The Effect of Variety and Fertilizer Application on Functional Properties of ‘Mukunuwenna’ (&lt;em&gt;Alternanthera sessilis)&lt;/em&gt;

Y.D.A Jayawardana,K.H Sarananda,R.H.M.K Ratnayake,S.M.A.C.U Senarathne

doi:10.4038/jfa.v11i2.5213

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, 2- diphenyl-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.

Highlights

Fruits and vegetables contain natural antioxidants which help to minimize the risks of cardiovascular diseases and cancers (Renaud et al, 1998; Temple, 2000)
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
The present study indicated that, A. sessilis grown with inorganic fertilizer and a mixture or inorganic and organic fertilizer contained significantly lower antioxidant levels compared to those grown organically and without fertilizer application

Summary

Introduction

Fruits and vegetables contain natural antioxidants which help to minimize the risks of cardiovascular diseases and cancers (Renaud et al, 1998; Temple, 2000). Research is focused towards identification of natural antioxidants from herbal sources because the synthetic antioxidants such as butylated. There are two major categories of antioxidants namely, enzymatic and non – enzymatic. Superoxide dismutase, catalase and glutathione peroxidase, which are produced endogenously, are enzymatic antioxidants. Tocopherols, carotenoids, ascorbic acid, flavonoids and tannins are non-enzymatic antioxidants which are obtained from natural sources (Lee et al, 2004). Phenolics and carotenoids are the three major groups of natural antioxidants in fruits and vegetables. Ascorbic acid and phenolics are hydrophilic antioxidants while carotenoids are lipophilic antioxidants (Halliwell, 1996). Polyphenol compounds are contained in edible and nonedible plants and they are reported to have multiple beneficial effects on human health (Kahkonen et al, 1999)

Objectives

Methods

Results

Conclusion