Synthesis of bile acid derivatives and in vitro cytotoxic activity with pro-apoptotic process on multiple myeloma (KMS-11), glioblastoma multiforme (GBM), and colonic carcinoma (HCT-116) human cell lines

Synthesis and Biological Evaluation of Bile Acid-Triclosan Conjugates: A Study on Antibacterial, Antibiofilm, and Molecular Docking

This work describes the synthesis, characterization, and antibacterial properties of four bile acid-triclosan conjugates. The in vitro antibacterial activity of synthetic bile acid-triclosan conjugates was investigated against a panel of Gram-positive and Gram-negative bacteria. Conjugates 3 and 4 show high activity against Escherichia coli (ATCC25922), with IC50 values of 2.94 ± 0.7 and 1.51 ± 0.05 μM, respectively. Conjugate 4 demonstrated 9 times the activity of triclosan (6.77 μM) and 18 times the potency of kanamycin, a well-known antibiotic. Compound 3 showed higher potential activity against all evaluated strains, including Bacillus megaterium (IC50: 3.05 ± 0.02), Bacillus amyloquefaciens (IC50: 8.79 ± 0.01), Serratia marcescens (IC50: 6.77 ± 0.4), and E. coli (IC50: 1.51 ± 0.05 μM). These findings indicate that it has broad-spectrum antibacterial activity. Bile acid-triclosan conjugates prevent biofilms by up to 99% at low doses (conjugates 4; 4.16 ± 0.8 μM), compared to triclosan. Conjugate 5 was most potent against B. amyloquefaciens (IC50 = 5.23 ± 0.2 μM), while conjugate 4 was most effective against B. megaterium (IC50 = 4.16 ± 0.8 μM) in biofilm formation. These conjugates inhibit biofilm formation by limiting the extracellular polymeric substance generation. The in vitro antibacterial study revealed that bile acid-triclosan conjugates were more effective than the parent molecule triclosan at inhibiting bacterial growth and biofilm formation against both Gram-positive and Gram-negative bacteria.

Secosteroid diacylhydrazines as novel effective agents against hormone-dependent breast cancer cells

This research aimed to develop novel selective secosteroids that are highly active against hormone-dependent breast cancer. A simple and convenient approach to N'-acylated 13,17-secoestra-1,3,5(10)-trien-17-oic acid hydrazides was disclosed and these novel types of secosteroids were screened for cytotoxicity against the hormone-dependent human breast cancer cell line MCF7. Most secosteroid N'-benzoyl hydrazides have demonstrated high cytotoxicity against MCF7 cells with IC50 values below 5 μM, which are superior to that of the reference drug cisplatin. Hit compounds 2c, 2e and 2i were characterized by high cytotoxicity (IC50 = 1.6-1.9 μM) and very good selectivity towards MCF7 breast cancer cells. The lead secosteroids 2c, 2e and 2i also exhibit antiestrogenic effects and alter the expression of cell cycle regulating proteins. The effect of selected compounds on PARP (poly(ADP-ribose) polymerase) and Bcl-2 (B-cell CLL/lymphoma 2) indicates their proapoptotic potential. The synthesized secosteroids may be considered as new promising anti-breast cancer agents targeting ERα and apoptosis pathways.

The anticancer activity of bile acids in drug discovery and development

Bile acids (BAs) constitute essential components of cholesterol metabolites that are synthesized in the liver, stored in the gallbladder, and excreted into the intestine through the biliary system. They play a crucial role in nutrient absorption, lipid and glucose regulation, and the maintenance of metabolic homeostasis. In additional, BAs have demonstrated the ability to attenuate disease progression such as diabetes, metabolic disorders, heart disease, and respiratory ailments. Intriguingly, recent research has offered exciting evidence to unveil their potential antitumor properties against various cancer cell types including tamoxifen-resistant breast cancer, oral squamous cell carcinoma, cholangiocarcinoma, gastric cancer, colon cancer, hepatocellular carcinoma, prostate cancer, gallbladder cancer, neuroblastoma, and others. Up to date, multiple laboratories have synthesized novel BA derivatives to develop potential drug candidates. These derivatives have exhibited the capacity to induce cell death in individual cancer cell types and display promising anti-tumor activities. This review extensively elucidates the anticancer activity of natural BAs and synthetic derivatives in cancer cells, their associated signaling pathways, and therapeutic strategies. Understanding of BAs and their derivatives activities and action mechanisms will evidently assist anticancer drug discovery and devise novel treatment.

Synthesis and in silico study of chenodeoxycholic acid and its analogues as an alternative inhibitor of spike glycoprotein of SARS-CoV-2

COVID-19, caused by SARS-CoV-2, is a viral infection that has generated one of the most significant health problems in the world. Spike glycoprotein is a crucial enzyme in viral replication and transcription mediation. There are reports in the literature on using bile acid in the fight against this virus through in vitro tests. This work presents the synthesis of nine chenodeoxycholic acid derivatives (1-9), which were prepared by oxidation, acetylation, formylation, and esterification reactions, and the analogs 6-9 have not yet been reported in the literature and the possibility of conducting an in silico study of bile acid derivatives as a therapeutic alternative to combat the virus using glycoprotein as a macromolecular target. As a result, five compounds (1, 6-9) possessed favorable competitive interactions with the lowest energies compared to the native ligand (BLA), and the highlighted compound 9 got the best scores. At the same time, analog 1 presented the best ADME filter result. Molecular dynamics also simulated these compounds to verify their stability within the active protein site to seek new therapeutic propositions to fight against the pandemic. Physical and spectroscopic data have fully characterized all the compounds.Communicated by Ramaswamy H. Sarma.

