Pentacyclic Triterpenoid Phytochemicals with Anticancer Activity: Updated Studies on Mechanisms and Targeted Delivery

Blocking the PD-1 signal transduction by occupying the phosphorylated ITSM recognition site of SHP-2

Targeting the PD-1/PD-L1 axis with small-molecular inhibitors is a promising approach for immunotherapy. Here, we identify a natural pentacyclic triterpenoid, Pygenic Acid A (PA), as a PD-1 signaling inhibitor. PA exerts anti-tumor activity in hPD-1 knock-in C57BL/6 mice and enhances effector functions of T cells to promote immune responses by disrupting the PD-1 signaling transduction. Furthermore, we identify SHP-2 as the direct molecular target of PA for inhibiting the PD-1 signaling transduction. Subsequently, mechanistic studies suggest that PA binds to a new druggable site in the phosphorylated PD-1 ITSM recognition site of SHP-2, inhibiting the recruitment of SHP-2 by PD-1. Taken together, our findings demonstrate that PA has a potential application in cancer immunotherapy and occupying the phosphorylated ITSM recognition site of SHP-2 may serve as an alternative strategy to develop PD-1 signaling inhibitors. In addition, our success in target recognition provides a paradigm of target identification and confirmation for natural products.

Synthesis and Characterization of PEGylated Liposomes and Nanostructured Lipid Carriers with Entrapped Bioactive Triterpenoids: Comparative Fingerprints and Quantification by UHPLC-QTOF-ESI+-MS, ATR-FTIR Spectroscopy, and HPLC-DAD

Background/Objectives: Pentacyclic triterpenoids, as bioactive phytochemicals, have proven to exhibit significant bioactivity (antioxidant, anti-inflammatory, hypoglycemic, and anticancer) and low cytotoxicity. This study developed convenient methods for extracting and characterizing a birch bark extract enriched in pentacyclic triterpenoids (betulin, betulinic acid, and lupeol) and entrapped in two bioavailable nanoformulations. The performance of ATR-FTIR spectroscopy as a cost-effective and non-destructive method was evaluated comparatively with accurate HPLC-based methods. Methods: The bark extract and pure betulin or betulinic acid were used to obtain PEGylated liposomes and nano lipid carriers (NLCs). Their size was characterized by light scattering diffraction. UV-Vis spectrometry was applied as a preliminary evaluation (1), as well as UHPLC-QTOF-ESI+-MS for structure identification (2), ATR-FTIR spectroscopy (for semi-quantitative evaluation) (3), and HPLC-DAD for an accurate quantification of each component, either in the organic solvents or in the nanoformulations (4). Results: The PEGylated liposomes had smaller sizes, and higher entrapment efficiency, significantly correlated between the three analytical methods. The performance of ATR-FTIR spectroscopy was positively correlated with HPLC-DAD data and confirmed the potential of this cheaper and reliable semi-quantitative method to evaluate the entrapment efficiency of TTs in liposome and NLC nanoformulations. Conclusions: The results recommend using liposomal nanoformulations for the entrapment of bioactive terpenoids and their characterization by ATR-FTIR after validation by HPLC-DAD. The ATR-FTIR spectroscopy also offers the possibility of screening in a short time different recipes of nanoformulations as well as their stability and bioavailability, which is useful for investigations in vitro and in vivo, which may confirm their efficacy as therapeutic agents.

The Role of Pentacyclic Triterpenoids in Non-Small Cell Lung Cancer: The Mechanisms of Action and Therapeutic Potential

