Screening of Cytotoxicity and Anti-Inflammatory Properties of Feijoa Extracts Using Genetically Modified Cell Models Targeting TLR2, TLR4 and NOD2 Pathways, and the Implication for Inflammatory Bowel Disease.

Yaoyao Peng,Siew Quek,Karen Bishop,Lynnette Ferguson

doi:10.3390/nu10091188

Abstract

Feijoa has been increasingly studied in the recent decade, while investigations into its bioactivities including anti-inflammatory activity are lacking. In this article, the cytotoxicity and anti-inflammatory properties of feijoa extracts, from flesh, peel and whole fruit, from four cultivars namely APOLLO, UNIQUE, OPAL STAR and WIKI TU are presented. Three inflammatory pathways, Toll-like receptor 2 (TLR2), TLR4 and nucleotide-binding oligomerization domain-containing protein 2 (NOD2), were investigated using genetically modified cell models namely HEK-Blue™ hTLR2, HEK-Blue™ hTLR4, NOD2-WT and NOD2-G908R. Results show that feijoa peel extract induced higher cytotoxicity than flesh and whole fruit extracts, and the APOLLO cultivar was the most anti-inflammatory among the four tested cultivars. The anti-inflammatory activity of feijoa flesh was detected only through the TLR2 pathway, and the activity of feijoa peel and whole fruit was evident mainly through the TLR2 and NOD2 pathways. Most notably, feijoa anti-inflammatory activity was superior to ibuprofen particularly through the TLR2 pathway, with significantly lower secreted embryonic alkaline phosphatase IC50 concentrations (7.88, 12.81, 30.84 and 442.90 μg/mL for APOLLO flesh, peel, whole fruit extract and ibuprofen respectively). These findings indicate that feijoa has great potential to be used in the treatment and prevention of inflammation-related diseases including inflammatory bowel disease.

Highlights

Feijoa (Acca sellowiana) is a subtropical fruit that originated in South America and is widely grown in New Zealand [1,2]
People only consume feijoa flesh, peel is a by-product in feijoa-processing industries, and the whole fruit is ideal for bioactive compound extraction to be made into natural supplements or medicines
The reason for employing both cytotoxicity assays was because the sulforhodamine B (SRB) assay is highly sensitive when cell density is low which makes it accurate in determining IC50 values, while the WST-1 assay is more sensitive in a high cell density environment and suitable for follow-up studies [27]

Summary

Introduction

Feijoa (Acca sellowiana) is a subtropical fruit that originated in South America and is widely grown in New Zealand [1,2]. The consumption of feijoa has greatly increased and the New Zealand feijoa-processing industries are booming. People only consume feijoa flesh, peel is a by-product in feijoa-processing industries (e.g., juicing companies), and the whole fruit is ideal for bioactive compound extraction to be made into natural supplements or medicines. Cultivar differences of a natural plant commonly leads to different chemical compound composition [7,8,9] and, is an important aspect when considering commercial applications such as functional food development. No clear preference for feijoa cultivar selection is evident from either fresh fruit markets or food-processing industries. The differences in bioactivity among feijoa flesh, peel and whole fruit and different cultivars remain unknown

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