Hederagenin amide derivatives as potential antiproliferative agents

Current Progress of Hederagenin and Its Derivatives for Disease Therapy (2017-Present)

Natural products have emerged as crucial sources of biologically active compounds, holding promise for applications in drug development. Among the extensively researched pentacyclic triterpenes, hederagenin (HG) stands out for its diverse biological activities and serves as a valuable scaffold for synthesizing novel derivatives. These derivatives hold significant promise for the development of novel therapeutic agents aimed at treating a wide range of diseases. Over the past years, a multitude of HG derivatives with varied bioactivities have been synthesized through chemical modifications. This review article consolidates the most recent findings (since 2017) on HG derivatives, emphasizing their biological effects and mechanisms of action in both in vitro and in vivo models. The objective of this compilation is to offer insights and direct future research endeavors in the realm of HG.

An updated review of the pharmacological effects and potential mechanisms of hederagenin and its derivatives

Hederagenin (HG) is a natural pentacyclic triterpenoid that can be isolated from various medicinal herbs. By modifying the structure of HG, multiple derivatives with superior biological activities and safety profiles have been designed and synthesized. Accumulating evidence has demonstrated that HG and its derivatives display multiple pharmacological activities against cancers, inflammatory diseases, infectious diseases, metabolic diseases, fibrotic diseases, cerebrovascular and neurodegenerative diseases, and depression. Previous studies have confirmed that HG and its derivatives combat cancer by exerting cytotoxicity, inhibiting proliferation, inducing apoptosis, modulating autophagy, and reversing chemotherapy resistance in cancer cells, and the action targets involved mainly include STAT3, Aurora B, KIF7, PI3K/AKT, NF-κB, Nrf2/ARE, Drp1, and P-gp. In addition, HG and its derivatives antagonize inflammation through inhibiting the production and release of pro-inflammatory cytokines and inflammatory mediators by regulating inflammation-related pathways and targets, such as NF-κB, MAPK, JAK2/STAT3, Keap1-Nrf2/HO-1, and LncRNA A33/Axin2/β-catenin. Moreover, anti-pathogen, anti-metabolic disorder, anti-fibrosis, neuroprotection, and anti-depression mechanisms of HG and its derivatives have been partially elucidated. The diverse pharmacological properties of HG and its derivatives hold significant implications for future research and development of new drugs derived from HG, which can lead to improved effectiveness and safety profiles.

Advances in the anti-tumor potential of hederagenin and its analogs

Hederagenin is a pentacyclic triterpenoid that is widely distributed as the main pharmaceutical ingredient in various medicinal plants. Similarly as other pentacyclic triterpenoids, hederagenin has various pharmacological effects such as anti-tumor, anti-inflammatory, anti-depressant, and anti-viral activities. In particular, the anti-tumor activity of hederagenin indicates its potential for development into highly effective chemotherapeutic agents. Studies revealed that hederagenin effectively suppresses the growth of various tumor cell lines in vitro and interacts with several molecular targets that play essential roles in various cellular signaling pathways. The compound suppresses transformation, inhibits proliferation, and induces apoptosis in tumor cells. In this review, we highlight research progress on the source, pharmacokinetics, pharmacological activity, and mechanism of action of hederagenin and the anti-tumor activity of its analogs by integrating and analyzing relevant domestic and international studies and providing a basis for their further development and application.

Pharmacological overview of hederagenin and its derivatives

Hederagenin is a pentacyclic triterpenoid isolated from plants and widely distributed in a variety of medicinal plants. By integrating and analyzing external related literature reports, the latest research progress on the pharmacological effects and structural modification of hederagenin was reviewed. Hederagenin has a wide range of pharmacological activities, including antitumor, anti-inflammatory, antidepressant, anti-neurodegenerative, antihyperlipidemic, antidiabetic, anti-leishmaniasis, and antiviral activities. Among them, it shows high potential in the field of anti-tumor treatment. This paper also reviews the structural modifications of hederagenin, including carboxyl group modifications and two hydroxyl group modifications. Future research on hederagenin will focus on prolonging its half-life, improving its bioavailability and structural modification to enhance its pharmacological activity, accelerating the preclinical research stage of hederagenin for it to enter the clinical research stage as soon as possible.