Lung cancer remains a major global health problem because of its high cancer-related mortality rate despite advances in therapeutic approaches. Non-small cell lung cancer (NSCLC), a major subtype of lung cancer, is more amenable to surgical intervention in its early stages. However, the prognosis for advanced NSCLC remains poor, owing to limited treatment options. This underscores the growing need for novel therapeutic strategies to complement existing treatments and improve patient outcomes. In recent years, pentacyclic triterpenoids, a group of natural compounds, have emerged as promising candidates for cancer therapy due to their anticancer properties. Pentacyclic triterpenoids, such as lupeol, betulinic acid, betulin, oleanolic acid, ursolic acid, glycyrrhetinic acid, glycyrrhizin, and asiatic acid, have demonstrated the ability to inhibit cell proliferation and angiogenesis, induce apoptosis, suppress metastasis, and modulate inflammatory and immune pathways in NSCLC cell line models. These compounds exert their effects by modulating important signaling pathways such as NF-κB, PI3K/Akt, and MAPK. Furthermore, advances in drug delivery technologies such as nanocarriers and targeted delivery systems have improved the bioavailability and therapeutic efficacy of triterpenoids. However, despite promising preclinical data, rigorous clinical trials are needed to verify their safety and efficacy. This review explores the role of triterpenoids in NSCLC and therapeutic potential in preclinical models, focusing on their molecular mechanisms of action.

Liposomal and Nanostructured Lipid Nanoformulations of a Pentacyclic Triterpenoid Birch Bark Extract: Structural Characterization and In Vitro Effects on Melanoma B16-F10 and Walker 256 Tumor Cells Apoptosis

Background/Objectives: Pentacyclic triterpenoids are increasingly studied as anticancer agents with many advantages compared to synthetic chemotherapeutics. The aim of this study was to prepare liposomal and nanostructured lipid formulations including a standardized extract of silver birch (Betula pendula) outer bark (TTs) and to evaluate their potential as anticancer agents in vitro, using Melanoma B16-F10 and Walker carcinoma cells. Methods: Appropriate solvents were selected for efficient TTs extraction, and original recipes were used to obtain Pegylated liposomes and nanolipid complexes with entrapped TTs, comparative to pure standards (betulinic acid and doxorubicin) in similar conditions. The composition, morphology, and sizes of all nanoformulations were checked by high-performance liquid chromatography/mass spectrometry, Transmission Electronic Microscopy, and Diffraction Light Scattering. The entrapment efficiency and its impact on cell viability, cell cycle arrest, and apoptosis by flow cytometry was also measured on both cancer cell lines. Conclusions: The standardized TTs, including betulin, lupeol, and betulinic acid, showed good stability and superior activity compared to pure betulinic acid. According to experimental data, TTs showed good entrapment in liposomal and NLC nanoformulations, both delivery systems including natural, biodegradable ingredients and enhanced bioavailability. The apoptosis and necrosis effects were more pronounced for TTs liposomal formulations in both types of cancer cells, with lower cytotoxicity compared to Doxorubicin, and can be correlated with their increased bioavailability.

Anticoccidial activity of the secondary metabolites in alpine plants frequently ingested by wild Japanese rock ptarmigans

The Japanese rock ptarmigan (Lagopus muta japonica) is an herbivorous species of partridges that inhabits only alpine zones. Alpine plants are their main source of food. These alpine plants contain toxic compounds to deter herbivores from consuming them. A previous analysis of the alpine plants frequently consumed by Japanese rock ptarmigans revealed the presence of a unique mixture of secondary metabolites and a novel compound. Additionally, wild Japanese rock ptarmigans are often infected by two species of Eimeria parasites. When these parasites were experimentally administered to Svalbard rock ptarmigans (Lagopus muta hyperborean), which do not feed on alpine plants, the birds exhibited symptoms, such as diarrhea and depression, and in some cases, they died. Although little is known about the pathogenesis of these parasites in wild Japanese rock ptarmigans, it was hypothesized that compounds found in alpine plants, their main food source, may reduce the pathogenicity of Eimeria parasites. In the present study, we evaluated the anticoccidial activity of the compounds derived from alpine plants in vitro using Eimeria tenella, which infects chickens belonging to the same pheasant family, as an experimental model. Twenty-seven natural components were extracted from eight alpine plants. The natural components were added to E. tenella sporozoites and incubated for 24 h to evaluate their direct effect. Additionally, Madin-Darby bovine kidney cells were incubated with sporozoites and natural components for 24 h to evaluate the inhibitory effect of the components on sporozoite cell invasion. Six compounds from four alpine plants decreased sporozoite viability by up to 88.3%, and two compounds inhibited sporozoite invasion into the cells. Although further studies are needed to evaluate the effects of these components against Eimeria infections in vivo, our findings suggest that these alpine plants may reduce the degree of infection by decreasing the number of sporozoites in the intestinal tract.

