Novel unsaturated glycyrrhetic acids derivatives: Design, synthesis and anti-inflammatory activity

Efficient glycyrrhetinic acid biomanufacturing through protein engineering and dual-GUS combination strategy with novel β-glucuronidase from Aspergillus calidoustus CLH-22

Glycyrrhetinicacid (GA) is a high-value pentacyclic triterpenoid with broad applications. However, the industrial production of GA is hindered by low yield and the accumulation of the intermediate product GlycyrrhetinicAcid3-O-Mono-β-D-Glucuronide (GAMG). This study first identified a novel β-glucuronidase (AcGUS) from Aspergillus calidoustus CLH-22 through transcriptomic analysis, demonstrating a substrate preference for GAMG. Subsequently, mutant AcGUS3G461C/Q462H/I575K with significantly improved activity (kcat/Km of 11.02-fold) was obtained via computer-aided engineering. Furthermore, the dual-GUS combination strategy was employed for the first timeto construct engineered Pichia pastoris for GA production, offering multiple advantages of enhanced conversion efficiency and reduced fermentation viscosity. Finally, under systematically optimized conditions and employing Glycyrrhizin (GL) as the substrate, the final concentration of GA was 48.73 g/L with a conversion of 97.26 % in a 1000-L fermenter, representing the optimal biocatalytic performance reported to date. This study provides new ideas and insights for industrial GA production.

Discovery of glycosidated glycyrrhetinic acid derivatives: Natural product-based soluble epoxide hydrolase inhibitors

There are few reports on soluble epoxide hydrolase (sEH) structure-activity relationship studies using natural product-based scaffolds. In this study, we discovered that C-30 urea derivatives of glycyrrhetinic acid such as 33, rather than C-20/C-3 urea derivatives, possess in vitro sEH inhibitory capabilities. Furthermore, we explored the impact of stereoconfigurations at C-3 and C-18 positions, and glycosidic bonds at the 3-OH on the compound's activity. Consequently, a glycoside of 33, specifically 49Cα containing alpha-oriented mannose, exhibited promising in vivo efficacy in alleviating carrageenan-induced paw edema and acetic acid-induced writhing. Meanwhile, 49Cα demonstrated potential in mitigating acute pancreatitis by modulating the ratios of anti-inflammatory epoxyeicosatrienoic acids (EETs) to pro-inflammatory dihydroxyeicosatrienoic acids (DHETs). The co-crystal structure of sEH in complex with 49Cα revealed that the N-tetrahydropyranylmethylene urea hydrogen bonded with the residues within the sEH tunnel, contrasting with the mannose component that extended beyond the tunnel's confines. Our findings highlight 49Cα (coded LQ-38) as a promising candidate for anti-inflammatory and analgesic effects, and pave the way for the future rational design of triterpenoid-based sEH inhibitors.

Structure-Activity Relationship of Oleanane-Type Pentacyclic Triterpenoids on Nuclear Factor κB Activation and Intracellular Trafficking and N-Linked Glycosylation of Intercellular Adhesion Molecule-1

In our previous study, two oleanane-type pentacyclic triterpenoids (oleanolic acid and maslinic acid) were reported to affect the N-glycosylation and intracellular trafficking of intercellular adhesion molecule-1 (ICAM-1). The present study was aimed at investigating the structure-activity relationship of 13 oleanane-type natural triterpenoids with respect to the nuclear factor κB (NF-κB) signaling pathway and the expression, intracellular trafficking, and N-glycosylation of the ICAM-1 protein in human lung adenocarcinoma A549 cells. Hederagenin, echinocystic acid, erythrodiol, and maslinic acid, which all possess two hydroxyl groups, decreased the viability of A549 cells. Celastrol and pristimerin, both of which possess an α,β-unsaturated carbonyl group, decreased cell viability but more strongly inhibited the interleukin-1α-induced NF-κB signaling pathway. Oleanolic acid, moronic acid, and glycyrrhetinic acid interfered with N-glycosylation without affecting the cell surface expression of the ICAM-1 protein. In contrast, α-boswellic acid and maslinic acid interfered with the N-glycosylation of the ICAM-1 protein, which resulted in the accumulation of high-mannose-type N-glycans. Among the oleanane-type triterpenoids tested, α-boswellic acid and maslinic acid uniquely interfered with the intracellular trafficking and N-glycosylation of glycoproteins.