Synthesis of bile acid-thiadiazole conjugates as antibacterial and antioxidant agents

The synthesis, characterization, and antibacterial and antioxidant activity of thiadiazole-deoxycholic/lithocholic acid conjugates are described in this communication. The structures of the synthesised bile acid-thiadiazole conjugates were studied using 1H NMR, 13C NMR and FTIR. Compounds 4c (IC50; 15.34 ± 0.07 μM) and 5c (IC50; 13.45 ± 0.25 μM) demonstrated greater antioxidant activity than the reference compound ascorbic acid (IC50; 20.72 ± 1.02 μM) in DPPH assay. The most effective conjugates against P. vulgarise were 4c (IC50; 24 ± 2.3 μM), 4 g (IC50; 29 ± 2.5 μM), and 5c (IC50; 93 ± 3.6 μM), whereas the most effective conjugates against E. coli were 4e (IC50; 55 ± 2.1 μM) and 4f (IC50; 52 ± 3.5 μM). Conjugates 4c and 5c were the most effective against B. megaterium of all the synthesised conjugates, with IC50 values of 15 ± 1.08 and 20 ± 1.1 μM, respectively. Thus, a large library of compounds derived from bile acid can be easily synthesised for extensive structure-activity relationship studies in order to identify the most appropriate antibacterial agents and antioxidant activity.

Converting bile acids into mitocans

Cholic acid (1, CD), deoxycholic (3, DCA), chenodeoxycholic acid (5, CDCA), ursodeoxycholic acid (7, UDCA), and lithocholic acid (9, LCA) were acetylated and converted into their piperazinyl spacered rhodamine B conjugates 16-20. While the parent bile acids showed almost no cytotoxic effects for several human tumor cell lines, the piperazinyl amides were cytostatic but an even superior effect was observed for the rhodamine B conjugates. Extra staining experiments showed these compounds as mitocans; they led to a cell arrest in the G1 phase.

Design and synthesis of bile acid derivatives and their activity against colon cancer

Bile acids (BAs) containing both hydrophilic hydroxyl and carboxyl groups and hydrophobic methyl and steroid nuclei can promote the absorption of fat and other substances in the intestine, and they are synthesized by cholesterol in the liver and then returned to the liver through enteric liver circulation. Because there are many BA receptors on the cell membrane of colon tissues, BAs can improve the specific delivery and transport of medicines to colon tissues. Moreover, BAs have a certain anticancer and inflammation activity by themselves. Based on this theory, a series of BA derivatives against colon cancer including cholic acid (CA), chenodeoxycholic acid (CDCA), ursodeoxycholic acid (UDCA) and lithocholic acid (LCA) were designed and synthesized, and their antitumor activity was evaluated. For in vitro anti-tumor tests, all the compounds displayed cell proliferative inhibition to nine human malignant tumor cell lines to some degree, and in particular they showed stronger inhibition to the colon cancer cells than the other cell lines. Among them, four compounds (4, 5, 6, and 7) showed stronger activity than the other compounds as well as the positive control 5-FU against HCT116 cells, and their IC50 was between 21.32 μmol L-1 and 28.90 μmol L-1; cell clone formation and migration tests showed that they not only effectively inhibited the formation of HCT116 cell colonies, but also inhibited the HCT116 cell migration and invasion; moreover, they induced apoptosis, arrested the mitotic process at the G2/M phase of the cell cycle, reduced the mitochondrial membrane potential, increased the intracellular ROS levels, and reduced the expression of Bcl-2 and p-STAT3 in HCT 116 cells. In addition, they also displayed intermediate anti-inflammatory activity by inhibiting inflammatory mediators NO and downregulating TNF-α expression, which also is one of the causes of colon cancer. This suggests that they deserve to be further investigated as candidates for colon cancer treatment drugs.

Bile Acids: Physiological Activity and Perspectives of Using in Clinical and Laboratory Diagnostics

Bile acids play a significant role in the digestion of nutrients. In addition, bile acids perform a signaling function through their blood-circulating fraction. They regulate the activity of nuclear and membrane receptors, located in many tissues. The gut microbiota is an important factor influencing the effects of bile acids via enzymatic modification. Depending on the rate of healthy and pathogenic microbiota, a number of bile acids may support lipid and glucose homeostasis as well as shift to more toxic compounds participating in many pathological conditions. Thus, bile acids can be possible biomarkers of human pathology. However, the chemical structure of bile acids is similar and their analysis requires sensitive and specific methods of analysis. In this review, we provide information on the chemical structure and the biosynthesis of bile acids, their regulation, and their physiological role. In addition, the review describes the involvement of bile acids in various diseases of the digestive system, the approaches and challenges in the analysis of bile acids, and the prospects of their use in omics technologies.

