Planta Med 2014; 80 - P1L102
DOI: 10.1055/s-0034-1394759

Antimicrobial screening of Plectranthus madagascariensis Benth. extracts

D Matias 1, 2, F Pereira 1, M Pereira 1, MF Simões 1, 3, AM Diaz-Lanza 2, CP Reis 1, P Rijo 1, 2
  • 1Universidade Lusófona Research Center for Biosciences & Health Technologies (CBIOS), Campo Grande, 376, 1749 – 024 Lisboa, Portugal
  • 2Dpto. Ciências Biomédicas, Univesidad de Alcalá, Plaza de San Diego, s/n, 28801 Alcalá de Henares, Madrid, Espanha
  • 3Instituto de Investigação do Medicamento (iMed.ULisboa), Faculdade de Farmácia da Universidade de Lisboa, Av. Professor Gama Pinto 1649 – 003 Lisboa, Portugal

Medicinal plants have been recognized as interesting sources of natural antimicrobial compounds which may lead to new therapeutic agents. Plectranthus species are known for the occurrence of abietane diterpenoids with significant biological activity such as antimicrobial properties. [1 – 2]. Thus, it is important to screen and identify their diterpenes as potential anti-infective agents. The aim of this work was to screen the antimicrobial activity of several P. madagascariensis Benth. extracts. Several methanolic and acetonic extracts have been prepared using maceration, supercritical fluid and ultrasonic methods. All the extracts were evaluated against a panel of Gram positive (Bacillus subtillis, Mycobacterium smegmatis, Staphylococcus epidermidis, S. aureus, MRSA, MRSA “wild type”, Enterococcus faecalis and VRE) and Gram negative bacteria (Klebsiella pneumonia, Pseudomonas aeruginosa and Escherichia coli,) and yeast strains (Candida albicans and Saccharomyces cerevisiae), using the well diffusion test and the microdilution method [3]. The ultrasonic acetone extract showed the highest antimicrobial activity against B. subtillis, S. epidermidis, S. aureus and E. faecalis (MIC values of 0.98 µg.mL-1 to 3.91 µg.mL-1; including resistant MRSA and VRE strains); K. pneumonia and M. smegmatis (MIC values of < 0.49 µg.mL-1 – 31.25 µg.mL-1). Moreover, the chromatographic profile of the ultrasonic acetone extract was carried out by HPLC-DAD, using several standard compounds that were previously isolated from Plectranthus spp. [2]. The known antimicrobial rosmarinic acid and 7α-acetoxy-6β-hydroxyroyleanone were identified as the major compounds. The P. madagascariensis species seems to be a good starting vegetal material for the isolation of lead antimicrobial drugs to further being chemically modified. This study will be pursued and a bioguided fractionation and subsequent isolation of the bioactive compounds will be performed.

Keywords: Plectranthus; Plectranthus madagascariensis; Antibacterial, Antifungal

References:

[1] Rice LJ, Brits GJ, Potgieter CJ, Van Staden J. Plectranthus: A plant for the future? South African Journal of Botany 2011; 77(4): 947 – 959

[2] Rijo P, Faustino C and Simões MF, Antimicrobial natural products from Plectranthus plants. In: Mendez-Vilas A, editor. Microbial pathogens and strategies for combating them: science, technology and education. Formatex Research Center; 2013; 2: 922 – 931

[3] Seanego, CT and Ndip RN. Identification and Antibacterial Evaluation of Bioactive Compounds from Garcinia kola (Heckel) Seeds. Molecules 2012; 17(6): 6569 – 6584