Research Article Antimicrobial Effect of the Triterpene 3,6,16-Trihydroxylup-20(29)-ene on Planktonic Cells and Biofilms from Gram Positive and Gram Negative Bacteria Francisco Flávio Vasconcelos Evaristo, 1 Maria Rose Jane R. Albuquerque, 2 Hélcio Silva dos Santos, 2 Paulo Nogueira Bandeira, 2 Fábio do Nascimento Ávila, 2 Bruno Rocha da Silva, 1 Ariana Azevedo Vasconcelos, 1 Érica de Menezes Rabelo, 1 Luiz Gonzaga Nascimento-Neto, 1 Francisco Vassiliepe Sousa Arruda, 1 Mayron Alves Vasconcelos, 1,3 Victor Alves Carneiro, 1 Benildo Sousa Cavada, 3 and Edson Holanda Teixeira 1 1 Integrated Laboratory of Biomolecules (LIBS/BioMol-Group), Department of Pathology and Legal Medicine, Faculty of Medicine, Federal University of Cear´ a, Fortaleza 60430-160, CE, Brazil 2 Centre of Exact Sciences and Technology, Acara´ u Valley State University, 62040-370 Sobral, CE, Brazil 3 Biologically Active Molecules Laboratory (BioMol-Lab/BioMol-Group), Department of Biochemistry and Molecular Biology, Federal University of Cear´ a, Fortaleza 60440-970, CE, Brazil Correspondence should be addressed to Edson Holanda Teixeira; edsonlec@gmail.com Received 12 February 2014; Accepted 10 June 2014; Published 29 June 2014 Academic Editor: Pascal O. Bessong Copyright © 2014 Francisco Fl´ avio Vasconcelos Evaristo et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Tis study evaluated the antimicrobial efect of3,6,16-trihydroxylup-20(29)-ene (CLF1), a triterpene isolated from Combretum leprosum Mart., in inhibiting the planktonic growth and bioflms of Gram positive bacteria Streptococcus mutans and S. mitis. Te antimicrobial activity was assessed by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Te antibioflm potential was determined by quantifying total biomass and enumerating bioflm-entrapped viable bacteria. In addition, the acute toxicity of CLF1 on Artemia sp. nauplii was also determined. Te results showed that CLF1 was able in inhibiting the growth of S. mutans and S. mitis with MIC and MBC of 7.8 g/mL and 15.6 g/mL, respectively. CLF1 was highly efective on bioflms of both bacteria. Only 7.8 g/mL CLF1 was enough to inhibit by 97% and 90% biomass production of S. mutans and S. mitis, respectively. On the other hand, such efects were not evident on Gram negative Pseudomonas aeruginosa and Klebsiella oxytoca. Te toxicity tests showed that the LC 50 of CLF1 was 98.19 g/mL. Terefore, CLF1 isolated from C. leprosum may constitute an important natural agent for the development of new therapies for caries and other infectious diseases caused by S. mutans and S. mitis. 1. Introduction Te resistance to available antimicrobials is currently a public health concern in the world. Several types of infectious diseases have become difcult to treat and expensive to cure mainly due to the low efciency of antimicrobials for current bacteria [1, 2]. Moreover, the socioeconomic impact caused by infectious diseases is quite signifcant as shown by the high amount of fnancial resources spent on the clinical treatment of patients [3, 4]. Taking this into consideration, the ability of microorganisms to grow as bioflms and the increased rate of microbial resistance to conventional antibiotics contribute to the expanding epidemiology of infectious diseases [5]. Bioflms are complex microbial communities that estab- lish themselves on a wide variety of surfaces and are generally associated with an extracellular matrix consisting of diferent Hindawi Publishing Corporation BioMed Research International Volume 2014, Article ID 729358, 7 pages http://dx.doi.org/10.1155/2014/729358