Increasing Antiradical Activity of Polyphenols from Lotus Seed Epicarp by Probiotic Bacteria Bioconversion.

Ying Liu,Xuekuan Hui,Wen Huang,Salam Ibrahim

doi:10.3390/molecules23102667

Abstract

Probiotic bacteria is able to metabolize polyphenols and produce functional compounds. In this study, we investigated the ability of probiotic bacteria including Lactobacillus, bifidobacteria and Enterococcus strains to increase the antioxidant capacity of polyphenols from lotus seed epicarp (PLSE) at full ripening stage. The results showed that the six selected strains of probiotic bacteria grew well in De Man, Rogosa and Sharpe (MRS) broth with PLSE, and their resistant extent to PLSE varied from strain to strain. The metabolized PLSE was found to have good antioxidant properties on 3-ethylbenzothiazoline-6-sulfonic acid (ABTS+) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radicals in vitro. Five polyphenol compounds—chlorogenic acid, caffeic acid, catechin, epicatechin and hyperoside—were suggested as the major bioactive metabolism for the antiradical activity of PLSE metabolized by Lactobacillus reuteri DSM20016, Enterococcus faecalis M74 and Bifidobacterium breve ATCC 15701. Moreover, L. reuteri DSM20016 and E. faecalis M74 were found to have a high PLSE bioconversion rate. Our results suggested that both L. reuteri DSM20016 and E. faecalis M74 might have excellent potential for the bioconversion of PLSE to increase its antiradical activity.

Highlights

Nelumbo nucifera Gaertn, known as lotus, is an important aquatic economic crop to be cultivated in Asia, Oceania and America for more than 3000 years and used as a medicinal herb in eastern Asia [1,2]
Our results suggested that L. reuteri DSM20016 and E. faecalis M74 would have the highest efficiency to increase the ABTS+ radical scavenging ability of polyphenols of lotus seed epicarp (PLSE)
Our results showed that the growth of the six strains of probiotics was not inhibited by PLSE during incubation of 48 h

Summary

Introduction

Nelumbo nucifera Gaertn, known as lotus, is an important aquatic economic crop to be cultivated in Asia, Oceania and America for more than 3000 years and used as a medicinal herb in eastern Asia [1,2]. Lotus seeds and leaves have multiple medicinal uses as antiemetic, anticancer, antiviral, inflammatory and antiobesity remedies [3,4,5]. The pharmacological activities of lotus are closely related to the abundant metabolites found in almost all of its tissues. These metabolites include alkaloids, steroids, flavonoids, triterpenoids, glycosides and polyphenols [8,9,10,11]. It was reported that some glycosylated flavonols and aglycone flavonols were isolated and identified from fresh lotus seed epicarp [12,13]. We identified epicatechin, hyperoside, catechin and isoquercitrin from polyphenols of lotus seed epicarp (PLSE). Polyphenols of lotus seed epicarp reportedly have good antioxidant properties including reducing power, 3-ethylbenzothiazoline-6-sulfonic acid (ABTS+ )

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