A review of typical biological activities of glycyrrhetinic acid and its derivatives

Glycyrrhetinic acid, a triterpenoid compound primarily sourced from licorice root, exhibits noteworthy biological attributes, including anti-inflammatory, anti-tumor, antibacterial, antiviral, and antioxidant effects. Despite these commendable effects, its further advancement and application, especially in clinical use, have been hindered by its limited druggability, including challenges such as low solubility and bioavailability. To enhance its biological activity and pharmaceutical efficacy, numerous research studies focus on the structural modification, associated biological activity data, and underlying mechanisms of glycyrrhetinic acid and its derivatives. This review endeavors to systematically compile and organize glycyrrhetinic acid derivatives that have demonstrated outstanding biological activities over the preceding decade, delineating their molecular structures, biological effects, underlying mechanisms, and future prospects for assisting researchers in finding and designing novel glycyrrhetinic acid derivatives, foster the exploration of structure-activity relationships, and aid in the screening of potential candidate compounds.

Discovery of novel TLR4/MD-2 inhibitors: Receptor structure-based virtual screening studies and anti-inflammatory evaluation

In this study, a receptor structure-based virtual screening strategy was constructed using a computer-aided drug design. First, the compounds were filtered based on the Lipinski pentad and adsorption, distribution, metabolism, excretion, and toxicity profiles. Then, receptor structure-based pharmacophore models were constructed and screened. Finally, the in vitro toxicity and anti-inflammatory activities of hit compounds were initially evaluated to investigate their in vitro anti-inflammatory effects and mechanisms of action. The results revealed that hit 94 had the best anti-inflammatory activity and low toxicity while inhibiting the activation of Toll-like receptor (TLR) 4/myeloid differentiation factor 2 (MD2)-associated signaling pathways of nuclear factor-κB and mitogen-activated protein kinase. In vivo adjuvant arthritis results also revealed that hit 94 ameliorated foot swelling to a greater extent in rats compared with the positive control drug indomethacin. These results suggest that hit 94 can be used as a potential TLR/MD2 inhibitor for inflammatory diseases.

Synthesis of novel 18β-glycyrrhetinic acid sulfonate derivatives displaying significant anti-oomycete activity against Phytophthora capsici

Using 18β-glycyrrhetinic acid (GA) as the lead compound, fourteen GA sulphonate derivatives (3a-n) were prepared by modifying its C-3 OH group, and their structures were well confirmed by 1H NMR, 13C NMR, HRMS and melting points. Moreover, we screened the anti-oomycete activity of these compounds against Phytophthora capsici by using the mycelial growth rate method. Among the fourteen GA sulphonate derivatives evaluated, four compounds 3f, 3j, 3k and 3l exhibited more potent anti-oomycete activity than that of the positive control zoxamide (EC50 = 25.17 mg/L), and had the median effective concentration (EC50) values of 23.04, 16.16, 22.55, and 13.93 mg/L, respectively. Especially compound 3l showed the best anti-oomycete activity against P. capsici with EC50 value of 13.93 mg/L. Overall, the introduction of sulfonyloxy groups at the C-3 position of GA has a significant impact on its anti-oomycete activity, and the corresponding derivative activity varies significantly with different substituents R.

Anti-inflammatory ent-cleistanthane-type diterpenoids from Phyllanthus rheophyticus

A bioactivity-guided isolation from the aerial parts of Phyllanthus rheophyticus obtained 17 undescribed ent-cleistanthane-type diterpenoids, namely phyllarheophols A-Q, as well as 12 known analogs. Their structures were characterized by a combination of spectroscopic data interpretation, single-crystal X-ray diffraction and ECD analysis. The anti-inflammatory activities of these compounds were evaluated by measuring their inhibitory effects on NO production in LPS-stimulated RAW264.7 macrophages, and their preliminary structure-activity relationships were also discussed. Further study showed that promising compounds phyllarheophol D and phyacioid B significantly suppressed the expressions of cytokines and nitric oxide synthase through the NF-κB signaling pathway.