Proteomics identifies differentially expressed proteins in glioblastoma U87 cells treated with hederagenin

OBJECTIVE

We investigated differentially expressed proteins (DEPs) in human glioblastoma U87 cells after treatment with hederagenin as a therapeutic screening mechanism and provided a theoretical basis for hederagenin in treating glioblastoma.

METHODS

The Cell Counting Kit 8 assay was used to analyze the inhibitory effect of hederagenin on the proliferation of U87 cells. Protein was identified by tandem mass tags and LC-MS/MS analysis techniques. Annotation of DEPs, Gene Ontology enrichment and function, and Kyoto Encyclopedia of Genes and Genomes pathways and domains were all examined by bioinformatics. According to the TMT results, hub protein was selected from DEPs for WB verification.

RESULTS

Protein quantitative analysis found 6522 proteins in total. Compared with the control group, 43 DEPs (P < 0.05) were involved in the highly enriched signaling pathway in the hederagenin group, among which 20 proteins were upregulated, and 23 proteins were downregulated. These different proteins are mainly involved in the longness regulating pathway-WORM, the hedgehog signaling pathway, Staphylococcus aureus infection, complement, coagulation cascades, and mineral absorption. KIF7 and ATAD2B expression were significantly down-regulated and PHEX and TIMM9 expression were significantly upregulated, according to WB analysis, supporting the TMT findings.

CONCLUSION

Hederagenin inhibition of GBM U87 cells may be related to KIF7, which is mainly involved in the hedgehog signaling pathway. Our findings lay a foundation for additional study of the therapeutic mechanism of hederagenin.

Novel flavonoid hybrids as potent antiviral agents against hepatitis A: Design, synthesis and biological evaluation

Two series of flavonoid hybrids, totaling 42 compounds, were designed, synthesized and evaluated to develop antiviral compounds effective against hepatitis A virus (HAV). A recombinant viral screening system revealed that most of the synthesized derivatives exhibited significant anti-HAV activity, and compounds B2, B3, B5 and B27 were identified as potential inhibitors of HAV. Post-treatment of cells with B2, B3, B5 and B27 after HAV infection strongly suppressed HAV infection, whereas pretreatment or simultaneous treatment were ineffective. Furthermore, these four compounds significantly inhibited HAV (HM175/18f strain) production in a dose-dependent manner. Analyses using HAV subgenomic replicon systems indicated that these compounds specifically inhibit HAV RNA replication. More importantly, the most potent compounds B2 and B27 also showed clear inhibitory effects on two other HAV strains, KRM031 and TKM005, which also isolated from clinical patients. Our study is the first to report these newly designed flavonoid hybrids as lead compounds for the development of novel anti-HAV drugs.

Madecassic Acid—A New Scaffold for Highly Cytotoxic Agents

Due to their manifold biological activities, natural products such as triterpenoids have advanced to represent excellent leading structures for the development of new drugs. For this reason, we focused on the syntheses and cytotoxic evaluation of derivatives obtained from gypsogenin, hederagenin, and madecassic acid, cytotoxicity increased—by and large—from the parent compounds to their acetates. Another increase in cytotoxicity was observed for the acetylated amides (phenyl, benzyl, piperazinyl, and homopiperazinyl), but a superior cytotoxicity was observed for the corresponding rhodamine B conjugates derived from the (homo)-piperazinyl amides. In particular, a madecassic acid homopiperazinyl rhodamine B conjugate 24 held excellent cytotoxicity and selectivity for several human tumor cell lines. Thus, this compound was more than 10,000 times more cytotoxic than parent madecassic acid for A2780 ovarian cancer cells. We assume that the presence of an additional hydroxyl group at position C–6 in derivatives of madecassic, as well as the (2α, 3β) configuration of the acetates in ring A, had a beneficial effect onto the cytotoxicity of the conjugates, as well as onto tumor/non-tumor cell selectivity.

From Marine Metabolites to the Drugs of the Future: Squalamine, Trodusquemine, Their Steroid and Triterpene Analogues

This review comprehensively describes the recent advances in the synthesis and pharmacological evaluation of steroid polyamines squalamine, trodusquemine, ceragenins, claramine, and their diverse analogs and derivatives, with a special focus on their complete synthesis from cholic acids, as well as an antibacterial and antiviral, neuroprotective, antiangiogenic, antitumor, antiobesity and weight-loss activity, antiatherogenic, regenerative, and anxiolytic properties. Trodusquemine is the most-studied small-molecule allosteric PTP1B inhibitor. The discovery of squalamine as the first representative of a previously unknown class of natural antibiotics of animal origin stimulated extensive research of terpenoids (especially triterpenoids) comprising polyamine fragments. During the last decade, this new class of biologically active semisynthetic natural product derivatives demonstrated the possibility to form supramolecular networks, which opens up many possibilities for the use of such structures for drug delivery systems in serum or other body fluids.