Study of Pentacyclic Triterpenes from Lyophilised Aguaje: Anti-Inflammatory and Antioxidant Properties

Mauritia flexuosa (M. flexuosa), commonly known as Aguaje or Moriche palm, is traditionally recognised in South America for its medicinal properties, particularly for its anti-inflammatory and antioxidant effects. However, the bioactive compounds responsible for these effects have not been thoroughly investigated. This study aims to isolate and characterise pentacyclic triterpenoid compounds from M. flexuosa and to evaluate their therapeutic potential. Using various chromatographic and spectroscopic techniques including Nuclear Magnetic Resonance (NMR) and Mass Spectrometry (MS), three pentacyclic triterpenoid compounds were successfully isolated. Among them, compound 1 (3,11-dioxours-12-en-28-oic acid) exhibited notable bioactivity, significantly inhibiting the activation of Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-κB) (IC50 = 7.39-8.11 μM) and of Nitric Oxide (NO) (IC50 = 4.75-6.59 μM), both of which are key processes in inflammation. Additionally, compound 1 demonstrated potent antioxidant properties by activating the antioxidant enzyme Superoxide Dismutase (SOD) (EC50 = 1.87 μM) and the transcription factor Nuclear factor erythroid 2-related factor 2 (Nrf2) (EC50 = 243-547.59 nM), thus showing its potential in combating oxidative stress. This study is the first to isolate and characterise the three compounds from M. flexuosa, suggesting that compound 1 could be a promising candidate for the development of safer and more effective therapies for inflammatory and oxidative stress-related diseases.

Synthesis and comparative analysis of the cytotoxicity and mitochondrial effects of triphenylphosphonium and F16 maslinic and corosolic acid hybrid derivatives

The cytotoxic profile and antiproliferative and mitochondrial effects of triterpene acid conjugates with mitochondriotropic lipophilic triphenylphosphonium (TPP+) and F16 cations were evaluated. Maslinic and corosolic acids chosen as the investigation objects were synthesized from commercially available oleanolic and ursolic acids. Study of the cytotoxic activity of TPP+ and F16 triterpenoid derivatives against six tumor cell lines demonstrated a comparable synergistic effect in the anticancer activity, which was most pronounced in the case of MCF-7 mammary adenocarcinoma cells and Jurkat and THP-1 leukemia cells. The corosolic and maslinic acid hybrid derivatives caused changes in the progression of tumor cell cycle phases when present in much lower doses than their natural triterpene acid precursors. The treatment of tumor cell lines with the conjugates resulted in the cell cycle arrest in the G1 phase and increase in the cell population in the subG1 phase. The cationic derivatives of the acids were markedly superior to their precursors as inducers of hyperproduction of reactive oxygen species and more effectively decreased the mitochondrial potential in isolated rat liver mitochondria. We concluded that the observed cytotoxic effect of TPP+ and F16 triterpenoid conjugates is attributable to the ability of these compounds to initiate mitochondrial dysfunctions. Their cytotoxicity, antiproliferative action, and mitochondrial effects depend little on the type of cationic groups used.

Cellular and molecular mechanisms underlying the potential of betulinic acid in cancer prevention and treatment

BACKGROUND

Betulinic acid (BA), which is a pentacyclic triterpenoid found in the bark of plane, birch, and eucalyptus trees, has emerged as a compound of significant interest in scientific research due to its potential therapeutic applications. BA has a range of well-documented pharmacological and biological effects, including antibacterial, immunomodulatory, diuretic, antiviral, antiparasitic, antidiabetic, and anticancer activities. Although numerous research studies have explored the potential anticancer effects of BA, there is a noticeable gap in the literature, highlighting the need for a more up-to-date and comprehensive evaluation of BA's anticancer potential.

