nitrofuran derivative, which is a drug applied in the gynaecology therapies that shows a broad antimicroorganism spectrum. The study shows high loading capacity of the copolymer, i.e., 146 mg of nifuratel per 1 g of copolymer. The load unimolecular micelles were characterized using DLS and TEM microscopy and compared with the reference glyceryl glycerol ether homopolymer sample. The presence of numerous 1,2-diol moieties in the shell of PFGE-b-PGG macromolecules enabled the formation of reversible cross-links with 2-acrylamidephenylboronic acid-based polyacrylamide. The obtained hydrogels were both injectable and self-healable, which was confirmed with a rheological study.

Investigating the dissolution profiles of amoxicillin, metronidazole, and zidovudine formulations used in Trinidad and Tobago, West Indies

Trinidad and Tobago is a twin-island Republic in the Caribbean and like many developing countries, it has included generic drugs on the national drug formulary to decrease the financial burden of pharmaceutical medications. However, to ensure that medications received by patients are beneficial, generic drugs need to be interchangeable with the innovator which has demonstrated safety, efficacy, and quality. The objective of the study was to compare the dissolution profiles and weight variations for different formulations of amoxicillin, metronidazole, and zidovudine that are on the national drug formulary and marketed in Trinidad and Tobago. All the products investigated are categorized as class 1 drugs according to the Biopharmaceutics Classification System (BCS) and the dissolution profiles were assessed according to the World Health Organization (WHO) criteria for interchangeability between products. The similarity factor, f 2, was used to determine sameness between the products. No generic formulation was found to be similar to Amoxil® 500-mg capsules. The two generic products for metronidazole 200-mg tablets demonstrated more than 85% drug release within 15 min in all three of the buffers; however, their 400-mg counterparts did not fulfill this requirement. The zidovudine 300-mg tablet complied with the requirements in buffer pH 4.5 and simulated gastric fluid (SGF) but not for simulated intestinal fluid (SIF). Some Class 1 pharmaceutical formulations may possess the same active ingredient and amount of drug but may show significant differences to in vitro equivalence requirements. Nevertheless, the dissolution process is suitable to detect these variations.

Screening and bioguided fractionation of Amaryllidaceae species with anti-Trichomonas vaginalis activity

The Amaryllidaceae family is known by its ornamental and medicinal value and has attracted considerable attention due to the content of alkaloids of its species, which showed interesting biological properties. The present study evaluated the anti-Trichomonas vaginalis activity of eighteen extracts (12.5 to 0.19 mg/mL) and six isolated alkaloids (125 to 1.9 µg/mL) from Amaryllidaceae species. The alkaloids diminished the trophozoites viability (from 15 to 40 %). The extracts from Hippeastrum breviflorum demonstrated the highest anti-T. vaginalis activity (viability was 60 % reduced), and a bioguided study was conducted. Six fractions with antiprotozoal activity had lycorine and lycosinine as major components suggesting a synergistic effect, taking into account the higher anti-T. vaginalis activity of extracts when compared to isolated alkaloids. Our results point out the antiprotozoal potential of the Amaryllidaceae species against T. vaginalis. This parasite causes trichomonosis, the most prevalent nonviral sexually transmitted diseases (STD) worldwide and a public health problem that requires new therapeutic alternatives as well bioactive natural products.

Efficacy of two plant extracts against vaginal trichomoniasis

Trichomoniasis vaginalis is now an important worldwide health problem. Metronidazole has so far been used in treatment, but the metronidazole-resistant strains and unpleasant adverse effects have been developed. Treatment of patients with metronidazole refractory vaginal trichomoniasis constitutes a major therapeutic challenge and treatment options are extremely limited. In the present study, 33 metronidazole-resistant T. vaginalis females were treated with a combined course of metronidazole and tinidazole. Those still resistant to the combined treatment were given Commiphora molmol (Myrrh) as two capsules for six to eight successive days on an empty stomach two hours before breakfast. Also, natural plant extract purified from (Roman) was in-vitro investigated for its efficacy against T. vaginalis on fresh Diamond media. The anti-trichomoniasis vaginalis activity of both P. granatum (in-vitro) and C. molmol (in-vivo) extracts gave promising results.

