Background Duckweed is well known for its high protein content and is gaining attention as a sustainable food source due to its rapid growth and excellent nutritional properties. However, comprehensive studies on the nutritional composition and bioactive potential of duckweed species in Sri Lanka remain scarce. Therefore, the aim of this study was to evaluate the nutritional composition, phytochemical characteristics, and bioactive properties of four duckweed species in Sri Lanka: Spirodela polyrhiza (SP), Lemna minor (LM), Lemna perpusilla (LP), and Landoltia punctata (LaP). Methods Proximate composition, mineral content, and fatty acid profiles of the four duckweed species were analyzed. Fourier Transform Infrared (FTIR) spectroscopy was used to identify functional groups. Bioactive properties were evaluated using α-amylase and lipase inhibition assays, antimicrobial activity against selected microbial strains, and a brine shrimp lethality assay. Polyphenolic compounds were identified and quantified using Liquid Chromatography–Mass Spectrometry (LC–MS). Results The carbohydrate, protein, fat, ash, and crude fiber content in these duckweed species ranged from 6.95 to 14.55%, 17.34–26.45%, 3.69–3.92%, 8.03–9.55%, and 5.26–9.49% (DW), respectively. K, Na, and Ca content varied from 45.62 to 20.17 g/kg, 5.61–37.73 g/kg, and 11.03–25.46 g/kg, respectively. High levels of omega-3 fatty acids (44.42–50.38%) were also found. FTIR analysis showed five distinct absorption bands associated with amides and carbohydrates. Among the species, Spirodela polyrhiza and Landoltia punctata demonstrated significant (p < 0.05) α-amylase inhibition (IC50 = 0.14 µg/mL), while Spirodela polyrhiza exhibited the highest (p < 0.05) lipase inhibition (IC50 = 1.39 µg/mL). Additionally, Spirodela polyrhiza showed notable inhibition (p < 0.05) against A. niger and E. coli, while Landoltia punctata showed notable inhibition (p < 0.05) against C. albicans, A. niger, and S. aureus. Rutin content is relatively more abundant than the other polyphenols analyzed (2.9612–3.0588 µg/mg DM). These duckweed species showed low to moderate toxicity (LC50 > 4000 ppm). Conclusions These findings demonstrate that the studied duckweed species possess valuable nutritional composition and promising bioactive properties, highlighting their potential as sustainable, nutrient-rich food sources with possible therapeutic applications. Graphical Abstract

Nutritional composition and bioactive properties of four duckweed species in Sri Lanka

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2026年6月3日

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Ruvini Hiththatiyage,
Sachini Senevirathne,
Malmi Wickramasinghe,
Isuri Rathnayaka,
Terrence Madhujith,
Barana Jayawardana,
Siril Wijesundara,
Ruvini Liyanage

摘要

Background

Duckweed is well known for its high protein content and is gaining attention as a sustainable food source due to its rapid growth and excellent nutritional properties. However, comprehensive studies on the nutritional composition and bioactive potential of duckweed species in Sri Lanka remain scarce. Therefore, the aim of this study was to evaluate the nutritional composition, phytochemical characteristics, and bioactive properties of four duckweed species in Sri Lanka: Spirodela polyrhiza (SP), Lemna minor (LM), Lemna perpusilla (LP), and Landoltia punctata (LaP).

Methods

Proximate composition, mineral content, and fatty acid profiles of the four duckweed species were analyzed. Fourier Transform Infrared (FTIR) spectroscopy was used to identify functional groups. Bioactive properties were evaluated using α-amylase and lipase inhibition assays, antimicrobial activity against selected microbial strains, and a brine shrimp lethality assay. Polyphenolic compounds were identified and quantified using Liquid Chromatography–Mass Spectrometry (LC–MS).

Results

The carbohydrate, protein, fat, ash, and crude fiber content in these duckweed species ranged from 6.95 to 14.55%, 17.34–26.45%, 3.69–3.92%, 8.03–9.55%, and 5.26–9.49% (DW), respectively. K, Na, and Ca content varied from 45.62 to 20.17 g/kg, 5.61–37.73 g/kg, and 11.03–25.46 g/kg, respectively. High levels of omega-3 fatty acids (44.42–50.38%) were also found. FTIR analysis showed five distinct absorption bands associated with amides and carbohydrates. Among the species, Spirodela polyrhiza and Landoltia punctata demonstrated significant (p < 0.05) α-amylase inhibition (IC₅₀ = 0.14 µg/mL), while Spirodela polyrhiza exhibited the highest (p < 0.05) lipase inhibition (IC₅₀ = 1.39 µg/mL). Additionally, Spirodela polyrhiza showed notable inhibition (p < 0.05) against A. niger and E. coli, while Landoltia punctata showed notable inhibition (p < 0.05) against C. albicans, A. niger, and S. aureus. Rutin content is relatively more abundant than the other polyphenols analyzed (2.9612–3.0588 µg/mg DM). These duckweed species showed low to moderate toxicity (LC₅₀ > 4000 ppm).

Conclusions

These findings demonstrate that the studied duckweed species possess valuable nutritional composition and promising bioactive properties, highlighting their potential as sustainable, nutrient-rich food sources with possible therapeutic applications.

Graphical Abstract