In the alarming context of antibiotic resistance, we explored the antibacterial potential of French mushrooms against wild-type and multidrug-resistant (MDR) bacteria. In order to accelerate the discovery of promising compounds, screenings were carried out by TLC-direct bioautography. A total of 70 extracts from 31 mushroom species were evaluated against five wild-type bacteria: Staphylococcus epidermidis, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa. This first screening revealed that 95% of the extracts contained antibacterial compounds. Generally, it was observed that EtOAc extracts exhibited more active compounds than methanolic extracts. In addition, all extracts were overall more active against Gram-positive bacteria than against Gram-negative strains. The most promising mushroom extracts were then screened against various multidrug-resistant strains of S. aureus and E. coli. Activity was globally less on MDR strains; however, two mushroom species, Fomitopsis pinicola and Scleroderma citrinum, still contained several compounds inhibiting the growth of these MDR pathogenic bacteria. Stearic acid was identified as a ubiquitous compound contributing to the antibacterial defence of mushrooms. This screening revealed the potential of macromycetes as a source of antibacterial compounds; further assays are necessary to consider fungal compounds as promising drugs to counter antibiotic resistance.

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Infectious diseases are among the greatest threats to global health in the 21st century, and one critical concern is due to antibiotic resistance developed by an increasing number of bacterial strains. New resistance mechanisms are emerging with many infections becoming more and more difficult if not impossible to treat. This growing phenomenon not only is associated with increased mortality but also with longer hospital stays and higher medical costs. For these reasons, there is an urgent need to find new antibiotics targeting pathogenic microorganisms such as ESKAPEE bacteria. Most of currently approved antibiotics are derived from microorganisms, but higher fungi could constitute an alternative and remarkable reservoir of anti-infectious compounds. For instance, pleuromutilins constitute the first class of antibiotics derived from mushrooms. However, macromycetes still represent a largely unexplored source. Publications reporting the antibacterial potential of mushroom extracts are emerging, but few purified compounds have been evaluated for their bioactivity on pathogenic bacterial strains. Therefore, the aim of this review is to compile up-to-date data about natural products isolated from fruiting body fungi, which significantly inhibit the growth of ESKAPEE pathogenic bacteria. When available, data regarding modes of action and cytotoxicity, mandatory when considering a possible drug development, have been discussed in order to highlight the most promising compounds.

In our search for natural compounds that stimulate glucagon-like peptide-1 secretion, an extract from the leaves of Oparanthus teikiteetinii (Asteraceae) was found to increase significantly GLP-1 secretion in vitro in a model cell line (mouse intestinal STC-1 cells). The phytochemical investigation of this extract resulted in the isolation of two new dihydrobenzofuran derivatives (1-2) identified as (2R)-2-(prop-1-en-2-yl)-2,3-dihydro-1-benzofuran-5-ol (1) and (2S,3R)-2-(prop-1-en-2-yl)-2,3-dihydro-1-benzofuran-3,5-diol (2). Thirteen other compounds were isolated, including eight known dihydrobenzofuran derivatives (3-10), jasopyran (11), and four sesquiterpene lactones (12-15) including a new one, grandulin (15). Their structures were established mainly by NMR and HRESIMS analysis and by comparison with data reported in the literature. Tested on STC-1 cells at the concentration of 100 µM, compounds 7, 11, and 12 increased GLP-1 secretion by 305, 218, and 156% respectively, compared to control cells, without affecting cell viability.