Cucurbitacin B purified from Ecballium elaterium (L.) A. Rich from Tunisia inhibits α5β1 integrin-mediated adhesion, migration, proliferation of human glioblastoma cell line and angiogenesis

Squirting Cucumber, Ecballium elaterium (L.) A. Ritch: An Update of Its Chemical and Pharmacological Profile

Ecballium elaterium, also known as squirting cucumber, is a plant which is widespread in temperate regions of Europe, Africa and Asia. The plant is considered to be one of the oldest used drugs. In the last decades, E. elaterium has been widely studied as a source of triterpene metabolites named cucurbitacins, often found as glycosylated derivatives, used by the plant as defensive agents. Such metabolites exhibit several biological activities, including cytotoxic, anti-inflammatory, and anti-cancer. Interestingly, the bioactive properties of E. elaterium extracts have been investigated in dozens of studies, especially by testing the apolar fractions, including the essential oils, extracted from leaves and fruits. The purpose of this review is to provide an overview of the chemical profile of different parts of the plants (leaves, flowers, and seeds) analyzing the methods used for structure elucidation and identification of single metabolites. The pharmacological studies on the isolated compounds are also reported, to highlight their potential as good candidates for drug discovery.

Regulation of neuroinflammation in Alzheimer's disease via nanoparticle-loaded phytocompounds with anti-inflammatory and autophagy-inducing properties

BACKGROUND

Alzheimer's disease (AD) is characterized by neuroinflammation linked to amyloid β (Aβ) aggregation and phosphorylated tau (τ) protein in neurofibrillary tangles (NFTs). Key elements in Aβ production and NFT assembly, like γ-secretase and p38 mitogen-activated protein kinase (p38MAPK), contribute to neuroinflammation. In addition, impaired proteosomal and autophagic pathways increase Aβ and τ aggregation, leading to neuronal damage. Conventional neuroinflammation drugs have limitations due to unidirectional therapeutic approaches and challenges in crossing the Blood-Brain Barrier (BBB). Clinical trials for non-steroidal anti-inflammatory drugs (NSAIDs) and other therapeutics remain uncertain. Novel strategies addressing the complex pathogenesis and BBB translocation are needed to effectively tackle AD-related neuroinflammation.

PURPOSE

The current scenario demands for a much-sophisticated theranostic measures which could be achieved via customized engineering and designing of novel nanotherapeutics. As, these therapeutics functions as a double edge sword, having the efficiency of unambiguous targeting, multiple drug delivery and ability to cross BBB proficiently.

METHODS

Inclusion criteria involve selecting recent, English-language studies from the past decade (2013-2023) that explore the regulation of neuroinflammation in neuroinflammation, Alzheimer's disease, amyloid β, tau protein, nanoparticles, autophagy, and phytocompounds. Various study types, including clinical trials, experiments, and reviews, were considered. Exclusion criteria comprised non-relevant publication types, studies unrelated to Alzheimer's disease or phytocompounds, those with methodological flaws, duplicates, and studies with inaccessible data.

RESULTS

In this study, polymeric nanoparticles loaded with specific phytocompounds and coated with an antibody targeting the transferrin receptor (anti-TfR) present on BBB. Thereafter, the engineered nanoparticles with the ability to efficiently traverse the BBB and interact with target molecules within the brain, could induce autophagy, a cellular process crucial for neuronal health, and exhibit potent anti-inflammatory effects. Henceforth, the proposed combination of desired phytocompounds, polymeric nanoparticles, and anti-TfR coating presents a promising approach for targeted drug delivery to the brain, with potential implications in neuroinflammatory conditions such as Alzheimer's disease.

Recent Advances in the Application of Cucurbitacins as Anticancer Agents

Cucurbitacins are tetracyclic triterpenoid secondary metabolites, widely distributed in the Cucurbitaceae family. These bitter-tasting compounds act primarily as defense mechanisms against external injuries, and thus against herbivores, and furthermore, they have also found use in folk medicine in the treatment of various diseases. Many studies have acknowledged significant biological activities of cucurbitacins, such as antioxidant and anti-inflammatory activities, antimicrobial properties, or antitumor potential. Overall, cucurbitacins have the ability to inhibit cell proliferation and induce apoptosis in various cancer cell lines. Both in vitro and in vivo studies were performed to evaluate the anticancer activity of varied cucurbitacins. Cucurbitacins offer a promising avenue for future cancer treatment strategies, and their diverse mechanisms of action make them attractive candidates for further investigation. The aim of the present study is to shed light on the chemical diversity of this group of compounds by providing the sources of origin of selected compounds and their chemical structure, as well as insight into their anticancer potential. In addition, within this paper molecular targets for cucurbitacins and signalling pathways important for cancer cell proliferation and/or survival that are affected by the described class of compounds have been presented.