Design, synthesis, characterization and anticancer activity evaluation of deoxycholic acid-chalcone conjugates

A series of deoxycholic acid-chalcone amides were synthesised and tested against the human lung cancer cell line, A549 and the cervical cancer cell line, SiHa. Among the synthesised deoxycholic acid-chalcone conjugates, some conjugates showed encouraging results as anticancer agents with good in vitro activity. More precisely, deoxycholic acid-chalcone conjugates 4b (IC50: 0.51 μM) and 4e (IC50: 0.84 μM) having 2‑nitrophenyl and 3,4,5‑trimethoxyphenyl groups exhibited a good activity against human cancer cell-line SiHa and while 4d (IC50: 0.25 μM) and 4b (IC50: 1.71 μM) showed better activity against A549 lung cancer cell line with respect to deoxycholic acid and chalcones. The anticancer activity of the bile acid conjugated chalcones was more than the activity of chalcone and deoxycholic acid alone. The results indicate that a bile acid conjugate strategy may be beneficial in improving the biological activity of chalcone derivatives. The enhanced activity of certain compounds may be due to their increased bioavailability.

Mechanism of Bile Acid-Induced Programmed Cell Death and Drug Discovery against Cancer: A Review

Bile acids are major signaling molecules that play a significant role as emulsifiers in the digestion and absorption of dietary lipids. Bile acids are amphiphilic molecules produced by the reaction of enzymes with cholesterol as a substrate, and they are the primary metabolites of cholesterol in the body. Bile acids were initially considered as tumor promoters, but many studies have deemed them to be tumor suppressors. The tumor-suppressive effect of bile acids is associated with programmed cell death. Moreover, based on this fact, several synthetic bile acid derivatives have also been used to induce programmed cell death in several types of human cancers. This review comprehensively summarizes the literature related to bile acid-induced programmed cell death, such as apoptosis, autophagy, and necroptosis, and the status of drug development using synthetic bile acid derivatives against human cancers. We hope that this review will provide a reference for the future research and development of drugs against cancer.

Synthesis of dihydrofuran-3-one and 9,10-phenanthrenequinone hybrid molecules and biological evaluation against colon cancer cells as selective Akt kinase inhibitors

A series of dihydrofuran-3-one and 9,10-phenanthrenequinone hybrid compounds were synthetized through a one-pot gold-catalyzed oxidative cyclization and Aldol-type addition cascade reaction of homopropargylic alcohols with 9,10-phenanthrenequinone. The cytotoxicity of newly synthesized compounds was evaluated in CCK8 assay against different human cancer cells, showing significantly antiproliferative activity against tested tumor cell lines with a lowest IC₅₀ value of 0.92 μM over HCT-116. Further investigation revealed that the treatment of HCT-116 cell line with the promising compound 4c induced cell death as a selective Akt inhibitor. In addition, controlled experiments and molecular docking study suggested that the significant antitumor activity might be attributed to the unique hybrid structure, which implied the promising potential of this dual heterocycle hybrid method in the discovery of novel bioactive molecules with structural diversity.

Bile acid-based receptors and their applications in recognition

Ion recognition has attracted great attention in the past decades because of its important role in biology, medicine, environment, and chemistry. The combination of rigidity, curved structure and amphiphilic nature makes bile acids a host system for ion recognition. In addition, the availability of hydroxyl groups in bile acids can be used for further derivatization to develop various ion recognition receptors. The detection of ions is revealed by the binding constant k_a value, log approach, and UV-visible or ¹H NMR titration, while visual detection is determined by gel-phase transition, colorimetric and fluorescent probes. In this review, we have discussed the bile acid-based receptors and their ion-recognition capability. These bile acid-based systems have the potential for the development of anion transport for biological activity.

Synthesis and Anti-Hepatoma Activities of U12 Derivatives Arresting G0/G1 Phase and Inducing Apoptosis by PI3K/AKT/mTOR Pathway

Ursodeoxycholic acid (UDCA) is a first-line clinical drug for the treatment of liver diseases. U12, a derivative of UDCA, showed effective anti-hepatoma activities in previous works. However, the low polarity and large doses limited the druglikeness of U12. In this study, the structural modification and optimization of U12 were further investigated and twelve U12 derivatives were synthesized by substitution, esterification and amidation reactions. The evaluation of the cytotoxicity of synthetic derivatives against hepatoma cell lines (HepG2) indicated that U12-I, U12a-d and U12h showed more effective cytotoxic effects on the growth of HepG2 cells than U12, and the preliminary structure–activity relationship was discussed. Among them, U12a exhibited the most potent anti-hepatocellular carcinoma activity. Mechanism studies indicated that U12a inhibited HepG2 cell proliferation by arresting the G0/G1 phase, and suppressed the activation of the PI3K/AKT/mTOR pathway. Further studies showed that U12a induced HepG2 cells apoptosis through activating the caspase signaling pathway. Furthermore, U12a evidently inhibits the growth of HepG2-derived tumor xenografts in vivo without observable adverse effects. Thus, U12a might be considered as a promising candidate for the treatment of hepatocellular carcinoma.

