Toxicity testing of pesticides in zebrafish-a systematic review on chemicals and associated toxicological endpoints.

The use of zebrafish (Danio rerio) has arisen as a promising biological platform for toxicity testing of pesticides such as herbicides, insecticides, and fungicides. Therefore, it is relevant to assess the use of zebrafish in models of exposure to investigate the diversity of pesticide-associated toxicity endpoints which have been reported. Thus, this review aimed to assess the recent literature on the use of zebrafish in pesticide toxicity studies to capture data on the types of pesticide used, classes of pesticides, and zebrafish life stages associated with toxicity endpoints and phenotypic observations. A total of 352 articles published between September 2012 and May 2019 were curated. The results show an increased trend in the use of zebrafish for testing the toxicity of pesticides, with a great diversity of pesticides (203) and chemical classes (58) with different applications (41) being used. Furthermore, experimental outcomes could be clustered in 13 toxicity endpoints, mainly developmental toxicity, oxidative stress, and neurotoxicity. Organophosphorus, pyrethroid, azole, and triazine were the most studied classes of pesticides and associated with various toxicity endpoints. Studies frequently opted for early life stages (embryos and larvae). Although there is an evident lack of standardization of nomenclatures and phenotypic alterations, the information gathered here highlights associations between (classes of) pesticides and endpoints, which can be used to relate mechanisms of action specific to certain classes of chemicals.

Risk assessment of the antifungal and insecticidal peptide Jaburetox and its parental protein the Jack bean (Canavalia ensiformis) urease.

Jaburetox (JBTX) is an insecticidal and antifungal peptide derived from jack bean (Canavalia ensiformis) urease that has been considered a candidate for developing genetically modified crops. This study aimed to perform the risk assessment of the peptide JBTX following the general recommendations of the two-tiered, weight-of-evidence approach proposed by International Life Sciences Institute. The urease of C. ensiformis (JBU) and its isoform JBURE IIb (the JBTX parental protein) were assessed. The history of safe use revealed no hazard reports for the studied proteins. The available information shows that JBTX possesses selective activity against insects and fungi. JBTX and JBU primary amino acids sequences showed no relevant similarity to toxic, antinutritional or allergenic proteins. Additionally, JBTX and JBU were susceptible to in vitro digestibility, and JBU was also susceptible to heat treatment. The results did not identify potential risks of adverse effects and reactions associated to JBTX. However, further allergen (e.g. serum IgE binding test) and toxicity (e.g. rodent toxicity tests) experimentation can be done to gather additional safety information on JBTX, and to meet regulatory inquiries for commercial approval of transgenic cultivars expressing this peptide.

Phenolic compounds of Triplaris gardneriana can protect cells against oxidative stress and restore oxidative balance.

This work aimed to add value to an underexploited plant species from Brazil, Triplaris gardneriana. To that, the phenolic compounds profile of its seed ethanolic extract and fractions was examined by HPLC and the antioxidant capacity assessed using chemical assays as well as in vitro cell imaging. Twelve compounds were quantified and classified as either phenolic acids or flavonoids. The fractionation process did not generate fractions with different compositions except for chloroformic fraction, which showed only 6 out of 12 standard compounds used. DPPH assay revealed samples with a concentration-dependent radical scavenging activity, being methanolic fraction the one with the largest activity (SC50 11.45±0.02µg/mL). Lipid peroxidation assessment, in the presence and absence of stress inducer, showed that particularly the ethanol extract (IC50 26.75±0.08µg/mL) and the ethyl acetate fraction (IC50 6.14±0.03µg/mL) could inhibit lipid peroxidation. The ethyl acetate fraction performed best in chelating iron (48% complexation at 1000µg/mL). Cell imaging experiments showed that the ethanolic extract could protect cells against oxidative stress as well as restore the oxidative balance upon stress induction. In conclusion, T. gardneriana seeds showed a promising phenolic compounds profile and antioxidant activity that may be further exploited.

Impact of bioaccessibility and bioavailability of phenolic compounds in biological systems upon the antioxidant activity of the ethanolic extract of Triplaris gardneriana seeds.

The most studied bioactive potential of phenolic compounds corresponds to antioxidant activity, which in turn, is associated with a reduction in the incidence of various human diseases. However, the total quantity of these bioactive substances in foods and medicinal preparations does not reflect the amount absorbed and metabolized by the body. The present study aimed to investigate the bioaccessibility of Triplaris gardneriana seeds ethanolic extract (EETg) by determination of phenolic composition and antioxidant activities before and after in vitro digestion as well as to estimate its bioavailability by chemical analysis of plasma and urine in animal models after oral administration. The bioaccessibility indexes of phenolic compounds in EETg were 48.65 and 69.28% in the presence and absence of enzymes, respectively. Among the identified phenolics classes, flavonoids, represented by galloylated procyanidins type B, proved to be more bioaccessible, 81.48 and 96.29% in the post-intestinal phase with and without enzymes, respectively. The oral administration in Wistar rats resulted in a significant decrease in plasma of the total antioxidant capacity, TAC, by FRAP assay 4h after beginning the experiment. For urine samples, an increase in TAC by DPPH and FRAP was observed from 1 and 4h after administration, respectively. UPLC-QTOF analysis of urine detected 2 metabolites originated from the degradation of phenolic compounds, i.e. hippuric acid and phenylacetil glycine. These results suggest that phenolic compounds in T. gardneriana are unstable under gastrointestinal conditions, being flavonoids the components with higher bioaccessibility; besides that, they showed limited bioavailability due to their rapid biotransformation and urinary elimination.

Polyphenol Composition, Antioxidant Activity and Cytotoxicity of Seeds from Two Underexploited Wild Licania Species: L. rigida and L. tomentosa.

Studies have shown the benefit of antioxidants in the prevention or treatment of human diseases and promoted a growing interest in new sources of plant antioxidants for pharmacological use. This study aimed to add value to two underexploited wild plant species (Licania rigida) and L. tomentosa) from Brazilian flora. Thus, the phenolic compounds profile of their seed ethanol extract and derived fractions were elucidated by HPLC, the antioxidant capacity was assessed by in vitro chemical tests and the cytotoxicity determined using the human carcinoma cell lines MCF-7 and Caco-2. Eleven phenolic compounds were identified in the extracts of each species. The extracts and fractions showed excellent antioxidant activity in the DPPH assay (SC50, ranging from 9.15 to 248.8 µg/mL). The aqueous fraction of L. rigida seeds was most effective in preventing lipid peroxidation under basal conditions (IC50 60.80 µg/mL) whereas, in the presence of stress inducer, the methanolic fraction of L. tomentosa performed best (IC50 8.55 µg/mL). None of the samples showed iron chelating capacity. Ethanolic seed extracts of both species did not reveal any cytotoxicity against MCF-7 and Caco-2 cells. Both plant species showed a promising phenolic profile with potent antioxidant capacity and deserve attention to be sustainably explored.