Characterization and ornidazole releasein vitro of a novel composite film prepared with chitosan/poly(vinyl alcohol)/alginate

To create a moist environment for rapid wound healing, a new C-P-A film with sustained antibacterial capacity had been developed by the casting/solvent evaporation method. This new type of C-P-A film consists of a chitosan top layer and sodium alginate sublayer separated by an ornidazole-incorporated poly(vinyl alcohol) layer, exhibited perfect binding characteristics among the three layers. Physical characterization of the C-P-A film showed that the triple-layerd film had excellent light transmittance, control of water vapor transmission rate, and fluid drainage ability promotion, compared with the single-layer film. From the in vitro release studies, about 90% of OD was released from the composite films within 60 min, and no significant difference was observed in cumulative release percentage with increases in the drug content. The composite film at low concentration of OD (1.0 mg/cm2) showed effective antimicrobial activity in the cultures of Staphylococcus aureus and Escherichia coli in agar plates. The results obtained in this work indicated that the new type of C-P-A composite film incorporated with ornidazole has the potential for wound dressing application.

Effect of Mexican medicinal plant used to treat trichomoniasis on Trichomonas vaginalis trophozoites

Crude methanolic extracts from 22 Mexican medicinal plants were screened for antitrichomonal activity against Trichomonas vaginalis, which is the etiological agent of trichomoniasis. Among the plants tested Carica papaya and Cocos nucifera showed the best antitrichomonal activity with IC(50) values of 5.6 and 5.8 microg/ml, respectively. The extracts of Bocconia frutescens, Geranium mexicanum, and Lygodium venustum showed moderate activity with IC(50) values ranging from 30.9 to 60.9 microg/ml. All the other plant extracts were inactive (IC(50)>100 microg/ml). All extracts tested were less active than metronidazole (IC(50) 0.037 microg/ml), an antiprotozoal drug used as positive control. The results of the antiprotozoal screening support the popular uses of five of the plants tested for the treatment of some urogenital tract disorders in Mexican traditional medicine. However, seeds of Carica papaya and aerial parts of Bocconia frutescens should be used in herbal medicine with care to avoid toxicity.

Study on poly(vinyl alcohol)/carboxymethyl-chitosan blend film as local drug delivery system

The distinguishable films composed of poly(vinyl alcohol) (PVA) and carboxymethyl-chitosan (CMCS) were prepared by blending/casting method, and loaded with ornidazole (OD) as local drug delivery system. In vitro test, the blend films showed pH-responsive swelling behavior and moderate drug release action, and also exhibited a little antimicrobial activity against E. coli and S. aureus strains. Those characteristics of CMCS/PVA blend films were essentially governed by the weight ratio of CMCS and PVA. Increasing the content of PVA in blend film would decrease swelling and decelerated the drug release. However, increasing the content of CMCS would enhance the antimicrobial activity. The biocompatibility and bioactivity of the blend film were also evaluated using rabbit blood and Wister rats. This blend drug system was of no hemolysis, no toxicity to rat periodontia and no cytotoxicity to the rat muscle. After subcutaneously implanting the blend drug films in Wister rat, the systems kept a good retention at the application site and maintained high drug concentration in long time (5 days) which was longer than the period of drug released in vitro (160 min).

Study on the compatibility of cefotaxime with tinidazole in glucose injection

An efficient HPLC method for the compatibility study of cefotaxime with tinidazole in glucose injection is described, which has been developed for the simultaneous determination of cefotaxime and tinidazole in glucose injection. The appearance and pH value of the mixed solution were investigated and the concentrations of cefotaxime and tinidazole were determined by RP-HPLC with an Agilent ZORBAX Eclipse XDB-C8 column, gradient elution and dual wavelength detection on diode-array-detector (DAD) at room temperature (20 degrees C) within 24 h. It was found that the resulting appearance and pH value of the mixed solution showed slight changes, on the other hand, the quantity of cefotaxime decreased significantly. The results show that the mixed solution of cefotaxime with tinidazole in glucose injection must be used within 8 h in clinical due to the possible degradation of cefotaxime in tinidazole glucose injection. This study provides a convenient method for rational use of compatible drugs in clinical practice.

Synthesis of benzenepropanamine analogues as non-detergent spermicides with antitrichomonas and anticandida activities

Fifteen analogues of benzenepropanamine were synthesized and evaluated for their spermicidal as well as microbicidal activities against Trichomonas vaginalis and Candida spp. Several compounds showed appreciable dual activities. Compound 12 exhibited good spermicidal (MEC=0.1%) along with substantial anticandidal (MIC=0.05%) activities, while compounds 3 and 6 showed significant microbicidal activities with moderate spermicidal effect. The SAR of these structures is being discussed here in this communication. It is concluded that suitable structural modifications in this class of compounds at 3-amino position may lead to a potent spermicide with associated microbicidal activity.