Piperazine skeleton in the structural modification of natural products: a review

Piperazine moiety is a cyclic molecule containing two nitrogen atoms in positions 1 and 4, as well as four carbon atoms. Piperazine is one of the most sought heterocyclics for the development of new drug candidates with a wide range of applications. Over 100 molecules with a broad range of bioactivities, including antitumor, antibacterial, anti-inflammatory, antioxidant, and other activities, were reviewed. This article reviewed investigations regarding piperazine groups for the modification of natural product derivatives in the last decade, highlighting parameters that affect their biological activity.

Physiology and Physical Chemistry of Bile Acids

Bile acids (BAs) are facial amphiphiles synthesized in the body of all vertebrates. They undergo the enterohepatic circulation: they are produced in the liver, stored in the gallbladder, released in the intestine, taken into the bloodstream and lastly re-absorbed in the liver. During this pathway, BAs are modified in their molecular structure by the action of enzymes and bacteria. Such transformations allow them to acquire the chemical-physical properties needed for fulling several activities including metabolic regulation, antimicrobial functions and solubilization of lipids in digestion. The versatility of BAs in the physiological functions has inspired their use in many bio-applications, making them important tools for active molecule delivery, metabolic disease treatments and emulsification processes in food and drug industries. Moreover, moving over the borders of the biological field, BAs have been largely investigated as building blocks for the construction of supramolecular aggregates having peculiar structural, mechanical, chemical and optical properties. The review starts with a biological analysis of the BAs functions before progressively switching to a general overview of BAs in pharmacology and medicine applications. Lastly the focus moves to the BAs use in material science.

Recent advances in the bile acid based conjugates/derivatives towards their gelation applications

Bile acids have contributed immensely to hydrogel research due to their peculiar physicochemical properties and biocompatibility. The wide accessibility of bile acids and their straightforward derivatization methods make them attractive building blocks for the design of novel hydrogels systems to deliver biomolecules, drugs, and vaccines. This review conceptualizes recent developments in bile acid-based hydrogels and their applications. These bile-based hydrogels have the ability to absorb carbon dioxide efficiently and may potentially work as alternative materials for carbon dioxide capture and storage. The hydrogels hold great potential in medicine and biology applications as drug carriers and models for fundamental self-assembly in pathological conditions. Herein, we have summarized the efforts that have been made for the development of molecular hydrogels in terms of biocompatibility, therapeutic applications, and challenges associated with existing molecular hydrogels.

Updates in bile acid-bioactive molecule conjugates and their applications

Bile acid conjugates are emerging as important chemical resources due to their low cost and wide availability of bile acids, making them privileged molecules in drug carrier systems and building blocks for derivatization and chiral template introduction into bioactive molecules. In recent years, bile acids as scaffolds in supramolecular, medicinal, and material chemistry attracted prime focus of researchers as an area of research to be followed with passion. Due to peculiar physicochemical and biological properties, bile acid exhibited various applications in biomedical and pharmaceutical fields. In this review, the bile acid conjugations with different bioactive compounds have been discussed to understand their influence on the bioavailability of bioactive compounds.

Design, Synthesis, and Anti-bacterial Activity of Novel Deoxycholic Acid- Amino Alcohol Conjugates

Background:

Numerous synthetic bile acid derivatives have been recognized for their various biological activities. Among these, bile acid amides have emerged as an attractive antibacterial agent. We herein illustrate the synthesis and antibacterial evaluation of deoxycholic acidamino alcohols conjugates.

Objective:

Design and Synthesis of novel deoxycholic acid-amino alcohol conjugates to investigate their antibacterial activity against E. coli and S. aureus.

Methods:

Novel deoxycholic acid-amino alcohol conjugates were synthesized, from conjugation of deoxycholic acid-NHS ester with amino alcohols. Various amino alcohols moieties were appended to the C24 position of deoxycholic acid to yield deoxycholic acid-amino alcohol conjugates. All the synthesized compounds were characterized by 1H NMR, 13C NMR, IR and massspectroscopy. The entire synthesized deoxycholic acid-amino alcohol conjugates were evaluated for their antibacterial activity against E. coli and S. aureus using the broth dilution method.

Results:

The outcome illustrated that some of the novel deoxycholic acid-amino alcohol conjugates exhibited enhanced anti-bacterial activities. Amongst them, deoxycholic acid-amino alcohol conjugate containing (-R)-2-aminocyclohexanol (1) demonstrated promising efficacy against both strains S. aureus ATCC 25923 (MIC 15 μg/mL) and E. coli ATCC 25922 (MIC 45 μg/mL) and was identified as a lead molecule.

Conclusion:

Numbers of novel deoxycholic acid-amino alcohol conjugates were synthesized and their antimicrobial activities provided useful information that the potency was strongly depending on the structures of deoxycholic acid-amino alcohol conjugates.

Germ Cell-Specific Gene 1-Like Protein Regulated by Splicing Factor CUGBP Elav-Like Family Member 5 and Primary Bile Acid Biosynthesis are Prognostic in Glioblastoma Multiforme

Background

Alternative splicing (AS) modifies 92-94% human genes, abnormal splicing events might relate to tumor development and invasion. Glioblastoma Multiforme (GBM) is a fatal, invasive, and malignant tumor in nervous system. The recurrence and development leads to poor prognosis. However, few studies have focused on AS in GBM.

