Evaluation of Antioxidant, Antidiabetic and Anticholinesterase Activities of Smallanthus sonchifolius Landraces and Correlation with Their Phytochemical Profiles.

Daniela Russo,Patrícia Valentão,Paula B Andrade,Luigi Milella,Eloy C Fernandez

doi:10.3390/ijms160817696

Abstract

The present study aimed to investigate the phytochemical profile of leaf methanol extracts of fourteen Smallanthus sonchifolius (yacon) landraces and their antioxidant, anticholinesterase and antidiabetic activities that could lead to the finding of more effective agents for the treatment and management of Alzheimer’s disease and diabetes. For this purpose, antioxidant activity was assessed using different tests: ferric reducing ability power (FRAP), 2,2-diphenyl-1-picryl hydrazyl (DPPH), nitric oxide (˙NO) and superoxide (O2˙−) scavenging and lipid peroxidation inhibition assays. Anticholinesterase activity was investigated by quantifying the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities, whereas antidiabetic activity was investigated by α-amylase and α-glucosidase inhibition tests. To understand the contribution of metabolites, phytochemical screening was also performed by high performance liquid chromatography-diode array detector (HPLC-DAD) system. Among all, methanol extract of PER09, PER04 and ECU44 landraces exhibited the highest relative antioxidant capacity index (RACI). ECU44 was found to be rich in 4,5-di-O-caffeoylquinic acid (CQA) and 3,5-di-O-CQA and displayed a good α-amylase and α-glucosidase inhibition, showing the lowest IC50 values. Flavonoids, instead, seem to be involved in the AChE and BChE inhibition. The results of this study revealed that the bioactive compound content differences could be determinant for the medicinal properties of this plant especially for antioxidant and antidiabetic activities.

Highlights

Medicinal plants, as source of remedies, are widely used as alternative therapeutic tools for the prevention or treatment of many diseases
Dried foliar tissue of 14 landraces of yacon was extracted by maceration technique by solvents of crescent polarity: n-hexane (E), chloroform (C), chloroform:methanol 9:1 (CM) and methanol (M)
The most active was found to be ECU44-M landrace for both enzyme inhibitory activities (IC50 = 0.26 ± 0.02 mg/mL for α-amylase inhibition and 1.30 ± 0.04 mg/mL for α-glucosidase); ECU41-M and PER09-M extracts act as α-amylase inhibitors; PER11-M can be considered a moderate inhibitor of α-glucosidase; on the other hand, the less active against both enzymes were PER01-M and PER04-M extracts

Summary

Introduction

As source of remedies, are widely used as alternative therapeutic tools for the prevention or treatment of many diseases. Great attention has been devoted to the use of natural compounds, due to their nutritional and pharmacological characteristics. Commonly called yacon, belongs to the Asteraceae family. It is a tuberous plant native to the Andes, but it has been introduced in Japan, New Zealand, Europe (primarily in Czech Republic) and United States [1]. Yacon is a perennial herb with large dark green leaves and two types of underground portions: edible tuberous roots, used by the plant for food storage, and fibrous roots used for vegetative reproduction.

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