Discovery and SAR study of hydroxyacetophenone derivatives as potent, non-steroidal farnesoid X receptor (FXR) antagonists

Development of potent isoflavone-based formyl peptide receptor 1 (FPR1) antagonists and their effects in gastric cancer cell models

Formyl peptide receptor-1 (FPR1) is a G protein-coupled chemoattractant receptor that plays a crucial role in the trafficking of leukocytes into the sites of bacterial infection and inflammation. Recently, FPR1 was shown to be expressed in different types of tumor cells and could play a significant role in tumor growth and invasiveness. Starting from the previously reported FPR1 antagonist 4, we have designed a new series of 4H-chromen-2-one derivatives that exhibited a substantial increase in FPR1 antagonist potency. Docking studies identified the key interactions for antagonist activity. The most potent compounds in this series (24a and 25b) were selected to study the effects of the pharmacological blockade of FPR1 in NCl-N87 and AGS gastric cancer cells. Both compounds potently inhibited cell growth through a combined effect on cell proliferation and apoptosis and reduced cell migration, while inducing an increase in angiogenesis, thus suggesting that FPR1 could play a dual role as oncogene and onco-suppressor.

Skin Depigmenting Agents in Anti-Aging Cosmetics: A Medicinal Perspective on Emerging Ingredients

Human skin aging results from intrinsic and extrinsic factors. Uneven pigmentation is one of the major changes of extrinsic aging. Many compounds have been tested for depigmenting activity but only a few are actually used by the cosmetic industry, which is continually looking for new ingredients. In this study, the trends in the use of skin depigmenting ingredients in a panel of anti-aging formulations commercialized in the Portuguese pharmacy market were analyzed, by comparing the composition of the products marketed in 2011 with products launched or reformulated in 2018 (59% and 74%, respectively). The analysis of the top 12 ingredients put forward three novelties for 2018: tranexamic acid, bakuchiol, and 4-butylresorcinol. Regarding their mechanisms of action, tranexamic acid inhibits melanin synthesis through inhibition of the plasminogen/plasmin system. Bakuchiol depigmenting efficacy was attributed to the ability to block both α-melanocyte-stimulating hormone and tyrosinase activation, while 4-butylresorcinol exerts its action through the inhibition of both tyrosinase and tyrosinase-related protein-1 (TRP-1). Industry-optimized and efficient synthetic methodologies that embrace green chemistry, reducing the environmental impact, are commonly used. This analysis aims to bring insights to both formulators, involved in the development of depigmenting cosmetic products, and chemists performing the synthesis of new and existing compounds intended for this purpose.

4-n-Butylresorcinol-Based Linear and Graft Polymethacrylates for Arbutin and Vitamins Delivery by Micellar Systems

A novel initiator, bromoester modified 4-n-butylresorcinol (4nBREBr₂), was prepared and utilized in controlled atom transfer radical polymerization (ATRP) to obtain three series of amphiphilic copolymers. The V-shaped copolymers of methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), and poly(ethylene glycol) methyl ether methacrylate (MPEGMA), abbreviated to P(HEMA-co-MMA), P(HEMA-co-MPEGMA), and P(MMA-co-MPEGMA), were synthesized. Moreover, P((HEMA-graft-PEG)-co-MMA) graft copolymers were prepared by combining the pre-polymerization modification of HEMA and a "click" reaction using a "grafting onto" approach. All copolymers could form micelles with encapsulated active substances (vitamin C (VitC), vitamin E (VitE), arbutin (ARB)), which are used in cosmetology. In vitro studies carried out in a PBS solution (pH 7.4) demonstrates that in most cases the maximum release of active substance was after 1 h. The polymeric systems presenting satisfactory encapsulation characteristics and release profiles are attractive micellar carriers of cosmetic substances, which show a positive effect on the skin condition.

Chemistry and Pharmacology of GPBAR1 and FXR Selective Agonists, Dual Agonists, and Antagonists

In the recent years, bile acid receptors FXR and GPBAR1 have attracted the interest of scientific community and companies, as they proved promising targets for the treatment of several diseases, ranging from liver cholestatic disorders to metabolic syndrome, inflammatory states, nonalcoholic steatohepatitis (NASH), and diabetes.Consequently, the development of dual FXR/GPBAR1 agonists, as well as selective targeting of one of these receptors, is considered a hopeful possibility in the treatment of these disorders. Because endogenous bile acids and steroidal ligands, which cover the same chemical space of bile acids, often target both receptor families, speculation on nonsteroidal ligands represents a promising and innovative strategy to selectively target GPBAR1 or FXR.In this review, we summarize the most recent acquisition on natural, semisynthetic, and synthetic steroidal and nonsteroidal ligands, able to interact with FXR and GPBAR1.