PURPOSE

The aim of this work is to critically assess the reported cellular and molecular mechanisms underlying the cancer preventive and therapeutic effects of BA.

METHODS

Relevant research on the inhibitory effects of BA against cancerous cells was searched using Science Direct, Scopus, Web of Science, and PubMed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

The anticancer properties of BA are mediated by the activation of cell death and cell cycle arrest, production of reactive oxygen species, increased mitochondrial permeability, modulation of nuclear factor-κB and Bcl-2 family signaling. Emerging evidence also underscores the combined anticancer effects of BA with other natural bioactive compounds or approved drugs. Notably, several novel BA nanoformulations have been found to exhibit encouraging antineoplastic activities.

CONCLUSION

BA, whether used alone or in combination, or as a form of nanoformulation, shows significant potential for cancer prevention and treatment. Nevertheless, further detailed studies are necessary to confirm the therapeutic effectiveness of this natural compound.

The Influence of Betulin and Its Derivatives on Selected Colorectal Cancer Cell Lines' Viability and Their Antioxidant Systems

Oxidative stress is considered one of the main reasons for the development of colorectal cancer (CRC). Depending on the stage of the disease, variable activity of the main antioxidant enzymes, i.e., superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), is observed. Due to limited treatment methods for CRC, new substances with potential antitumor activity targeting pathways related to oxidative stress are currently being sought, with substances of natural origin, including betulin, leading the way. The betulin molecule is chemically modified to obtain new derivatives with improved pharmacokinetic properties and higher biological activity. The aim of this study was to evaluate the effects of betulin and its new derivatives on viability and major antioxidant systems in colorectal cancer cell lines. The study showed that betulin and its derivative EB5 affect the antioxidant enzyme activity to varying degrees at both the protein and mRNA levels. The SW1116 cell line is more resistant to the tested compounds than RKO, which may be due to differences in the genetic and epigenetic profiles of these lines.

Drug Delivery Systems of Betulin and Its Derivatives: An Overview

Natural origin products are regarded as promising for the development of new therapeutic therapies with improved effectiveness, biocompatibility, reduced side effects, and low cost of production. Betulin (BE) is very promising due to its wide range of pharmacological activities, including its anticancer, antioxidant, and antimicrobial properties. However, despite advancements in the use of triterpenes for clinical purposes, there are still some obstacles that hinder their full potential, such as their hydrophobicity, low solubility, and poor bioavailability. To address these concerns, new BE derivatives have been synthesized. Moreover, drug delivery systems have emerged as a promising solution to overcome the barriers faced in the clinical application of natural products. The aim of this manuscript is to summarize the recent achievements in the field of delivery systems of BE and its derivatives. This review also presents the BE derivatives mostly considered for medical applications. The electronic databases of scientific publications were searched for the most interesting achievements in the last ten years. Thus far, it is mostly nanoparticles (NPs) that have been considered for the delivery of betulin and its derivatives, including organic NPs (e.g., micelles, conjugates, liposomes, cyclodextrins, protein NPs), inorganic NPs (carbon nanotubes, gold NPs, silver), and complex/hybrid and miscellaneous nanoparticulate systems. However, there are also examples of microparticles, gel-based systems, suspensions, emulsions, and scaffolds, which seem promising for the delivery of BE and its derivatives.

Tuning of the Anti-Breast Cancer Activity of Betulinic Acid via Its Conversion to Ionic Liquids

Betulinic acid (BA) is a natural pentacyclic triterpene with diverse biological activities. However, its low water solubility limits its pharmaceutical application. The conversion of pharmaceutically active molecules into ionic liquids (ILs) is a promising strategy to improve their physicochemical properties, stability, and/or potency. Here, we report the synthesis and characterization of 15 novel ILs containing a cation ethyl ester of a polar, non-polar, or charged amino acid [AAOEt] and an anion BA. Except for [ValOEt][BA], we observed preserved or up to 2-fold enhanced cytotoxicity toward hormone-dependent breast cancer cells MCF-7. The estimated IC50 (72 h) values within the series varied between 4.8 and 25.7 µM. We found that the most cytotoxic IL, [LysOEt][BA]2, reduced clonogenic efficiency to 20% compared to that of BA. In addition, we evaluated the effect of a 72 h treatment with BA or [LysOEt][BA]2, the most cytotoxic compound, on the thermodynamic behavior of MCF-7 cells. Based on our data, we suggest that the charged amino acid lysine included in the novel ILs provokes cytotoxicity by a mechanism involving alteration in membrane lipid organization, which could be accompanied by modulation of the visco-elastic properties of the cytoplasm.