Voltammetric sensor for tinidazole based on poly(carmine) film-modified electrode and its application

A poly(carmine) film-modified glassy carbon electrode (GCE) was fabricated and the electrochemical behavior of tinidazole at the modified electrode was investigated by electrochemical methods. A well-defined reduction peak was observed at 0.61 V and was applied for the determination of tinidazole. Compared with that at a bare GCE, the reduction peak potential of tinidazole shifted negatively and the reduction peak current increased significantly. The influences of some parameters on the reduction of tinidazole were also examined. Based on the experimental data, a possible mechanism was proposed for the electrochemical reaction of tinidazole at the modified electrode. It was found that the reduction peak current was proportional to the concentration of tinidazole in the range from 1.0 x 10(-7) to 5.0 x 10(-5)mol L(-1). The detection limit was about 1.0 x 10(-8)mol L(-1) after accumulation 90 s at a constant potential of 0.0 V. The proposed method was applied to determine tinidazole in drugs and the result was satisfied.

The spermicidal and antitrichomonas activities of SSRI antidepressants

The study investigated spermicidal and antitrichomonas activities of selective serotonin reuptake inhibitor (SSRI) antidepressants with a view to generate new lead for development of dual-function spermicidal microbicides, which is an urgent global need. Fluoxetine, Sertraline, and Fluvoxamine exhibited both spermicidal and anti-STI (antitrichomonas) activities in vitro, whereas Paroxetine and Citalopram showed only the spermicidal activity. Fluoxetine exhibited better activity profile than the other antidepressant drugs with its spermicidal and antitrichomonas activities being comparable to that of the OTC contraceptive Nonoxynol-9. The non-detergent nature of Fluoxetine and a much lower spermicidal ED50 value (than N-9) may add considerably to its merit as a candidate for microbicidal contraceptive. Thus, the antidepressants exhibiting both spermicidal and antitrichomonas activities might provide useful lead for the development of novel, dual-function spermicidal contraceptives.

A linear discrimination analysis based virtual screening of trichomonacidal lead-like compounds: Outcomes of in silico studies supported by experimental results

A computational (virtual) screening test to identify potential trichomonacidals has been developed. Molecular structures of trichomonacidal and non-trichomonacidal drugs were represented using stochastic and non-stochastic atom-based quadratic indices and a linear discrimination analysis (LDA) was trained to classify molecules regarding their antiprotozoan activity. Validation tests revealed that our LDA-QSAR models recognize at least 88.24% of trichomonacidal lead-like compounds and suggest using this methodology in virtual screening protocols. These classification functions were then applied to find new lead antitrichomonal compounds. In this connection, the biological assays of eight compounds, selected by computational screening using the present models, give good results (87.50% of good classification). In general, most of the compounds showed high activity against Trichomonas vaginalis at the concentration of 100 microg/ml and low cytotoxicity to this concentration. In particular, two heterocyclic derivatives (VA7-67 and VA7-69) maintained their efficacy at 10 microg/ml with an important trichomonacidal activity (100.00% of reduction), but it is remarkable that the compound VA7-67 did not show cytotoxic effects in macrophage cultivations. This result opens a door to a virtual study considering a higher variability of the structural core already evaluated, as well as of other chemicals not included in this study.

Antitrichomonal and antioxidant activities of Dorstenia barteri and Dorstenia convexa

Dorstenia barteri and D. convexa extracts and some isolated components of the former were investigated for effectiveness against Trichomonas gallinarum and compared with quercetin and quercitrin. The antioxidant activity of the extracts/compounds was also determined. The minimum lethal concentrations (MLCs) for the extract of D. barteri leaves and twigs at 24 h were found to be 15.625 and 15.625 microg/ml, respectively. However, the MLCs of the leaf and twig extract of D. convexa were 125 and 437.5 microg/ml, respectively. The prenylated and geranylated chalcones were as active as the prenylated flavones, 6-prenylapigenin and the diprenylated derivative 6,8-diprenyleridictyol. The order of the antitrichomonal activity of the compounds at 24 h was: quercetin (0.121 microg/ml) > quercitrin (0.244 microg/ml) > or = bartericin B (0.244 microg/ml) > bartericin A (0.73 microg/ml) > stigmasterol (0.98 microg/ml) > 6,8-diprenyleridictyol = isobavachalcone = dorsmanin F (31.25 microg/ml). D. barteri extracts, quercitrin, and bartericin A, and the prenylated flavonoids had potent antioxidant properties. The twig extract of D. barteri was more potent than the leaf extract. Moderate (EC50 >50 microg/ml) and high (EC50 <50 microg/ml) antioxidant activities were detected in the leaf and twig extracts of D. barteri and the prenylated flavonoids. Prenylated flavonoids and the isolated compounds with antioxidant properties described here may account for the anti-inflammatory action of these extracts. The antitrichomonal and antioxidant activities shown by the extracts and compounds in this study are consistent with the ethnomedicinal and local use of the Dorstenia species studied.