Discovery of anti-hepatoma agents from 1,4,5,6,7,8-hexahydropyrido[4,3-d]pyrimidine by inhibiting PI3K/AKT/NF-κB pathway activation

In order to obtain new anti-hepatoma drugs with low toxicity, some 1,4,5,6,7,8-hexahydropyrido[4,3-d]pyrimidines (PPMs, 4a-t) were synthesized in this study. Many of them showed significant anti-hepatoma effects against HCC cells and low toxicity toward HHL-5 cells. Combined with their anti-hepatoma activity and toxicity, 4-CF₃-substituted 4k was selected as an effective lead compound. Preliminary mechanistic studies revealed that 4k could up-regulate the expression levels of Bax and caspase-3 proteins, down-regulate the expression levels of Bcl-2 protein, promote significant apoptosis of HepG2, and block cells in G2-M phase to prevent cells from completing mitosis. Also, 4k could significantly inhibit the activation of PI3K/AKT/NF-κB pathway by blocking the phosphorylation of PI3K, AKT, NF-κB/p65 and IFN-γ-induced nuclear transport. Docking analysis showed that 4k could reasonably bind to the active sites of Bcl-2, NF-κB/p65, PI3K and AKT. This result suggested that 4k could be used as a new type of NF-κB inhibitor, which provides a scientific basis for further research into the treatment of hepatoma.

Novel cannabidiol-carbamate hybrids as selective BuChE inhibitors: Docking-based fragment reassembly for the development of potential therapeutic agents against Alzheimer's disease

Cannabidiol (CBD) and rivastigmine have been launched as drugs for treating dementia and cholinesterases (ChEs) are ideal drug targets. This study focused on developing novel ChE inhibitors as drug leads against dementia through molecular modeling and fragment reassembly approaches. A potent carbamate fragment binding to active site gorge of BuChE was found via a docking-based structural splicing approach, thus, 17 novel compounds were designed by structural reassembly. Compound C16 was identified as a highly selective potent BuChE inhibitor (IC₅₀ = 5.3 nM, SI > 4000), superior to CBD (IC₅₀ = 0.67 μM). C16 possessed BBB penetrating ability, benign safety, neuroprotection, antioxidant and pseudo-irreversible BuChE inhibition (K_d = 13 nM, k₂ = 0.26 min^-1), showing good drug-like properties. In vivo studies confirmed that C16 significantly ameliorated the scopolamine-induced cognition impairment, almost entirely recovered the Aβ_1-42 (icv)-impaired cognitive function to the normal level, showed better behavioral performance than donepezil and good anti-amyloidogenic effect. Hence, the potential BuChE inhibitor C16 can be developed as a promising disease-modifying treatment of AD.

Effects of citronellol grafted chitosan oligosaccharide derivatives on regulating anti-inflammatory activity

In order to improve the anti-inflammatory activity of chitosan oligosaccharide (COS), chitosan oligosaccharide graft citronellol derivatives (COS-g-Cit1-3) were successfully synthesized via grafting citronellol (Cit) onto COS backbone. The degrees of substitution (DS) of COS-g-Cit1-3 were 0.165, 0.199 and 0.182, respectively. The structure of COS-g-Cit1-3 was confirmed by UV-vis, FT-IR, ¹H NMR and elemental analysis. The in vivo anti-inflammatory activity evaluation results displayed that COS-g-Cit1-3 drastically reduced the paw swelling, and the oedema inhibitions were 22.58 %, 29.03 % and 25.81 %, respectively. The results indicated that the anti-inflammatory effects of COS-g-Cit1-3 were significantly higher than COS and COS-g-Cit2 exhibited the highest anti-inflammatory ability. The results also presented that COS-g-Cit1-3 reduced the expression levels of TNF-α by promoting the secretion of IL-4 and IL-10. Moreover, western blot analysis data proved that COS-g-Cit1-3 inactivated the NF-κB signaling pathway via inhibiting the phosphorylation of p65, IKBα and IKKβ.