Identification and quantification of cucurbitacin in watermelon frost using molecular networking integrated with ultra-high-performance liquid chromatography-tandem mass spectrometry

Watermelon frost, a traditional Chinese medicine produced using watermelon and Glauber's salt, has been widely used for the therapy of oral and throat disorders. Watermelon contains various phytochemical compounds including cucurbitacins and their glycoside derivatives, which have attracted considerable attention because of their medicinal values. However, whether the composition of cucurbitacins existed in watermelon frost was rarely reported. In this study, three cucurbitacins including cucurbitacin B, isocucurbitacin B, and cucurbitacin E were found from watermelon frost extract assisted by ultra-high-performance liquid chromatography-tandem mass spectrometry and molecular networking guided strategy, and the compounds were verified using standard solutions. Furthermore, a quantification method for simultaneously targeted analysis of cucurbitacins was established using ultra-high-performance liquid chromatography-tandem mass spectrometry operating in the multiple reaction monitoring mode. Among them, cucurbitacin B and cucurbitacin E in watermelon frost samples were determined, and the concentrations were 3.78 ± 0.18 and 0.86 ± 0.19 ng/ml, respectively. While isocucurbitacin B was not detected due to the lower content possibly. In conclusion, ultra-high-performance liquid chromatography-tandem mass spectrometry combined with molecular networking is a very useful technique for the rapid identification of unknown cucurbitacin components in watermelon frost.

Effects of Dietary Phytochemicals on DNA Damage in Cancer Cells

With the increasing incidence of cancer worldwide, the prevention and treatment of cancer have garnered considerable scientific attention. Traditional chemotherapeutic drugs are highly toxic and associated with substantial side effects; therefore, there is an urgent need for developing new therapeutic agents. Dietary phytochemicals are important in tumor prevention and treatment because of their low toxicity and side effects at low concentrations; however, their exact mechanisms of action remain obscure. DNA damage is mainly caused by physical or chemical factors in the environment, such as ultraviolet light, alkylating agents and reactive oxygen species that cause changes in the DNA structure of cells. Several phytochemicals have been shown inhibit the occurrence and development of tumors by inducing DNA damage. This article reviews the advances in phytochemical research; particularly regarding the mechanisms related to DNA damage and provide a theoretical basis for future chemoprophylaxis research.

Cucurbitacins as potential anticancer agents: new insights on molecular mechanisms

Since ancient times, plants have been an extensive reservoir of bioactive compounds with therapeutic interest for new drug development and clinical application. Cucurbitacins are a compelling example of these drug leads, primarily present in the plant kingdom, especially in the Cucurbitaceae family. However, these natural compounds are also known in several genera within other plant families. Beyond the Cucurbitaceae family, they are also present in other plant families, as well as in some fungi and one shell-less marine mollusc. Despite the natural abundance of cucurbitacins in different natural species, their obtaining and isolation is limited, as a result, an increase in their chemical synthesis has been developed by researchers. Data on cucurbitacins and their anticancer activities were collected from databases such as PubMed/MedLine, TRIP database, Web of Science, Google Scholar, and ScienceDirect and the information was arranged sequentially for a better understanding of the antitumor potential. The results of the studies showed that cucurbitacins have significant biological activities, such as anti-inflammatory, antioxidant, antimalarial, antimicrobial, hepatoprotective and antitumor potential. In conclusion, there are several studies, both in vitro and in vivo reporting this important anticancer/chemopreventive potential; hence a comprehensive review on this topic is recommended for future clinical research.

Inhibitory effect of phenolic extract from squirting cucumber (Ecballium elaterium (L.) A. Rich) seed oil on integrin-mediated cell adhesion, migration and angiogenesis

