Fátima Cerqueira

Xanthones as inhibitors of growth of human cancer cell lines and Their effects on the proliferation of human lymphocytes In Vitro

Twenty-seven oxygenated xanthones have been assessed for their capacity to inhibit in vitro the growth of three human cancer cell lines, MCF-7 (breast cancer), TK-10 (renal cancer) and UACC-62 (melanoma). The effect of these xanthones on the proliferation of human T-lymphocytes was also evaluated. Differences on their potency towards the effect on the growth of the human cancer cell lines as well as on the proliferation of human T-lymphocytes can be ascribed to the nature and positions of the substituents on the xanthonic nucleus.

Catechols from abietic acid synthesis and evaluation as bioactive compounds.

Catechols from abietic acid were prepared by a short and good yielding chemical process and further evaluated for several biological activities namely, antifungal, antitumoral, antimutagenic, antiviral, antiproliferative and inhibition of nitric oxide. Their properties were compared with those of carnosic acid (6), a naturally occurring catechol with an abietane skeleton and known to possess potent antioxidant activity, as well as anticancer and antiviral properties. From all the synthetic catechols tested compound 2 showed the best activities, stronger than carnosic acid.

Miconazole-loaded nanostructured lipid carriers (NLC) for local delivery to the oral mucosa: improving antifungal activity.

Miconazole is a widely used antifungal agent with poor aqueous solubility, which requires the development of drug delivery systems able to improve its therapeutic activity. For this purpose, a miconazole-loaded nanostructured lipid carriers (NLC) dispersion was prepared and characterized. Further, the dispersion was used to prepare a NLC-based hydrogel formulation proposed as an alternative system to improve the local delivery of miconazole to the oral mucosa. NLC dispersion showed particles in the nanometer range (≈ 200 nm) with low polidispersity index (<0.3), good physical stability and high encapsulation efficiency (>87%). A controlled miconazole release was observed from NLC and NLC-based hydrogel formulations, in contrast to a commercial oral gel formulation, which demonstrated a faster release. Additionally, it was observed that the encapsulation of miconazole in the NLC improved its antifungal activity against Candida albicans. Therefore, it was demonstrated that the encapsulation of miconazole in NLC allows for obtaining the same therapeutic effect of a commercial oral gel formulation, using a 17-fold lower dose of miconazole.

Chlamydia trachomatis infection: implications for HPV status and cervical cancer.

Genital Chlamydia trachomatis (CT) infections have been identified as a major health problem concern. CT is associated with adverse effect on women reproduction and also associated with cervical hypertrophy and induction of squamous metaplasia, providing a possible relationship with human papillomavirus (HPV) infection. Infection by high-risk HPV types is crucial to the pathogenesis of invasive cervical cancer (ICC), but other co-variants/cofactors must be present for the development of malignancy. CT biological effect may damage the mucosal barrier, improving HPV infection, or may interfere in immune response and viral clearance supporting the persistence of HPV infection. Moreover, CT-related chronic cervical inflammation, decrease of lower genital tract antigen-presenting cells, inhibition of cell-mediated immunity, and anti-apoptotic capacity may influence the natural history of HPV infection, namely persistence progression or resolution. Although several epidemiological studies have stated a positive association involving CT and HPV-related cervical neoplastic lesions and/or cervical cancer (CC), the specific role of this bacterium in the pathogenesis of cervical neoplasia has not been completely clarified. The present review summarizes several studies on CT role in cervical cancer and suggests future research directions on HPV and CT interaction.

Isomeric Kielcorins and Dihydroxyxanthones: Synthesis, Structure Elucidation, and Inhibitory Activities of Growth of Human Cancer Cell Lines and on the Proliferation of Human Lymphocytes In Vitro

The synthesis, structure elucidation, and biological activities of five isomeric xanthonolignoids, (±)-trans-kielcorin C, (±)-cis-kielcorin C, (±)-trans-kielcorin D, (±)-trans-isokielcorin D, and (±)-trans-kielcorin E, are reported. The synthetic approach is based on the oxidative coupling of coniferyl alcohol with an appropriate xanthone. The influence of different oxidizing agents was studied, and the best results were obtained with potassium hexacyanoferrate(III). The structure elucidation was achieved by 2D-NMR techniques such as COSY, HETCOR, HSQC, and HMBC. Long-range C,H connectivities were used to establish the orientation of the substituents on the 1,4-dioxine rings, while NOE experiments were used to determine the configurations of these rings. These xanthonolignoids, as well as (±)-trans-kielcorin, (±)-trans-kielcorin B, (±)-trans-isokielcorin B, and the xanthonic building blocks 3,4-, 1,2-, and 2,3-dihydroxy-9H-xanthen-9-ones, and 2,3-dihydroxy-4-methoxy-9H-xanthen-9-one, were evaluated for their in vitro effect on the growth of three human cancer cell lines, MCF-7 (breast), TK-10 (renal), and UACC-62 (melanoma), and on the proliferation of human lymphocytes.

Inhibition of lymphocyte proliferation by prenylated flavones: artelastin as a potent inhibitor.

