Dereplication and antibiofilm activity of macrophytes species of Pantanal

Nocchi, S. R.1,2; Boaretto, A.2; Macedo, A. J.3; Silva, D. B.2; Carollo, C. A1,2.
1 Programa de Pós-graduação em Biologia Vegetal. Universidade Federal de Mato Grosso do Sul (UFMS), 79070-900, Campo Grande, MS, Brazil.
2 Laboratório de Produtos Naturais e Espectrometria de Massas (LaPNEM), Faculdade de Ciências Farmacêuticas, Alimentos e Nutrição (FACFAN), (UFMS).
3 Laboratório de Biofilmes e Diversidade Microbiana (LaBDiM), Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul (UFRGS), 90040-060, Porto Alegre (RS), Brazil.
E-mail: [email protected]

Macrophytes are plants that live from swamps to totally submerged environments. They survive in harsh conditions and show resistance to humidity and diffusion capacity. To grow in these conditions thy probably produce secondary metabolites to protect them against adverse factors, such as microorganisms. Thus, antimicrobial compounds can be identified from these samples.
Microbial biofilms are communities formed by bacterial cells embedded in a self-produced extracellular polymeric matrix of polysaccharides, proteins, and DNA which protect bacteria against antimicrobial agents and increasing resistance to the host immune system[1]. Biofilms can attach to abiotic and biotic surfaces and the biofilm formation is associated with persistent tissue infections[2].
Strategies to inhibit the biofilm formation or to combat formed biofilms are attractive for therapeutic area. This study aimed to evaluate the antibiofilm activity from five macrophytes species (Azolla filiculoides Lam., Echinodorus paniculatus Micheli, Ludwigia helminthorrhiza (Mart.) H. Hara, Nymphaea caerulea Savigny and Pistia stratiotes L.) of Pantanal and to identify their main constituents by LC-DAD-MS.
The chemical composition of bioactive species (L. helminthorrhiza and N. caerulea) was established based on UV and MS/MS data. From L. helminthorrhiza extract, ellagitannins, O-pentosyl quercetin, O-deoxyhexosyl-quercetin, gallic acid and its derivatives O-galloyl O-hexosyl quercetin and O-pentosyl myricetin were identified. From N. caerulea extract, ellagitannins, O-hexosyl myricetin, O-coumaroyl O-hexosyl myricetin and O-feruloyl O-hexosyl myricetin were identified.
Hydroethanolic extracts from macrophytes species were evaluated for bacterial growth, biofilm formation and biofilm erradication on the ATCC strains of Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa. The extracts of L. helminthorrhiza and N. caerulea were active on S. aureus biofilm formation at 10 µg/mL, indicating that these extracts can interfere with the adhesion of this microorganism to polystyrene surfaces. However, they did not show activity when they were tested on the formed biofilm.
Several studies show antimicrobial and antibiofilm properties of tannins[3],[4] and flavonoid derivatives[5],[6],[7]. Vikram et al.[7] explain the inhibition of biofilm formation by the presence of flavonoids, such as quercetin, kaempferol, naringenin, and apigenin, which are capable of reducing biofilm synthesis because they can suppress the activity of the autoinducer-2 responsible for cell-to-cell communication.
Additional studies will be performed to obtain the fractionation of the bioactive extracts and evaluate the activity of fractions. In addition, more studies are necessary to elucidate the mechanism of interference in adhesion of microorganisms and consequently biofilm formation.

References
[1] Donlan & Costerton. Clinical Microbiology Reviews, 15(2),167–193, 2002.
[2] Römling, U., and Balsalobre, C. Journal of Internal Medicine, 272, 541–561, 2012.
[3] Shukla; Bhathena. Applied Biochemistry and Biotechnology, 175, 3542-5556, 2015.
[4] Lipinska, L.; Klewicka, E.; Sójka, M. Acta Scientiarum Polonorum, 13(3), 289-299, 2014.
[5] Wang et al. Frontiers in Pharmacology, 16(8), 379, 2017.
[6] Cushnie, T. P.; Lamb, A. J. International Journal of Antimicrobial Agents, 26(5), 343-356, 2005.
[7] Vikram et al. Journal of Applied Microbiology, 109(2), 515–527, 2010.