Phytochemical Composition and In Vitro Biological Activity of Iris spp. (Iridaceae): A New Source of Bioactive Constituents for the Inhibition of Oral Bacterial Biofilms.

Lan Hoang,Jitka Viktorová,Eva Baldassarre Švecová,Miroslav Vosátka,Marie Fenclová,Kateřina Řehořová,František Beneš,Petr Kaštánek,Olga Kronusová,Viviana Švarcová,Tomáš Ruml,Jana Hajšlová

doi:10.3390/antibiotics9070403

Abstract

The inhibition and eradication of oral biofilms is increasingly focused on the use of plant extracts as mouthwashes and toothpastes adjuvants. Here, we report on the chemical composition and the antibiofilm activity of 15 methanolic extracts of Iris species against both mono-(Pseudomonas aeruginosa, Staphylococcus aureus) and multi-species oral biofilms (Streptococcus gordonii, Veillonella parvula, Fusobacterium nucleatum subsp. nucleatum, and Actinomyces naeslundii). The phytochemical profiles of Iris pallida s.l., Iris versicolor L., Iris lactea Pall., Iris carthaliniae Fomin, and Iris germanica were determined by ultra-high performance liquid chromatography-high-resolution tandem mass spectroscopy (UHPLC-HRMS/MS) analysis, and a total of 180 compounds were identified among Iris species with (iso)flavonoid dominancy. I. pallida, I. versicolor, and I. germanica inhibited both the quorum sensing and adhesion during biofilm formation in a concentration-dependent manner. However, the extracts were less active against maturated biofilms. Of the five tested species, Iris pallida s.l. was the most effective at both inhibiting biofilm formation and disrupting existing biofilms, and the leaf extract exhibited the strongest inhibitory effect compared to the root and rhizome extracts. The cytotoxicity of the extracts was excluded in human fibroblasts. The inhibition of bacterial adhesion significantly correlated with myristic acid content, and quorum sensing inhibition correlated with the 7-β-hydroxystigmast-4-en-3-one content. These findings could be useful for establishing an effective tool for the control of oral biofilms and thus dental diseases.

Highlights

Bacterial biofilms, communities of microorganisms in a self-produced extracellular polymeric substance matrix, cause more than 60% of human microbial infections [1]
The highest number offlavonoids was detected in I. pallida leaves and roots, which consisted of 35 and 38flavonoids, respectively, while less than half of them were detected in the rhizomes of this species
In this study, the extracts were further analyzed for potential phytochemical components using UHPLC-HRMS/MS-targeted screening, and some of the detected compounds may associate with the activity observed against the tested bacterial biofilms

Summary

Introduction

Communities of microorganisms in a self-produced extracellular polymeric substance matrix, cause more than 60% of human microbial infections [1]. Quorum sensing (QS) is known as a cell–cell communication pathway that initiates and regulates various physiological activities such as biofilm formation, bioluminescence, and virulence production. Both Gram-positive and Gram-negative bacteria use QS for communication, but they produce distinct signal molecules (autoinducers): N-acyl homoserine lacton (AHL) molecules (autoinducer-1, AI-1) are mainly used by Gram-negative bacteria, while Gram-positive bacteria predominantly use modified oligopeptides (autoinducer peptides, AIP or QS peptides). Another type of signal molecules is autoinducer-2

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