Methods

RNA-seq and Alternative splicing events (ASEs) data of GBM samples were downloaded from The Cancer Genome Atlas (TCGA) and TCGASpliceSeq databases, respectively. Firstly, the Cox regression analysis was utilized to identify the overall survival splicing events (OS-SEs). Secondly, a multivariable model was applied to access the prognostic value of risk score. Then, we constructed a co-expressed network between splicing factors (SFs) and overall survival alternative splicing events (OS-SEs). Additionally, to explore the relationship between the potential prognostic signaling pathways and OS-SEs, we constructed a network between these pathways and OS-SEs. Ultimately, to better explain the results, validations from multi-dimension platforms were applied.

Results

In the first step, 1,062 OS-SEs were selected by Cox regression. Then, 11 OS-SEs were integrated in a multivariate model by Lasso regression. The area under the curve (AUC) of receiver operator characteristic (ROC) curve was 0.861. In addition, the risk score generated from the multivariate model was confirmed to be an independent prognostic factor (P < 0.001). What's more, in the network of SFs and ASEs, CELF5 significantly regulated GSG1L|35696|AP and GSG1L|35698|AP (P < 0.001, R = 0.511 and = -0.492). Additionally, GSG1L|35696|AP (P = 0.006) and GSG1L|35698|AP (P = 0.007) showed a significant relationship with cancer status. Eventually, KEGG pathways related to prognosis of GBM were selected by GSVA. The primary bile acid synthesis (P < 0.001, R = 0.420) was the significant pathway co-expressed with Germ Cell-Specific Gene 1-Like Protein (GSG1L).

Conclusions

Based on the comprehensive bioinformatics analysis, we proposed that aberrant splicing factor CUGBP Elav-like family member 5 (CELF5) significantly, positively and negatively, regulated ASE of GSG1L, and the primary bile acid synthesis pathway might play an important role in tumorigenesis and prognosis of GBM.

Dihydroartemisinin-Bile Acid Hybridization as an Effective Approach to Enhance Dihydroartemisinin Anticancer Activity

A series of hybrid compounds based on natural products-bile acids and dihydroartemisinin-were prepared by different synthetic methodologies and investigated for their in vitro biological activity against HL-60 leukemia and HepG2 hepatocellular carcinoma cell lines. Most of these hybrids presented significantly improved antiproliferative activities with respect to dihydroartemisinin and the parent bile acid. The two most potent hybrids of the series exhibited a 10.5- and 15.4-fold increase in cytotoxic activity respect to dihydroartemisinin alone in HL-60 and HepG2 cells, respectively. Strong evidence that an ursodeoxycholic acid hybrid induced apoptosis was obtained by flow cytometric analysis and western blot analysis.

Bile acids: Lipase-catalyzed synthesis of new hyodeoxycholic acid derivatives

In this work we present an efficient, environmentally friendly approach to the synthesis of a series of hyodeoxycholic acid derivatives applying Biocatalysis. Fifteen acetyl and ester derivatives, twelve of them new, were obtained through an enzymatic strategy in a fully regioselective way and in very good to excellent yield. In order to find the optimal reaction conditions, the influence of several parameters such as enzyme source, alcohol or acylating agent:substrate ratio, enzyme:substrate ratio, temperature and reaction solvent was considered. The excellent results obtained made this procedure very efficient, particularly considering the low amount of enzyme required. In addition, this methodology uses mild reaction conditions and has reduced environmental impact, making biocatalysis a suitable way to obtaining these bile acids derivatives.

Lipase-Catalyzed Acetylation and Esterification of Bile Acids

In this chapter we describe the application of lipases as catalysts in reactions on a relevant family of steroids: the bile acids. Twenty three monoacetyl, diacetyl, and ester derivatives of deoxycholic, chenodeoxycholic, lithocholic, and cholic acids, 15 of them new compounds, were obtained through lipase-catalyzed acetylation, esterification, and alcoholysis reactions in very good to excellent yield and a highly regioselective way. Among them, acetylated ester products, in which the lipase catalyzed both reactions in one pot, were obtained. The influence of various reaction parameters in the enzymatic reactions, such as enzyme source, nucleophile/substrate ratio, enzyme/substrate ratio, solvent, and temperature, was studied. Some of the reported products are novel, and it is not possible to obtain them satisfactorily by following traditional synthetic procedures. Due to its singular structure containing three hydroxyl groups, cholic acid showed a different behavior in the enzymatic reactions, from that observed for the other three bile acids studied. In order to shed light to different behaviors of bile acids in the enzymatic reactions, molecular modeling was applied to substrates and some derivatives.

