Utility of Glycocholic acid

Introduction

Glycocholic acid (GCA;Figure 1) is a steroid acid and one of the main glycine-conjugated bile components in mammalian bile, which is involved in the emulsification and absorption of fats and sterols. It is long-known that the amphipathic nature of bile acids enables them to interact with the lipid membrane of Gram-positive bacteria and act as potent antimicrobial compounds. Nevertheless, Gram-negative Enterobacteriaceae species inhabiting the intestinal tract of mammals are considered to be more bile-resistant compared to Gram-positive bacteria and are thought to tolerate high bile concentrations.[1]

The Effect of glycocholic acid on the Enterobacteriaceae

This study show that 1-2% of glycocholic acid inhibit the growth of Enterobacteriaceae species, including E. coli, Salmonella enterica. Klebsiella spp., Citrobacter spp., and Raoultella spp. during their late logarithmic phase in liquid culture, but not in solid media. Despite their lipopolysaccharide membrane layer, researchers demonstrate that, in liquid, glycocholic acid increases permeability, changes the surface of the Enterobacteriaceae membrane, and compromises its integrity. These changes result in leakage of cytoplasmic proteins and enhancement of their susceptibility to antibiotics. Moreover, glycocholic acid significantly reduces bacterial motility, the frequency of bacterial conjugation and horizontal acquisition of antibiotic resistance genes. These phenotypes are associated with repression of flagellin (fliC) transcription and a sharp decrease in the occurrence of conjugative pili in the presence of glycocholic acid, respectively. Researchers show that the presence of the bile component glycocholic acid has a pleiotropic effect on the physiology of Enterobacteriaceae family members that are traditionally considered as relatively bileresistant. Researchers demonstrated that the growth of these bacteria is inhibited in liquid, but not in solid media, and that their membrane permeability and susceptibility to antibiotics are notably increasing in the presence of 2% GCA. Moreover, bacterial motility,conjugation frequency, and the occurrence of conjugative pili dramatically decreased following exposure to glycocholic acid. These results  highlight the potential use of GCA as an antimicrobial agent that can fulfill a multidimensional purpose of limiting bacterial growth,preventing the conjugation and dissemination of antibiotic resistance genes, and increasing the antibiotic sensitivity of resistant bacteria. Further structural optimization and SRA studies may increase the effectiveness of this compound be used either alone or in combination with standard antibiotic therapy against resistant infections.

Overall, these findings broaden the current understanding about bile resistance of Gram-negative bacteria and suggest that glycocholic acid can be used to inhibit bacterial growth, augment the activity of antimicrobial compounds and diminish acquisition and dissemination of antibiotic resistance genes by conjugation.[1]

Glycocholic acid as a novel selective and sensitive biomarker for hepatocellular carcinoma

Glycocholic acid has been identified as a novel selective and sensitive biomarker for hepatocellular carcinoma (HCC). In this work, a recombinant antibody, scFv-G11, which was shown previously to have selective reactivity for glycocholic acid, was labeled with biotin using a chemical and an enzymatic method, respectively. The enzymatic method proved superior giving sensitive scFv-biotin preparations. Based on biotinylated scFv against glycocholic acid and a biotin-streptavidin system for signal amplification, an indirect competitive biotin-streptavidin-amplified enzyme-linked immunosorbent assay (BA-ELISA) has been established for the sensitive and rapid detection of  glycocholic acid. Several physiochemical factors that influenced assay performance, such as organic cosolvent, ionic strength, and pH, were studied. Under the optimized conditions, the indirect competitive BA-ELISA based on the obtained biotinylated scFv antibodies indicated that the average concentration required for 50% inhibition of binding (IC50) and the limit of detection (LOD) for glycocholic acid were 0.42 μg mL-1 and 0.07 μg mL-1, respectively, and the linear response range extended from 0.14 to 1.24 μg mL-1. Cross-reactivity of biotinylated scFv antibodies with various bile acid analogues was below 1.89%, except for taurocholic acid. The recoveries of GCA from urine samples via this indirect competitive BA-ELISA ranged from 108.3% to 131.5%, and correlated well with liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS), which indicated the accuracy and reliability of biotinylated scFv-based ELISA in the detection of glycocholic acid in urine samples. This study also demonstrates the broad utility of scFv for the development of highly sensitive immunoassays.[2]

Glycocholic acid in chronic active hepatitis and mild liver diseases

Glycocholic acid was found to be an useful marker in noncirrhotic liver diseases. Patients with more severe liver disease,i.e.,CAH,showed significantly higher glycocholic acid levels and a higher percentage of increased values than those with MLD and controls. On the other hand, MD patients did not show significant differences versus controls in either glycocholic acid serum levels or percentage of abnormal values. These results support those of other authors [6, 10] whohave also found higher GCA levels in severe liver disease as compared with MLD.

Serum levels of fasting glycocholic acid were measured in various noncirrhotic liver diseases. Forty-five patients were evaluated, 15 with chronic active hepatitis and 30 with mild liver diseases including chronic persistent hepatitis, steatosis, and minimal changes. There were increased levels of glycocholic acid in 53.3% of chronic active hepatitis cases and in 10% of mile liver disease cases (P = 0.003), and the levels reached by patients with chronic active hepatitis were higher than those in patients with mild liver disease (P < 0.0001). The latter did not show significant differences in their serum levels or in the percentage of abnormal results with respect to control group. There were weak, although significant, correlations between glycocholic acid and transaminases, alkaline phosphatase, gamma-glutamyltranspeptidase, albumin, and gammaglobulin. In the present study, the specificity of glycocholic acid was high in the detection of chronic active hepatitis patients at different cut-off levels. Glycocholic acid appeared to reflect histological severity in this group of noncirrhotic liver diseases and might have practical applications in the management of these patients.[3]

References

[1]Piscon B, Fichtman B, Harel A, Adler A, Rahav G, Gal-Mor O. The Effect of glycocholic acid on the growth, membrane permeability, conjugation and antibiotic susceptibility of Enterobacteriaceae. Front Cell Infect Microbiol. 2025;15:1550545. Published 2025 Mar 20. doi:10.3389/fcimb.2025.1550545

[2]Cui X , Vasylieva N , Shen D , et al. Biotinylated single-chain variable fragment-based enzyme-linked immunosorbent assay for glycocholic acid. Analyst. 2018;143(9):2057-2065. doi:10.1039/c7an02024d

[3]Collazos J. Glycocholic acid in chronic active hepatitis and mild liver diseases. Clin Investig. 1993;72(1):36-39. doi:10.1007/BF00231114

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