Integrin targeted therapies by natural bioactive compounds have attracted attention in the field of oncology and cancer treatment. This study evaluates the potential of phenolic extract from the medicinal herb Ecballium elaterium L. seed oil (PEO) to inhibit the adhesion and migration of the highly invasive human fibrosarcoma cell line HT1080. At safe concentrations (up to 40 μg mL-1), results show that PEO dose-dependently inhibits adhesion and migration of HT1080 to fibronectin (IC50 = 18 μg mL-1) and fibrinogen (IC50 = 12.86 μg mL-1). These observations were associated with the reduction of cell motility and migration velocity as revealed in the Boyden chamber and random motility using two-dimensional assays, respectively. Additional experiments using integrin blocking antibodies showed that PEO at the highest safe concentration (40 μg mL-1) competitively inhibited the attachment of HT1080 cell to anti-αvβ3 (>98%), anti-α5β1 (>86%), and to a lesser extent anti-α2 (>50%) immobilized antibodies, suggesting that αvβ3 and α5β1 integrins were selectively targeted by PEO. Moreover, PEO specifically targeted these integrins in human microvascular endothelial cells (HMEC-1) and dose-dependently blocked the in vitro tubulogenesis. In the CAM model, PEO inhibited the VEGF-induced neoangiogenesis confirming its anti-angiogenic effect. Collectively, these results indicate that PEO holds promise for the development of natural integrin-targeted therapies against fibrosarcoma.

Pharmacokinetics and Biological Activity of Cucurbitacins

Cucurbitacins are a class of secondary metabolites initially isolated from the Cucurbitaceae family. They are important for their analgesic, anti-inflammatory, antimicrobial, antiviral, and anticancer biological actions. This review addresses pharmacokinetic parameters recently reported, including absorption, metabolism, distribution, and elimination phases of cucurbitacins. It includes recent studies of the molecular mechanisms of the biological activity of the most studied cucurbitacins and some derivatives, especially their anticancer capacity, to propose the integration of the pharmacokinetic profiles of cucurbitacins and the possibilities of their use. The main botanical genera and species of American origin that have been studied, and others whose chemo taxonomy makes them essential sources for the extraction of these metabolites, are summarized.

Cucurbitacins Elicit Anti-Platelet Activity via Perturbation of the Cytoskeleton and Integrin Function

Cucurbitacins are dietary compounds that have been shown to elicit a range of anti-tumour, anti-inflammatory and anti-atherosclerotic activities. Originally identified as signal transducer and activator of transcription, STAT, inhibitors, a variety of mechanisms of action have since been described, including dysregulation of the actin cytoskeleton and disruption of integrin function. Integrin outside-in signalling and cytoskeletal rearrangements are critical for the propagation of stable thrombus formation and clot retraction following platelet adhesion at the site of vessel damage. The effects of cucurbitacins on platelet function and thrombus formation are unknown. We report for the first time anti-platelet and anti-thrombotic effects of cucurbitacins B, E and I in human platelets. Treatment of platelets with cucurbitacins resulted in attenuation of platelet aggregation, secretion and fibrinogen binding following stimulation by platelet agonists. Cucurbitacins were also found to potently inhibit other integrin- and cytoskeleton-mediated events, including adhesion, spreading and clot retraction. Further investigation of cytoskeletal dynamics found treatment with cucurbitacins altered cofilin phosphorylation, enhanced activation and increased F actin polymerisation and microtubule assembly. Disruption to cytoskeletal dynamics has been previously shown to impair integrin activation, platelet spreading and clot retraction. Anti-platelet properties of cucurbitacins were found to extend to a disruption of stable thrombus formation, with an increase in thrombi instability and de-aggregation under flow. Our research identifies novel, anti-platelet and anti-thrombotic actions of cucurbitacins that appear to be linked to dysregulation of cytoskeletal dynamics and integrin function.

Cucurbitacins: Nature’s Wonder Molecules

Abstract:

Over the past decades, several natural constituents belonging to different classes have been isolated from plants for medicinal purposes. Cucurbitacins is one such type of natural compound. Cucurbitacin is any of a class of biochemical compounds that some plants notably members of the pumpkin and gourd family, Cucurbitaceae produce and which function as a defense against herbivores. They and their derivatives have been found in many plant families (including Brassicaceae, Cucurbitaceae, Scrophulariaceae, Begoniaceae, Elaeocarpaceae, Datiscaceae, Desfontainiaceae, Polemoniaceae, Primulaceae, Rubiaceae, Sterculiaceae, Rosaceae, and Thymelaeaceae), in some mushrooms (including Russula and Hebeloma) and even in some marine mollusks. They have been isolated from various plant species, chiefly belonging to the Cucurbitaceae family which comprises around 130 genera and 800 species. Cucurbitacins are a group of tetracyclic triterpenoid substances that are highly oxygenated and contain a cucurbitane skeleton characterized by 9β-methyl−19-norlanosta-5-ene. Cucurbitacins can be categorized into twelve main groups according to variations in their side-chains. Cucurbitacins A, B, C, D, E, F, I, J, K, L, O, P, Q, R, S, and their glycosides are mainly found in Cucurbitaceae family members. These plants have been used as folk medicines in some countries because of their broad spectrum of crucial pharmacological activities such as anti-inflammatory, anti-cancer, anti-diabetic, and anti-atherosclerotic effects. The present review explores the possibility of a correlation between the chemistry of various Cucurbitacins and the uses of the plants which contain them, thereby opening avenues for further phytochemical, ethnomedicinal, and modern pharmacological research on these important molecules.