New cholic acid analogs: synthesis and 17β-hydroxydehydrogenase (17β-HSD) inhibition activity

The 17β-hydroxysteroid dehydrogenase (17β-HSD) enzyme family is involved in the biosynthesis of active steroids and its inhibition constitutes an interesting approach for treating estrogen-, androgen-dependent cancers and osteoporosis. In this study, a new series of cholic acid analogs was designed with the goal of improving the biological activity as 17β-HSD1 and 17β-HSD2 inhibitors. To this end, 23-cholyl amides 4–7, 3-O-p-toluenesulfonyl-23-cholyl amides 10–12, 23-cholyl-carbohydrazide 14, carbothioamide analog 15, and 23-cholyl-acylhydrazone derivatives 18–22 were synthesized from cholic acid (3) via coupling, sulfonation and substitution reactions. Basic treatment of keto group of 5 with p-bromoaniline afforded 8, meanwhile acidic treatment of 3 with thiosemicarbazide furnished the 23-cholyl-thiadiazole derivative 16. The synthesized compounds were evaluated for their inhibition activity against 17β-HSD1 and 17β-HSD2, and were found inactive at 1.0 μm concentration (inhibition <10%). However, the steroids 12, 21 and 22 showed inhibition of 21.1, 23.9 and 21.3%, respectively, against 17β-HSD2 at the same concentration. Therefore, these steroidal analogs can be further structurally modified to optimize their inhibition activity against 17β-HSD2 for the development of potential therapeutics.

Synthesis and evaluation of antitumor, anti-inflammatory and analgesic activity of novel deoxycholic acid derivatives bearing aryl- or hetarylsulfanyl moieties at the C-3 position

Novel deoxycholic acid (DCA) derivatives were stereoselectively synthesised with -OH and -CH₂SR moieties at the C-3 position, where R was a substituted aryl [2-aminophenyl (8) or 4-chlorophenyl (9)] or hetaryl [1-methylimidazolyl (5), 1,2,4-triazolyl (6), 5-amino-1,3,4-thiadiazolyl (7), pyridinyl (10) or pyrimidinyl (11)]. These compounds were prepared in good yields from the C-3β-epoxy derivative 2 in the epoxide ring-opening reaction by S-nucleophiles. These derivatives were evaluated for their in vitro anti-proliferation activity in a panel of tumor cell lines. Data showed that: (i) heterocycle-containing derivatives displayed higher cytotoxicity profiles than the parent molecule; (ii) heterocyclic substituents were more preferable than aryl moieties for enhancing anti-proliferation activity; (iii) the sensitivity of tumor cell lines to analysed compounds decreased in the following order: HuTu-80 (duodenal carcinoma)>KB-3-1 (cervical carcinoma)>HepG2 (hepatocellular carcinoma)>MH-22a (hepatoma); (iv) compounds 5, 6 and 11 exhibited a high cytotoxic selectivity index (HuTu-80: SI>7.7, 38.5 and 12.0, respectively). Compounds 2 and 6-8 markedly inhibited NO synthesis by interferon γ-induced macrophages. Screening for anti-inflammatory activity of these derivatives in vivo showed their high potency on histamine- (5, 10) and formalin- (2, 10, 11) induced paw edema models.

Haemolytic activity of formyl- and acetyl-derivatives of bile acids and their gramine salts

Bile acids (lithocholic: LCA, deoxycholic: DCA and cholic: CA) and their formyl- and acetyl-derivatives can be used as starting material in chemical synthesis of compounds with different biological activity strongly depended on their chemical structures. Our previous studies showed that biological activity of bile acids salts with gramine toward human erythrocytes was significantly different from the activity of bile acids alone. Moreover, gramine effectively modified the membrane perturbing activity of other steroids. As a continuation of our work, the haemolytic activity of formyl- and acetyl-substituet bile acids as well as their gramine salts was studied in vitro. The structures of new compounds were confirmed by spectral (NMR, FT-IR) analysis, mass spectrometry (ESI-MS) as well as PM5 semiempirical methods. The results shown that the haemolytic activity of formyl- and acetyl-LCA and DCA was significantly higher in comparison with their native forms at the whole concentration range. At high concentration, formyl derivative of CA was as effective as LCA and DCA derivatives whereas at lower concentration its haemolytic activity was at the level of original acid. The acetyl-CA was not active as membrane perturbing agents. Furthermore, gramine significantly decreased the membrane-perturbing activity of hydrophobic bile acids derivatives. The results obtained with the cellular system are in line with physicochemical calculation.

Opioid Tripeptides Hybridized with trans-1-Cinnamylpiperazine as Proliferation Inhibitors of Pancreatic Cancer Cells in Two- and Three-Dimensional in vitro Models

According to the World Health Organization, the mortality rate among patients with pancreatic cancer will increase in the upcoming years. Gemcitabine is the first choice for treatment of pancreatic malignancy, but increasing resistance to this drug is decreasing its overall efficacy. Studies on new therapies that target metabolic pathways, growth factor inhibitors, and tumor stroma or tumor stem cells are currently underway in many research groups. Herein we report the bioactive properties (cytotoxicity and hemolytic activity) of synthetic peptidomimetics containing an opioid tripeptide fragment (Tyr-R¹ -R² -; where R¹ is d-Ala or d-Thr, and R² is Phe or Trp) hybridized with trans-1-cinnamylpiperazine. These compounds are stable in plasma up to 96 h and exhibit low hemotoxicity and good inhibitory effects on cancer cell growth in two- and three-dimensional in vitro models of pancreatic cancer.