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.

Obeticholic Acid Derivative, T-2054 Suppresses Osteoarthritis via Inhibiting NF-κB-Signaling Pathway

Osteoarthritis (OA), a degenerative joint disorder, has been reported as the most common cause of disability worldwide. The production of inflammatory cytokines is the main factor in OA. Previous studies have been reported that obeticholic acid (OCA) and OCA derivatives inhibited the release of proinflammatory cytokines in acute liver failure, but they have not been studied in the progression of OA. In our study, we screened our small synthetic library of OCA derivatives and found T-2054 had anti-inflammatory properties. Meanwhile, the proliferation of RAW 264.7 cells and ATDC5 cells were not affected by T-2054. T-2054 treatment significantly relieved the release of NO, as well as mRNA and protein expression levels of inflammatory cytokines (IL-6, IL-8 and TNF-α) in LPS-induced RAW 264.7 cells. Moreover, T-2054 promoted extracellular matrix (ECM) synthesis in TNF-α-treated ATDC5 chondrocytes. Moreover, T-2054 could relieve the infiltration of inflammatory cells and degeneration of the cartilage matrix and decrease the levels of serum IL-6, IL-8 and TNF-α in DMM-induced C57BL/6 mice models. At the same time, T-2054 showed no obvious toxicity to mice. Mechanistically, T-2054 decreased the extent of p-p65 expression in LPS-induced RAW 264.7 cells and TNF-α-treated ATDC5 chondrocytes. In summary, we showed for the first time that T-2054 effectively reduced the release of inflammatory mediators, as well as promoted extracellular matrix (ECM) synthesis via the NF-κB-signaling pathway. Our findings support the potential use of T-2054 as an effective therapeutic agent for the treatment of OA.

Design and synthesis of novel glycyrrhetin ureas as anti-inflammatory agents for the treatment of acute kidney injury

To develop new anti-inflammatory drugs for the prevention and treatment of acute kidney injury, a series of novel glycyrrhetic ureas were designed, synthesized and evaluated for anti-inflammatory activity using RAW264.7 cells. Compounds 5r-5u (2.04, 2.50, 3.25 and 2.48 μM, respectively) with acidic or neutral amino acid showed potent anti-inflammatory activity (IC₅₀ = 2-3 μM for NO inhibition), amongst them, compound 5r also inhibited tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in a dose-dependent manner. In cisplatin-induced AKI mice model, compound 5r significantly reduced the level of pro-inflammatory factors, ameliorated the pathological damage of kidney tissue, and maintained the normal metabolic capacity.

Regioselectivity of aminomethylation in 3-acetyl-7-hydroxycoumarins: Mannich bases and Betti bases

The atomic electron density distribution in 3-acetyl-7-hydroxycoumarin was analysed to elucidate the regioselectivity of aminomethylation.

Design, synthesis and biological evaluation of novel arylpropionic esters for the treatment of acute kidney injury

Acute kidney injury (AKI) is associated with a strong inflammatory response, and inhibiting the response effectively prevents or ameliorates AKI. A series of novel arylpropionic esters were designed, synthesized and evaluated their biological activity in LPS-stimulated RAW264.7 cells. Novel arylpropionic esters bearing multi-functional groups showed significant anti-inflammatory activity, in which, compound 13b exhibited the most potent activity through dose-dependent inhibiting the production of nitric oxide (NO, IC₅₀ = 3.52 μM), TNF-α and IL-6 (84.1% and 33.6%, respectively), as well as suppressing the expression of iNOS, COX-2 and TLR4 proteins. In C57BL/6 mice with cisplatin-induced AKI, compound 13b improved kidney function, inhibited inflammatory development, and reduced pathological damage of kidney tissues. In brief, this arylpropionic ester scaffold may be developed as anti-inflammatory agents.