Inhibitory effect of hederagenin on Streptococcus pneumoniae pneumolysin in vitro

Streptococcus pneumoniae is an important pathogen that causes otitis media, pneumonia, meningitis and bacteremia. As an important virulence factors of S. pneumoniae, pneumolysin (PLY) can penetrate cell membranes and lead to cell lysis and inflammation, which is one of the main causes of infection and damage of S. pneumoniae. Therefore, using pneumolysin as a target to study its inhibitors can provide a new treatment strategy for pneumococcal disease. This study analyzed the inhibitory effect of the natural compound hederagenin on PLY in vitro. The results show that hederagenin has great potential as a new strategy for the treatment of pneumococcal diseases.

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.

Chemical modifications of ergostane-type triterpenoids from Antrodia camphorata and their cytotoxic activities

In order to discover potential antitumor agents from natural products, chemical modifications of ergostane-type triterpenoids from Antrodia camphorata yielded ten new compounds. They include nine C-26 amide derivatives of antcin G (1) and a methyl antcin B (4) derivative with hydroxyamino groups at C-3 and C-7. Chemical structures of the new compounds were elucidated by NMR and MS analyses. Furthermore, cytotoxicities of the triterpenoid derivatives were evaluated using four human cancer cell lines (HL60, U251, SW480, and MCF-7). As a result, 1a, 1g, and 4a exhibited potent cytotoxic activities against HL60, U251, and SW480 with IC₅₀ values of 0.7 ± 0.9, 2.9 ± 1.3, and 2.2 ± 0.6 μM, respectively. Molecular docking indicates that 1a, 1g, and 4a have strong binding affinity with DNA topoisomerase IIα (-9.3, -7.9, and -7.4 kcal/mol, respectively), and that they could be potent topoisomerase IIα inhibitors.

Synthesis and biological evaluation of novel withangulatin A derivatives as potential anticancer agents

Novel withangulatin A (WA) derivatives were synthesized and evaluated for antiproliferative activity against four human cancer cell lines (U2OS, MDA-MB-231, HepG2, and A549). Among these derivatives, 10 exhibited the most potent antiproliferative activity, with an IC₅₀ value of 74.0 nM against the human breast cancer cell line MDA-MB-231 and potency that was 70-fold that of WA (IC₅₀ = 5.22 µM). Moreover, 10 caused G2-phase cell cycle arrest in a concentration-dependent manner and induced the apoptosis of MDA-MB-231 cells by increasing intracellular reactive oxygen species (ROS). Compound 10 showed a high selectivity index (SI = 267.03) for breast cancer MDA-MB-231 cells. These results suggest that 10 is a promising anticancer agent.

Design, synthesis, and biological evaluation of hederagenin derivatives with improved aqueous solubility and tumor resistance reversal activity

Multidrug resistance (MDR) has become a major obstacle to malignancies treatment by chemotherapeutic drugs, therefore, it is important to develop MDR reversal agents with high activity. We have previously found that the hederagenin (HD) derivative HBQ showed good tumor MDR reversal activity in vitro and in vivo but had poor solubility. In this study, to enhance the aqueous solubility and tumor MDR reversal activity of HBQ, three series of HD derivatives were designed and synthesized. Nitrogen-containing heterocyclic-substituted, PEGylated, and ring-A substituted derivatives significantly reversed the MDR phenotype of KBV (multidrug-resistant oral epidermoid carcinoma) cells toward paclitaxel at a concentration of 10 μM in MTT assays. The PEGylated derivatives 10c-10e had increased aqueous solubility compared with HBQ by 18-657 fold, while maintaining tumor MDR reversal activity. The most in vitro active compound 10c possessed good chemical stability to an esterase over 24 h and enhanced the sensitivity of KBV cells to paclitaxel and vincristine with IC₅₀ values of 4.58 and 0.79 nM, respectively. Mechanism studies indicated that compound 10c increased the accumulation of P-glycoprotein (P-gp) substrates rhodamine 123 and Flutax1 in KBV cells and MCF-7T (paclitaxel-resistant breast carcinoma) cells, that is to say, compound 10c exerted the reversal effect of tumor MDR by inhibiting the efflux function of P-gp. Finally, the structure-activity relationships were further investigated by analyzing the relationship between structure and tumor MDR reversal activity of HD derivatives. This study highlights the potential of PEGylated HD derivatives such as compound 10c for the development of tumor MDR reversal agents and provides information for the further improvement of the aqueous solubility and tumor MDR reversal activity of HD derivatives in the future.

