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BackgroundWater hyacinth is an invasive aquatic weed in many regions of the world. In this study, the bioherbicidal potential of allelopathic plant Leucaena leucocephala against water hyacinth was investigated using a leaf disc assay.ResultsL. leucocephala leachate enhanced electrolyte leakage from water hyacinth leaf discs in a concentration-dependent manner. Control experiments eliminated the possibilities that increased membrane permeability in the leachate-treated leaf discs was due to pH or osmotic effects of the leachate. Thus, the loss of membrane stability in the leachate-treated leaf discs was likely due to phytotoxins detected in the leachate, namely mimosine and phenolic constituents. Decline in tissue respiration was detected in leachate-treated water hyacinth leaf discs. This suggests that the L. leucocephala leachate may contain compounds which acted as respiratory inhibitors. Enhanced reactive oxygen species production coincided with inhibition of catalase and ascorbate peroxidase activities in the leachate-treated water hyacinth leaf tissues. The injurious effects of L. leucocephala leachate on water hyacinth leaf discs probably involved direct inhibition of antioxidant enzymes in addition to direct involvement of some allelochemicals in reactive oxygen species formation.ConclusionIn summary, the toxic effects of L. leucocephala leachate on water hyacinth leaf discs likely lay in its ability to effectively compromise the membrane integrity, tissue respiration and antioxidant defence of the latter.Electronic supplementary materialThe online version of this article (doi:10.1186/1999-3110-54-8) contains supplementary material, which is available to authorized users.

Edible freshwater macrophytes (EFM) are edible, macroscopic freshwater plants, many of which are also used as traditional/folk medicine. This minireview highlights phytochemical and pharmacological evidence pertaining to anticancer and antioxidative natural products derived from EFM, with special attention to Centella asiatica (Indian pennywort), Nelumbo nucifera (sacred lotus), Nasturtium officinale (watercress), Ipomoea aquatica (water spinach) and Ludwigia adscendens (water primrose). Current knowledge gaps and further research opportunities are also discussed. EFM is a promising source of anticancer and antioxidative natural products which warrants more extensive exploration. More research is needed before such natural products can be exploited for application in food and medicine.

Background:The phytochemistry and bioactivity of wetland macrophytes are underexplored. Plants are known as the natural sources of phytochemical beneficial to health.Objective:The objective of this study is to analyze the phytochemical profiles and bioactivities of 10 extracts prepared from different plant parts of wetland macrophytes Hanguana malayana, Ludwigia adscendens and Monochoria hastata.Materials and Methods:High performance liquid chromatography (HPLC) was used to analyze the phytochemical profile of the extracts. Antioxidant assay such as 2,2-diphenyl-1-picrylhydrazyl, nitric oxide (NO) radical scavenging activity and ferric reducing antioxidant power were performed. Bioactivity assays carried out were anti-lipoxygenase, anti-glucosidase, and iron chelating.Results:Leaf extract of L. adscendens had the highest 2,2-diphenyl-1-picrylhydrazyl (half of maximal effective concentration [EC50] =0.97 mg/mL) and NO (EC50 = 0.31 mg/mL) scavenging activities. The extract also exhibited the highest iron chelating (EC50 = 3.24 mg/mL) and anti-glucosidase (EC50 = 27.5 μg/mL) activities. The anti-glucosidase activity of L. adscendens leaf extract was comparable or superior to those of acarbose, myricetin and quercetin. Correlation between iron chelating and radical scavenging activities among the extracts implies the presence of dual-function phytoconstituents with concurrent iron chelating and radical scavenging activities. HPLC analysis revealed the presence of p-coumaric acid (p-CA), gallic acid (GA) and myricetin in all or most extracts. M. hastata fruit and leaf extracts had the highest p-hydroxybenzoic acid content. Antioxidant and anti-glucosidase activities of the extracts were correlated with p-CA, GA, and myricetin contents.Conclusion:Our study demonstrated that wetland macrophytes H. malayana, L. adscendens and M. hastata are potential sources of health-promoting phytochemicals with potent therapeutically-relevant bioactivities.