From Digestion to Drug Design: Bile Acids Emerge as a Powerful Therapeutic Platform

Bile acids have long been typecast as the digestive system’s humble detergents, molecules churned out by the liver simply to emulsify fats from a meal. A comprehensive new review published in the Journal of Pharmaceutical Investigation argues that this view is dramatically out of date. Synthesized from cholesterol in hepatocytes, bile acids now sit at the crossroads of lipid metabolism, glucose homeostasis, energy balance, immune regulation, and intestinal barrier integrity. Because of their amphiphilic character and their rigid, steroidal molecular scaffold, the authors describe them as among the most pharmacologically actionable platforms in modern drug discovery, a claim supported by a rapidly growing catalogue of semisynthetic derivatives, receptor agonists, and bile acid-inspired biomaterials now moving through laboratories and clinics worldwide.

The review, led by Minho Seo and Jae-Hyeon Lee of Konkuk University together with colleagues under the supervision of Jooho Park, traces the mechanistic foundations that make bile acids such versatile drugs. Their biological effects are mediated largely through a set of dedicated receptors: the nuclear farnesoid X receptor, or FXR, which acts as a master homeostat for hepatic nutrient metabolism, and the cell-surface G-protein-coupled receptor TGR5, also known as GPBAR1, which links bile acid sensing to energy expenditure and immune tone. Activation of TGR5 in enteroendocrine cells promotes glucagon-like peptide-1 secretion, a pathway of intense interest for diabetes and obesity, while FXR signaling suppresses bile acid synthesis and orchestrates the enterohepatic feedback loop that keeps the bile acid pool in check. Additional receptors, including the pregnane X receptor, the constitutive androstane receptor, the vitamin D receptor, and the sphingosine-1-phosphate receptor 2, broaden the signaling repertoire considerably.

Structural biology has sharpened these targets considerably in recent years. High-resolution structures of the bile acid transporter NTCP, which doubles as the receptor for hepatitis B and D viruses, and of the apical sodium-dependent bile acid transporter, ASBT, have revealed the molecular details of how bile acids are shuttled across membranes. Crystallographic snapshots of GPBAR activation have likewise clarified how subtle differences in the steroidal scaffold translate into receptor selectivity. This structural knowledge underpins the design of transporter-targeted delivery systems, in which bile acid motifs are grafted onto drugs to hijack the body’s own recycling machinery, allowing orally administered molecules, including large peptides, to cross the intestinal epithelium through transporter-mediated endocytosis.

The clinical track record of bile acid therapeutics is already substantial. Ursodeoxycholic acid has been a mainstay for cholestatic liver disease for decades, and its semisynthetic relatives, including norursodeoxycholic acid, have shown anticholestatic and anti-inflammatory effects in models of sclerosing cholangitis and fatty liver disease. Obeticholic acid, a potent semisynthetic FXR agonist derived from chenodeoxycholic acid, demonstrated significant improvements in patients with primary biliary cholangitis in a placebo-controlled trial and has been evaluated extensively in non-alcoholic steatohepatitis, now termed metabolic dysfunction-associated steatohepatitis, or MASH. Phase 2 and phase 3 studies of obeticholic acid in fibrotic NASH showed reductions in hepatic injury markers, even as the community continues to weigh long-term safety and lipid effects.

Alongside these steroidal agonists, a wave of non-bile acid FXR modulators has entered the clinic. Tropifexor, a highly potent non-bile acid agonist, was well tolerated in healthy volunteers and abrogated steatohepatitis and fibrosis in rodent models through an antioxidative gene expression profile. EDP-305, another non-bile acid agonist, potently suppressed liver injury and fibrosis in preclinical studies and advanced into a phase 2 dose-ranging trial in NASH patients, while MET409, a structurally optimized FXR agonist, reduced liver fat content over twelve weeks in patients. Dual agonists such as INT-767, which activates both FXR and TGR5, and BAR502, which promotes browning of white adipose tissue while reversing liver steatosis and fibrosis, illustrate the trend toward multi-receptor engagement. The review emphasizes that improving receptor selectivity and tissue specificity remains the central medicinal chemistry challenge in this field.