Enhanced Cytotoxicity and Antimelanoma Activity of Novel Semisynthetic Derivatives of Betulinic Acid with Indole Conjugation

The prevalence and severity of skin cancer, specifically malignant melanoma, among Caucasians remains a significant concern. Natural compounds from plants have long been explored as potential anticancer agents. Betulinic acid (BI) has shown promise in its therapeutic properties, including its anticancer effects. However, its limited bioavailability has hindered its medicinal applications. To address this issue, two recently synthesized semisynthetic derivatives, N-(2,3-indolo-betulinoyl)diglycylglycine (BA1) and N-(2,3-indolo-betulinoyl)glycylglycine (BA2), were compared with previously reported compounds N-(2,3-indolo-betulinoyl)glycine (BA3), 2,3-indolo-betulinic acid (BA4), and BI. These compounds were evaluated for their effects on murine melanoma cells (B164A5) using various in vitro assays. The introduction of an indole framework at the C2 position of BI resulted in an increased cytotoxicity. Furthermore, the cytotoxicity of compound BA4 was enhanced by conjugating its carboxylic group with an amino acid residue. BA2 and BA3, with glycine and glycylglycine residues at C28, exhibited approximately 2.20-fold higher inhibitory activity compared to BA4. The safety assessment of the compounds on human keratinocytes (HaCaT) has revealed that concentrations up to 10 µM slightly reduced cell viability, while concentrations of 75 µM resulted in lower cell viability rates. LDH leakage assays confirmed cell membrane damage in B164A5 cells when exposed to the tested compounds. BA2 and BA3 exhibited the highest LDH release, indicating their strong cytotoxicity. The NR assay revealed dose-dependent lysosome disruption for BI and 2,3-indolo-betulinic acid derivatives, with BA1, BA2, and BA3 showing the most cytotoxic effects. Scratch assays demonstrated concentration-dependent inhibition of cell migration, with BA2 and BA3 being the most effective. Hoechst 3342 staining revealed that BA2 induced apoptosis, while BA3 induced necrosis at lower concentrations, confirming their anti-melanoma properties. In conclusion, the semisynthetic derivatives of BI, particularly BA2 and BA3, show promise as potential candidates for further research in developing effective anti-cancer therapies.

Synthesis, Pharmacological Properties, and Potential Molecular Mechanisms of Antitumor Activity of Betulin and Its Derivatives in Gastrointestinal Cancers

Gastrointestinal (GI) cancers are an increasingly common type of malignancy, caused by the unhealthy lifestyles of people worldwide. Limited methods of treatment have prompted the search for new compounds with antitumor activity, in which betulin (BE) is leading the way. BE as a compound is classified as a pentacyclic triterpene of the lupane type, having three highly reactive moieties in its structure. Its mechanism of action is based on the inhibition of key components of signaling pathways associated with proliferation, migration, interleukins, and others. BE also has a number of biological properties, i.e., anti-inflammatory, hepatoprotective, neuroprotective, as well as antitumor. Due to its poor bioavailability, betulin is subjected to chemical modifications, obtaining derivatives with proven enhanced pharmacological and pharmacokinetic properties as a result. The method of synthesis and substituents significantly influence the effect on cells and GI cancers. Moreover, the cytotoxic effect is highly dependent on the derivative as well as the individual cell line. The aim of this study is to review the methods of synthesis of BE and its derivatives, as well as its pharmacological properties and molecular mechanisms of action in colorectal cancer, hepatocellular carcinoma, gastric cancer, and esophageal cancer neoplasms.