Abstract:
Plant secondary metabolism is affected by environmental factors. Generally, levels and activities of plant secondary metabolites, which are radical scavengers, increase in response to stress. In this study, the radical scavenging abilities of water hyacinths found in different areas in Laguna Lake were investigated. Water hyacinth leaves were collected from three sites. Phytochemical screening of leaf ethanolic extracts revealed the presence of alkaloids, flavonoids, phenols, and terpenoids. In the superoxide radical scavenging assay, the extracts of water hyacinth leaves collected from Central Bay, Central West Bay, and Northern West Bay showed 22.50%, 13.09%, and 40.71% mean scavenging abilities, respectively. In the hydroxyl radical scavenging assay, the mean scavenging abilities presented were 77.36%, 69.27%, and 94.98%, accordingly. Briefly, the radical scavenging assays showed that leaves from Northern West Bay had the highest radical scavenging ability, followed by the leaves from Central Bay, then those from Central West Bay. This finding can be attributed to the differences in the water quality parameters of the sites. Higher chemical oxygen demand (COD), lower amount of nitrate, and presence of lead and cadmium in higher concentrations in Northern West Bay compared to the other sites possibly increased the production of flavonoids and other phenolic compounds resulting in increased radical scavenging activity.