N-acetyl-β-d-hexosaminidase from Trichomonas vaginalis: substrate specificity and activity of inhibitors

Among chitinolytic activities previously described in Trichomonas vaginalis, N-acetyl-beta-D-hexosaminidase (NAHase) was the enzyme system expressing the highest level of specific activity. We report here some biochemical characteristics of NAHase purified from T. vaginalis. We found at first that the use of 4-methylumbellifferyl-substrate was responsible for a substrate affinity for the enzyme, about 1000-fold higher than those when using p-nitrophenyl-substrates (PNP). Whereas the optimum pH was 7.0 using PNP-substrate, it was at 4.5 using 4-methylumbelliferyl-substrate. Four different substrates were compared for their action on T. vaginalis NAHase and we have found that N-acetyl-beta-D-glucosaminide substrate was the most specific. DTT had no effect on enzyme activity suggesting that thiol group are not involved at the catalytic site. The use of previously described inhibitors showed a positive correlation between trichomonacidal activity and NAHase inhibition.

Intracellular release of nitric oxide by NCX 972, an NO-releasing metronidazole, enhances in vitro killing of Entamoeba histolytica

The activity of NCX 972, a new molecule obtained by adding a nitric oxide (NO) moiety to metronidazole, was tested against six isolates of Entamoeba histolytica in xenic cultures. NCX 972 released NO into trophozoite cells and enhanced killing of amoebas in a dose- and time-dependent manner compared to metronidazole.

On the hydrolytic behavior of tinidazole, metronidazole, and ornidazole

Using two UV-spectrophotometric methods, the hydrolysis of tinidazole was studied at pH 1.00-8.45 at 80 degrees C. The reaction followed apparent first-order kinetics throughout the studied range. No kinetic salt effect was detected, indicating that at least one of the reacting partners forming the transition state has a charge of 0. The reaction rate macro constants M(1)-M(4) were calculated to be 3.35 x 10(-2) M(-1) h(-1), 1.45 x 10(-2) h(-1), 3.76 x 10(-6) M h(-1), and 2.85 x 10(-11) M(2) h(-1), respectively. At pH >or= 7, the uncharged tinidazole was decomposed by the hydroxide ion; the reaction was found out to involve a proton transfer from the ethylsulfonylethyl side chain. At around pH 4.5, the degradation of the uncharged tinidazole was due to the solvent. In more acidic conditions, the reaction mechanism could not be fully resolved. The alkaline hydrolysis of metronidazole was studied on the basis of literature data. A general reaction mechanism was proposed, but an unequivocal explanation for the inflection point in the pH rate profile at pH 6 could not be found. The implications of the proposed reaction mechanism for the hydrolytic behavior of ornidazole were discussed.

The crystal structure of Trichomonas vaginalis ferredoxin provides insight into metronidazole activation

Crystallographic studies revealing the three-dimensional structure of the oxidized form of the [2Fe-2S] ferredoxin from Trichomonas vaginalis (TvFd) are presented. TvFd, a member of the hydrogenosomal class of ferredoxins, possesses a unique combination of redox and spectroscopic properties, and is believed to be the biological molecule that activates the drug metronidazole reductively in the treatment of trichomoniasis. It is the first hydrogenosomal ferredoxin to have its structure determined. The structure of TvFd reveals a monomeric, 93 residue protein with a fold similar to that of other known [2Fe-2S] ferredoxins. It contains nine hydrogen bonds to the sulfur atoms of the cluster, which is more than the number predicted on the basis of the spectroscopic data. The TvFd structure contains a large dipole moment like adrenodoxin, and appears to have a similar interaction domain. Our analysis demonstrates that TvFd has a unique cavity near the iron-sulfur cluster that exposes one of the inorganic sulfur atoms of the cluster to solvent. This cavity is not seen in any other [2Fe-2S] ferredoxin with known structure, and is hypothesized to be responsible for the high rate of metronidazole reduction by TvFd.

