Prevention strategies play a key role in the fight against HIV/AIDS. Vaginal and rectal microbicides hold great promise in tackling sexual transmission of HIV-1, but effective and safe products are ...yet to be approved and made available to those in need. While most efforts have been placed in finding and testing suitable active drug candidates to be used in microbicide development, the last decade also saw considerable advances in the design of adequate carrier systems and formulations that could lead to products presenting enhanced performance in protecting from infection. One strategy demonstrating great potential encompasses the use of nanosystems, either with intrinsic antiviral activity or acting as carriers for promising microbicide drug candidates. Polymeric nanoparticles, in particular, have been shown to be able to enhance mucosal distribution and retention of promising antiretroviral compounds. One important aspect in the development of nanotechnology-based microbicides relates to the design of pharmaceutical vehicles that allow not only convenient vaginal and/or rectal administration, but also preserve or even enhance the performance of nanosystems. In this manuscript, we revise relevant work concerning the selection of vaginal/rectal dosage forms and vehicle formulation development for the administration of microbicide nanosystems. We also pinpoint major gaps in the field and provide pertinent hints for future work.
Bacteria are able to colonize and thrive in a variety of different environments as a biofilm, but only within the last half century new insights have been gained in this complex biosystem. Bacterial ...biofilms play a major role in human health by forming a defensive barrier against antibacterial chemical therapeutics and other potential pathogens, and in infectious disease when the bacteria invade normally sterile compartments. Quorum sensing is the signaling network for cell-to-cell communication and utilized by bacteria to regulate biofilms and other cellular processes. This review will describe recent advances in quorum sensing and biofilms. Initially, it will focus on Streptococcus pneumoniae biofilm regulation and the involvement of the ComABCDE pathway. As part of this review an original analysis of the genotypic and phenotypic variation of the signaling molecule, ComC and its cognate receptor ComD, firstly within the pneumococcal species and then within the genus Streptococcus will be presented. Additionally, a pathway similar to ComABCDE, the BlpABCSRH that regulates bacteriocin and immunity protein production that inhibit the growth of competing bacteria will be described. This review will then examine a third quorum sensing mechanism in the pneumococcus, the LuxS/AI-2, and present a novel gene and protein sequence comparative analysis that indicates its occurrence is more universal across bacterial genera compared with the Com pathway, with more sequence similarities between bacterial genera that are known to colonize the mucosal epithelium.
Films have undoubtedly seen the most significant advances in their development in recent years of all the pharmaceutical forms for the vaginal administration of drugs. Films combine the advantages of ...gels and solid pharmaceutical forms, and their great versatility is largely determined by the numerous polymers that can be used for their fabrication. They may be based on many natural polymers, and cellulose derivatives, polyvinyl alcohol or acrylic derivatives – among others – are also frequently used. The combination of different polymers and the inclusion of plasticizing agents makes them extremely versatility for responding to a range of therapeutic needs. The techniques used to produce films have also undergone substantial development. Although the solvent casting technique is by far the most widely used in fabrication, alternative options have also emerged such as electrospinning, moulding extrusion and 3D printing. Various research groups have proposed a proliferation of assays to characterise vaginal films in recent years, which highlight the importance of the preliminary evaluation and determination of the films' uniformity, in addition to tests to determine their permeability and hydrophilic/hydrophobic coefficient and their mechanical properties, the application of imaging techniques and thermal analysis, and especially the evaluation of the mucoadhesive properties and control over the drug release. This article offers a critical overview of the advances in the development and fabrication of films intended for vaginal drug delivery, and summarises current clinical applications for vaginal films.
Display omitted
•Film technology provides platforms adaptable to the desired drug release profile.•Several natural and synthetic polymers have been considered to obtain vaginal films.•Plasticisers and other excipients allow modifying the relevant properties of films.•Solvent casting is the most common manufacturing method, but others are emerging.•Films could be useful against STDs, unintended pregnancy and other FGT disorders.
Interest is growing in “smart” vaginal microbicides as a strategy to protect women from sexual transmission of human immunodeficiency virus (HIV). The concept is based on the development of products ...featuring low drug release in acidic media such as vaginal fluid but switch to a fast release profile when the medium becomes neutral or slightly alkaline. This mimics the surge in pH occurring in the vagina after sexual intercourse due to the seminal fluid. Semen is the main vehicle for HIV-1, and increasing antiretroviral drug levels in the vagina upon ejaculation may contribute to enhanced protection against viral sexual transmission. This work explores the use of different pharmaceutical-grade methacrylic acid-based polymers (EudragitⓇ RL, RS, L and S) for developing vaginal films allowing the pH-dependant release of the antiretroviral drug tenofovir (TFV). EudragitⓇ L 100 and EudragitⓇ S 100, containing triethyl citrate as plasticiser, proved to be suitable for manufacturing films with optimal dual in vitro drug-release behaviour. TFV-release can be sustained for several days after film administration and all the drug is released in a few hours in conditions simulating ejaculation. The films’ mechanical properties were also deemed suitable for comfortable vaginal administration. Two optimized films were further assessed using HEC-1-A and Ca Ski cell monolayer models and were found to possess favourable drug permeability profiles and drug levels associated to cell monolayer as compared to free TFV. Overall, pH-dependant films containing tenofovir may constitute promising candidates for “smart” vaginal microbicides to protect women from sexual HIV transmission.