Cholestatic disease has also been transformed by a different class of bile acid-directed drugs: the ileal bile acid transporter inhibitors. By blocking ASBT-mediated reabsorption in the terminal ileum, agents such as odevixibat, maralixibat, and linerixibat increase fecal bile acid excretion and reduce the toxic pool circulating in cholestatic liver. Odevixibat has shown benefit in phase 3 trials of progressive familial intrahepatic cholestasis and received regulatory approval for associated pruritus, while maralixibat demonstrated efficacy in Alagille syndrome and in a multicenter phase 3 trial of progressive familial intrahepatic cholestasis. Norursodeoxycholic acid improved cholestasis in primary sclerosing cholangitis, and recent work characterizing the carrier cross-reactivity profiles of these inhibitors is helping clinicians match the right molecule to the right patient population.

Perhaps the most visually striking frontier described in the review is the use of bile acids as building blocks for drug delivery. Their facial amphiphilicity, one hydrophobic face and one hydrophilic face on the same rigid steroid, makes them superb self-assembling units. Researchers have exploited this to create drug conjugates, polymeric carriers, peptide-based platforms, and nanostructured delivery systems. Cholic acid-conjugated oxaliplatin has been developed as a liver-targeted prodrug, glycocholic acid-modified micelles have enabled oral delivery of gemcitabine, and ursodeoxycholic acid-based molecular blocks respond to the acidic tumor microenvironment. Catechol-modified bile acid conjugates have been engineered into pH-responsive nanoparticles that exploit ASBT for intestinal uptake, and charge-based supramolecular peptide nanocomplexes have been designed for oral delivery via transporter-driven endocytosis, a strategy relevant to biologics such as semaglutide and liraglutide.

Bile acid chemistry is even reaching into oncology and immunotherapy. Ursodeoxycholic acid platinum(IV) conjugates have been reported as antiproliferative and antimetastatic agents that remodel the tumor microenvironment by suppressing JAK2/STAT3 signaling. Self-assembled nanocrystals combining obeticholic acid with atorvastatin accumulate in the liver and potentiate treatment of metabolic-associated fatty liver disease. Bile acid-containing lipid nanoparticles have been shown to enhance extrahepatic mRNA delivery, an intriguing twist for the mRNA medicine field, while facially amphiphilic bile acid-functionalized antimicrobials combat pathogenic bacteria, fungi, and their biofilms. Bone tissue engineering based on bile acid scaffolds rounds out a materials portfolio that extends far beyond the gut and liver.

The review also situates bile acids within the ecology of the gut microbiome, an area that has exploded in the past decade. Microbial enzymes, including bile salt hydrolases that catalyze the formation of amine-conjugated bile acids, dramatically expand the chemical diversity of the bile acid pool, and microbiome-driven dehydroxylation pathways generate species with distinct receptor activities. Because microbial bile acid modulation shapes host metabolism, immunity, and digestive health, the authors note that future therapeutics may need to be designed with the microbiome in mind, either by resisting microbial transformation or by deliberately harnessing it. This systems-level perspective reinforces the idea that bile acids function less like simple detergents and more like a distributed endocrine signaling network.

Looking ahead, the authors argue that continued innovation in receptor-selective derivatives and transporter-targeted delivery systems should accelerate clinical translation, particularly for hepatobiliary, metabolic, and oncological diseases. The outstanding barriers are familiar ones: oral bioavailability for large conjugates, tissue-specific targeting that avoids off-target receptor activation, and long-term clinical safety, especially for chronic metabolic indications. With the structural biology of transporters and receptors now largely solved, and with biomaterial engineering supplying an expanding toolbox of conjugates and nanocarriers, the field appears positioned to convert a century-old physiological curiosity into a next-generation therapeutic platform, one rigid steroidal scaffold at a time.

Subject of Research: Bile acid-based therapeutics, including semisynthetic derivatives, receptor agonists, and bile acid-inspired drug delivery systems

Article Title: Bile acid-based therapeutics: recent advances in bile acid conjugates and derivatives

Article References: Seo, M., Lee, J.-H., Yang, S.-B., Ma, G., Lee, H., Han, J., Ryu, Y., & Park, J. (2026). Bile acid-based therapeutics: recent advances in bile acid conjugates and derivatives. Journal of Pharmaceutical Investigation. https://doi.org/10.1007/s40005-026-00830-5

Image Credits: AI Generated

DOI: 10.1007/s40005-026-00830-5

Keywords: bile acids, FXR agonists, TGR5, bile acid transporters, obeticholic acid, cholestasis, MASH, drug delivery, nanoparticles, gut microbiome, drug conjugates, pharmaceutical research