Abstract:
The study investigated the functional
properties, such as antioxidant activity,
phenolic content and ascorbic acid content of
the popular leafy vegetable, Alternanthera
sessilis (‘Mukunuwenna’). Two varieties
such as Piliyandala and Colombo Selection
grown under four different fertilizer
application types namely, Inorganic fertilizer
mixture recommended by the Department of
Agriculture (Urea 9 kg/1000 m2, MOP 13.5
kg/1000 m2, TSP 10 kg/1000 m2), Integrated
treatment [mixture of inorganic (Urea, MOP
and TSP) and organic fertilizer (cattle
manure and gliricidia)], Organic fertilizer
(cattle manure and gliricidia) and Homescale
cultivation (No fertilizer) were used.
Antioxidant activity (AOA) of the methanolic
leaf extract was determined by using 2, 2diphenyl-1-picryl
hydrazyl (DPPH) Radical
Scavenging Assay. Phenolic content (PC) and
ascorbic acid content (AAC; IC50 value) were measured by the Folin-Ciocalteu method and
2, 6-Dichlorophenol-indophenol titration
method, respectively. A 2-factor factorial
experiment was used in the study. Varieties
Piliyandala (7.92 mg/mL) and Colombo
Selection (9.50 mg/mL) did not differ in their
AOA while variety Colombo Selection
recorded a higher phenolic content (472.67
mg GAE/100 g) compared to Piliyandala
(343.83 mg GAE/100 g). Ascorbic acid
contents of Piliyandala and Colombo
Selection varieties were 11.48 and 12.44
mg/100 mg, respectively. Home-scale
cultivation and organic fertilizer treatment
resulted in significantly higher (p˂0.05) AOA
of 3.364 and 8.034 mg/mL and PC of 410.87
and 404.99 mg GAE/100 g, respectively.
Organic fertilizer application significantly
increased (p˂0.05) the antioxidant activity of
variety Piliyandala but not in Colombo
Selection. Results indicated that, A. sessilis
grown with inorganic fertilizer and a
mixture of inorganic and organic fertilizer
contained significantly lower antioxidant
levels and phenolic contents compared to
those grown organically and in home-scale
without fertilizer application.
