In vitro α-amylase, α-glucosidase and Lipase Inhibiting Activities of Duckweed (Wolffia globosa), the Possibility as Functional Food

Duckweed (Wolffia globosa) is a valuable source of protein, essential amino acids, dietary fiber, vitamin B12 and bioactive compounds, including antioxidants. It has potential as a functional food for managing metabolic syndrome, particularly by helping to control glycemic levels in individuals with diabetes through dietary interventions. This study aimed to determine the antioxidant properties and evaluate enzyme inhibitory activities of W. globosa extract (WE) against key enzymes involved in lipid and glucose metabolism.

Fresh W. globosa plants were dried, pulverized and extracted using ethanol by maceration. The total phenolic content (TPC) and total flavonoid content (TFC) of the extract were assessed using the Folin-Ciocalteu and aluminum chloride methods, respectively. Antioxidant activities were evaluated through several assays: DPPH radical scavenging, nitric oxide (NO) radical scavenging, ferrous iron-ferrozine complex and ferric iron-thiocyanate complex assays. In vitro enzyme inhibitory activities of WE were tested against pancreatic lipase, α-amylase and α-glucosidase.

The extract contained phenolic compounds (TPC = 28.19±0.79 mg GAE/g) but lacked detectable flavonoids. WE exhibited antioxidant activity in the DPPH and NO radical scavenging assays and inhibited lipid peroxidation (IC₅₀ = 0.34±0.05, 0.23±0.06 and 80.51±16.02 mg/ml, respectively). However, the extract showed no metal ion chelation activity. WE strongly inhibited pancreatic lipase (IC₅₀ = 1.55±0.20 mg/ml) and α-amylase (IC₅₀ = 0.02±0.01 mg/ml), while it showed poor inhibition of α-glucosidase (IC₅₀>1,000 mg/ml). These findings support the potential of WE as a functional food ingredient for managing metabolic conditions such as diabetes and hyperlipidemia.