Solange Bosio Tedesco

Efeito anti-proliferativo das infusões de Achyrocline satureioides DC (Asteraceae) sobre o ciclo celular de Allium cepa

Achyrocline saturoides (marcela) is used in Brazilian folk medicine as a tea in the treatment of digestive and inflammatory diseases. The anti-proliferative effect of infusions of marcela on onion cell cycle was evaluated by using the inflorescences of recently collected marcela and after the storage for 30 months. Marcela inflorescences were collected for the infusion preparations in 2003 and in 2005 (used still fresh). We prepared the infusions at two concentrations 5.0 mg/mL (concentration used as tea) and 20 mg/mL. We used two groups of six onion bulbs for each population of marcela, and one group of bulbs of each population was withdrawn as a control group. All bulbs rooted in distilled water and after they were transferred to the extracts of marcela and they were kept there for 24 hours (control bulbs remained under water). The root tips were collected, after fixed in ethanol acetic acid (3:1) for 24 hours and, stored under alcohol 70%. A total of 6000 cells per group of bulbs was analyzed, and the mitotic indexes were calculated and undergone to statistical analysis by using c2 at 5%. The conclusions were that the infusions of marcela have anti-proliferative action on the cell cycle of onion and that this inhibitory action on the cell division increases according to the increase of the infusion concentration, after storage as well.

Uso do sistema teste de Allium cepa como bioindicador de genotoxicidade de infusões de plantas medicinais

All over the world, many species of medicinal plants are used for disease treatments. However, most of them were not deeply studied; and the presence of cytotoxic or mutagenic substances in their composition or resulting from their metabolism may be harmful to human beings. The mutagenic effects caused by such substances result in chromosomal changes which are detecTable during the cell cycle of a species through cytogenetic analysis. The Allium cepa test system is widely used for evaluating the genotoxic potential of infusions (tea) made of medicinal plants, through the cell cycle analysis. The knowledge of the genotoxic potential of such species through the Allium cepa test serves as a warning and safety bioindicator for the population who uses medicinal tea quite often as the unique alternative for disease treatment of its people. In the review article, we intend to inform people about the importance of the Allium cepa test for evaluating the genotoxicity of infusions of medicinal plants.

Hydrogel containing dexamethasone-loaded nanocapsules for cutaneous administration: preparation, characterization, and in vitro drug release study.

Context: Our group previously reported the development of dexamethasone-loaded polymeric nanocapsules as an alternative for topical dermatological treatments. Objective: Our study aimed to prepare and characterize a hydrogel containing this system to improve the effectiveness of the glucocorticoid for cutaneous disorders. Methods: For the antiproliferative activity assay, a dexamethasone solution and D-NC were tested on Allium cepa root meristem model. D-NC were prepared by the interfacial deposition of preformed polymer. Hydrogels were prepared using Carbopol Ultrez® 10 NF, as polymer, and characterized according to the following characteristics: pH, drug content, spreadability, viscosity, and in vitro drug release. Results and Discussion: Nanocapsules showed mean particle size and zeta potential of 201 ± 6 and −5.73 ± 0.42 nm, respectively. They demonstrated a lower mitotic index (4.62%) compared to free dexamethasone (8.60%). Semisolid formulations presented acidic pH values and adequate drug content (between 5.4% and 6.1% and 100% and 105%, respectively). The presence of nanocapsules in hydrogels led to a decrease in their spreadability factor. Intact nanoparticles were demonstrated by TEM as well as by dynamic light scattering (mean particle size < 300 nm). In vitro studies showed a controlled dexamethasone release from hydrogels containing the drug associated to the nanocapsules following the Higuchis squared root model (k = 20.21 ± 2.96 mg/cm2/h1/2) compared to the hydrogels containing the free drug (k = 26.65 ± 2.09 mg/cm2/h1/2). Conclusion: Taking all these results together, the hydrogel containing D-NC represent a promising approach to treat antiproliferative-related dermatological disorders.