In vitro activity of nitazoxanide and related compounds against isolates of Giardia intestinalis, Entamoeba histolytica and Trichomonas vaginalis

The activities of the N-(nitrothiazolyl) salicylamide nitazoxanide and its metabolite tizoxanide were compared with metronidazole in vitro in microplates against six axenic isolates of Giardia intestinalis. Tizoxanide was eight times more active than metronidazole against metronidazole-susceptible isolates and twice as active against a resistant isolate. In 10 axenic isolates of Entamoeba histolytica, while tizoxanide was almost twice as active as metronidazole against more susceptible isolates, it was more than twice as active against less susceptible isolates. Fourteen metronidazole-susceptible isolates of Trichomonas vaginalis were 1.5 times more susceptible to tizoxanide, which was nearly five times as active against resistant isolates. Two highly metronidazole-resistant isolates retained complete susceptibility to tizoxanide, and one moderately resistant isolate showed reduced susceptibility. In all three organisms, nitazoxanide results paralleled those of tizoxanide. Analogues lacking the reducible nitro-group had similar low activities against susceptible G. intestinalis, E. histolytica and T. vaginalis, indicating that nitro-reduction and free radical production was a probable mode of action. Nitazoxanide and its metabolite tizoxanide are more active in vitro than metronidazole against G. intestinalis, E. histolytica and T. vaginalis. Although, like metronidazole, they depend on the presence of a nitro-group for activity, they retain some activity against metronidazole-resistant strains, particularly of T. vaginalis. The results suggest that resistance mechanisms for metronidazole can be bypassed by nitazoxanide and tizoxanide.

Electrochemical reduction of metronidazole at activated glassy carbon electrode and its determination in pharmaceutical dosage forms

A voltammetric method has been developed for the determination of metronidazole in dosage forms. The method is based on the electrochemical reduction of the drug at a glassy carbon electrode activated by applying a new pretreatment. The influence of pH, concentration, scan rate and presence of organic solvent and surfactant has been studied. The current is proportional to the concentration and permits the drug to be determined in the concentration range 2 x 10(-6)-6 x 10(-4) M in Britton-Robinson buffer (pH 10). Furthermore, results obtained by the proposed method have been compared with USP XXIII procedure which involves a HPLC method.

Stability of ketoconazole, metolazone, metronidazole, procainamide hydrochloride, and spironolactone in extemporaneously compounded oral liquids

The stability of drugs commonly prescribed for use in oral liquid dosage forms but not commercially available as such was studied. Ketoconazole 20 mg/mL, metolazone 1 mg/mL, metronidazole 50 mg/mL, procainamide hydrochloride 50 mg/ mL, and spironolactone 25 mg/mL were prepared in a 1:1 mixture of Ora-Sweet and Ora-Plus (Paddock Laboratories), a 1:1 mixture of Ora-Sweet SF and Ora-Plus (Paddock Laboratories), and cherry syrup and placed in 120-mL polyethylene terephthalate bottles. The sources of the drugs were powder, capsules, and tablets. Six bottles were prepared per liquid; three were stored at 5 degrees C and three at 25 degrees C, all in the dark. A sample was removed from each bottle immediately after preparation and at intervals up to 60 days and analyzed for drug concentration by stability-indicating high-performance liquid chromatography. At least 93% of the initial drug concentration was retained in all the oral liquids for up to 60 days. There were no substantial changes in the appearance or odor of the liquids, or in the pH. Ketoconazole 20 mg/mL, metolazone 1 mg/mL, metronidazole 50 mg/mL, procainamide hydrochloride 50 mg/ mL, and spironolactone 25 mg/mL were stable for up to 60 days at 5 and 25 degrees C in three extemporaneously compounded oral liquids. INDEX TERMS: Anti-infective agents; Antifungals; Capsules; Cardiac drugs; Cherry syrup; Compounding; Containers; Diuretics; Incompatibilities; Ketoconazole; Liquids; Metolazone; Metronidazole; Polyethylene terephthalate; Powders; Procainamide hydrochloride; Spironolactone; Stability; Storage; Suspending agents; Tablets; Temperature; Vehicles.

High performance thin layer chromatographic analysis of hydrolyzed tinidazole solutions. II. Hydrolysis kinetics of tinidazole

In a citrate-borate-phosphate buffer, 5 mM tinidazole solutions exhibited maximum stability stability around pH 4.0-5.0. The hydrolysis of tinidazole was mostly a first-order reaction. At pH 10.0 and 60-80 degrees C, tinidazole had an activation energy of 122 kJ mol-1 for hydrolysis. It was postulated that tinidazole decomposes by different mechanisms under basic and neutral/acidic conditions.

Heterocyclic betaines. XXII. Azinium(azolium) 4-nitrobenzimidazolate inner salts and their derivatives with several interannular spacers. Synthesis, characterization and antitrichomonal activity

The synthesis of an ensemble of pyridinium(imidazolium) 4-nitrobenzimidazolate betaines and their derivatives with several interannular linkages has been explored. Their antiprotozoal activity has also been examined.