Antiproliferative and immunomodulative potential of Citrullus colocynthis and its bioactive compounds in human lymphocytes and lung cells

ETHNOPHARMACOLOGICAL RELEVANCE

Citrullus colocynthis (L.) Schrad is a member of the Cucurbitaceae plant family which has been used in traditional medicine for the treatment of lung diseases such as asthma and bronchitis.

AIM OF THE STUDY

The study was conducted to investigate antiproliferative and immunomodulating effects of C. colocynthis and isolated cucurbitacins on human T lymphocytes and lung epithelial cells in order to evaluate their potential in the treatment of airway diseases.

MATERIALS AND METHODS

Different concentrations of an ethanolic extract of C. colocynthis fruits and cucurbitacins B (CuB), E (CuE) and E-glucopyranoside (CuE-Glu) were analysed for their cytotoxicity and immunomodulatory potential on Peripheral Blood Mononuclear Cells (PBMCs) of healthy donors and on the epithelial lung cancer cell line A549. Viability and proliferation were tested using WST1 and CFSE assays. Flow cytometric analysis of AnnexinV/PI staining was used to investigate cell death through apoptosis/necrosis. Effects on regulatory mechanisms of T lymphocytes, such as CD69 and CD25 marker activation, cytokine production of the cytokines interleukin 2 (IL2), tumor necrosis factor α (TNFα) and interferon γ (IFNy) were also analysed via flow cytometry. Influences on the activator protein 1 (AP1), nuclear factor of activated T-cells (NFAT) or nuclear factor 'kappa-light-chain-enhancer' of activated B-cells (NFκB) pathways were analysed in the Jurkat reporter cell line. Cytokine secretion in A549 cells stimulated with virus-like particles was analysed using the bead-based Legendplex™ assay.

RESULTS

Non-toxic concentrations of C. colocynthis and CuE-Glu showed dose-dependent effects on viability and proliferation in both T lymphocytes and A549 cells. The extracts inhibited lymphocyte activation and suppressed T cell effector functions, which was also shown by lower production of cytokines IL2, TNFα and IFNy. A dose dependent inhibition of the pathways NFκB, NFAT and AP1 in Jurkat cells could be observed. In A549 cells, especially CuE and CuE-Glu showed inhibitory effects on cytokine production following a simulated viral infection. Unglycosylated cucurbitacins were more effective in suppressing the immune function in lymphocytes than glycosylated cucurbitacins, however this activity is limited to cytotoxic concentrations.

CONCLUSION

In our study we could confirm the immunmodulating effect of C. colocynthis and cucurbitacins B, E and E-glucopyranoside in vitro by suppression of different pathways of inflammation and T cell proliferation. Activity in a lung cell model using a virus-like stimulation shows promise for further research regarding cucurbitacins in airway diseases.

Apoptotic and antimetastatic effect of cucurbitacins in cancer: recent trends and advancement

The Cucurbitaceae family produces a class of secondary metabolites known as cucurbitacins. The eight cucurbitacin subunits are cucurbitacin B, D, E, I, IIa, L glucoside, Q, and R with the most significant anticancer activity. They are reported to inhibit cell proliferation, invasion, and migration; induce apoptosis; and encourage cell cycle arrest, as some of their modes of action. The JAK-STAT3, Wnt, PI3K/Akt, and MAPK signaling pathways, which are essential for the survival and apoptosis of cancer cells, have also been shown to be suppressed by cucurbitacins. The goal of the current study is to summarize potential molecular targets that cucurbitacins could inhibit in order to suppress various malignant processes. The review is noteworthy since it presents all putative molecular targets for cucurbitacins in cancer on a single podium.

