Avaliação da composição da biomassa e dos efeitos toxicológicos de extratos de Lemna aequinoctialis: abordagem experimental e meta-analítica
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Data
2025-08-28
Autores
Nati, Natália
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Universidade Federal do Espírito Santo
Resumo
Duckweeds (Araceae) are fast-growing aquatic plants with a promising biochemical composition, offering potential applications in environmental biotechnology, bioinputs, and functional foods. This thesis investigated the nutritional composition, toxicity, and biological activity of Lemna aequinoctialis through three complementary approaches: analysis of cultivated biomass, toxicological assessment of plant extracts, and a meta analysis of duckweed composition. Biomass of L. aequinoctialis cultivated in an integrated multitrophic aquaculture system (IMTA) with fish-farming effluent was compared with biomass from in loco samples. Proximate composition, amino acid and fatty acid profiles, photosynthetic pigments, metal contents, and chemical characterization by high-resolution mass spectrometry (HRMS), which identified oxylipins, phenolics, organic acids, and polysaccharides, were determined. Extracts were then prepared using water (aqueous) and hydroalcoholic solution (ethanolic), along with fractions obtained with ethyl acetate and methanol, and tested at concentrations ranging from 15.625 to 250 µg/mL. Cytotoxicity was evaluated using the MTT cell viability assay, performed in vitro on HTC (Rattus norvegicus) cell lines. Toxicity was assessed in Artemia salina (survival at 24, 48, and 72 h) and Lactuca sativa (germination and root growth). For L. sativa, germination index (GI) and root growth index (RGI) were calculated, along with Spearman’s correlation. Finally, a meta-analysis compiled data from 81 studies on protein, starch, and lipid contents in duckweeds of the genera Landoltia, Lemna, Spirodela, Wolffia, and Wolffiella cultivated under different experimental conditions. Analyses included random-effects models and subgroup comparisons (genus, medium, and cultivation period). Results showed that cultivated biomass had higher protein content (35.1% dry weight), lower metal accumulation, and no significant cytotoxicity. In A. salina, the aqueous and ethanolic extracts, as well as ethyl acetate and methanolic fractions, showed no significant toxicity over the evaluation periods. In L. sativa, the ethyl acetate extract caused severe inhibition at higher concentrations, whereas the methanolic fraction stimulated root growth, with GI values exceeding 200%. Positive correlations between germination and root growth were found for the methanolic (ρ = 0.694; p < 0.001) and aqueous (ρ = 0.418; p = 0.027) extracts. The meta-analysis revealed significant differences according to genus, culture medium, and experimental duration. The highest protein levels (>40% dry weight) were observed in Wolffia and Wolffiella. Starch accumulation was favored by long-term cultivation under nutrient-limited conditions, reaching values above 70%. Nitrogen- and phosphorus-rich media increased protein content, whereas organic carbon supplementation enhanced lipid content, particularly under mixotrophic conditions. Overall, the findings demonstrate that L. aequinoctialis cultivated under controlled management exhibits superior nutritional composition, lower toxicological risk, and potential for the production of selective extracts with applications in sustainable agriculture, alternative nutrition, and bioactive compound prospecting.
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Bioensaios ecotoxicológicos , Composição nutricional , Lemna aequinoctialis , Metanálise , Citotoxicidade