The antimicrobial and cytotoxic activities of Gochnatia polymorpha ssp floccosa, a medicinal plant used against respiratory diseases, were evaluated. Successive petroleum ether, dichloromethane and ethanol extracts of dried leaves, trunk bark and stems were used in the brine shrimp lethality bioassay and tested against 22 strains of microorganisms (Gram-positive and Gram-negative bacteria and fungi) by the well-diffusion agar method. None of the extracts showed cytotoxicity on the brine shrimp bioassay. The extracts of leaves showed a mild activity against some strains of Staphylococcus aureus and Streptococcus mutans. The ethanol extracts of trunk bark and dichloromethane extract of stems also showed activity against Micrococcus luteus, Staphylococcus aureus and S. epidermidis. The highest activity was found in the dichloromethane extract of trunk bark, which showed significant antibacterial and antifungal activities against Micrococcus luteus, Staphylococcus aureus, S. epidermidis, Streptococcus mutans, Enterococcus faecalis and Candida albicans. Diterpenes are present in this extract and could be responsible for the activity. All the screened extracts were shown to be inactive (at 5.0 mg/mL) against strains of Gram-negative bacteria tested. These results indicate the potential of G. polymorpha ssp floccosa as a source of antibacterial compounds and partly support the use of this plant in folk medicine.
Gochnatia polymorpha; Asteraceae; antimicrobial activity; cytotoxic activity; diterpenes