Synthesis of novel 18β-glycyrrhetinic piperazine amides displaying significant in vitro and in vivo antibacterial activities against intractable plant bacterial diseases

BACKGROUND

The limited amount of agrochemicals targeting plant bacterial diseases has motivated us to study innovative antibacterial surrogates with fresh modes of action. Notably, fabrication of violent apoptosis inducers to control the reproduction of pathogenic bacteria should be a feasible way to control plant bacterial diseases. To achieve this aim, we constructed a series of novel 18β-glycyrrhetinic piperazine amides based on the natural bioactive ingredient 18β-glycyrrhetinic acid to evaluate the in vitro and in vivo antibacterial activity and induced apoptosis behaviors on tested pathogens.

RESULTS

Screening results suggested that these designed compounds were extremely bioactive against two notorious pathogens, Xanthomonas oryzae pv. oryzae and X. axonopodis pv. citri. This conclusion was highlighted by the biological effects of compounds A₃ and B₁ , affording the related EC₅₀ values of 2.28 and 0.93 μg mL^-1 . In vivo trials confirmed the prospective application for managing rice bacterial blight disease with control efficiency within 50.57-53.70% at 200 μg mL^-1 . In particular, target compounds could induce the generation of excessive reactive oxygen species (ROS) in tested pathogens, subsequently leading to a strong apoptotic effect at a very low drug concentration (≤ 10 μg mL^-1 ). This finding was consistent with the observed ROS-enhanced fluorescent images and morphological changes of pathogens from scanning electron microscopy patterns.

CONCLUSION

Given these features, we anticipate that these novel piperazine-tailored 18β-glycyrrhetinic hybrids can provide an perceptible insight for fighting bacterial infections by activation of the apoptosis mechanism. Novel 18β-glycyrrhetinic piperazine amides were reported to have excellent antibacterial efficacy toward phytopathogens Xanthomonas oryzae pv. oryzae and X. axonopodis pv. citri. A possible apoptosis mechanism was proposed from the remarkable apoptotic behaviors triggered by target compounds. © 2020 Society of Chemical Industry.

Design, synthesis and anti-inflammatory activity of 3-amino acid derivatives of ocotillol-type sapogenins

Ocotillol-type sapogenins (OTS) are major ginsenoside metabolites in human hepatic tissue. In order to better utilize OTS and derivatives thereof as anti-inflammatory compounds, present study produced multiple novel 3-amino acid OTS derivatives and evaluated their anti-inflammatory activity in vitro. The nitric oxide (NO) inhibitory activity of these compounds was used for OTS structure-activity relationship (SAR) evaluations, revealing that both R/S stereochemistry at C-24 and the amino acid type at C-3 influence such NO inhibitory activity. This activity was highest for an N-Boc-protected neutral aliphatic amino acid derivative of 24R-OTS (5a), which performed better than even hydrocortisone sodium succinate in vitro. Compound 5a was also able to markedly suppress the LPS-induced upregulation of TNF-α, IL-6, iNOS, and COX-2 via the NF-κB and MAPK pathways. This suggests that OTS derivatives may be valuable anti-inflammatory compounds worthy of further preclinical evaluation.

Synthesis and Structure-Activity Relationship of Pyxinol Derivatives as Novel Anti-Inflammatory Agents

Pyxinol, the main metabolite of 20S-protopanaxadiol in human liver, was chosen as a novel skeleton for the development of anti-inflammatory agents. Pyxinol derivatives modified at C-3, C-12, or C-25 and selected stereoisomers were designed, prepared, and investigated for in vitro anti-inflammatory activities. Structure-activity relationship (SAR), focused on skeleton, was analyzed based on their ability to inhibit lipopolysaccharide (LPS)-induced nitric oxide (NO) synthesis. The preliminary SAR results signified that the biological activity of the pyxinol derivatives is largely dependent on the R/S stereochemistry of pyxinol skeleton and the hydroxy at C-3 is a modifiable position. Among the tested compounds, the 3-oximinopyxinol (4a) exhibited the most potent NO-inhibitory activity and was even comparable to the steroid drug. Furthermore, compound 4a also significantly decreased LPS-induced TNF-α and IL-6 synthesis and iNOS and COX-2 expressions via the NF-κB pathway. This study proves that pyxinol is an interesting skeleton for anti-inflammatory drug discovery.

