ß-cyclodextrin dendritic derivatives as permeation mediators to enhance the in vitro albendazole cysticidal activity by the improvement of the diffusion component.

The improvement of permeation of drugs across parasites' membranes to promote their diffusion component represents a challenge to achieve better therapeutic effects, including the avoidance of drug resistance. In the context of medicinal chemistry, suitable structural modifications can be made, either on a drug or a nanocarrier, to trigger different mechanisms that promote the influx across membranes. This study aimed to demonstrate the potential of a set of dendritic derivatives of ß-cyclodextrin (m2G, h2G, and m3G) as nanocarriers, based on their physicochemical and biological behavior in terms of (i) stability, monitored by 1H NMR at pH 7 for seven days, (ii) ability to complex, and subsequently release around 50-80% of the cargo molecule (albendazole) in a biphasic medium and (iii) the absence of in vitro cysticidal effect in cysticercus cultures. The albendazole/nanocarrier inclusion complexes (ICs) were proved in the T. crassiceps model. According to the EC50 values related to the cysticidal activity of albendazole, either free or complexed, the potency of this drug in the ICs experienced a significant increase, which may be attributed to the enhancement of its solubility but also to a better permeation mediated by the amphiphilic dendritic moieties, which ultimately positively impacts the diffusion of this drug through the tegument of the cysticerci. Additional considerations akin to synthetic ease of the dendritic nanocarriers, and production cost, along with the obtained outcomes, allowed us to place m2G followed by m3G as the best options to be considered for further in vivo assays.

Mono-Dendronized ß-Cyclodextrin Derivatives as Multitasking Containers for Curcumin. Impacting Its Solubility, Loading, and Tautomeric Form.

In this study, three mono-dendronized ß-cyclodextrin (ßCD) derivatives (ßCD-1G, ßCD-2G, and ßCD-3G) were used as multitasking containers of curcumin (CUR) to influence its aqueous solubility and tautomerism, both of which are related to its biological activity. We evaluated the relevant physicochemical properties of these containers associated with their potential hosting capacity. All mono-dendronized derivatives exhibited enhanced solubility in different solvents, including water, in comparison with native ßCD. Gas-phase geometry optimizations by density functional theory (DFT) confirmed that none of the dendrons blocked the passage of CUR into the ßCD cavity, and depending on the generation, different preorganization scenarios were promoted before complexation. Phase solubility diagrams showed that all the dendronized containers have superior performance for solubilizing CUR compared to native ßCD. We proved that coprecipitation is most efficient than lyophilization for forming inclusion complexes (ICs) with dendronized containers. Even though ßCD-3G with the largest 3G dendron exhibited the highest CUR loading, the complexation of CUR with ßCD-2G provided the supramolecular system that contains CUR preferentially in its diketo tautomer, which is known for its antioxidant activity.

Dendronization: A practical strategy to improve the performance of molecular systems used in biomedical applications.

Nanomedicine is an emerging area that largely influences the efficacy of various therapies through the rational design of new materials exhibiting more targeted behavior. The synthetic effort, the amount of used material, and the cost are critical parameters to bear in mind if the production of the designed material is intended to be scaled for their widespread use. Even though materials science offers diverse options for different types of therapies, it is a difficult task to meet all the parameters mentioned above. The dendronization appears as an insightful approach to incorporate all the known benefits of the dendritic architecture by the attachment of dendrons to therapeutic agents, but in a much more affordable manner in terms of synthetic effort, amount of material, and cost. As will be presented, the most common dendrons used for biomedical applications are polyamide, polyester, carbosilane, polyether, and glycol-type, which are bonded to biological active molecules (BAMs), or molecular nanoplatforms (MPs) by hydrolysable bonds. Also relevant is the fact that the incorporation of dendrons not larger than third generation (G3) is sufficient to improve essential properties of these molecular systems, such as aqueous solubility, stability, and cellular internalization, among others. The type of dendron and its location on the BAMs or MPs, similar to placing a Lego piece on a model, will be decisive for obtaining the desired properties.

Convergent click synthesis of macromolecular dendritic ß-cyclodextrin derivatives as non-conventional drug carriers: Albendazole as guest model.

From a materials science perspective, herein we present the design and synthesis of six macromolecular carbohydrate derivatives, obtained by combining the native cyclic oligosaccharide ßCD and dendritic poly(ester) moieties, coupled by CuAAc click reactions, in a convergent fashion. We envisioned two structural variables to promote the formation of inclusion complexes (ICs) with the anti-parasitic drug Albendazole, the degree of substitution on the ßCD (mono or hepta-substitution) and the dendritic generation (from first to third). In terms of synthetic effort and cost, the mono-substituted ßCD derivatives were obtained in more approachable experimental conditions in comparison to the ßCD dendrimers (hepta-substituted macrocycle). The six dendritic derivatives were more soluble in water and showed better complexation capacity than native ßCD. For both, mono and hepta-substituted ßCD, we observed that the amount of encapsulated ABZ increases when the dendron generation increases. Interestingly, different degrees of substitution (mono and hepta) lead comparable results of ABZ complexation. In conclusion, the encapsulation performance and the consequent solubility enhancement, make these molecular containers excellent materials to positively impact the therapeutic desirability of ABZ.

PEGylated ß-cyclodextrins: Click synthesis and in vitro biological insights.

We present three easily rationalized star-shaped PEGylated ß-cyclodextrin (ßCD) derivatives synthesized via conjugation of different molecular weight PEG chains (5000, 2000, and 550 Da) to the ßCD primary face by click chemistry (ßCD-PEG5000, ßCD-PEG2000, ßCD-PEG550 respectively). ßCDPEG systems are envisioned to further carry bioactive molecules, therefore, their interactions with biological interfaces must be determined at an early stage of development. Hence, the effect of ßCDPEGs chain length on cell viability was investigated. To this aim, three models were selected: Vero cells for their fibroblast-like features; HeLa cells that are commonly used for preliminary viability screening; and human peripheral monocytes which are macrophage precursors. Of the three pegylated derivatives, ßCD-PEG550 was the one that significantly affected HeLa cells and human monocytes viability. Despite the popularity of PEGylation approach, our results underscore the importance of careful and systematic PEGylated materials design for their future success in drug delivery systems.

Synthesis of a poly(ester) dendritic ß-cyclodextrin derivative by "click" chemistry: Combining the best of two worlds for complexation enhancement.

In spite of the progress in the cyclodextrins chemistry, the synthesis of monodisperse derivatives with a defined degree of substitution is still a challenge. In this work we present a novel dendritic material produced by combining ßCD and second generation poly(ester) dendrons. The selective attachment of dendrons in the seven positions of the ßCD-primary face was performed through a CuAAC click reaction, which along with a very simple work-up, allowed obtaining the monodisperse material in very high yields. The product showed a great aqueous solubility and an in vitro non-toxic profile. The enhanced complexation potential of the product was evidenced through the formation of an inclusion complex with albendazole, which presented a Kc = 29636.17 M-1. In this system, albendazole was 45 times more water-soluble in comparison to the complex albendazole-native ßCD. All these features make the dendritic material very attractive for further applications in the formulation and drug delivery fields.