Improving bioactive compounds extractability of Amorphophallus paeoniifolius (Dennst.) Nicolson

Anabela S.G Costa,João C.M Barreira,Adilson Ruas,Ana F Vinha,Filipa B Pimentel,Rita C Alves,Isabel C.F.R Ferreira,M Beatriz P.P Oliveira

doi:10.1016/j.indcrop.2015.11.019

Abstract

Elephant foot yam (Amorphophallus paeoniifolius (Dennst.) Nicolson) is an underground, unbranched deciduous plant that produces a large tubercle (rhizome) with recognized health effects. In this study, the influence of solvent nature (water, water/etanol (1:1) and absolute ethanol) and processing type (fresh, lyophilized and boiled) on the antioxidant activity and bioactive compounds extractability of elephant foot yam was evaluated. Extracts were compared for their contents in total phenolics, flavonoids and tannins. Moreover, their antioxidant capacity was assessed by the ferric reducing antioxidant power (FRAP) and the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging capacity assays. Phenolics (154mg GAE/L) and tannins (109mg GAE/L) were maximized in lyophilized samples extracted with the hydroalcoholic solvent, which attained also the highest FRAP value (711mg FSE/L). In turn, flavonoids reached the highest yields in lyophilized samples (95mg ECE/L) extracted with pure ethanol, as well as the highest DPPH scavenging activity. These findings might have practical applications to define the best processing methodology regarding the enhancement of elephant foot yam, either for prompt consumption, as well as to develop food supplements or pharmaceutical related products.

Highlights

Oxidative stress is involved in the etiology of various disorders and diseases, being reasonable to expect beneficial effects of antioxidants in maintaining our health and lowering disease risk (Kris-Etherton et al, 2002; Niki, 2010)
In what regards to antioxidant activity, two assays were performed to evaluate different mechanisms of action: ferric reducing antioxidant power (FRAP), an electron transfer method, which cannot detect compounds that act by radical quenching, but detects compounds with redox potentials lower than 0.7 V; and the diphenyl-1-picrylhydrazyl radical (DPPH) scavenging assay, where the radicals may be neutralized either by direct reduction via electron transfers, or by radical quenching via H atom transfer (Prior et al, 2005)
This significant interaction might be observed in the estimated marginal means (EMM), where the variation in total phenols, tannins and flavonoids (Fig. 1A–C) among fresh, lyophilized and boiled samples were clearly dependent on the solvent type

Summary

Introduction

Oxidative stress is involved in the etiology of various disorders and diseases, being reasonable to expect beneficial effects of antioxidants in maintaining our health and lowering disease risk (Kris-Etherton et al, 2002; Niki, 2010). Some antioxidants can be produced in the body, but the amounts maybe insufficient, under conditions where production of free radicals is increased. Plants are natural alternative sources of antioxidants that might complement the production of these compounds in living organisms. The antioxidant activity in plants is often correlated to their phenolic contents (Cai et al, 2004; Razali et al, 2012). The preparation of dietary supplements/nutraceuticals and some pharmaceutical products is increasingly based on the extraction of bioactive compounds from natural matrices (Dai and Mumper, 2010)

Methods

Results

Conclusion