Effects of Pterocaulon polystachyum DC. (Asteraceae) on onion (Allium cepa) root-tip cells

In Brazil leaf infusions of the plant Pterocaulon polystachyum DC (Asteraceae) are used to treat digestive problems. We used plants from six P. polystachyum populations to prepare fresh aqueous leaf infusions at the concentration normally used in Brazil (2.5 g L-1) and at twice (5 g L-1) and four times (10 g L-1) this concentration. We rooted onion bulbs in a water control or one of the infusions for 24 h and used the in vivo onion (Allium cepa) root-tip cell test to investigate the potential mutagenicity of the infusions by calculating the mitotic index for the control and the experimental treatments and comparing them using the Chi-squared test (c2, p = 0.05). There was a highly significant decrease in the mitotic index of root-tip cells treated with infusion as compared to those exposed to water only. These results indicate that P. polystachyum infusions present cytotoxic and anti-proliferative activity and therefore have therapeutic potential.

Bioindicator of Genotoxicity: The Allium cepa Test

Solange Bosio Tedesco1,2 and Haywood Dail Laughinghouse IV3,4 1Graduate Program in Agrobiology, Department of Biology Universidade Federal de Santa Maria (UFSM), Santa Maria 2Graduate Program in Agronomy, UFSM, Santa Maria 3National Museum of Natural History, Smithsonian Institution, Washington, DC 4College of Computer, Mathematical & Natural Sciences University of Maryland, College Park, MD 1,2RS Brazil 3,4USA

Extracts affecting mitotic division in root-tip meristematic cells

Some species of Psychotria (Rubiaceae) are important in herbal medicine, where their extracts are used internally for infections of the female reproductive system, bronchitis, gastrointestinal disturbances, skin irritations, tumors, ulcers, and eye disturbances. The antiproliferative and genotoxic effects of Psychotria myriantha Mull. Arg. and P. leiocarpa Cham. et Schlecht infusions on the Allium cepa L. cell cycle were evaluated. The teas were prepared by infusing the leaves in distilled water, in two concentrations: 1.13 mg/mL and 6.78 mg/mL. Three groups of four bulbs were used for each Psychotria species. After the bulbs rooted in distilled water, they were transferred to the teas for 24 hours, except for the control that stayed in water. The rootlets were then collected, fixed in ethanol-acetic acid (3:1) for 24 hours, and stored in 70% ethanol. For each group of bulbs, 4000 cells were analyzed, calculating the mitotic indexes, submitting them to statistic analysis, using the χ2 test (p = 0.05). The results showed a decrease in mitotic index with an increase in tea concentration in both species. In P. leiocarpa, the mitotic index values differed significantly between the control and concentration of 6.78 mg/mL (χ2 = 9.863). For P. myriantha, the values referring to the mitotic index differed greatly between the control and the treatments (χ2 = 124.8). With this study, it was determined that P. myriantha and P. leiocarpa infusions possess antiproliferative effects on the A. cepa cell cycle, and teas of P. myriantha also have genotoxic activity.

Biomonitoring genotoxicity and cytotoxicity of Microcystis aeruginosa (Chroococcales, Cyanobacteria) using the Allium cepa test

