Antiviral and virucidal activities against SARS-CoV-2 and antibacterial properties of bile acids and their salts with naturally occurring organic cations of l-carnitine, creatinine, and choline

Abstract

Bile acids have many roles in biological systems, and they have received great attention recently. Bile from a cow, known as gall, together with garlic, wine, and leeks, is used in the traditional medicine recipe of Bald's Leechbook, a thousand-year-old Anglo-Saxon formula for the treatment of infected eyelash follicles. Different aspects of previous works on bile acids have been reported, and this work adds antiviral, virucidal, and antibacterial properties of bile acids and their salts against SARS-CoV-2. Four bile acids, lithocholic acid (LCA, 1), deoxycholic acid (DCA, 5), ursodeoxycholic acid (UDCA, 9), and chenodeoxycholic acid (CDCA, 13), were used to form salts with L-carnitine [X], creatinine [Y], and choline [Z], which are naturally occurring compounds. Bile acids and their salts were evaluated for antiviral and virucidal activities against SARS-CoV-2 as well as for their antibacterial properties. Among the bile acids tested, LCA (1) was found to display virucidal activity against SARS-CoV-2 with an EC₅₀ of 9.69 µg mL⁻¹ and a selectivity index (SI) of >5.16. However, its salts, [LCA][X] (2), [LCA][Y] (3), and [LCA][Z] (4), were 1.31–3.27 times less active than the bile acid LCA (1), indicating that salt forms of this bile acid did not have improved virucidal activity. Bile acids DCA (5), UDCA (9), and CDCA (13) exhibited antibacterial activity against Gram-positive bacteria (Bacillus cereus, Staphylococcus aureus, Staphylococcus epidermidis, and Enterococcus faecalis) and against a Gram-negative bacterium (Escherichia coli). Cholinium salts of these bile acids exhibited enhanced antibacterial activity; for example, 41.4–41.5% antibacterial improvement was observed for the [DCA][Z] (8) salt when compared with its corresponding bile acid DCA (5). This work provides evidence that certain salts of bile acids have improved antibacterial activity, but they do not enhance antiviral properties.