Planta Med 2009; 75(8): 823-828
DOI: 10.1055/s-0029-1185437
Pharmacology
Original Paper
© Georg Thieme Verlag KG Stuttgart · New York

The Diterpenoid ent-16-Kauren-19-oic Acid Acts as an Uncoupler of the Bacterial Respiratory Chain

Janet Torres-Bustos1 , Leonardo Farías1 , Alejandro Urzúa2 , Leonora Mendoza3 , Marcela Wilkens1
  • 1Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
  • 2Laboratorio de Química Ecológica, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
  • 3Departamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
Weitere Informationen

Publikationsverlauf

received July 9, 2008 revised January 16, 2009

accepted January 27, 2009

Publikationsdatum:
18. März 2009 (online)

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Abstract

ent-16-Kauren-19-oic acid is a bacteriolytic diterpenoid present in the resin of the medicinal plant Pseudognaphalium vira vira. The compound and its methyl ester showed strong activity against gram-positive bacteria, whereas the derivative 3β-hydroxy-ent-kauren-19-oic acid was inactive against all assayed bacteria at the maximal concentration used (250 µg/mL). The bacteriolytic effect of ent-16-kauren-19-oic acid (5 µg/mL) was confirmed with cultures of Bacillus cereus and Staphylococcus aureus, whereas the methyl derivative (12 µg/mL) showed only a bacteriostatic effect. Both compounds stimulated oxygen consumption and proton conduction of whole cells, as reflected by an abrupt increase in the extracellular pH. These results indicate that ent-16-kauren-19-oic acid acts as a respiratory chain uncoupler, and that this function is strongly affected by minor structural substitutions, suggesting a tight activity-structure relationship. The ultimate effect of the uncoupling mechanism demonstrated by ent-16-kauren-19-oic acid is bacterial lysis. The disruption of the bacterial membrane integrity caused by the diterpenoid compound was determined using SYTOX Green stain and visualized by fluorescence microscopy.

References

Dr. Marcela Wilkens

Departamento de Biología
Facultad de Química y Biología
Universidad de Santiago de Chile

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Chile

Telefon: + 56 27 18 11 21

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eMail: mwilkens@usach.cl