Abstract
The thermophilic fungus
Penicillium
species was isolated from Ghamiqa hot spring sediments in Saudi Arabia. Extract of
Penicillium
species cultured on solid rice medium yielded two new compounds 3-(furan 12-carboxylic acid)-6-(methoxycarbonyl)-4-hydroxy-4-methyl-4 and 5-dihydro-2H-pyran
1
3
α
-methyl-7-hydroxy-5-carboxylic acid methyl ester-1-indanone
2
. In addition, three known compounds, austinol
3
, emodin
4
, and 2-methyl-penicinoline
5
, were isolated. The structures of the new compounds were unambiguously determined by comprehensive analysis of spectroscopic data, one- and two-dimensional NMR spectroscopy, and high-resolution mass spectrometry. All isolated metabolites were studied for their antibiotic effect against several pathogenic bacteria and for their cytotoxicity against the lymphoma human cancer cell line HTB-176. Austinol
3
exhibited strong antibacterial activity against
P. aeruginosa
bacterial strain with an MIC value of 0.13 ± 0.4
µ
g·mL
−1
, whereas emodin
4
demonstrated significant cytotoxicity against the tested HTB-176 cell line with an IC
50
value of 2 ± 7.6
µ
M, while the other compounds were moderate to inactive with IC
50
ranging from 4.3 ± 0.25–22 ± 2.94
µ
M in this assay.