Self-Assembled Teicoplanin Micelles as Amphotericin B Nanocarrier.

Teicoplanin (Teico) is an antimicrobial agent that spontaneously forms micelles in aqueous media. In this work, we characterized the physicochemical properties of nanoparticles formed by the interaction of Teico with Amphotericin B (AmB). Teico-AmB micelles structure spontaneously in aqueous media, with a particle size of 70-100 nm and a zeta potential of -28 mV. Although the characterization of these nanostructures yielded satisfactory results, in vitro cytotoxicity tests showed high toxicity. Based on this, adding cholesterol to the formulation was evaluated to try to reduce the toxicity of the drug. These Teico-AmB-Chol nanostructures have a larger size, close to 160 nm, but a lower polydispersity index. They also showed strongly negative surface charge and were more stable than Teico-AmB, remaining stable for at least 20 days at 4 °C and 25 °C and against centrifugation, dilution, freezing, lyophilization and re-suspension processes with a recovery percentage of AmB greater than 95%, maintaining their initial size and zeta potential. These Teico-AmB-Chol micelles show lower cytotoxic effect and higher biological activity than Teico-AmB, even than Amfostat® and Ambisome® formulations. These two new nanoparticles, with and without Chol, are discussed as potential formulations able to improve the antifungal therapeutic efficiency of AmB.

Spontaneous photosensitization by Heterophyllaea pustulata Hook. f. (Rubiaceae), in sheep from Northwestern Argentina.

Heterophyllaea pustulata Hook. f. (Rubiaceae) is a phototoxic plant. It grows in the Andean area of northwest of Argentina, and it causes significant economic losses in the livestock. This plant induces dermal lesions by photosensitization probably due to its content of photosensitizing anthraquinones. This paper describes an outbreak of poisoning in Corriedale sheepfold, which had an incidence of 49%. Ear skin biopsies and blood samples were collected of six affected animals. Liver enzymes remained within the reference limits. Histopathologically, a deep necrotizing dermatitis was identified in all samples. H. pustulata was identified in the areas of grazing. Anthraquinone concentration in leaves was 0.84% p/p, expressed as rubiadin. All findings allow us to conclude that the diagnosis is a primary photosensitization. Huge regional economic losses could be attributed to H. pustulata poisoning, although its toxicity has been little studied.

In Vitro and In Vivo Cytogenotoxic Effects of Hot Aqueous Extract of Achyrocline satureioides (Lam.) DC.

In this work we extend the toxicological studies of hot aqueous extract of A. satureioides (As-HAE) evaluating cytotoxic and apoptotic effects on human peripheral blood mononuclear cells (PBMCs). We also determine genotoxic action of this extract in vivo. In addition, the extract was chemically characterized. Finally, we established a comparison with previous data of cold aqueous extract. The As-HAE induced cytotoxicity on PBMCs determined by trypan blue dye exclusion (CC50 = 653 µg/mL) and MTT (CC50 = 588 µg/mL) assays being more toxic than cold extract. However, As-HAE as well as cold extract did not induce apoptosis measured by Hoechst 33258 staining, TUNEL assay, and DNA fragmentation analysis. The in vivo micronucleus test showed that As-HAE exerted cytogenotoxic effects on bone marrow of mice, contrary to what was observed with cold extract. The chemical study of As-HAE allowed identifying the flavonoids found in cold extract: luteolin, quercetin, and 3-O-methylquercetin, but at higher concentrations. We suggest that toxic effects induced by As-HAE could be due to high concentrations of these flavonoids. Given that As-HAE is the most used in folkloric medicine, its administration should be controlled in order to prevent potential cell damage.

Comparisons between conventional, ultrasound-assisted and microwave-assisted methods for extraction of anthraquinones from Heterophyllaea pustulata Hook f. (Rubiaceae).

This work reports a comparative study about extraction methods used to obtain anthraquinones (AQs) from stems and leaves of Heterophyllae pustulata Hook (Rubiáceae). One of the conventional procedures used to extract these metabolites from a vegetable matrix is by successive Soxhlet extractions with solvents of increasing polarity: starting with hexane to eliminate chlorophylls and fatty components, following by benzene and finally ethyl acetate. However, this technique shows a low extraction yield of total AQs, and consumes large quantities of solvent and time. Ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) have been investigated as alternative methods to extract these compounds, using the same sequence of solvents. It was found that UAE increases the extraction yield of total AQs and reduces the time and amount of solvent used. Nevertheless, the combination UAE with benzene, plus MAE with ethyl acetate at a constant power of 900 W showed the best results. A higher yield of total AQs was obtained in less time and using the same amount of solvent that UAE. The optimal conditions for this latter procedure were UAE with benzene at 50 °C during 60 min, followed by MAE at 900 W during 15 min using ethyl acetate as extraction solvent.

Photodynamic activity of anthraquinones isolated from Heterophyllaea pustulata Hook f. (Rubiaceae) on MCF-7c3 breast cancer cells.

Searching for agents that could be effective in the treatment of cancer, special highlight has focused on the study of numerous plant-derived compounds. We previously demonstrated that anthraquinones (AQs) isolated from a vegetal species: Heterophyllaea pustulata Hook f. (Rubiaceae), such as rubiadin, rubiadin-1-methyl ether, soranjidiol, soranjidiol-1-methyl ether exhibit photosensitizing properties without antecedents as photodynamic agents in malignant cells. In the present study, we investigated the potential role of these AQs as a phototoxic agent against human breast carcinoma using MCF-7c3 cells. All AQs exhibited significant photocytotoxicity on cancer cells at the concentration of 100 µM with 1 J/cm(2) light dose, resulting soranjidiol-1-methyl ether in complete cell destruction. The observed cellular killing by photoactivated AQs exhibited close relation with singlet oxygen production, except for soranjidiol-1-methyl ether, where cell viability decrease is in relation to uptake by tumor cells.

Antibacterial activity of anthraquinone derivatives from Heterophyllaea pustulata (Rubiaceae).

Photosensitizing anthraquinones isolated from Heterophyllaea pustulata Hook f. (Rubiaceae), namely soranjidiol, rubiadin, damnacanthal and 5,5'-bisoranjidiol, showed antibacterial activity (bacteriostatic/bactericide) on Staphylococcus aureus. The mechanism of action seems to involve an increase in the levels of superoxide anion (O(2)(·-)) and/or singlet molecular oxygen ((1)O(2)). Moreover, the effect of actinic irradiation as a boosting agent for the production of both reactive species of oxygen as well as its influence on antibacterial activity was assessed. The routine susceptibility assay (minimum inhibitory concentration determination) was carried out by means of the broth macrodilution method. Bactericide activity was determined counting the colony-forming units per milliliter (cfu/mL) in plate. The O(2)(·-) production was determined by means of an indirect photobiological assay (Nitroblue Tetrazolium test), and the production of (1)O(2) was followed using an indirect steady-state method, with methionine as the (1)O(2) chemical quencher.