Synthesis, in vitro and in vivo biological evaluation of novel lappaconitine derivatives as potential anti-inflammatory agents

Lappaconitine (LA), a natural compound with a novel C18-diterpenoid alkaloid skeleton, displayed extensive biological profile. Recent research on LA is focused mainly on its anti-tumor and analgesic effects, and therefore we aimed to investigate its anti-inflammatory potential. A series of novel LA derivatives with various substituents on the 20-N position was designed and synthesized. In the initial screening of LA derivatives against NO production, all the target compounds, except compound E2, exhibited excellent inhibitory ability relative to that of LA. Particularly, compound A4 exhibited the most potent inhibition with IC₅₀ of 12.91 μmol/L. The elementary structure-activity relationships (SARs) of NO inhibitory activity indicated that replacement of the benzene ring with an electron donating group could improve the anti-inflammatory efficacy. Furthermore, compound A4 shows an anti-inflammatory mechanism by inhibiting NO, PGE2, and TNF-α generation via the suppression of NF-κB and MAPK signaling pathways. Notably, compound A4 could exert a significant therapeutic effect on LPS-induced acute lung injury (ALI) in vivo. Based on the above research, we further investigated the preliminary pharmacokinetic property of A4 in rats. Therefore, compound A4 could be a promising candidate for the development of anti-inflammatory agents in the future.

Supramolecular structure, in vivo biological activities and molecular-docking-based potential cardiotoxic exploration of aconine hydrochloride monohydrate as a novel salt form

Despite the high profile of aconine in WuTou injection, there has been no preparative technology or structural studies of its salt as the pharmaceutical product. The lack of any halide salt forms is surprising as aconine contains a tertiary nitrogen atom. In this work, aconine was prepared from the degradation of aconitine in Aconiti kusnezoffii radix (CaoWu). A green chemistry technique was applied to enrich the lipophilic-poor aconine. Reaction of aconine with hydrochloride acid resulted in protonation of the nitrogen atom and gave a novel salt form (C₂₅H₄₂NO₉⁺·Cl^-·H₂O; aconine hydrochloride monohydrate, AHM), whose cation in the crystal structure was elucidated based on extensive spectroscopic and X-ray crystallographic analyses. The AHM crystal had a Z' = 3 structure with three independent cation-anion pairs, with profound conformational differences among the aconine cations. The central framework of each aconine cation was compared with that of previously reported aconitine, proving that protonation of the nitrogen atom induced the structure rearrangement. In the crystal of AHM, aconine cations, chloride anions and water molecules interacted through inter-species O-H...Cl and O-H...O hydrogen bonds; this complex hydrogen-bonding network stabilizes the supramolecular structure. The seriously disordered solvent molecules were treated using the PLATON SQUEEZE procedure [Spek (2015). Acta Cryst. C71, 9-18] and their atoms were therefore omitted from the refinement. Bioactivity studies indicated that AHM promoted in vitro proliferative activities of RAW264.7 cells. Molecular docking suggested AHM could target cardiotoxic protein through the hydrogen-bonding interactions. The structural confirmation of AHM offers a rational approach for improving the pharmaceutical technology of WuTou injection.