Heterodimers with a cucurbitane-type triterpenoid skeleton from the branches of Elaeocarpus dubius

Four undescribed and two known cucurbitane-type triterpenoids, including two heterodimers, elaeocarpudubins A and B, were isolated from the branches of Elaeocarpus dubius (Elaeocarpaceae). The chemical structures of these undescribed isolates were determined by analyses of 1D and 2D NMR and MS data, electronic circular dichroism (ECD) calculations, and chemical transformation. Biogenetically, elaeocarpudubins A and B might be derived from cucurbitacin F through Michael addition with vitamin C and (-)-catechin, respectively. These six isolates were evaluated for their cytotoxic activities against human leukemia HL-60, human lung adenocarcinoma A549, human hepatoma SMMC-7721, human breast cancer MCF-7, human colon cancer SW480, and paclitaxel-resistant A549 (A549/Taxol) cell lines, for their antioxidant properties using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, and for their differentiation effects on nerve growth factor (NGF)-mediated neurite outgrowth in rat pheochromocytoma PC12 cells. Cucurbitacins F (IC₅₀ of 4.98-38.11 μM) and D (IC₅₀ of 0.03-4.40 μM) showed growth-inhibitory activities against these six cancer cell lines. Elaeocarpudubin B (IC₅₀ of 61.04 μM) and elaeocarpudoside B (IC₅₀ of 6.93 μM) showed antioxidant activities. Elaeocarpudubin B and elaeocarpudoside B also showed neurite outgrowth-promoting activities in PC12 cells at a concentration of 10 μM.

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.

Xuedan Sustained Release Pellets Ameliorate Dextran Sulfate Sodium-Induced Ulcerative Colitis in Rats by Targeting Gut Microbiota and MAPK Signaling Pathways

Cucurbitacins have a variety of bioactivities, such as anticancer, anti-inflammatory, antidepressant-like, and antiviral effects, but their pharmacological effect in ulcerative colitis (UC) has not been reported until now. Thus, this study aims to investigate the preventive effects of Xuedan sustained release pellets (XSPs) on UC rats and the underlying mechanisms. XSPs were prepared by extracting cucurbitacins from Hemsleya. Experimental UC rats were induced by the intake of 4% dextran sulfate sodium (DSS) for a week and treated with different doses of XSP (0.95, 1.90, and 3.8 mg/kg). The body weight, colon length, disease activity index (DAI), and histological changes of colonic tissue were measured. In addition, the expressions of pro-inflammatory cytokines were detected by using the enzyme-linked immunosorbent assay. Pathways involved in the intestinal inflammation were targeted by RNA-sequencing. Moreover, the changes of gut microbial diversity and composition were analyzed by the 16SrNA analysis and the contents of short-chain fatty acids (SCFAs) were detected by GC-MS. The results revealed that XSP intervention greatly restored the weight loss and colonic shortening (p < 0.05) and reduced the raised DAI scores, myeloperoxidase, and nitric oxide activities in UC in rats (p < 0.05). XSP administration also downregulated the protein levels of pro-inflammatory factors IL-1β, IL-6, and TNF-α. Notably, it was found that XSP considerably suppressed the activation of the MAPK signaling pathway. In addition, XSP treatment improved the balance of gut microbiota that was disturbed by DSS. The beneficial bacteria Lachnospiraceae_NK4A136 group and Lactobacillus at the genus level significantly increased in the XSP group, which had decreased with the use of DSS (p < 0.05). Pathogenic bacteria including Escherichia-Shigella and Bacteroides in UC in rats were reduced by XSP intervention. Furthermore, XSP significantly elevated the production of SCFAs in UC in rats (p < 0.05). These alterations in inflammatory status were accompanied with changes in gut microbiota diversity and SCFA production. In conclusion, XSP exhibited protective effects against DSS-induced UC in rats. XSP treatment decreased inflammation via modulation of gut microbiota composition and SCFA production.