Eight natural prenylated flavones, previously isolated from Artocarpus elasticus, were evaluated for their effect on the mitogenic response of human lymphocytes to PHA. They all exhibited a dose-dependent suppression effect. An interesting relationship was observed between their antiproliferative activity and their chemical structure. Indeed, the most potent flavones possessed a 3,3-dymethylallyl group (prenyl) at C-8, such as artelastin, which exhibited the highest antiproliferative activity. Studies of the mechanism underlying its effect revealed that artelastin had an irreversible inhibitory effect on the PHA-induced lymphocyte proliferation and could affect the course of the ongoing mitogenic response either at the initial induction phase or at the late phase of proliferation. This prenylated flavone was also shown to be a potent inhibitor of both T- and B-lymphocyte mitogen induced proliferation although B-mitogenic response was the more sensitive one. Artelastin did not affect either the basal levels of the early marker of activation CD69 on non-stimulated splenocytes or its expression on ConA- or LPS-stimulated splenocytes. However, it decreased the production of IFN-gamma, IL-2, IL-4 and IL-10 in ConA-stimulated splenocytes. Furthermore, artelastin had no effect on apoptosis of splenocytes.

Oncogenic HPV Types Infection in Adolescents and University Women from North Portugal: From Self-Sampling to Cancer Prevention

This study aimed to characterize the HPV infection status in adolescents and young university women in Portugal. The distribution of HPV genotypes was evaluated by PCR DNA genotyping after self-sampling collection from 435 women of exfoliated cervical cells using a commercial kit. We observed an overall frequency of HPV infection of 11.5%. Furthermore, HPV DNA prevalence was 16.6% in those young women that self-declared as sexually active. The more frequently detected HPV types were 31, 16, 53, and 61. Statistical analysis identified median age (OR = 3.56; P = 0.001), the number of lifetime sexual partners (OR = 4.50; P < 0.001), and years of sexual activity (OR = 2.36; P = 0.008) as risk factors for HPV acquisition. Hence, our study revealed that oncogenic HPV infection is common in young asymptomatic women Portuguese women, with a history of 2–5 sexual partners and over 2 year of sexual activity. Moreover, these results demonstrate that HPV detection performed in self-collected samples may be important to appraise better preventive strategies and to monitorize the influence of vaccination programmes within different populations.

The natural prenylated flavone artelastin is an inhibitor of ROS and NO production

Artelastin, a prenylated flavone previously isolated from Artocarpus elasticus, was evaluated for its effect on the production of reactive oxygen species (ROS) by human polymorphonuclear neutrophils (PMNs) and nitric oxide (NO) by J774 murine macrophage cell line. Artelastin showed to be an inhibitor of ROS production due to a strong O2- scavenging activity. No effect was observed on the activity of myeloperoxidase (MPO). Artelastin showed also to be an inhibitor of NO production without NO scavenging activity. This flavone seems to interfere with the expression of the inducible nitric oxide synthase (iNOS) immediately after LPS-IFNgamma-macrophage stimulation.

Improvement of the inhibitory effect of xanthones on NO production by encapsulation in PLGA nanocapsules.

For the first time the inhibitory effect of xanthone and 3-methoxyxanthone on nitric oxide (NO) production by IFN-γ /LPS activated J774 macrophage cell line is reported. A remarkable improvement of this effect promoted by encapsulation of these compounds in nanocapsules of poly (dl-lactide-co-glycolide) (PLGA) is also demonstrated. A weak inhibitory effect of 3.6% on NO production by activated macrophages was observed for xanthone at the highest studied concentration (100 μM). This effect was slightly higher for 3-methoxyxanthone at the same concentration, producing a reduction of 16.5% on NO production. In contrast, equivalent concentrations of xanthone and 3-methoxyxanthone incorporated in nanocapsules produced a significant decrease on NO production of 91.8 and 80.0%, respectively. Empty nanocapsules also exhibited a slight NO inhibitory activity, which may be due to the presence of soybean lecithin in the composition of the nanosystems. The viability of the macrophages was not affected either by free or nanoencapsulated xanthones. Fluorescence microscopy analysis confirmed that a phagocytic process was involved in the macrophage uptake of xanthone- and 3-methoxyxanthone-loaded PLGA nanocapsules. Phagocytosis might be the main mechanism responsible for the enhancement of the intracellular delivery of both compounds and consequently for the improvement of their biological effect.

Effect of Natural 2,5-Diaryl-3,4-dimethyltetrahydrofuran Lignans on Complement Activation, Lymphocyte Proliferation, and Growth of Tumor Cell Lines

(+)-Machillin F, isolated from the bark of Persea membranacea, Kosterm and four other 2,5-diaryl-3,4-dimethyltetrahydrofuran-type lignans from Talauma hodgsonii Hook, F. & Thoms., (−)-galbacin, (−)-talaumidin, (−)-talaumidin methyl ether, and acetyl talaumidin, were evaluated for their influence on the classical and alternative pathways of activation of human complement system, mitogen-induced proliferation of human lymphocytes, and growth of human tumor cell lines. All these lignans exhibited moderate inhibitory activities. (+)-Machillin F showed the highest anticomplementary activity, and (−)-talaumidin methyl ether exhibited the strongest suppressive effect on lymphocyte proliferation. (−)-Talaumidin, acetyl talaumidin, and (+)-machillin F inhibited the growth of MCF-7, TK-10, and UACC-62 cell lines, whereas (−)-galbacin was inactive against UACC-62 and (−)-talaumidin methyl was inactive against both TK-10 and UACC-62. A characterization of the structural features of these lignans that is important to their biological activities is discussed.