Solvent-Dependent Variation in yield and Toxicity of Aquatic and Semi-Aquatic Plant Extracts

This study investigates the influence of different solvents on the extraction yield and toxicity of extracts from 15 aquatic and semi-aquatic plant species widely used in traditional medicine. Plants were extracted sequentially using solvents of varying polarity (hexane, ethyl acetate, ethanol, methanol, and water) to evaluate solvent-dependent extraction efficiency and toxicological profiles. Extraction yields were highest with methanol and ethanol, confirming their superior ability to dissolve phenolics, flavonoids, and glycosides, while hexane and water yielded the least extractable material. Toxicity was assessed using two bioassays: brine shrimp lethality test (BSLT) and zebrafish larval assay, providing a dual-organism approach to determine toxic effects. The majority of extracts exhibited low toxicity (LC₅₀ > 1000 μg/mL in BSLT; > 500 μg/mL in zebrafish), supporting their safety profiles. However, Ipomoea carnea extracts showed significant cytotoxicity in ethyl acetate and polar solvents, aligning with known toxic alkaloid content. Moderate toxicity was also observed in Echinochloa crusgalli and Scoparia dulcis in specific solvent fractions. The study highlights the critical role of solvent polarity in optimizing yield without compromising safety, identifying methanol as the optimal solvent for sustainable extraction of therapeutic compounds with minimal toxicity. Furthermore, the dual-assay toxicity evaluation reinforces the reliability of these bioassays in preliminary phytochemical safety screening. 

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