Cucurbitacins and the Immune System: Update in Research on Anti-inflammatory, Antioxidant, and Immunomodulatory Mechanisms

Cucurbitacins are a wide group of natural products found in several plant families, especially in the Cucurbitaceae family. In the last decade, there has been a significant increase in studies aimed at identifying new biological activities of cucurbitacins and describing their mechanisms of action. The most researched pharmacological activities are antineoplastic and anti-inflammatory activity, the first being recently reviewed. The present review explains the anti-inflammatory, antioxidant, and immunomodulatory potential of cucurbitacins, identifying the most studied compounds in this area and exploring their mechanisms of action already studied. A brief report was made about the main structural characteristics of cucurbitacins, in addition to an update on the biological activities attributed to this class in the last 5 years. Cucurbitacin B and cucurbitacin E have been identified as the most investigated when it comes to the immune response, playing roles in both innate and adaptive immunity. The most cited mechanisms were inhibition of COX-2 and NOS, reduction of oxidative stress, suppression of proinflammatory cytokines and modulation of acquired immunity proteins. It was found that cucurbitacins are promising molecules in the search for therapeutic innovation and have wide versatility in the immune response.

Pentacyclic and hexacyclic cucurbitacins from Elaeocarpuspetiolatus

Four undescribed cucurbitacins, designated as petiolaticins A-D, and four known cucurbitacins were isolated from the bark and leaves of Elaeocarpus petiolatus (Jack) Wall. Their chemical structures were elucidated based on detailed analyses of the NMR and MS data. The absolute configuration of petiolaticin A was also determined by X-ray diffraction analysis. Petiolaticin A represents a cucurbitacin derivative incorporating a 3,4-epoxyfuranyl-bearing side chain, while petiolaticin B possesses a furopyranyl unit fused to the tetracyclic cucurbitane core structure. Petiolaticins A, B, and D were evaluated in vitro against a panel of human breast, pancreatic, and colorectal cancer cell lines. Petiolaticin A exhibited the greatest cytotoxicity against the MDA-MB-468, MDA-MB-231, MCF-7, and SW48 cell lines (IC₅₀ 7.4, 9.2, 9.3, and 4.6 μM, respectively). Additionally, petiolaticin D, 16α,23α-epoxy-3β,20β-dihydroxy-10αH,23βH-cucurbit-5,24-dien-11-one, and 16α,23α-epoxy-3β,20β-dihydroxy-10αH,23βH-cucurbit-5,24-dien-11-one 3-O-β-_D-glucopyranoside were tested for their ability to inhibit cell entry of a pseudotyped virus bearing the hemagglutinin envelope protein of a highly pathogenic avian influenza virus. Petiolaticin D showed the highest inhibition (44.3%), followed by 16α,23α-epoxy-3β,20β-dihydroxy-10αH,23βH-cucurbit-5,24-dien-11-one (21.0%), and 16α,23α-epoxy-3β,20β-dihydroxy-10αH,23βH-cucurbit-5,24-dien-11-one 3-O-β-_D-glucopyranoside showed limited inhibition (9.0%). These preliminary biological assays have demonstrated that petiolaticins A and D possess anticancer and antiviral properties, respectively, which warrant for further investigations.

An integrated transcriptome and metabolome approach reveals the accumulation of taste-related metabolites and gene regulatory networks during watermelon fruit development

Accumulation patterns and gene regulatory networks of sugars and cucurbitacins and related primary and secondary metabolites during cultivated watermelon 'Cheng Lan' and wild watermelon 'PI 632,751' fruit development were identified. Metabolites are the end products of cellular regulatory processes and play important roles in fruit taste formation. However, comprehensive studies on the accumulation patterns of watermelon fruit metabolites and transcriptional regulatory networks are still scarce. In this study, 451 annotated metabolites were identified at four key fruit developmental stages in wild watermelon 'PI 632,751' and modern cultivated watermelon 'Cheng Lan'. Interestingly, 11 sugars and 25 major primary metabolites were mainly accumulated in 'Cheng Lan' during fruit development, which are considered to be the potential metabolites beneficial to the formation of watermelon taste. Cucurbitacins and the main flavonoids were mainly specifically accumulated in 'PI 632,751', not being considered to be responsible for the taste. Moreover, forty-seven genes involved in carbohydrate metabolism, glycolysis, and TCA cycle were highly expressed in 'Cheng Lan', which was positively correlated with the accumulation of major primary metabolites. Alternatively, seven UDP-glycosyltransferase genes are closely related to the glycosylation of cucurbitacins through co-expression analysis. Our findings established a global map of metabolite accumulation and gene regulation during fruit development in wild and cultivated watermelons and provided valuable information on taste formation in watermelon fruit.