Inhibition of the HIF-1 Survival Pathway as a Strategy to Augment Photodynamic Therapy Efficacy

Photodynamic therapy (PDT) is a non-to-minimally invasive treatment modality that utilizes photoactivatable drugs called photosensitizers to disrupt tumors with locally photoproduced reactive oxygen species (ROS). Photosensitizer activation by light results in hyperoxidative stress and subsequent tumor cell death, vascular shutdown and hypoxia, and an antitumor immune response. However, sublethally afflicted tumor cells initiate several survival mechanisms that account for decreased PDT efficacy. The hypoxia inducible factor 1 (HIF-1) pathway is one of the most effective cell survival pathways that contributes to cell recovery from PDT-induced damage. Several hundred target genes of the HIF-1 heterodimeric complex collectively mediate processes that are involved in tumor cell survival directly and indirectly (e.g., vascularization, glucose metabolism, proliferation, and metastasis). The broad spectrum of biological ramifications culminating from the activation of HIF-1 target genes reflects the importance of HIF-1 in the context of therapeutic recalcitrance. This chapter elaborates on the involvement of HIF-1 in cancer biology, the hypoxic response mechanisms, and the role of HIF-1 in PDT. An overview of inhibitors that either directly or indirectly impede HIF-1-mediated survival signaling is provided. The inhibitors may be used as pharmacological adjuvants in combination with PDT to augment therapeutic efficacy.

Understanding the role of integrins in breast cancer invasion, metastasis, angiogenesis, and drug resistance

Integrins are cell adhesion receptors, which are typically transmembrane glycoproteins that connect to the extracellular matrix (ECM). The function of integrins regulated by biochemical events within the cells. Understanding the mechanisms of cell growth by integrins is important in elucidating their effects on tumor progression. One of the major events in integrin signaling is integrin binding to extracellular ligands. Another event is distant signaling that gathers chemical signals from outside of the cell and transmit the signals upon cell adhesion to the inside of the cell. In normal breast tissue, integrins function as checkpoints to monitor effects on cell proliferation, while in cancer tissue these functions altered. The combination of tumor microenvironment and its associated components determines the cell fate. Hypoxia can increase the expression of several integrins. The exosomal integrins promote the growth of metastatic cells. Expression of certain integrins is associated with increased metastasis and decreased prognosis in cancers. In addition, integrin-binding proteins promote invasion and metastasis in breast cancer. Targeting specific integrins and integrin-binding proteins may provide new therapeutic approaches for breast cancer therapies. This review will examine the current knowledge of integrins' role in breast cancer.

Targeted Modulation of FAK/PI3K/PDK1/AKT and FAK/p53 Pathways by Cucurbitacin B for the Antiproliferation Effect Against Human Cholangiocarcinoma Cells

Inadequate responses to traditional chemotherapeutic agents in cholangiocarcinoma (CCA) emphasize a requirement for new effective compounds for the treatment of this malignancy. This study aimed to investigate the antiproliferative property of cucurbitacin B on KKU-100 CCA cells. The determination of underlying molecular mechanisms was also carried out. The results revealed that cucurbitacin B suppressed growth and replicative ability to form colonies of CCA cells, suggesting the antiproliferative effect of this compound against the cells. Flow cytometry analysis demonstrated that the interfering effect of cucurbitacin B on the CCA cell cycle at the G2/M phase was accountable for its antiproliferation property. Accompanied with cell cycle disruption, cucurbitacin B altered the expression of proteins involved in the G2/M phase transition including downregulation of cyclin A, cyclin D1, and cdc25A, and upregulation of p21. Additional molecular studies demonstrated that cucurbitacin B suppressed the activation of focal adhesion kinase (FAK) which consequently resulted in inhibition of its kinase-dependent and kinase-independent downstream targets contributing to the regulation of cell proliferation including PI3K/PDK1/AKT and p53 proteins. In this study, the transient knockdown of FAK using siRNA was employed to ascertain the role of FAK in CCA cell proliferation. Finally, the effect of cucurbitacin B on upstream receptor tyrosine kinases regulating FAK activation was elucidated. The results showed that the inhibitory effect of cucurbitacin B on FAK activation in CCA cells is mediated via interference of EGFR and HER2 expression. Collectively, cucurbitacin B might be a promising drug for CCA treatment by targeting FAK protein.