One and Two-Carbon Homologation of Primary and Secondary Alcohols to Corresponding Carboxylic Esters Using β-Carbonyl BT Sulfones as a Common Intermediate

Herein we report the efficient one- and two-carbon homologation of 1° and 2° alcohols to their corresponding homologated esters via the Mitsunobu reaction using β-carbonyl benzothiazole (BT) sulfone intermediates. The one-carbon homologation approach uses standard Mitsunobu C-S bond formation, oxidation and subsequent alkylation, while the two-carbon homologation uses a less common C-C bond forming Mitsunobu reaction. In this latter case, the use of β-BT sulfone bearing esters lowers the p K_a sufficiently enough for the substrate to be used as a carbon-based nucleophile and deliver the homologated β-BT sulfone ester, and this superfluous sulfone group can then be cleaved. In this paper we describe several methods for the effective desulfonylation of BT sulfones and have developed methodology for one-pot alkylation-desulfonylation sequences. As such, overall, a one-carbon homologation sequence can be achieved in a two-pot (four step) procedure and the two-carbon homologation in a two-pot (three step) procedure (three-pot; four step when C-acid synthesis is included). This methodology has been applied to a wide variety of functionality (esters, silyl ethers, benzyls, heteroaryls, ketones, olefins and alkynes) and are all tolerated well providing good to very good overall yields. The power of our method was demonstrated in site-selective ingenol C20 allylic alcohol two-carbon homologation.

Synthesis and biological evaluations of chalcones, flavones and chromenes as farnesoid x receptor (FXR) antagonists

Farnesoid X receptor (FXR), a nuclear receptor mainly distributed in liver and intestine, has been regarded as a potential target for the treatment of various metabolic diseases, cancer and infectious diseases related to liver. Starting from two previously identified chalcone-based FXR antagonists, we tried to increase the activity through the design and synthesis of a library containing chalcones, flavones and chromenes, based on substitution manipulation and conformation (ring closure) restriction strategy. Many chalcones and four chromenes were identified as microM potent FXR antagonists, among which chromene 11c significantly decreased the plasma and hepatic triglyceride level in KKay mice.

Discovery and optimization of benzimidazole derivatives as a novel chemotype of farnesoid X receptor (FXR) antagonists

We describe here a novel chemotype with substituted benzimidazole scaffold for nonsteroidal farnesoid X receptor (FXR) antagonists starting from the identification of a screening hit, BB-4. Structure diversity in four regions A-D of BB-4 or 1 is discussed. In particular, regions A and C had an effect on an antagonism against FXR as demonstrated by the derivatives represented by 7 and 15, respectively. Thus, compound 19 arising from the combination of regions A and C underscored an important fact on antagonism against FXR, also showing the reduced small heterodimer partner and the increased cholesterol 7α-hydroxylase expression levels.

Discovery and SAR study of 3-(tert-butyl)-4-hydroxyphenyl benzoate and benzamide derivatives as novel farnesoid X receptor (FXR) antagonists

3-(tert-Butyl)-4-hydroxyphenyl 2,4-dichlorobenzoate (1) was discovered in our in-house high throughput screening as a moderate FXR antagonist. To improve the potency and the stability of the hit 1, forty derivatives were synthesized and SAR was systematically explored. The results turn out that replacing the 2,4-dichlorophenyl with 2,6-dichloro-4-amidophenyl shows great improvement in potency, replacing the benzoate with benzamide shows improvement in stability and slight declining of potency and 3-(tert-butyl)-4-hydroxyphenyl unit is essential in obtaining the FXR antagonistic activity.

Nuclear bile acid signaling through the farnesoid X receptor

Bile acids (BAs) are amphipathic molecules produced from cholesterol by the liver. Expelled from the gallbladder upon meal ingestion, BAs serve as fat solubilizers in the intestine. BAs are reabsorbed in the ileum and return via the portal vein to the liver where, together with nutrients, they provide signals to coordinate metabolic responses. BAs act on energy and metabolic homeostasis through the activation of membrane and nuclear receptors, among which the nuclear receptor farnesoid X receptor (FXR) is an important regulator of several metabolic pathways. Highly expressed in the liver and the small intestine, FXR contributes to BA effects on metabolism, inflammation and cell cycle control. The pharmacological modulation of its activity has emerged as a potential therapeutic strategy for liver and metabolic diseases. This review highlights recent advances regarding the mechanisms by which the BA sensor FXR contributes to global signaling effects of BAs, and how FXR activity may be regulated by nutrient-sensitive signaling pathways.