Display omitted
Vulvovaginal candidiasis (VVC) represents a considerable health burden for women. Despite the availability of a significant array of antifungal drugs and topical products, the management of the ...infection is not always effective, and new approaches are needed. Here, we explored cationic N-(2-hydroxy)-propyl-3-trimethylammonium, O-palmitoyl chitosan nanoparticles (NPs) as carriers of clotrimazole (CLT) for the topical treatment of VVC. CLT-NPs with approximately 280 nm in diameter were obtained by self-assembly in water and subsequent stabilization by ionic crosslinking with tripolyphosphate. The nanosystem featured pH-independent sustained drug release up to 24 h, which affected both in vitro anti-Candida activity and cytotoxicity. The CLT-loaded nanostructured platform yielded favorable selectivity index values for a panel of standard strains and clinical isolates of Candida spp. and female genital tract cell lines (HEC-1-A, Ca Ski and HeLa), as compared to the free drug. CLT-NPs also improved in vitro drug permeability across HEC-1-A and Ca Ski cell monolayers, thus suggesting that the nanocarrier may provide higher mucosal tissue levels of the active compound. Overall, data support that CLT-NPs may be a valuable asset for the topical treatment of VVC.
Topical azoles such as clotrimazole (CLT) are first line antifungal drugs for the management of vulvovaginal candidiasis (VVC), but their action may be limited by issues such as toxicity and poor capacity to penetrate the genital mucosa. Herein, we report on the ability of a new cationic N-(2‑hydroxy)-propyl-3-trimethylammonium, O-dipalmitoyl chitosan derivative (DPCat35) to yield tripolyphosphate-reinforced micelle-like nanostructures that are suitable carriers for CLT. In particular, these nanosystems were able to improve the in vitro selectivity index of the drug and to provide enhanced epithelial drug permeability when tested in cell monolayer models. These data support that CLT-loaded DPCat35 nanoparticles feature favorable properties for the development of new nanomedicines for the topical management of VVC.
Display omitted
Vaginal films featuring the pH-dependent release of tenofovir (TFV) were developed for the prevention of sexual transmission of human immunodeficiency syndrome (HIV). Films based on hydroxypropyl ...methylcellulose and zein were prepared incorporating different plasticizers oleic acid, lactic acid, glycerol, and polyethylene glycol 400 (PEG) and evaluated for in vitro drug release in an acidic simulated vaginal fluid (pH 4.2) and a slightly alkaline mixture of simulated seminal and vaginal fluids (pH 7.5). Results revealed that optimal biphasic TFV release was possible with proper combination of plasticizers (PEG and oleic acid, 1:7 w/w) and by adjusting the plasticizer/matrix-forming material ratio. The films had similar or higher levels of TFV associated with genital epithelial cells (Ca Ski or HEC-1-A cells) but lower drug permeability compared to the free drug. These data confirm that films have the potential to achieve suitable mucosal levels of TFV with low systemic exposure. The films developed could protect women from HIV sexual transmission.
β-Carotene and other carotenoids are common food additives industrially produced by Dunaliella salina. However, the cultivation production costs are substantial and determine the economic viability ...of production in large-scale systems. There is a strong interest in recycling the cultivation medium in order to reduce the microalgae production costs. This work aims to study several oxidation techniques for treatment of permeate produced during harvesting of microalga Dunaliella salina by membrane filtration. The treated permeate produced is assessed for reuse as cultivation medium of Dunaliella salina. The permeate produced during membrane harvesting of Dunaliella salina was recovered and treated by ozonation and UV radiation. The different types of permeate produced were tested as cultivation media. The results obtained indicate that the permeate treated by UV with addition of H2O2 was best suited for the growth of Dunaliella salina during carotenogenesis. Nevertheless, although not performing as well as the selected cultivation medium, the use of untreated permeate seems a reasonable alternative to it, as the untreated permeate has potential to be the most cost efficient solution.
