Tripodanthus acutifolius and Psittacanthus cuneifolius: Loranthaceae. Sources of natural antimicrobials

SOBERÓN, J.R.; SGARIGLIA, M. A.; SAMPIETRO, D. A.; QUIROGA, E. N.; VATTUONE, M. A.

Molecular Medicinal Chemistry

IDECEFYN

Lugar: Buenos Aires; Año: 2006 vol. 11 p. 24 - 25

1666-888X

The development of microbial resistance to conventional therapies has been increased during the last decades. These facts support the importance of a study of the antimicrobial activity, and the necessity of finding alternative sources for this therapy that could contribute to the fight against the scourge that represent microbial infections. The purpose of this work is to study the antibacterial activity of three different extractive forms prepared from Tripodanthus acutifolius (Ruiz & Pav.) Blume and Psittacanthus cuneifolius (Ruiz & Pav.) Van Tieghem. Powder of leaves from each species were subjected to three different extractive forms: infusions, decoctions and tinctures, according to Pharmacopeia Argentina. Antimicrobial sensitivity tests included eight Gram-negative strains. Agar macrodilution and Broth microdilution tests were used. MIC and MBC were determined. The plant tinctures had the highest antibacterial activity, regarding the aqueous extractive forms. The tinctures of both plants inhibited the growth of the 17 strains studied in either the same concentrations or higher than 101 ug EM/ml. Aqueous extracts (infusions and decoctions) of T. acutifolius showed higher antibacterial activity than those of P. cuneifolius, the former being active against the 17 tested strains  either at the same concentrations or higher than 126 ug EM/ml. Infusions of P. cuneifolius  exhibited neither bacteriostatic nor bactericide activity against 5 Gram-negative and 2 Gram-positive strains, and bactericide on Proteus mirabilis (Gram-negative) and three strains of Enterococcus sp. (Gram-positive). This extractive form only showed activity either at the same concentrations or higher than 1595 ug EM/ml. The antibacterial activity profile of the decoction of P. cuneifolius was similar to that of the infusion, being active either at the same concentrations or higher than 607 ug EM/ml. Data obtained by microdilution demonstrated that MIC and MBC values of the plant extracts are, in general, higher than the values obtained with reference antibiotics. The results indicate that T. acutifolius and P. cuneifolius represent interesting sources of natural antibiotics owing to their wide spectrum action, comparable to that of commercial antibiotics. Our study also demonstrated the importance of the extractive form used, since the biological activity is strogly affected by solvent and used methodology. The antimicrobial activity analogy of the studied plants could be attributed partially to its relationship, since both belong to the Loranthaceae family.