Design and synthesis of polyhydroxy steroids as selective inhibitors against AKR1B10 and molecular docking

AKR1B10 is a member of the human aldo-keto reductase superfamily which is highly expressed in several types of cancers, and has been regarded as a promising cancer therapeutic target. In this paper, a series of polyhydroxy steroids were designed and synthesized to selectively inhibit AKR1B10 activity. The most selective compound, novel compound 6, has an IC50 of 0.83±0.07μM and a selectivity of more than 120-fold for AKR1B10/AKR1B1. Structure-activity relation analyses indicate that hydroxyl at C-19 can significantly improve the selective inhibition of AKR1B10. The binding mode of AKR1B10 and its inhibitors were studied.

Synthesis, characterization and biological evaluation of bile acid-aromatic/heteroaromatic amides linked via amino acids as anti-cancer agents

A series of bile acid (Cholic acid and Deoxycholic acid) aryl/heteroaryl amides linked via α-amino acid were synthesized and tested against 3 human cancer cell-lines (HT29, MDAMB231, U87MG) and 1 human normal cell line (HEK293T). Some of the conjugates showed promising results to be new anticancer agents with good in vitro results. More specifically, Cholic acid derivatives 6a (1.35 μM), 6c (1.41 μM) and 6m (4.52 μM) possessing phenyl, benzothiazole and 4-methylphenyl groups showed fairly good activity against the breast cancer cell line with respect to Cisplatin (7.21 μM) and comparable with respect to Doxorubicin (1 μM), while 6e (2.49μM), 6i (2.46 μM) and 6m (1.62 μM) showed better activity against glioblastoma cancer cell line with respect to both Cisplatin (2.60 μM) and Doxorubicin (3.78 μM) drugs used as standards. Greater than 65% of the compounds were found to be safer on human normal cell line.

Synthesis of conjugated bile acids/azastilbenes as potential antioxidant and photoprotective agents

A series of 14 bile acids/azastilbenes conjugates (1a-g and 2a-g) was prepared through the condensation of bile amides (1 and 2) and aromatic aldehydes. The newly synthesized conjugates were evaluated in vitro for their antioxidant and photoprotective activities. Six compounds (1, 1a, 1b, 2, 2a and 2b) showed promising antioxidant activity with IC50 values of 19.60-31.83 μg mL(-1). The synthesized compounds presented a varied photoprotection profile, with the SPF ranging from 2 to 9. Among the 16 compounds tested for the protection against UVB sunrays, 3 compounds (2c, 2e and 2g) presented more significant protection than resveratrol and the free azastilbene 3; while the UVAPF increased from 2 in resveratrol and 5 in 3 to 5-11 in the majority of the conjugates.

Biomedical potential of natural products derived through metagenomic approaches

Microbes are ubiquitous, irrespective of the environment they thrive in. Only 1% of these are culturable in laboratory. Metagenomics is useful in exploring biomedically important small molecules using culture independent approaches.

Synthesis and biological evaluation of bile carboxamide derivatives with pro-apoptotic effect on human colon adenocarcinoma cell lines

We previously reported that the cinnamylpiperazinyl group in the side chain of the chenodeoxycholic acid showed apoptosis-inducing activity on multiple myeloma cancer cell line KMS-11. In the present study, we synthesized and tested the pro-apoptotic potency of fifteen new piperazinyl bile carboxamide derived from cholic, ursodeoxycholic, chenodeoxycholic, deoxycholic and lithocholic acids on human colon adenocarcinoma cell lines DLD-1, HCT-116, and HT-29. Cell viability was first measured using XTT assay. The most of the synthetic bile carboxamide derivatives decreased significantly cell viability in a dose-dependent manner. HCT-116 and DLD-1 cell lines were more sensitive than HT-29 to tested compounds. 9c, 9d showed the best in vitro results in term of solubility and dose-response effect on the three colon adenocarcinoma cell lines. Additionally, flow cytometric and Western-blotting analysis showed that 9c induced pro-apoptosis in DLD-1 and HCT-116 whereas 9d did not. We conclude that the benzyl group improved anti-proliferative activity and that the α-hydroxyl group was found to be more beneficial at the 7-position in steroid skeleton.

Isolation of acetylated bile acids from the sponge Siphonochalina fortis and DNA damage evaluation by the comet assay

From the organic extracts of the sponge Siphonochalina fortis, collected at Bahía Bustamante, Chubut, Argentina, three major compounds were isolated and identified as deoxycholic acid 3, 12-diacetate (1), cholic acid 3, 7, 12-triacetate (2) and cholic acid, 3, 7, 12-triacetate. (3). This is the first report of acetylated bile acids in sponges and the first isolation of compound 3 as a natural product. The potential induction of DNA lesions by the isolated compounds was investigated using the comet assay in lymphocytes of human peripheral blood as in vitro model. The results showed that the administration of the bile acid derivatives would not induce DNA damages, indicating that acetylated bile acids are nontoxic metabolites at the tested concentrations. Since the free bile acids were not detected, it is unlikely that the acetylated compounds may be part of the sponge cells detoxification mechanisms. These results may suggest a possible role of acetylated bile acids as a chemical defense mechanism, product of a symbiotic relationship with microorganisms, which would explain their seasonal and geographical variation, and their influence on the previously observed genotoxicity of the organic extract of S. fortis.