Water pollution caused by toxic cyanobacteria is a problem worldwide, increasing with eutrophication. Due to its biological significance, genotoxicity should be a focus for biomonitoring pollution owing to the increasing complexity of the toxicological environment in which organisms are exposed. Cyanobacteria produce a large number of bioactive compounds, most of which lack toxicological data. Microcystins comprise a class of potent cyclic heptapeptide toxins produced mainly by Microcystis aeruginosa. Other natural products can also be synthesized by cyanobacteria, such as the protease inhibitor, aeruginosin. The hepatotoxicity of microcystins has been well documented, but information on the genotoxic effects of aeruginosins is relatively scarce. In this study, the genotoxicity and ecotoxicity of methanolic extracts from two strains of M. aeruginosa NPLJ-4, containing high levels of microcystin, and M. aeruginosa NPCD-1, with high levels of aeruginosin, were evaluated. Four endpoints, using plant assays in Allium cepa were applied: rootlet growth inhibition, chromosomal aberrations, mitotic divisions, and micronucleus assays. The microcystin content of M. aeruginosa NPLJ-4 was confirmed through ELISA, while M. aeruginosa NPCD-1 did not produce microcystins. The extracts of M. aeruginosa NPLJ-4 were diluted at 0.01, 0.1, 1 and 10 ppb of microcystins; the same procedure was used to dilute M. aeruginosa NPCD-1 used as a parameter for comparison, and water was used as the control. The results demonstrated that both strains inhibited root growth and induced rootlet abnormalities. The strain rich in aeruginosin was more genotoxic, altering the cell cycle, while microcystins were more mitogenic. These findings indicate the need for future research on non-microcystin producing cyanobacterial strains. Understanding the genotoxicity of M. aeruginosa extracts can help determine a possible link between contamination by aquatic cyanobacteria and high risk of primary liver cancer found in some areas as well as establish water level limits for compounds not yet studied.

Biomonitoring hospital effluents by the Allium cepa L. test.

Hospital effluents are serious problems in developing countries like Brazil, and when not treated adequately, can cause mutagenic effects on live organisms. Biomonitors, like Allium cepa L., which is one of the most used plant species when monitoring effluent genotoxicity, have been used to alert the world population about environmental contamination and genotoxic chemical emissions. The Allium cepa test was used to evaluate the genotoxicity of a hospital effluent in Santa Maria, Rio Grande do Sul State, Brazil. During the study, chromosomal disruptions, anaphasic bridges, and micronuclei during telophase were observed, indicating environmental toxicity risk.

Promoção de enraizamento de microestacas de um clone de Eucalyptus sp. por Trichoderma spp.

The purpose of this research was to apply antagonistic isolates of fungi to induce microcutting rooting of an Eucalyptus sp. clone. One non-pathogenic isolate of Cylindrocladium spp. and three antagonistic isolates of Trichoderma spp (E15, S2 and St) were used for the microcutting rooting experiment. The latter gave better results in the antagonistic in vitro test using the method of direct confrontation against the pathogenic isolate of Cylindrocladium spp, being inoculated in the microcutting rooting substrate, in greenhouse conditions. Increase of microcutting survival was observed in the presence of isolates of Trichoderma spp. and Cylindrocladium spp. when compared with control in an environment naturally infested with Botrytis cinerea. The treatments with the isolates ST, E15 and S2 of Trichoderma spp. and Cyl of Cylindrocladium spp. increased the survival of Eucalyptus sp. microcuttings. The E15 isolate promoted a significant increase in the rooting percentage (62.25%) compared to the control treatment (28.77% ).

Influence of the type of vegetable oil on the drug release profile from lipid-core nanocapsules and in vivo genotoxicity study.

Abstract The use of rice bran (RB), soybean (SB) or sunflower seed (SF) oils to prepare lipid-core nanocapsules (LNCs) as controlled drug delivery systems was investigated. LNCs were prepared by interfacial deposition using the preformed polymer method. All formulations showed negative zeta potential and adequate nanotechnological characteristics (particle size 220–230 nm, polydispersity index < 0.20). The environmental safety was evaluated through an in vivo protocol (Allium cepa test) and LNCs containing RB, SB or SF oils did not present genotoxic potential. Clobetasol propionate (CP) was selected as a model drug to evaluate the influence of the type of vegetable oil on the control of the drug release from LNCs. Biphasic drug release profiles were observed for all formulations. After 168 h, the concentration of drug released from the formulation containing SF oil was lower (0.36 mg/mL) than from formulations containing SB (0.40 mg/mL) or RB oil (0.45 mg/mL). Good correlations between the consistency indices for the LNC cores and the burst and sustained drug release rate constants were obtained. Therefore, the type of the vegetal oil was shown as an important factor governing the control of drug release from LNCs.