Cyclometalated Ir(III)-8-oxychinolin complexes acting as red-colored probes for specific mitochondrial imaging and anticancer drugs

A new class of luminescent Ir^III antitumor agents, namely, [Ir(CP1)(PY1)₂] (Ir-1), [Ir(CP1)(PY2)₂] (Ir-2), [Ir(CP1)(PY4)₂] (Ir-3), [Ir(CP2)(PY1)₂] (Ir-4), [Ir(CP2)(PY4)₂] (Ir-5), [Ir(CP3)(PY1)₂]⋅CH₃OH (Ir-6), [Ir(CP4)(PY4)₂]⋅CH₃OH (Ir-7), [Ir(CP5)(PY2)₂] (Ir-8), [Ir(CP5)(PY4)₂]⋅CH₃OH (Ir-9), [Ir(CP6)(PY1)₂] (Ir-10), [Ir(CP6)(PY2)₂]⋅CH₃OH (Ir-11), [Ir(CP6)(PY3)₂] (Ir-12), [Ir(CP6)(PY41)₂] (Ir-13), and [Ir(CP7)(PY1)₂] (Ir-14), supported by 8-oxychinolin derivatives and 1-phenylpyrazole ligands was prepared. Compared with SK-OV-3/DDP and HL-7702 cells, the Ir-1-Ir-14 compounds exhibited half maximal inhibitory concentration (IC₅₀) values within the high nanomolar range (50 nM-10.99 μM) in HeLa cells. In addition, Ir-1 and Ir-3 accumulated and stained the mitochondrial inner membrane of HeLa cells with high selectivity and exhibited a high antineoplastic activity in the entire cervical HeLa cells, with IC₅₀ values of 1.22 ± 0.36 μM and 0.05 ± 0.04 μM, respectively. This phenomenon induced mitochondrial dysfunction, suggesting that these cyclometalated Ir^III complexes can be potentially used in biomedical imaging and Ir(III)-based anticancer drugs. Furthermore, the high cytotoxicity activity of Ir-3 is correlated with the 1-phenylpyrazole (H-PY4) secondary ligands in the luminescent Ir^III antitumor complex.

Design and synthesis of pentacyclic triterpene conjugates and their use in medicinal research

Triterpenoids are natural products from plants and many other organisms that have various biological activities, such as antitumor, antiviral, antimicrobial, and protective activities. This review covers the synthesis and biological evaluation of pentacyclic triterpene (PT) conjugates with other molecules that have been found to increase the IC₅₀ or improve the pharmacological profile of the parent PT. Some of these molecules are designed to target specific proteins or cellular organelles, which has resulted in highly selective lead structures for drug development. Other PT conjugates are useful for investigating their mechanism of action. This concept has been very successful: 1) Many compounds, especially mitochondria-targeting PT conjugates, have reached a selective cytotoxicity at low nanomolar concentrations in cancer cells. 2) A number of PT conjugates have had high activity against HIV or the influenza virus. 3) Fluorescent PT conjugates have been able to visualize the PT in living cells, which has allowed quantification of the uptake and distribution of the PT within the cell. 4) Biotinylated PT conjugates have been used to identify target proteins, which may help to show their mechanism of action. 5) A large number of PT conjugates with polyethylene glycol (PEG), polyamines, etc. form nanometer-sized micelles that have a much better pharmacological profile than the PT alone. In summary, the connection of a PT to an appropriate modifying molecule has resulted in extremely useful semisynthetic compounds with a high potential to treat cancer or viral infections or compounds that are useful for the study of the mechanism of action of PTs at the molecular level.

Synthesis of gypsogenin and gypsogenic acid derivatives with antitumor activity by damaging cell membranes

Forty-five gypsogenin and gypsogenic acid derivatives were synthesized and screened for their cytotoxic activities.