Background
African wild lettuce (Lactuca taraxacifolia Willd.) is an underutilised indigenous leafy vegetable containing essential nutrients and medicinal properties. Hence, this study aimed to determine the chemical composition, antioxidant activities, α-amylase, α-glucosidase and angiotensin converting enzyme inhibitory potentials of wild lettuce leaves powder samples.
Methods
Freshly harvested Wild Lettuce leaves were processed into whole leafy powder (WLF), extracted powder (WLE), residue (WLR) and leaf protein isolate (WPI). Chemical composition, antioxidant activities, α-amylase, α-glucosidase and angiotensin-converting enzyme inhibitory potentials of the powder samples were determined.
Results
Crude protein of Wild Lettuce leaves ranged from 23.27 to 46.57 and crude fiber from 4.17–37.37 g/100 g. Phosphorous was the most abundant element, while zinc had the lowest concentration. The samples essential amino acids, protein efficiency ratio, essential amino acid index and biological values were 39.83–50.65 mg/100 g protein. 2.79–3.51, 77.03–92.36% and 72.26–88.97%, respectively. Saponin, tannin, oxalate, phytate, terpennoids, flavonoid and phenol in the leafy vegetable samples were within tolerable levels. The African wild lettuce leaf protein isolate (WPI) had higher DPPH antioxidant activity (91.88%), percentage inhibitory properties on α-amylase (26.11%), α-glucosidase (64.24%) and angiotensin-1-converting enzyme (97.53%) than WLF (18.28, 25.44, 55.41 and 67.56), WLE (70.85, 24.97, 62.53 and 93.27) and WLR (53.07, 24.68, 50.03 and 85.28) respectively.
Conclusion
African wild lettuce leaf samples, particularly protein isolate, contain essential nutrients, antioxidant activities and ability to inhibit angiotensin-1-converting, α-amylase and α-glucosidase enzymes Therefore, the leafy vegetable samples, particularly WPI, may be suitable as antioxidant, antidiabetic and antihypertensive agent.