Antibiotic-modifying activity of riachin, a non-cyanogenic cyanoglycoside extracted from Bauhinia pentandra

Abstract

Pablo Antonio Maia de Farias,1,3 Fernando Gomes Figueredo,2,3 Aline Maria Brito Lucas,3 Rafael Barbosa de Moura,3 Henrique Douglas Melo Coutinho,2 Tania Maria Sarmento da Silva,4 Ana Luiza de Aguiar Rocha Martin,2,3 Marta Maria de França Fonteles1 1Development and Technological Innovation in Medicines, Universidade Federal do Ceará – UFC, Fortaleza-CE, 2College of Biomedicine, Faculdade Leão Sampaio-FLS, 3College of Pharmacy, Faculdade de Medicina Estácio de Juazeiro do Norte-Estácio, Juazeiro do Norte-CE, 4Department of Molecular Sciences, Universidade Federal Rural de Pernambuco, Recife, PE, Brazil Background: The search for new active compounds from the Brazilian flora has intensified in recent years, especially for new drugs with antibiotic potential. Accordingly, the aim of this study was to determine whether riachin has antibiotic activity in itself or is able to modulate the activity of conventional antibiotics.Methods: A non-cyanogenic cyanoglycoside known as riachin was isolated from Bauhinia pentandra, and was tested alone and in combination with three antibiotics (clindamycin, amikacin, and gentamicin) against multiresistant bacterial strains (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus).Results: Riachin did not show significant antibiotic activity when tested alone against any strain (P>0.05). However, when combined with conventional antibiotics, it showed drug-modifying activity against strains of S. aureus exposed to clindamycin (P<0.001) as well as against P. aeruginosa exposed to amikacin (P<0.001). Although riachin did not show direct antibiotic activity, it had synergistic activity when combined with amikacin or clindamycin. The mechanism of action of this synergism is under investigation.Conclusion: The results of this work demonstrate that some substances of natural origin can enhance the effectiveness of certain antibiotics, which means a substantial reduction in the drug dose required and possibly in consequent adverse events for patients. Keywords: riachin, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus