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

Design, synthesis, and biological evaluation of C-12 modified ocotillol-type derivatives as novel P-glycoprotein modulators for overcoming multidrug resistance

Ocotillol-type ginsenoside derivatives exhibit significant potential as modulators of P-glycoprotein (Pgp). To date, structural investigations of Ocotillol-type saponins have predominantly focused on modifications at the C-3 position of the A-ring, with limited exploration of the C-12 position on the C-ring. In this study, we designed and synthesized a series of C-12 modified ocotillol-type derivatives and assessed their efficacy in reversing multidrug resistance (MDR) in KBV cells. Most of the newly synthesized derivatives exhibited minimal cytotoxicity and potent MDR reversal capabilities. Notably, compound 9e emerged as the most effective agent in reversing tumor MDR in vitro, showing more than twice the potency of verapamil. Furthermore, 9e displayed high selectivity for Pgp, being 40- and 20-fold more effective than verapamil in inhibiting Rh123 efflux and enhancing doxorubicin sensitivity, respectively. Molecular docking analysis revealed that 9e possesses a unique T-shaped configuration that occupies the access channel of Pgp, obstructing the peristaltic extrusion mechanism of TM12 and TM9, thereby inhibiting the efflux function of Pgp. Overall, 9e represents a promising lead compound for the development of novel Pgp modulators to overcome MDR in cancer therapy.

A Novel Dipterocarpol Derivative That Targets Alpha-Glucosidase and NLRP3 Inflammasome Activity for Treatment of Diabetes Mellitus

Type 2 diabetes mellitus is a chronic metabolic disorder characterized by persistent hyperglycemia, chronic inflammation, impaired insulin secretion, and/or peripheral insulin resistance. Current α-glucosidase inhibitors approved for clinical use exhibit limited efficacy compared to other glucose-lowering agents. In this study, a series of mono- and bis-benzylidene derivatives were synthesized via aldol condensation of 3-oxo-dammarane triterpenoids with terephthalic aldehyde. The target mono- and bis-benzylidene derivatives, based on the dammarane triterpenoids hollongdione 1, (20S)-23,24-epoxy-25,26,27-trinordammar-3,24-dione 2, and 24(R,S)-20(S)-epoxy-25-hydroxy-dammar-3-one 3, were successfully synthesized. Several of these inhibitors demonstrated significantly greater efficacy than the reference drug acarbose. Notably, compound 4 inhibited S. cerevisiae α-glucosidase with an IC50 of 2.67 μM. Furthermore, the target compounds effectively inhibited NLRP3 inflammasome activation, reducing IL-1β production in LPS+ATP-stimulated murine peritoneal macrophages without detectable cytotoxicity. Compound 8, which exhibited dual activity, was further characterized as an inhibitor of NLRP3 activation in peripheral blood mononuclear cells, leading to the prevention of pyroptosis and IL-1β release. Additionally, compound 8 was shown to promote neuronal survival in LPS+ATP-treated rat hippocampal slices, highlighting its potential as a promising antidiabetic agent that targets both postprandial hyperglycemia and metaflammation.

Ocotillol Derivatives Mitigate Retinal Ischemia-Reperfusion Injury by Regulating the Keap1/Nrf2/ARE Signaling Pathway

Retinal ischemia-reperfusion (RIR) injury can lead to various retinal diseases. Oxidative stress is considered an important pathological event in RIR injury. Here, we designed and synthesized 34 ocotillol derivatives, then examined their antioxidant and anti-inflammatory capacities; we found that compounds 7 (C24-R) and 8 (C24-S) were most active. To enhance their water solubility, sustained release, and biocompatibility, compounds 7 and 8 were encapsulated into liposomes for in vivo activity and mechanistic studies. In vivo studies indicated that compounds 7 and 8 protected normal retinal structure and physiological function after RIR injury, reversed damage to retinal ganglion cells, and the S-configuration exhibited significantly stronger activity compared with the R-configuration. Mechanistic studies showed that compound 8 exerted a therapeutic effect on RIR injury by activating the Keap1/Nrf2/ARE signaling pathway; compound 7 did not influence this pathway. We also demonstrated that differential isomerization at the C-24 position influenced protection against RIR injury.

Synthesis and biological evaluation of panaxadiol ester derivatives possessing pyrazole and pyrrole moiety as HIF-1α inibitors

Hypoxia-inducing factor-1α (HIF-1α) is overexpressed in variety of tumor patients and plays an important role in the regulation of hypoxia response in tumor cells. Therefore, its inhibitors have become one of the targets for the treatment of a variety of cancers. Two series of panaxadiol (PD) ester derivatives containing pyrazole (18a-j) and pyrrole (19a-n) moiety were synthesized and their HIF-1α inhibitory activities were evaluated. Among all the target compouds, compounds 18c, 19d, and 19n (IC50 = 8.70-10.44 μM) showed better HIF-1α inhibitory activity than PD (IC50 = 13.35 μM). None of these compounds showed cytotoxicity above 100 μM and inhibited HIF-1α transcription in a dose-dependent manner. These compounds showed good antitumor activity and provide lead compounds for further design and activity study of PD ester derivatives.

Novel pyxinol amide derivatives bearing an aliphatic heterocycle as P-glycoprotein modulators for overcoming multidrug resistance

P-glycoprotein (Pgp) modulators are promising agents for overcoming multidrug resistance (MDR) in cancer chemotherapy. In this study, via structural optimization of our lead compound S54 (nonsubstrate allosteric inhibitor of Pgp), 29 novel pyxinol amide derivatives bearing an aliphatic heterocycle were designed, synthesized, and screened for MDR reversal activity in KBV cells. Unlike S54, these active derivatives were shown to transport substrates of Pgp. The most potent derivative 4c exhibited promising MDR reversal activity (IC50 of paclitaxel = 8.80 ± 0.56 nM, reversal fold = 211.8), which was slightly better than that of third-generation Pgp modulator tariquidar (IC50 of paclitaxel = 9.02 ± 0.35 nM, reversal fold = 206.6). Moreover, the cytotoxicity of this derivative was 8-fold lower than that of tariquidar in human normal HK-2 cells. Furthermore, 4c blocked the efflux function of Pgp and displayed high selectivity for Pgp but had no effect on its expression and distribution. Molecular docking revealed that 4c bound preferentially to the drug-binding domain of Pgp. Overall, 4c is a promising lead compound for developing Pgp modulators.

Discovery of novel ocotillol derivatives modulating glucocorticoid receptor/NF-κB signaling for the treatment of sepsis

Glucocorticoids (GCs) have been used in the treatment of sepsis because of their potent anti-inflammatory effects. However, their clinical efficacy against sepsis remains controversial because of glucocorticoid receptor (GR) downregulation and side effects. Herein, we designed and synthesized 30 ocotillol derivatives and evaluated their anti-inflammatory activities. Ocotillol 24(R/S) differential isomers were stereoselective in their pharmacological action. Specifically, 24(S) derivatives had better anti-inflammatory activity than their corresponding 24(R) derivatives. Compound 20 most effectively inhibited NO release (85.97% reduction), and it exerted dose-dependent inhibitory effects on interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) levels. Mechanistic studies revealed that compound 20 reduces the degradation of GR mRNA and GR protein. Meanwhile, compound 20 inhibited the activation of nuclear factor-κB (NF-κB) signaling, thereby inhibiting the nuclear translocation of p65 and attenuating the inflammatory response. In vivo studies revealed that compound 20 attenuated hepatic, pulmonary, and renal pathology damage in mice with sepsis and suppressed the production of inflammatory mediators. These results indicated that compound 20 is a promising lead compound for designing and developing anti-sepsis drugs.

Synthesis of urolithin derivatives and their anti-inflammatory activity

Two series of urolithin derivatives, totally 38 compounds, were synthesized. Their anti-inflammatory activity was investigated by detecting the inhibitory effects on the expression of TNF-α in bone marrow-derived macrophages (BMDMs), showing that 24 of 38 ones reduced the expression of TNF-α. Compound B2, the ring C opened derivative of urolithin B with a butoxycarbonyl substitution in ring A, showed the strongest inhibitory activity compared with that of indomethacin. Furthermore, B2 treatment decreased the expression of pro-inflammatory factors IL-1β, IL-6, iNOS and COX-2. Mechanically, the anti-inflammatory effect of B2 was related to the inhibition of NF-κB signaling pathway. These results clearly illustrated that B2 hold potential for application as an anti-inflammatory agent. The present study provided a viable approach to modify the gut metabolites for anti-inflammatory drug development.

Synthesis, Anti-Inflammatory Activities, and Molecular Docking Study of Novel Pyxinol Derivatives as Inhibitors of NF-κB Activation

Pyxinol, an active metabolite of ginsenosides in human hepatocytes, exhibits various pharmacological activities. Here, a series of C-3 modified pyxinol derivatives was designed and virtually screened by molecular docking with the key inflammation-related proteins of the nuclear factor kappa B (NF-κB) pathway. Some of the novel derivatives were synthesized to assess their effects in inhibiting the production of nitric oxide (NO) and mitochondrial reactive oxygen species (MtROS) in lipopolysaccharide-triggered RAW264.7 cells. Derivative 2c exhibited the highest NO and MtROS inhibitory activities with low cytotoxicity. Furthermore, 2c decreased the protein levels of interleukin 1β, tumor necrosis factor α, inducible nitric oxide synthase, and cyclooxygenase 2 and suppressed the activation of NF-κB signaling. Cellular thermal shift assays indicated that 2c could directly bind with p65 and p50 in situ. Molecular docking revealed that 2c's binding to the p65-p50 heterodimer and p50 homodimer was close to their DNA binding sites. In summary, pyxinol derivatives possess potential for development as NF-κB inhibitors.

Pyxinol Fatty Acid Ester Derivatives J16 against AKI by Selectively Promoting M1 Transition to M2c Macrophages

Acute kidney injury (AKI) is a common, multicause clinical condition that, if ignored, often progresses to chronic kidney disease (CKD) and end-stage kidney disease, with a mortality rate of 40-50%. However, there is a lack of universal treatment for AKI. Inflammation is the basic pathological change of early kidney injury, and inflammation can exacerbate AKI. Macrophages are the primary immune cells involved in the inflammatory microenvironment of kidney disease. Therefore, regulating the function of macrophages is a crucial breakthrough for the AKI intervention. Our team chemically modified pyxinol, an ocotillol-type ginsenoside, to prepare PJ16 with higher solubility and bioavailability. In vitro, using a model of macrophages stimulated by LPS, it was found that PJ16 could regulate macrophage function, including inhibiting the secretion of inflammatory factors, promoting phagocytosis, inhibiting M1 macrophages, and promoting M1 transition to the M2c macrophage. Further investigation revealed that PJ16 may shield renal tubular epithelial cells (HK-2) damaged by LPS in vitro. Based on this, PJ16 was validated in the animal model of unilateral ureteral obstruction, which showed that it improves renal function and inhibits renal tissue fibrosis by decreasing inflammatory responses, reducing macrophage inflammatory infiltration, and preferentially upregulating M2c macrophages. In conclusion, our study is the first to show that PJ16 resists AKI and fibrosis by mechanistically regulating macrophage function by modulating the phenotypic transition from M1 to M2 macrophages, mainly M2c macrophages.

20(S)-Ginsenoside Rg2 amino acid derivatives for anti hemorrhagic shock: Synthesis, characterization and evaluation

The purpose of this study is to screen a novel Rg2 derivative for anti hemorrhagic shock. Eight Rg2 amino acid ester derivatives were designed and synthesized, and their effects on hypoxia and shock were studied. Among them, the derivative 1 (D1) exhibited excellent anti hypoxia by promoting survival rate of H9c2 cells damaged by hypoxia. D1 improved physiological indicators of the rats in hemorrhagic shock, such as blood pressure, heart rate, lactate, acid-base balance, and alleviate oxidative stress and inflammatory damage. Its latent mechanisms were explored by a method of plasma metabolomics based on UPLC-QTOF-MS. As a result, a total of 16 biomarkers were identified involving 6 metabolic pathways. The results of this study contained that the derivative 1 could be considered as potent drug candidates for anti shock and deserved further research and development.

Design and synthesis of forsythin derivatives as anti-inflammatory agents for acute lung injury

Acute lung injury (ALI) is a clinically high mortality disease, which has not yet been effectively treated. The development of anti-ALI drugs is imminent. ALI can be effectively treated by inhibiting the inflammatory cascade and reducing the inflammatory response in the lung. Forsythia suspense is a common Chinese herbal medicine with significant anti-inflammatory activity. Using forsythin as the parent, 27 Forsythin derivatives were designed and synthesized, and the anti-AIL activity of these compounds was evaluated. Among them, compound B5 has the best activity to inhibit the release of IL-6, and the inhibition rate reaches 91.79% at 25 μM, which was 7.5 times that of the parent forsythin. In addition, most of the compounds have no significant cytotoxicity in vitro. Further studies showed that compound B5 had a concentration-dependent inhibitory effect on NO, IL-6 and TNF-α. And the IC50 values of compound B5 for NO and IL-6 are 10.88 μM and 4.93 μM, respectively. We also found that B5 could significantly inhibit the expression of some immune-related cytotoxic factors, including inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). In addition, B5 inhibits NF-κB/MAPK signaling pathway. In vivo experiments showed that B5 could alleviate lung inflammation in LPS-induced ALI mice and inhibit IL-6, TNF-α, COX-2 and iNOS. In summary, B5 has anti-inflammatory effects and alleviates ALI by regulating inflammatory mediators and inhibiting MAPK and NF-κB signaling pathways.

Dual COX-2/TNF-α Inhibitors as Promising Anti-inflammatory and Cancer Chemopreventive Agents: A Review

Cyclooxygenases (COX) play a pivotal role in inflammation and are responsible for the production of prostaglandins (PGs). Two types of COXs have been identified as key biological targets for drug design: Constitutive COX-1 and inducible COX-2. Nonsteroidal anti-inflammatory drugs (NSAIDs) target COX-1, while selective COX-2 inhibitors are designed for COX-2. These COX isoforms are involved in multiple physiological and pathological pathways throughout the body. Overproduction of tumor necrosis factor-alpha (TNF-α) plays a role in COX-2's inflammatory activity. Tumor necrosis factor-alpha can contribute to cardiac fibrosis, heart failure, and various cancers by upregulating the COX-2/PGE2 axis. Therefore, suppressing COX activity has emerged as a potentially effective treatment for chronic inflammatory disorders and cancer. This review explores the mechanisms of TNF-α-induced COX-2/PGE2 expression, a significant pathophysiological feature of cancer development. Furthermore, we summarize chemical compounds with dual COX-2/TNF-α inhibitory actions, providing an overview of their structure-activity relationship. These insights may contribute to the development of new generations of dual-acting COX-2/TNF-α inhibitors with enhanced efficacy.

Synthesis and structure-activity relationship studies of fusidic acid derivatives as anti-inflammatory agents for acute lung injury

Acute lung injury (ALI) are severe forms of diffuse lung disease that impose a substantial health burden all over the world. In the United States, approximately 190,000 cases per year of ALI each year, with an associated 74,500 deaths per year. Anti-inflammatory therapy has become a reasonable approach for the treatment of patients with ALI. In this study, fusidic acid derivatives were used to design new anti-inflammatory compounds with high pharmacological activity and low toxicity. A total of 30 new fusidic acid derivatives were discovered, synthesized, and screened for their anti-inflammatory activity against lipopolysaccharide (LPS)-treated RAW264.7 cells. Of them, b2 was found to be the most active, with a higher efficiency compared with fusidic acid and celecoxib in 10 μM. In vitro, we further measured b2 inhibited inflammatory factor NO (IC50 = 5.382 ± 0.655 μM), IL-6 (IC50 = 7.767 ± 0.871 μM), and TNF-α (IC50 = 7.089 ± 0.775 μM) and b2 inhibited inflammatory cytokines COX-2 and iNOS, ROS production, NF-κB/MAPK and Bax/Bcl-2 signaling pathway pathway. In vivo,b2 attenuated ALI pathological changes and inhibited inflammatory cytokines COX-2 and iNOS in lung tissue and NF-κB/MAPK and Bax/Bcl-2 signaling pathway. In conclusion, b2 may be a promising anti-inflammatory lead compound.

Discovery of Pyxinol Amide Derivatives Bearing Amino Acid Residues as Nonsubstrate Allosteric Inhibitors of P-Glycoprotein-Mediated Multidrug Resistance

Nonsubstrate allosteric inhibitors of P-glycoprotein (Pgp), which are considered promising modulators for overcoming multidrug resistance (MDR), are relatively unknown. Herein, we designed and synthesized amino acids bearing amide derivatives of pyxinol, the main ginsenoside metabolite produced by the human liver, and examined their MDR reversal abilities. A potential nonsubstrate inhibitor (7a) was identified to undergo high-affinity binding to the putative allosteric site of Pgp at the nucleotide-binding domains. Subsequent assays confirmed that 7a (25 μM) was able to suppress both basal and verapamil-stimulated Pgp-ATPase activities (inhibition rates of 87 and 60%, respectively) and could not be pumped out by Pgp, indicating that it was a rare nonsubstrate allosteric inhibitor. Moreover, 7a interfered with Pgp-mediated Rhodamine123 efflux while exhibiting high selectivity for Pgp. Notably, 7a also markedly enhanced the therapeutic efficacy of paclitaxel, with a tumor inhibition ratio of 58.1%, when used to treat nude mice bearing KBV xenograft tumors.

Ginsenosides from Panax ginseng as Key Modulators of NF-κB Signaling Are Powerful Anti-Inflammatory and Anticancer Agents

Nuclear factor kappa B (NF-κB) signaling pathways progress inflammation and immune cell differentiation in the host immune response; however, the uncontrollable stimulation of NF-κB signaling is responsible for several inflammatory illnesses regardless of whether the conditions are acute or chronic. Innate immune cells, such as macrophages, microglia, and Kupffer cells, secrete pro-inflammatory cytokines, such as TNF-α, IL-6, and IL-1β, via the activation of NF-κB subunits, which may lead to the damage of normal cells, including neurons, cardiomyocytes, hepatocytes, and alveolar cells. This results in the occurrence of neurodegenerative disorders, cardiac infarction, or liver injury, which may eventually lead to systemic inflammation or cancer. Recently, ginsenosides from Panax ginseng, a historical herbal plant used in East Asia, have been used as possible options for curing inflammatory diseases. All of the ginsenosides tested target different steps of the NF-κB signaling pathway, ameliorating the symptoms of severe illnesses. Moreover, ginsenosides inhibit the NF-κB-mediated activation of cancer metastasis and immune resistance, significantly attenuating the expression of MMPs, Snail, Slug, TWIST1, and PD-L1. This review introduces current studies on the therapeutic efficacy of ginsenosides in alleviating NF-κB responses and emphasizes the critical role of ginsenosides in severe inflammatory diseases as well as cancers.

Fusion of Michael-acceptors enhances the anti-inflammatory activity of ginsenosides as potential modulators of the NLRP3 signaling pathway

Ginsenosides are a promising group of secondary metabolites for developing anti-inflammatory agents. In this study, Michael acceptor was fused into the aglycone A-ring of protopanoxadiol (PPD)-type ginsenosides (MAAG), the main pharmacophore of ginseng, and its liver metabolites to produce novel derivatives and assess their anti-inflammatory activity in vitro. The structure-activity relationship of MAAG derivatives was assessed based on their NO-inhibition activities. Of these, a 4-nitrobenzylidene derivative of PPD (2a) was the most effective and dose-dependently inhibited the release of proinflammatory cytokines. Further studies indicated that 2a-induced downregulation on lipopolysaccharide (LPS)-induced iNOS protein expression and cytokine release may be related to its inhibitory effect on MAPK and NF-κB signaling pathways. Importantly, 2a almost completely inhibited LPS-induced production of mitochondrial reactive oxygen species (mtROS) and LPS-induced NLRP3 upregulation. This inhibition was higher than that by hydrocortisone sodium succinate, a glucocorticoid drug. Overall, the fusion of Michael acceptors into the aglycone of ginsenosides greatly enhanced the anti-inflammatory activities of the derivatives, and 2a alleviated inflammation considerably. These findings could be attributed to the inhibition of LPS-induced mtROS to block abnormal activation of the NLRP3 pathway.

Design, synthesis, and discovery of Eudistomin Y derivatives as lysosome-targeted antiproliferation agents

Eudistomin Y is a novel class of β-carbolines of marine origin with potential antiproliferation activity against MDA-MB-231 cells (triple-negative breast carcinoma). However, the subcellular target or the detailed mechanism against cancer cell proliferation has not yet been identified. In this study, based on its special structure, a novel series of Eudistomin Y fluorescent derivatives were designed and synthesized by enhancing the electron-donor effect of N-9 to endow it with fluorescent properties through N-alkylation. The structure-activity relationships against the proliferation of cancer cells were also analyzed. A quarter of Eudistomin Y derivatives showed much higher potency against cancer cell proliferation than the original Eudistomin Y₁. Fluorescent derivative H1k with robust antiproliferative activity could arrest MDA-MB-231 cells in the G2-M phase. The subcellular localization studies of the probes, including H1k, and Eudistomin Y1 were performed in MDA-MB-231 cells, and the co-localization and competitive inhibition assays revealed their lysosome-specific localization. Moreover, H1k could dose-dependently increase the autophagy signal and downregulate the expression of cyclin-dependent kinase (CDK1) and cyclin B1 which principally regulated the G2-M transition. Furthermore, the specific autophagy inhibitor 3-methyladenine significantly inhibited the H1k-triggered antiproliferation of cancer cells and the downregulation of CDK1 and cyclin B1. Overall, the lysosome is identified as the subcellular target of Eudistomin Y for the first time, and derivative H1k showed robust antiproliferative activity against MDA-MB-231 cells by decreasing Cyclin B1-CDK1 complex via a lysosome-dependent pathway.

Design, Synthesis, and Anti-Inflammatory Activities of 12-Dehydropyxinol Derivatives

Pyxinol skeleton is a promising framework of anti-inflammatory agents formed in the human liver from 20S-protopanaxadiol, the main active aglycone of ginsenosides. In the present study, a new series of amino acid-containing derivatives were produced from 12-dehydropyxinol, a pyxinol oxidation metabolite, and its anti-inflammatory activity was assessed using an NO inhibition assay. Interestingly, the dehydrogenation at C-12 of pyxinol derivatives improved their potency greatly. Furthermore, half of the derivatives exhibited better NO inhibitory activity than hydrocortisone sodium succinate, a glucocorticoid drug. The structure-activity relationship analysis indicated that the kinds of amino acid residues and their hydrophilicity influenced the activity to a great extent, as did R/S stereochemistry at C-24. Of the various derivatives, 5c with an N-Boc-protected phenylalanine residue showed the highest NO inhibitory activity and relatively low cytotoxicity. Moreover, derivative 5c could dose-dependently suppress iNOS, IL-1β, and TNF-α via the MAPK and NF-κB pathways, but not the GR pathway. Overall, pyxinol derivatives hold potential for application as anti-inflammatory agents.

Synthesis of 1-(5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazol-3-yl)-2-morpholinoethane-1,2-dione analogues and their inhibitory activities with reduced cytotoxicity in lipopolysaccharide-induced BV2 cells

A series of rimonabant analogues, where the N-aminopiperidine moiety was replaced by various amines and an additional carbonyl group, were synthesized and their inhibition of nitric oxide (NO) production was evaluated in lipopolysaccharide (LPS)-induced BV2 microglial cells. Among the synthesized compounds, the morpholine analogue 7y (IC₅₀ = 4.71 ± 0.11 μM) showed significantly higher inhibitory activity than rimonabant (IC₅₀ = 16.17 ± 0.56 μM), and suppressed NO production dose-dependently without cytotoxicity. In addition, 7y inhibited the expression of iNOS, COX-2 and pro-inflammatory cytokines and attenuated LPS-induced activation of nuclear factor-kappa B (NF-κB) and ERK MAPK phosphorylation in BV2 cells. These results demonstrated that 7y exerted anti-inflammatory effects by ERK pathway in BV2 cells, which can be used for the prevention and treatment of neuroinflammatory diseases.

Design, synthesis, and biological evaluation of ocotillol derivatives fused with 2-aminothiazole via A-ring as modulators of P-glycoprotein-mediated multidrug resistance

Overexpression of P-glycoprotein (P-gp) plays a key role in the development of multidrug resistance (MDR), the major reason for the failure of chemotherapy in clinics. Ocotillol and its derivatives had been reported with good P-gp-mediated tumor MDR reversal activity in vitro. Herein, a series of ocotillol derivatives fused with 2-aminothiazole (2-AT) via A-ring were designed and synthesized to further improve the tumor MDR reversal potency. These compounds were evaluated for their MDR reversal activity against the KBV cells by MTT assay. Among them, the most promising derivative against P-gp-mediated MDR was compound 12 with 2-AT and glycine in the A-ring. Rhodamine123 (Rh123) accumulation assay, Western blot assay, and P-gp-Glo™ assay showed that compound 12 efficiently inhibited the efflux function of P-gp by stimulating P-gp ATPase rather than downregulating its expression. Moreover, compound 12 sensitized KBV cells to paclitaxel arrested cells in the G₂/M phase and induced cell apoptosis. Importantly, compound 12 significantly inhibited the growth of KBV cell-derived xenograft tumors in nude mice by increasing the sensitivity of paclitaxel in vivo. Finally, the structure-activity relationships (SARs) of ocotillol derivatives were further investigated. In summary, compound 12 has the potential to overcome MDR in cancer caused by P-gp.

Pseudo-sapogenin DQ 3-mimaleate acid derivative induces ovarian carcinoma cell apoptosis via mitochondrial pathway

In the present study, four novel ginsenosides fatty acid and aromatic acid derivatives were designed and synthesized, and their cytotoxic effects on human ovarian carcinoma cells (SKOV3) were assessed using the MTT assay. The results demonstrated that all derivatives inhibited SKOV3 cell growth, and Compound 3 showed the most outstanding anti-proliferative effect on SKOV3 cells. The IC₅₀ value of Compound 3 was 33.8 ± 2.21 μM, less than half of that of cis-platinum (70.1 ± 7.64 μM). Subsequent analysis revealed that Compound 3 could promote SKOV3 cell apoptosis, and the percentage of apoptotic cell population increased with increasing Compound 3 concentrations. In addition, the expression ratios of Bax/Bcl-2, cleaved-Caspase-3/Caspase-3 and cleaved-Caspase-9/Caspase-9 were gradually elevated in Compound 3-treated SKOV3 cells compared with control cells. Furthermore, translocation of Bax to mitochondria was associated with the release of Cytochrome C. Molecular docking analysis revealed three hydrogen-bonds existed in Compound 3 with PARP receptor (PDB code: 5DSY), which may be the target of the anti-ovarian cancer effect of Compound 3. Altogether, our study indicates that Compound 3 induces SKOV3 cell apoptosis via ROS-dependent mitochondrial pathway, and can serve as an anti-cancer agent for treating ovarian carcinoma.

Synthesis and Antiproliferative Activity of Ester Derivatives of Mogrol through JAK2/STAT3 Pathway

In attempt to enhance the antiproliferative activity of mogrol, two series of ester derivatives modified at C₃ -OH and C₁₁ -OH were designed and synthesized. The activity against human cancer cells including A549, NCI-H460 and CNE1 was screened by Cell Counting Kit-8 (CCK8) assay. According to the results, modifications of the mogrol core through introduction of different ester scaffolds drastically improved the cytotoxicity, and some of the derivatives exhibited even higher activity than the positive drug. Among them, compound M2h exhibited nearly 4 times more cytotoxic than 5-Fu against CNE1 cells, derivative M6c showed ten times higher activity with the IC₅₀ value of 10.59 μM than mogrol against NCI-H460 cells, and compound M6a which contained one 1,2,3-triazole motif showed the strongest activity with an three folds lower IC₅₀ value than mogrol. Furthermore, the most potent compound M2h could lead to cell cycle arrest at G2 phase on CNE1 cell lines and M6a induced G1 phase arrest on A549 cell lines. It was noteworthy that both M2h and M6a regulated signal transducer and activator of transcription 3 (STAT3) signal pathway through inhibiting phosphorylation of Janus Kinase 2 (JAK2) and STAT3, and simultaneously increasing the protein level of downstream cyclin p21.

Pyxinol bearing amino acid residues: Easily achievable and promising modulators of P-glycoprotein-mediated multidrug resistance

The P-glycoprotein (Pgp) is a major transporter involved in multidrug resistance (MDR) of cancer cells leading to chemotherapy failure. In our previous study, we demonstrated that the amide derivatives of pyxinol are promising modulators against Pgp-mediated MDR in cancer. In the present study, we designed and synthesized novel pyxinol derivatives linked to amino acid residues. We evaluated MDR (paclitaxel (Ptx) resistance) reversal potency of forty pyxinol derivatives in KBV cells and analyzed their structure-activity relationships. Half of our derivatives sensitized KBV cells to Ptx at non-toxic concentrations, among which the pyxinol compound bearing a methionine residue (3c) exhibited the best activity in MDR reversal. Compound 3c was found to possess high selectivity toward Pgp and sensitize the KBV cells to Pgp substrates by blocking the efflux function of Pgp. This manifestation may be attributed to its high binding affinity with Pgp, as suggested by docking studies. Overall, the biological profile and ease of synthesizing these pyxinol derivatives render them promising lead compounds for further development for Pgp-mediated MDR.

Synthesis and Anti-Hepatocarcinoma Effect of Amino Acid Derivatives of Pyxinol and Ocotillol

Aiming at seeking an effective anti-hepatocarcinoma drug with low toxicity, a total of 24 amino acid derivatives (20 new along with 4 known derivatives) of two active ocotillol-type sapogenins (pyxinol and ocotillol) were synthesized. Both in vitro and in vivo anti-hepatocarcinoma effects of derivatives were evaluated. At first, the HepG2 human cancer cell was employed to evaluate the anti-cancer activity. Most of the derivatives showed obvious enhanced activity compared with pyxinol or ocotillol. Among them, compound 2e displayed the most excellent activity with an IC₅₀ value of 11.26 ± 0.43 µM. Next, H22 hepatoma-bearing mice were used to further evaluate the anti-liver cancer activity of compound 2e. It was revealed that the growth of H22 transplanted tumor was significantly inhibited when treated with compound 2e or compound 2e combined with cyclophosphamide (CTX) (p < 0.05, p < 0.01), and the inhibition rates of tumor growth were 35.32% and 55.30%, respectively. More importantly, compound 2e caused limited damage to liver and kidney in contrast with CTX causing significant toxicity. Finally, the latent mechanism of compound 2e was explored by serum and liver metabolomics based on ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) technology. A total of 21 potential metabolites involved in 8 pathways were identified. These results suggest that compound 2e is a promising agent for anti-hepato-carcinoma, and that it also could be used in combination with CTX to increase efficiency and to reduce toxicity.

Recent Advances in the Semisynthesis, Modifications and Biological Activities of Ocotillol-Type Triterpenoids

Ginseng is one of the most widely consumed herbs in the world and plays an important role in counteracting fatigue and alleviating stress. The main active substances of ginseng are its ginsenosides. Ocotillol-type triterpenoid is a remarkably effective ginsenoside from Vietnamese ginseng that has received attention because of its potential antibacterial, anticancer and anti-inflammatory properties, among others. The semisynthesis, modification and biological activities of ocotillol-type compounds have been extensively studied in recent years. The aim of this review is to summarize semisynthesis, modification and pharmacological activities of ocotillol-type compounds. The structure-activity relationship studies of these compounds were reported. This summary should prove useful information for drug exploration of ocotillol-type derivatives.