Intercollegiate Faculty of Biotechnology UG & MUG. PhD seminar
Date of seminar
Combining silver nanoparticles and plant extracts in the aim of
eradicating bacterial and fungal human pathogens
Marta Krychowiak, Laboratory of Biologically Active Compounds
Supervisor: Prof. UG, dr hab. Aleksandra Królicka
Silver nanoparticles (AgNPs) and plant extracts provide an alternative strategy in the
treatment of infectious diseases (i.e. burn wound infections ) caused by antibiotic-resistant pathogens.
Silver nanoparticles are particles of metallic silver between 1 and 100 nm in diameter. Extracts derived
from plant tissues, in turn, may be another alternative to antibiotics due to large amounts of active
secondary metabolites. The idea behind studying synergy of silver nanoparticles and plant extract is
the concept of multi-drug therapy. Antimicrobial action of two therapeutics in a synergistic way could
significantly reduce effective doses of both and elevate the efficiency of antimicrobial therapy.
Studies on the antimicrobial potential of Dionaea muscipula (Venus flytrap, VFT), Drosera binata,
Rubus idaeus and Vitania somnifera against Pseudomonas areuginosa, Staphylococcus aureus and
Candida albicans demonstrated that tissues from VFT are the most potent source of antimicrobial
secondary metabolites. Thus, studies were performed to optimize the conditions of in vitro culture and
extraction of metabolites from plant tissue. It was observed that tetrahydrofuran extract from VFT
tissues possesses high antimicrobial activity against S. aureus and C. albicans correlated with
plumbagin content. P. aeruginosa which is resistant to plumbagin, turned out to be more sensitive to
methanol extract from D. muscipula tissues. In addition to plumbagin these results revealed the
presence of further secondary metabolites with antibacterial activity. A synergistic mode of action
against S. aureus planktonic cultures and biofilm was observed when combining commercially
available silver nanoparticles and the extract from D. binata or D. muscipula. The simultaneous use of
VFT extract and AgNPs resulted in the synergistic effect against planktonic cultures of P. aeruginosa.
Synergy between VFT extract and AgNPs seems to be correlated with the presence of an unidentified
secondary metabolite in the extract derived from plant tissues. The influence of extracts from VFT or
D. binata and AgNPs on the viability of keratinocytes cultured in vitro was determined. It revealed
high cytotoxicity of plant extracts toward human cells attributed probably to high amounts of
plumbagin.
Future plans include identification of the compound responsible for bactericidal activity of methanol
extract from VFT against P. aeruginosa and the compound responsible for synergy with AgNPs. It is
also planned to determine the range of antimicrobial activity of these unidentified compounds and
their mode of action in combination with AgNPs and alone.
KSZTAŁCIMY NAJLEPSZYCH – kompleksowy program rozwoju doktorantów, młodych doktorów oraz akademickiej kadry
dydaktycznej Uniwersytetu Gdańskiego. Zad. 2. Life Sciences and Mathematics Interdisciplinary Doctoral Studies (LiSMIDoS)
Project co-funded by European Union under the European Social Fund