New Bioactive Metabolites from the Thermophilic FungusPenicilliumsp. Isolated from Ghamiqa Hot Spring in Saudi Arabia

Abstract

The thermophilic fungusPenicilliumspecies was isolated from Ghamiqa hot spring sediments in Saudi Arabia. Extract ofPenicilliumspecies 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-pyran13α-methyl-7-hydroxy-5-carboxylic acid methyl ester-1-indanone2. In addition, three known compounds, austinol3, emodin4, and 2-methyl-penicinoline5, 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. Austinol3exhibited strong antibacterial activity againstP. aeruginosabacterial strain with an MIC value of 0.13 ± 0.4 µg·mL−1, whereas emodin4demonstrated significant cytotoxicity against the tested HTB-176 cell line with an IC50value of 2 ± 7.6 µM, while the other compounds were moderate to inactive with IC50ranging from 4.3 ± 0.25–22 ± 2.94 µM in this assay.