Evaluation of the cytotoxic and genotoxic potential of water from the River Paraíba do Sul, in Brazil, with the Allium cepa L. test

This work investigated the cytotoxic and genotoxic potential of water from the River Paraíba do Sul (Brazil) using Allium cepa roots. An anatomo-morphological parameter (root length), mitotic indices, and frequency of micronuclei were analysed. Eight bulbs were chosen at random for treatment for 24 to 120 hours with the River water collected in the years of 2005 and 2006 from sites in the cities of Tremembé and Aparecida (São Paulo state, Brazil). Daily measurements of the length of the roots grown from each bulb were carried out throughout the experiment. Mitotic index (MI) and frequency of micronuclei (MN) were determined for 2000 cells per root, using 3-5 root tips from other bulbs (7-10). Only in the roots treated with samples of the River water collected in 2005 in Tremembé city was there a decrease in the root length growth compared to the respective control. However, a reduction in MI values was verified for both sites analysed for that year. Considering the data involving root length growth and especially MI values, a cytotoxic potential is suggested for the water of the River Paraíba do Sul at Tremembé and Aparecida, in the year of 2005. On the other hand, since in this year the MN frequency was not affected with the river water treatments, genotoxicity is not assumed for the river water sampled at the aforementioned places.

Chitosan/tripolyphosphate Nanoparticles Loaded With Paraquat Herbicide: An Environmentally Safer Alternative For Weed Control.

Paraquat is a fast acting nonselective contact herbicide that is extensively used worldwide. However, the aqueous solubility and soil sorption of this compound can cause problems of toxicity in nontarget organisms. This work investigates the preparation and characterization of nanoparticles composed of chitosan and sodium tripolyphosphate (TPP) to produce an efficient herbicidal formulation that was less toxic and could be used for safer control of weeds in agriculture. The toxicities of the formulations were evaluated using cell culture viability assays and the Allium cepa chromosome aberration test. The herbicidal activity was investigated in cultivations of maize (Zea mays) and mustard (Brassica sp.), and soil sorption of the nanoencapsulated herbicide was measured. The efficiency association of paraquat with the nanoparticles was 62.6 ± 0.7%. Encapsulation of the herbicide resulted in changes in its diffusion and release as well as its sorption by soil. Cytotoxicity and genotoxicity assays showed that the nanoencapsulated herbicide was less toxic than the pure compound, indicating its potential to control weeds while at the same time reducing environmental impacts. Measurements of herbicidal activity showed that the effectiveness of paraquat was preserved after encapsulation. It was concluded that the encapsulation of paraquat in nanoparticles can provide a useful means of reducing adverse impacts on human health and the environment, and that the formulation therefore has potential for use in agriculture.

Action Of Essential Oils From Brazilian Native And Exotic Medicinal Species On Oral Biofilms.

Essential oils (EO) obtained from twenty medicinal and aromatic plants were evaluated for their antimicrobial activity against the oral pathogens Candida albicans, Fusobacterium nucleatum, Porphyromonas gingivalis, Streptococcus sanguis and Streptococcus mitis. The antimicrobial activity of the EO was evaluates by microdilution method determining Minimal Inhibitory Concentration. Chemical analysis of the oils compounds was performed by Gas chromatography-mass spectrometry (CG-MS). The most active EO were also investigated as to their actions on the biolfilm formation. The most of the essential oils (EO) presented moderate to strong antimicrobial activity against the oral pathogens (MIC--Minimal Inhibitory Concentrations values between 0.007 and 1.00 mg/mL). The essential oil from Coriandrum sativum inhibited all oral species with MIC values from 0.007 to 0.250 mg/mL, and MBC/MFC (Minimal Bactericidal/Fungicidal Concentrations) from 0.015 to 0.500 mg/mL. On the other hand the essential oil of C. articulatus inhibited 63.96% of S. sanguis biofilm formation. Through Scanning Eletronic Microscopy (SEM) images no changes were observed in cell morphology, despite a decrease in biofilm formation and changes on biofilm structure. Chemical analysis by Gas Chromatography-Mass Spectrometry (GC-MS) of the C. sativum essential oil revealed major compounds derivatives from alcohols and aldehydes, while Cyperus articulatus and Aloysia gratissima (EOs) presented mono and sesquiterpenes. In conclusion, the crude oil from C. articulatus exhibited the best results of antimicrobial activity e ability to control biofilm formation. The chemical analysis showed the presence of terpenes and monoterpenes such as a-pinene, a-bulnesene and copaene. The reduction of biofilms formation was confirmed from SEM images. The results of this research shows a great potential from the plants studied as new antimicrobial sources.

Chitosan Nanoparticles Loaded The Herbicide Paraquat: The Influence Of The Aquatic Humic Substances On The Colloidal Stability And Toxicity.

Polymeric nanoparticles have been developed for several applications, among them as carrier system of pesticides. However, few studies have investigated the fate of these materials in the environment in relation to colloidal stability and toxicity. In nature, humic substances are the main agents responsible for complexation with metals and organic compounds, as well as responsible for the dynamics of these nanoparticles in aquatic and terrestrial environments. In this context, the evaluation of the influence of aquatic humic substances (AHS) on the colloidal stability and toxicity of polymeric nanoparticles of chitosan/tripolyphosphate with or without paraquat was performed. In this study, the nanoparticles were prepared by the ionic gelation method and characterized by size distribution measurements (DLS and NTA), zeta potential, infrared and fluorescence spectroscopy. Allium cepa genotoxicity studies and ecotoxicity assays with the alga Pseudokirchneriella subcapitata were used to investigate the effect of aquatic humic substances (AHS) on the toxicity of this delivery system. No changes were observed in the physical-chemical stability of the nanoparticles due to the presence of AHS using DLS and NTA techniques. However some evidence of interaction between the nanoparticles and AHS was observed by infrared and fluorescence spectroscopies. The ecotoxicity and genotoxicity assays showed that humic substances can decrease the toxic effects of nanoparticles containing paraquat. These results are interesting because they are important for understanding the interaction of these nanostructured carrier systems with species present in aquatic ecosystems such as humic substances, and in this way, opening new perspectives for studies on the dynamics of these carrier systems in the ecosystem.