| Title |
Biophysical characterization of antibacterial compounds derived from pathogenic fungi Ganoderma boninense |
| Author |
Syahriel Abdullah1, Yoon Sin Oh2, Min-Kyu Kwak2*, and KhimPhin Chong1* |
| Address |
1Faculty of Science and Natural Resources, Universiti Malaysia Sabah, Jalan UMS, 88400, Kota Kinabalu, Sabah, Malaysia, 2Department of Food and Nutrition, Institute of Food and Nutrition Science, Eulji University, Seongnam 13135, Republic of Korea |
| Bibliography |
Journal of Microbiology, 59(2),164–174, 2021,
|
| DOI |
|
| Key Words |
antibacterial activity, disc diffusion assay, ergosterol,
ganoboninketal, Ganoderma boninense, lanostane |
| Abstract |
There have been relatively few studies which support a link
between Ganoderma boninense, a phytopathogenic fungus
that is particularly cytotoxic and pathogenic to plant tissues
and roots, and antimicrobial compounds. We previously observed
that liquid-liquid extraction (LLE) using chloroformmethanol-
water at a ratio (1:1:1) was superior at detecting
antibacterial activities and significant quantities of antibacterial
compounds. Herein, we demonstrate that antibacterial
secondary metabolites are produced from G. boninense mycelia.
Antibacterial compounds were monitored in concurrent
biochemical and biophysical experiments. The combined
methods included high performance thin-layer chromatography
(HPTLC), gas chromatography-mass spectrometry
(GC-MS), high-performance liquid chromatography (HPLC),
fourier transform infrared (FTIR), and nuclear magnetic resonance
(NMR) spectroscopy. The antibacterial compounds
derived from mycelia with chloroform-methanol extraction
through LLE were isolated via a gradient solvent elution system
using HPTLC. The antibacterial activity of the isolated
compounds was observed to be the most potent against Staphylococcus
aureus ATCC 25923 and multidrug-resistant S.
aureus NCTC 11939. GC-MS, HPLC, and FTIR analysis confirmed
two antibacterial compounds, which were identified
as 4,4,14α-trimethylcholestane (m/z = 414.75; lanostane,
C30H54) and ergosta-5,7,22-trien-3β-ol (m/z = 396.65; ergosterol,
C28H44O). With the aid of spectroscopic evaluations,
ganoboninketal (m/z = 498.66, C30H42O6), which belongs to
the 3,4-seco-27-norlanostane triterpene family, was additionally
characterized by 2D-NMR analysis. Despite the lack of
antibacterial potential exhibited by lanostane; both ergosterol
and ganoboninketal displayed significant antibacterial activities
against bacterial pathogens. Results provide evidence
for the existence of bioactive compounds in the mycelia of
the relatively unexplored phytopathogenic G. boninense, together
with a robust method for estimating the corresponding
potent antibacterial secondary metabolites. |