Antiproliferative activity of standardized phytopreparations from Ibervillea sonorae (S. Watson) Greene

Ibervillea sonorae (Cucurbitaceae) is a medicinal plant utilized in Northwest Mexico against Diabetes and cancer. This natural product is taken orally, its presentation is capsules containing the plant's dried and powdered caudices. There is no regulation or standardized dosage that allows reproducibility of its pharmacological effects. Cucurbitacins are the main group of compounds found in I. sonorae and are known for their antiproliferative activity in cancer cells. Cucurbitacin IIb (CIIb), one of the compounds present in I. sonorae, has demonstrated in experimental models with HeLa cervical cancer cells an apoptotic and anti-tumoral activity. The objective of this study is to obtain and standardize two phytopreparations of I. sonorae based on their CIIb content, evaluate their antiproliferative activity in cancer cell lines, and compare the results with those obtained with CIIb; expecting to find phytopreparations with anti-cancer potential. APCI-IT-MSn is utilized for the identification of cucurbitacins, FT-ICR-MS/MS for the quantification of CIIb, and the MTT assay for the evaluation of the antiproliferative activity. The CIIb content was 0.67% for Fito-Ison-EtOH and 1.84% for Fito-Ison-EtOAc. In both phytopreparations, six cucurbitacins have been identified, and a seventh one not previously identified. Phytopreparations were more effective against HeLa, with IC₅₀ of 30.0 and 18.6 µg/mL for Fito-Ison-EtOH and Fito-Ison-EtOAc, respectively. This effect is lower than observed on CIIb in HeLa (5.8 µg/mL). There are no significant differences (p > 0.05) in the antiproliferative activity between Fito-Ison-EtOAc and CIIb in A549, LS180, and MDA-MB-231 cells. Phytopreparations of I. sonorae have potential for the development of anti-cancer products.

A Citrullus colocynthis fruit extract acutely enhances insulin-induced GLUT4 translocation and glucose uptake in adipocytes by increasing PKB phosphorylation

ETHNOPHARMACOLOGICAL RELEVANCE

Citrullus colocynthis (L.) Schrad is a common fruit in traditional medicine and used as remedy against various diseases, especially diabetes. Up to now, its anti-diabetic effects have been fully attributed to its enhancement of pancreatic insulin secretion. Whether C. colocynthis also ameliorates insulin action in peripheral tissues has not been investigated.

AIM OF THE STUDY

In the present study, using 3T3-L1 adipocytes as cell model, we have investigated whether colocynth fruit extracts affect insulin action.

MATERIALS AND METHODS

Various extracts were prepared from the C. colocynthis fruit and screened using a cell-based 96 well plate GLUT4 translocation assay. Promising extracts were further studied for their effects on glucose uptake and cell viability. The effect on insulin signal transduction was determined by Western blot and the molecular composition was established by LC-MS.

RESULTS

The ethyl acetate fractions of aqueous non-defatted extracts of seed and pulp, designated Sna1 and Pna1, acutely enhanced insulin-induced GLUT4 translocation. In accordance, both extracts increased insulin-stimulated cellular glucose uptake. Pna1, which displayed greater effects on GLUT4 and glucose uptake than Sna1, was further investigated and was demonstrated to increase GLUT4 translocation without changing the half-maximum dose (ED50) of insulin, nor changing GLUT4 translocation kinetics. At the molecular level, Pna1 was found to enhance insulin-induced PKB phosphorylation without changing phosphorylation of the insulin receptor. Pna1 appeared not to be toxic to cells and, like insulin, restored cell viability during serum starvation. By investigating the molecular composition of Pna1, nine compounds were identified that made up 87% of the mass of the extract, one of which is likely to be responsible for the insulin-enhancing effects of Pna1.