Synthesis and antitumor activity of N-sulfonyl-3,7-dioxo-5β-cholan-24-amides, ursodeoxycholic acid derivatives

A series of N-sulfonyl-3,7-dioxo-5β-cholan-24-amides, ursodeoxycholic acid derivatives, have been designed and synthesized in nine steps starting from ursodeoxycholic acid. The in vitro antitumor activity of the target compounds has been evaluated against HCT-116, MCF-7, K562, and SGC-7901 cell lines. The pharmacological results showed that most of the prepared compounds display excellent selective cytotoxicity toward HCT-116, MCF-7, and K562 cell lines. Particularly, compounds 10c, 10f and 10g show high inhibitory activity on these human cancer cell lines (IC50: 2.39-9.34 μM). Conversely, all compounds are generally inactive against SGC-7901, with only 10b having IC₅₀ below 50 μM.

Bile acids in the colon, from healthy to cytotoxic molecules

Bile acids are natural detergents mainly involved in facilitating the absorption of dietary fat in the intestine. In addition to this absorptive function, bile acids are also essential in the maintenance of the intestinal epithelium homeostasis. To accomplish this regulatory function, bile acids may induce programmed cell death fostering the renewal of the epithelium. Here we first discuss on the different molecular pathways of cell death focusing on apoptosis in colon epithelial cells. Bile acids may induce apoptosis in colonocytes through different mechanisms. In contrast to hepatocytes, the extrinsic apoptotic pathway seems to have a low relevance regarding bile acid cytotoxicity in the colon. On the contrary, these molecules mainly trigger apoptosis through direct or indirect mitochondrial perturbations, where oxidative stress plays a key role. In addition, bile acids may also act as regulatory molecules involved in different cell signaling pathways in colon cells. On the other hand, there is increasing evidence that the continuous exposure to certain hydrophobic bile acids, due to a fat-rich diet or pathological conditions, may induce oxidative DNA damage that, in turn, may lead to colorectal carcinogenesis as a consequence of the appearance of cell populations resistant to bile acid-induced apoptosis. Finally, some bile acids, such as UDCA, or low concentrations of hydrophobic bile acids, can protect colon cells against apoptosis induced by high concentrations of cytotoxic bile acids, suggesting a dual behavior of these agents as pro-death or pro-survival molecules.

Estrogen receptor β potentiates the antiproliferative effect of raloxifene and affects the cell migration and invasion in HCT-116 colon cancer cells

BACKGROUND

Estrogen receptor β (ERβ) is the predominant ER in the colorectal epithelium, whose expression is greatly reduced in colorectal cancer compared with normal colon tissue. Recent in vitro studies suggested that ERβ may suppress tumor growth. No research was reported whether ERβ can be used as therapeutic agent for colon cancer.

METHODS

In this study, ERβ gene constructed into adenoviral (Ad) vectors was used to treat colon cancer HCT-116 cells alone or in combination with raloxifene. In vitro and in vivo studies were conducted to investigate the therapeutic effects of ERβ and raloxifene in HCT-116 cells.

RESULTS

Our results indicated that, although Ad-ERβ alone had no effect on the proliferation of HCT-116 cells, the combination of Ad-ERβ with raloxifene significantly inhibited the proliferation of HCT-116 cells. The apparently apoptotic induction effects may partly explain the cytotoxicity of the two agents. The results of the study of ERβ on migration and invasion of HCT-116 cells demonstrated that overexpression of ERβ significantly decreased cell migration and increased invasion of cells. The antitumor efficacies of ERβ as well as raloxifene were further investigated on HCT-116 tumor bearing mice. Results demonstrated that both Ad-ERβ and raloxifene individually inhibited tumor growth. The combination group showed the highest inhibitory efficiency compared with other three groups.

CONCLUSION

These findings demonstrated that combined administration of Ad-ERβ with raloxifene represents a promising colon cancer therapeutic strategy.

Synthesis and antiproliferative activity of some steroidal lactams

Using cholesterol as starting material, a series of 6-substituted-3-aza-A-homo-3-oxycholestanes and 6-substituted-4-aza-A-homo-3-oxycholestanes were synthesized by the oxidation, reduction, oximation, Beckman rearrangement and condensation reaction. These synthesized compounds displayed a distinct cytotoxicity against MGC 7901, HeLa and SMMC 7404 cancer cells. Our results revealed that the structures of functional groups at position-6 on the steroidal ring are crucial for the IC(50) value of antiproliferative activities of these compounds and the cytotoxic activity against MGC 7901 and SMMC 7404 cells was not significantly different between 4-N-lactams and 3-N-lactams when its 6-substituted group was a carbonyl or a hydroximino, but all 3-N-lactams showed a higher cytotoxicity against HeLa cells than 4-N-lactams. In particular, compounds 6, 8, 9 (IC(50)6: 6.5 μmol/L; 8: 7.7 μmol/L; 9: 5.6 μmol/L) were even more cytotoxic than cisplatin to HeLa cells (positive contrast, 10.1 μmol/L). The information obtained from the studies may be useful for the design of novel chemotherapeutic drugs.