Scheme of the harvesting and permeate recycle for Dunaliella salina cultivation. Display omitted
•Permeate recovered from harvesting of Dunaliella salina by ultrafiltration•Permeate treated by advanced oxidation processes for recycling cultivation medium•Permeate treated with UV + H2O2 suitable for cultivation of Dunaliella salina•UV + H2O2 treatment allows D. salina to grow and to produce high-value compounds.
No inicio do século XX, as microalgas começaram a despertar interesse na comunidade científica e, desde então, novos estudos permitiram o reconhecimento do seu potencial a ser usado para diversos ...fins. A Chlorella é uma das microalgas produzidas e comercializadas mundialmente. Existem neste momento três espécies de Chlorella reconhecidas no mercado Europeu como Novel Food o que permite que sejam comercializadas para alimentação humana. Devido ao facto de o consumo de algas não ser uma prática comum na União Europeia, nos últimos anos surgiram estudos para a incorporação desta alga na dieta europeia, com benefícios para a saúde humana. O objetivo deste trabalho foi induzir a carotenogénese em duas estirpes de Chlorella vulgaris e uma estirpe de Chlorella protothecoides, privando as culturas da fonte de azoto no meio de cultivo. Numa primeira etapa, as duas estirpes de Chlorella vulgaris foram inoculadas em reatores de 5 L com meio f/2 modificado. No passo seguinte, foram testas duas condições: na primeira condição as culturas foram inoculadas com meio f/2 sem KNO3 e na segunda condição o meio de cultivo apenas continha água da cimenteira. Em ambas as culturas, foi avaliada a concentração de clorofila e carotenóides, ao longo do ensaio. Verificou-se um decréscimo no teor de clorofila em ambas as culturas e uma acumulação de carotenóides apenas nas condições controlo. Foi observada a mudança de cor verde para cor amarela em Chlorella vulgaris e para cor alaranjada em Chlorella vulgaris Beijerinck (estirpe de controlo). O ensaio seguinte, foi realizado em outdoor num Fotobiorreator de 2000L (FBR) e em três Green-wall de 45L (GW), usando Chlorella vulgaris crescida em fermentador. Após a indução das culturas, não foi observada uma mudança de cor significativa. Neste ensaio, foi avaliada a concentração de proteína. Observou-se uma descida na concentração de proteína nos reatores à medida que a fonte de azoto ia sendo consumida. No último ensaio, o crescimento fez-se de modo heterotrófico usando a estirpe Chlorella protothecoides . Para isso, numa primeira etapa foi feito um teste em matraz com diferentes concentrações de amónia, onde se constatou que quanto mais baixa a concentração de amónia, maior a alteração da cor da cultura. A etapa seguinte foi realizada num fermentador de 5 L, onde não se observou mudança de cor da cultura.Neste trabalho, foi possível realizar a indução nas culturas, mas apenas nos ensaios em pequena escala (ensaio em balão e em matraz).
The industrial production of axenic Chlorella vulgaris is very challenging as bacterial contaminations are common both in open and closed cultivation systems. Some microalgae and bacteria can ...establish symbiotic relationships in which both microorganisms benefit from one another, that can result in improved growth and culture robustness. This strategy would be advantageous to co-cultivate C. vulgaris with a well-known starter culture of bacteria that is able to promote the microalga’s growth. The benefits would be: the establishment of a symbiotic relationship that could improve the growth rates of C. vulgaris and the presence of a beneficial bacteria consortium that would prevent the occupation of those niches by unknown and detrimental bacterial contaminants.The aim of the present work was to find bacterial species that could establish a symbiotic relationship with Chlorella vulgaris strain, in co-culture, to improve the latter’s growth and culture robustness. Thereby, bacterial strains that had previously been isolated from pilot scale cultures of C. vulgaris in mixotrophic conditions were co-cultivated with this microalga. Also, a commercially available culture of Lactic Acid Bacteria was tested in co-culture with C. vulgaris. The growth of these microorganisms and the constitution of the ecosystems was evaluated throughout time.Results from this study suggested that two bacteria (LL_Bc07 and LL_Bc11) may have a positive impact on C. vulgaris in batch mode while one bacterial isolate (LL_Bc02) may have a negative impact, under the same conditions. On the contrary, in semi-continuous regime, bacterial consortia did not affect the growth of the microalga. It was clear that LAB did not grow well in the mixotrophic medium used, as they are fastidious bacteria. Therefore, the microalga’s growth was not affected by the presence of LAB.Regarding community stability, co-cultures containing two of the bacterial isolates LL_Bc02, LL_Bc07 and LL_Bc11, kept their composition stable from the beginning to the end of the test. On the contrary the monoalgal control and the mixed culture containing C. vulgaris and LAB suffered contaminations from one or more of the bacterial isolates.
PDF