Design, Synthesis and Investigation of the Potential Anti-Inflammatory Activity of 7-O-Amide Hesperetin Derivatives

To develop new anti-inflammatory agents, a series of 7-O-amide hesperetin derivatives was designed, synthesized and evaluated for anti-inflammatory activity using RAW264.7 cells. All compounds showed inhibitory effect on LPS-induced NO production. Among them, 7-O-(2-(Propylamino)-2-oxoethyl)hesperetin (4d) and 7-O-(2-(Cyclopentylamino)-2-oxoethyl)hesperetin (4k) with hydrophobic side chains exhibited the most potent NO inhibitory activity (IC₅₀ = 19.32 and 16.63 μM, respectively), showing stronger inhibitory effect on the production of pro- inflammatory cytokines tumor necrosis factor (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) than indomethacin and celecoxib at 10 μM. The structure-activity relationships (SARs) suggested that the 7-O-amide unit was buried in a medium-sized hydrophobic cavity of the bound receptor. Furthermore, compound 4d could also significantly suppress the expression of inducible nitric oxide synthase enzymes (iNOS) and cyclooxygenase-2 (COX-2), through the nuclear factor-kappa B (NF-κB) signaling pathway.

Modification, Antitumor Activity, and Targeted PPARγ Study of 18β-Glycyrrhetinic Acid, an Important Active Ingredient of Licorice

Licorice is a traditional Chinese medicine, which is often used as sweetener and cosmetic ingredients in food and pharmaceutical industries. Among them, glycyrrhetic acid is one of the most important agents. Studies have shown that glycyrrhetic acid exhibited antitumor activities as PPARγ agonist. However, the limited number of PPARγ glycyrrhetinic agonists and their high toxicity greatly limit the design based on the structure. Therefore, clarifying the binding mode between PPARγ and small molecules, we focused on the introduction of a natural active piperazine skeleton in the position of glycyrrhetinic acid C-3. According to the Combination Principle and the Structure-Based Drug Design, 19 glycyrrhetic acid derivatives were designed and synthesized as potential PPARγ agonists. Compounds 4c and 4q were screened as high-efficiency and low-toxicity lead compounds.

Nicotinamide Augments the Anti-Inflammatory Properties of Resveratrol through PARP1 Activation

Resveratrol (RSV) and nicotinamide (NAM) have garnered considerable attention due to their anti-inflammatory and anti-aging properties. NAM is a transient inhibitor of class III histone deacetylase SIRTs (silent mating type information regulation 2 homologs) and SIRT1 is an inhibitor of poly-ADP-ribose polymerase-1 (PARP1). The debate on the relationship between RSV and SIRT1 has precluded the use of RSV as a therapeutic drug. Recent work demonstrated that RSV facilitates tyrosyl-tRNA synthetase (TyrRS)-dependent activation of PARP1. Moreover, treatment with NAM is sufficient to facilitate the nuclear localization of TyrRS that activates PARP1. RSV and NAM have emerged as potent agonists of PARP1 through inhibition of SIRT1. In this study, we evaluated the effects of RSV and NAM on pro-inflammatory macrophages. Our results demonstrate that treatment with either RSV or NAM attenuates the expression of pro-inflammatory markers. Strikingly, the combination of RSV with NAM, exerts additive effects on PARP1 activation. Consistently, treatment with PARP1 inhibitor antagonized the anti-inflammatory effect of both RSV and NAM. For the first time, we report the ability of NAM to augment PARP1 activation, induced by RSV, and its associated anti-inflammatory effects mediated through the induction of BCL6 with the concomitant down regulation of COX-2.

Synthesis and inhibition of α-glucosidase of methyl glycyrrhetinate glycosides

The synthesis of the methyl glycyrrhetinate glycosides and inhibition of α-glucosidase were studied. The carboxyl group of glycyrrhetinic acid was methylated, and glucose and galactose were introduced into the hydroxyl group to obtain compounds 7 and 12. Compound 1, 2, 7, 12 and glycyrrhizic acid (GL) were evaluated for their inhibitory activities against α-glucosidase. As a result, Compound 1, 2, 7, 12 and GL all showed significant α-glucosidase inhibitory activity and IC₅₀ values were 0.465, 1.352, 0.759, 0.687 and 2.085 mM, respectively, and acted as non-competitive inhibitors. The activity of the compound 2, 7, 12 was lower than compound 1, but significantly higher than GL. Therefore, it was concluded that the change of structure in glycyrrhetinic acid by chemical modification had certain effect on bioactivity, and the change of carboxyl group, hydroxyl group and the type of monosaccharide introduced were the influencing factors.

