Toxicity evaluation of nanocrystalline silver-impregnated coated dressing on the life cycle of worm Caenorhabditis elegans

In recent times, however, due to the emergence of bacterial strains with resistance to conventional antibiotics, silver has again gained attention as an alternative for developing new efficient bactericides, including the use of silver nanoparticles (AgNPs). However, the improper disposal of these items after use may cause toxicological effects on organisms in the environment. To evaluate the potential environmental hazard of nanosilver-coated dressings, the nematode Caenorhabditis elegans was chosen as a test organism. The assays were conducted in 24-well plates that contain four different sizes of coated dressing to obtain different concentrations. L1 and L4 C. elegans larval stages were exposed to these nanosilver concentrations. Dressing cutouts were arranged between two layers of agar for 3 days and Escherichia coli (OP 50 strain) was added as food source for the worms. After the exposure period, growth, reproduction, fertility, silver concentration in the medium and the concentration of reactive oxygen species (ROS) in the worms were evaluated. Scanning and transmission electron microscopy analyses were performed on the coated dressings, as well as analyses of zeta potential, ionic release and antibacterial power in two bacterial strains (Pseudomonas aeruginosa and Staphylococcus aureus). It was verified the antibacterial power of the coated dressing, in both bacteria strains tested. Characterization of the coated dressing indicated heterogeneous nanoparticles, as well as distinct zeta potentials for the medium in water and saline medium (0.9% NaCl). L1 larval worms exposed to nanosilver-coated dressing showed a high ROS concentration and reductions in growth, fertility and reproduction. Worms exposed to the coated dressing during the L4 stage showed almost no response. Overall, the obtained results indicate the potential environmental hazard of nanosilver-coated dressings.

Regulatory framework for dietary supplements and the public health challenge

OBJECTIVE

The new regulatory framework for dietary supplements in Brazil prompted this analysis of the current outlook of these products and the challenges posed by the new guidelines.

METHODS

We conducted a qualitative, observational and descriptive study of dietary supplements commercialized in Brazilian online stores with the help of the Google® search tool. We considered the ingredients on the labels, the effects attributed to these products and the commercial claims used as a means of promoting them to assess the necessary changes for the legal framework in the new guidelines. Finally, with the help of a database, we compared the effects declared by the manufacturers and attributed to certain ingredients with the scientific evidence described in literature.

RESULTS

In total, we purchased 44 dietary supplements from Brazilian online stores (n = 7). Of the samples studied, 34.2% could not be classified in the category Dietary Supplements, as recommended by the new regulation of the Brazilian Health Regulatory Agency due to the presence of prohibited substances; 16% of products should be commercialized as medicines. Regarding the commercial appeals, 97.7% had banned expressions. Numerous claims of effects attributed to certain products were characterized as consumer fraud because they have no scientific evidence.

CONCLUSIONS

The necessary changes represent a major regulatory and production challenge due to the wide range of dietary supplements and markets, an effort that aims to protect the consumers' health. Some previous gaps in the regulatory framework were not fully solved.

A new approach to ion exchange chromatography with conductivity detection for adulterants investigation in dietary supplements

The extent of adulteration of dietary supplements has significantly increased in recent years. This situation worries health authorities and requires auxiliary analytical tools for the investigation of illegal substances purposely added. Ion exchange chromatography with conductivity detection is a consolidated analytical technique for the determination of inorganic compounds in various matrices. This technique has been applied to the pharmaceutical characterization of mainly impurities and degradation products. This work presents a new approach to ion exchange chromatography as a screening method to investigate the presence of amfepramone, femproporex, sibutramine, bisacodyl and amiloride in dietary supplements advertised for weight loss. The method was optimized and validated using a Metrosep C4 100/4.0 cation exchange column. The mobile phase consisted of 1.8 mm HNO₃ containing 2% acetonitrile (v/v), with a flow rate of 0.9 ml min^-1 , and nonsuppressed conductivity detection was applied. The limits of detection and quantification varied from 1.01 to 3.62 mg L^-1 and from 1.48 to 8.72 mg L^-1 , respectively. The proposed method was successful applied to 78 solid dietary supplement samples, in two of which adulterations were found. Moreover, ion exchange chromatography with conductivity detection could be easily used for quality control without prior complex sample pre-treatment.