Publications by authors named "Helena C Marques"

Owing to their beneficial functional capabilities, essential oils were largely used. However, their low aqueous solubility, instability, and high volatility urged scientists to their encapsulation with cyclodextrins (CDs) to tackle their shortcomings. In this study, the co-precipitation method was used to prepare β-CD/Eucalyptus globulus essential oil (EGEO) inclusion complexes (ICs).

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Article Synopsis
  • This review examines the impact of UV radiation on skin aging (photoaging) and highlights tretinoin (all-trans retinoic acid) as an effective treatment for reversing these effects.
  • Tretinoin works by activating retinoic acid receptors, leading to changes in gene expression that reduce skin cell proliferation, promote differentiation, and inhibit tumor growth.
  • The combined use of tretinoin with other treatments, like hydroquinone and corticosteroids, remains the best approach for conditions like melasma, although more clinical trials are needed to support other new therapies.
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This review focuses on the photoprotection conferred by lycopene, one of the most potent anti-oxidants. Lycopene has been recently proposed to play a critical role on anticarcinogenic action at different levels. The photoprotective properties of lycopene remain contradictory.

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Introduction: Ultradeformable vesicles are highly promising tools to enhance the percutaneous transport of different drugs such as tretinoin across the skin barrier and also to increase the formulation stability at absorption site and reduce the drug induced irritation.

Methods: Topical delivery of tretinoin-loaded ultradeformable vesicles (tretinoin-UDV) was evaluated concerning different studies, such as: the release and permeation profiles (tape stripping); skin penetration (fluorescence analysis); induced electrical changes in skin barrier properties; cytotoxicity (Trypan Blue assay) and skin irritation in in vivo conditions (Draize test). The novel formulation performance was also compared to a commercial tretinoin formulation regarding in vivo studies.

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Purpose: The aims of this experimental work were the incorporation and full characterization of the system Tretinoin-in-dimethyl-beta-cyclodextrin-in-ultradeformable vesicles (Tretinoin-CyD-UDV) and Tretinoin-in-ultradeformable vesicles (Tretinoin-UDV).

Methods: The Tretinoin-CyD complex was prepared by kneading and the UDV by adding soybean phosphatidylcholine (SPC) to Tween® 80 followed by an appropriate volume of sodium phosphate buffer solution to make a 10%-20% lipid suspension. The resulting suspension was brought to the final mean vesicles size, of approximately 150 nm, by sequential filtration.

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Introduction: Several aspects are known to influence the drug distribution within the low respiratory tract, with particular emphasis on those related to the inhalation device. The aim of this work was to assess the performance of three spacers in the drug release, and also the quantity of active agent deposited inside these devices.

Materials And Methods: In order to evaluate the behaviour of particles in suspension delivered through the Ventilan®HFA inhaler coupled to three different spacers (Volumatic®, AeroChamber MAX® and NebuChamber®) the Multistage Liquid Impinger (MSLI) was used, according to the Portuguese Pharmacopoeia.

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Reactive oxygen species (ROS) and free radicals have been implicated in a number of diseases and disorders, and the skin, for its localization, is exposed to a large number of environmental threats. Free radical scavengers and antioxidants have thus been proposed as protective or therapeutic agents against ROS-mediated injuries. Oral treatment with several antioxidants has been reported to provide skin protection against deleterious effects of ultraviolet radiation.

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The aim of this work is to prepare tretinoin/dimethyl-beta-cyclodextrin complexes and fully characterize them through various analytical techniques. According to the phase solubility studies performed, the equilibrium for maximum complexation is reached in about 8 days presenting an A(L)-type diagram (soluble complexes) corresponding mainly to 1:1 stoichiometry (K(s) = 13,600 M(-1)), although the possibility of the presence of 1:2 complexes was mathematically proven. Differential scanning calorimetry, X-ray diffraction and all the other analytical techniques have proven the presence of true complex formation in all the preparation methods tested.

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