Elemental analysis and in vitro evaluation of antibacterial and antifungal activities of Usnea barbata (L.) Weber ex F.H. Wigg from Călimani Mountains, Romania
- Author:
- Popovici V., Bucur L., Calcan S.I., Cucolea E.I., Costach T., Rambu D., Schröder V., Gîrd C.E., Gherghel D., Vochita G., Caraiane A. & Badea V.
- Year:
- 2022
- Journal:
- Plants
- Pages:
- 11: 32 [21 p.]
- Url:
- https://doi.org/10.3390/plants11010032
This study aims to complete our research on Usnea barbata (L.) Weber ex F.H. Wigg (U.
barbata) from the Calimani Mountains, Romania, with an elemental analysis and to explore its
antibacterial and antifungal potential. Thus, we analyzed twenty-three metals (Ca, Fe, Mg, Mn, Zn,
Al, Ag, Ba, Co, Cr, Cu, Li, Ni, Tl, V, Mo, Pd, Pt, Sb, As, Pb, Cd, and Hg) in dried U. barbata lichen (dUB)
by inductively coupled plasma mass spectrometry (ICP-MS). For the second study, we performed
dried lichen extraction with five different solvents (ethyl acetate, acetone, ethanol, methanol, and
water), obtaining five U. barbata dry extracts (UBDE). Then, using an adapted disc diffusion method
(DDM), we examined their antimicrobial activity against seven bacterial species—four Gram-positive
(Staphylococcus aureus, Enterococcus casseliflavus, Streptococcus pyogenes, and Streptococcus pneumoniae)
and three Gram-negative (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa)—and two
fungi species (Candida albicans and Candida parapsilosis). Usnic acid (UA) was used as a positive control.
The ICP-MS data showed a considerable Ca content (979.766 g/g), followed by, in decreasing order,
Mg, Mn, Al, Fe, and Zn. Other elements had low levels: Ba, Cu, Pb, and Cr (3.782–1.002 g/g);
insignificant amounts (<1 g/g) of Hg and V were also found in dUB. The trace elements Ag, As,
Cd, Co, Li, Tl, Mo, Pd, Pt, and Sb were below detection limits (<0.1 g/g). The DDM results—
expressed as the size (mm) of the inhibition zone diameter (IZs)—proved that the water extract did
not have any inhibitory activity on any pathogens (IZs = 0 mm). Gram-positive bacteria displayed the
most significant susceptibility to all other UBDE, with Enterococcus casseliflavus showing the highest
level (IZs = 20–22 mm). The most susceptible Gram-negative bacterium was Pseudomonas aeruginosa
(IZs = 16–20 mm); the others were insensitive to all U. barbata dry extracts (IZs = 0 mm). The inhibitory
activity of UBDE and UA on Candida albicans was slightly higher than on Candida parapsilosis.
Keywords: Usnea barbata (L.)Weber ex F.H.Wigg; elemental analysis; metals; antibacterial activity;
antifungal activity; disc diffusion method; usnic acid; polyphenols; tannins.
- Id:
- 34012
- Submitter:
- zdenek
- Post_time:
- Friday, 24 December 2021 02:18