Synthesis and Evaluation of Glycyrrhetic Acid-aromatic Hybrids as Antiinflammatory Agents

BACKGROUND

Inflammation is a biological response of body tissues to harmful stimuli, so it is desirable to search for novel anti-inflammatory agents with improved pharmaceutical profiles and reduced adverse effects.

OBJECTIVE

This study was to explore natural anti-inflammatory agents and improve therapeutic application of glycyrrhetic acid (GA) through molecular hybridization with active aromatics.

METHODS

Fourteen novel GA-aromatic hybrids were synthesized and evaluated for their antiinflammatory activities by inhibiting LPS-induced nitric oxide (NO) release in RAW264.7 cells. The synthesized compounds were characterized by single-crystal X-ray diffraction, 1H NMR, 13C NMR and HRMS.

RESULTS

The structure-activity relationship (SAR) study indicated that compounds with styryl displayed better NO inhibitory activity. Among them, compounds 2a and 3c exhibited the most promising activity with IC50 values of 9.93 μM and 12.25 μM, respectively. In addition, X-ray singlecrystal diffraction data for compounds 2e and 3c showed that the absolute configuration of GA skeleton was consistent with that of natural 18 β-glycyrrhetic acid.

CONCLUSION

The results showed that GA-aromatic hybrids were a new class of anti-inflammatory agents and this study provided useful information on further optimization.

Synthesis of new ent-labdane diterpene derivatives from andrographolide and evaluation of their anti-inflammatory activities

Two series of andrographolide derivatives with nitrogen-containing heterocycles, phenols and aromatic acids as bioisostere moiety of lactone ring were synthesized. 8 from 18 tested compounds showed stronger inhibitory effect on LPS-induced NO production in RAW264.7 macrophage than hydrocortisone. Among them, compound 8m exhibited the most potent inhibition with IC₅₀ of 3.38 ± 1.03 μM. The structure-activity relationships (SARs) suggested that the replacement of lactone ring with small-molecule phenols could improve the anti-inflammatory efficacy. Furthermore, compound 8m significantly reduced the levels of pro-inflammatory cytokine IL-1β and IL-6 with no influence on cell survival, decreased the expression of iNOS and COX-2, and down-regulated the level and phosphorylation of IκBα, as well as the expression of NF-κB. Also it blocked the nuclear translocation of NF-κB in LPS-induced macrophage. Therefore, the anti-inflammation mechanism of compound 8m was related to the inhibition of COX-2, iNOS and NF-κB signal pathway.

Discovery and optimization of tetrahydropyrido[4,3-d]pyrimidine derivatives as novel ATX and EGFR dual inhibitors

In order to discovery autotaxin (ATX) and EGFR dual inhibitors with potential therapeutic effect on IPF-LC, a series of novel tetrahydropyrido[4,3-d]pyrimidine derivatives possessing semicarbazones moiety were designed and synthesized. The preliminary investigation at the cellular level indicated six compounds (7h, 8a, 8c, 8d, 9a and 9d) displayed preferable anti-tumor activities against A549, H1975, MKN-45 and SGC cancer cells. Further enzymatic assay against EGFR kinase identified 8a and 9a as promising hits with IC₅₀ values of 18.0 nM and 24.2 nM. Meanwhile, anti-inflammatory assessment against cardiac fibroblasts (CFs) cell and RAW264.7 macrophages led to the discovery of candidate 9a, which exhibited considerable potency both on inhibition rate of 77% towards CFs and on reducing NO production to 1.05 μM at 10 μg/mL. Simultaneously, 9a indicated preferable potency towards ATX with IC₅₀ value of 29.1 nM. Significantly, a RT-PCR study revealed the function of 9a to down-regulate the mRNA expression of TGF-β and TNF-α in a dose-dependent manner. The molecular docking analysis together with the pharmacological studies validated 9a as a potential ATX and EGFR dual inhibitor for IPF-LC treatments.