In Vitro and In Vivo Antitumor Activity of Cucurbitacin C, a Novel Natural Product From Cucumber

Cucurbitacin C (CuC), a novel analogue of triterpenoids cucurbitacins, confers a bitter taste in cucumber. Genes and signaling pathways responsive for biosynthesis of CuC have been identified in the recent years. In the present study, we explored the anti-cancer effects of CuC against human cancers in vitro and in vivo. CuC inhibited proliferation and clonogenic potential of multiple cancer cells in a dose-dependent manner. Low-dose CuC treatment induced cell cycle arrest at G1 or G2/M stage in different cancer lines, whereas high-dose treatment of CuC caused apoptosis in cancer cells. PI3K-Akt signaling pathway was found to be one of the major pathways involved in CuC-induced cell growth arrest and apoptosis by RNA-Seq and Western blotting. Mechanistic dissection further confirmed that CuC effectively inhibited the Akt signaling by inhibition of Akt phosphorylation at Ser473. In vivo CuC treatment (0.1 mg/kg body weight) effectively inhibited growth of cancer cell-derived xenograft tumors in athymic nude mice and caused significant apoptosis. Our findings for the first time demonstrated the potential therapeutic significance of CuC against human cancers.

Anti-Stress and Glial Differentiation Effects of a Novel Combination of Cucurbitacin B and Withanone (CucWi-N): Experimental Evidence

Background

Natural extracts and compounds used in traditional home medicine are known for their safety and a variety of health promoting and therapeutic potentials. In contrast to the single molecule mediated targets, the combinational therapies are preferred for their multi-functional and limited toxic regimens and may be useful for disease therapeutics as well as to increase the quality of life during a variety of environmental stresses.

Purpose

We aimed to combine the active ingredients of Chinese (Helicteres angustifolia) and Indian (Withania somnifera) ginsengs to develop a natural, efficient, and welfare combinatorial mixture with high anti-stress and glial differentiation potentials.

Methods

Using cultured cells as a model system, we developed a combination of active ingredients of Chinese (Cucurbitacin B [Cuc]) and Indian (Withanone [Wi-N]) ginsengs. Eleven chemical models of environmental stresses were used. Cytotoxicity studies were performed using human skin fibroblast for anti-stress and rat glioma cells for glial differentiation effects.

Results

We demonstrate that the novel combination of Cuc and Wi-N, CucWi-N, was non-toxic to normal cells. It caused stress protection in assays using normal human fibroblasts subjected to a variety of stresses. Of note, cells showed remarkable protection against oxidative and UV stresses and marked by decrease in DNA damage and reactive oxygen species. We examined and found the glial differentiation potential of CucWi-N in rat glioblastoma cells. CucWi-N clearly induced differentiation phenotype, well-marked with upregulation of GAP43, MAP2, and GFAP, which have been shown to play a key role in glial differentiation.

Conclusion

These data demonstrate anti-stress and glial differentiation potential of CucWi-N (a novel combination of Cuc and Wi-N) that could be recruited in nutraceutical and pharmaceutical avenues and hence warrant further evaluation and mechanistic studies.

Naturally occurring cell adhesion inhibitors

This paper reviews naturally occurring cell adhesion inhibitors derived from a plant, microbial and marine origin. Plant-derived inhibitors are classified according to a type of structure. Microbially and marine-derived inhibitors were described according to age. In addition, effects of inhibitors on cell proliferation and that of standards on cell adhesion are listed as much as possible.

Cucurbitacin B and cancer intervention: Chemistry, biology and mechanisms (Review)

Cancer is one of the most important healthcare matters, with the worst prognosis but the best possibilities for scientific development. It is likely to increase in the future and cause global havoc designating it as an epidemic. Cancer development requires urgent intervention. Past few decades have witnessed extensive research to challenge carcinogenesis. Treatment involving synthetic discipline is often associated with severe adverse effects, or even worsened prognosis. Accordingly, newer economic and patient friendly molecules are warranted. Many natural substances have proved their potential so far. Cucurbitacin B against cancer and other diseases has achieved towering popularity among the researchers around the world, as detailed in the below sections with summarized tables. In line with the fascinating role of cucurbitacin B against various types of cancers, through various molecular signaling pathways, it is justifiable to propose cucurbitacin B as a mainline chemotherapy before the onset and after the diagnosis of cancer.