CONCLUSIONS

The C. colocynthis fruit possesses insulin-enhancing activity. This activity may explain in part its anti-diabetic effects in traditional medicine. It also identifies the C. colocynthis as a source of a potential novel insulin enhancer that may prove to be useful to reduce hyperglycemia in type 2 diabetes.

Use of cucurbitacins for lung cancer research and therapy

As the main substance in some traditional Chinese medicines, cucurbitacins have been used to treat hepatitis for decades in China. Currently, the use of cucurbitacins against cancer and other diseases has achieved towering popularity among researchers worldwide, as detailed in this review with summarized tables. Numerous studies have reported the potential tumor-killing activities of cucurbitacins in multiple aspects of human malignancies. Continuous research on its anticancer activity mechanisms also brings a glimmer of light to the treatment of patients with lung cancer. In line with the promising roles of cucurbitacins against cancer, through various molecular signaling pathways, it is justifiable to propose the use of cucurbitacins as a potential mainline chemotherapy before the onset and after the diagnosis of lung cancers. Here, this article mainly summarized the findings about the biological functions and underlying mechanisms of cucurbitacins on lung cancer pathogenesis and treatment. In addition, we also discussed the safety and efficacy of their application for further research and even clinical practice.

Phytomedicinal relevance of South African Cucurbitaceae species and their safety assessment: A review

ETHNOPHARMACOLOGICAL RELEVANCE

South Africa has a very rich flora. Many of these species such as those in the Cucurbitaceae family are exploited as medicines for the treatment of various infections.

AIM OF THE REVIEW

The aim of the review was to synthesize the existing but scattered literature of some plant species in the Cucurbitaceae family used as sources of medicines in South Africa.

MATERIALS AND METHODS

A literature survey was carried out on the ethnopharmacology, phytochemistry, pharmacological relevance and safety assessment of the South African Cucurbitaceae used as medicines.

RESULTS

A total of 11 plants namely; Coccinia rehmannii Cogn., Cucumis africanus L.f., Cucumis anguria L. var. longaculeatus J.H.Kirkbr., Cucumis myriocarpus Naudin subsp. myriocarpus, Cucumis zeyheri Sond., Cucumis metuliferus E. Mey ex Naudin, Kedrostis nana (Lam) Cogn., Lagenaria siceraria (Molina) Standl., Momordica balsamina L., Momordica charantia L., and Momordica foetida Schumach. and Thonn were identified. Various traditional medicinal uses for these plants, from common ailments to life-threatening infections were reported. Biological activities including antidiabetic, antioxidant, antimicrobial, anticancer, anti-inflammatory and hepatoprotective were reported. However, some of the plants have not been investigated for some of the biological activities related to their traditional uses. In addition, most of the studies were carried out using non-standardized extracts. Thus, only a few studies on their bioactive constituents exist. Common compounds identified within the species are hydroxycinnamic and hydroxybenzoic acids such as sinapic, gallic, vanillic and salicylic acids; flavonoids such as naringenin, quercetin, kaempferol and rutin; fatty acids such as linoleic, palmitoleic, myristic and stearic acids; the saponin glycosides, momordicin alkaloids and cucurbitacins. However, most of these compounds have not been tested for biological activities. Cucurbitacins were implicated as a major class of toxic compounds present in the plants resulting in poisoning and death.

CONCLUSIONS

Adequate knowledge of the traditional use of these plants in medicine and the parts used are very important due to the presence of toxic substances and their wide usage. Proper screening of the safety of these plants and products derived from them calls for urgent attention.

Fruits

Fruits come in a wide variety of colors, shapes, and flavors. This chapter will cover selected fruits that are known to be healthy and highly nutritious. These fruits were chosen due to their common usage and availability. Since it is not possible to cover all health benefits or essential nutrients and important phytochemicals of the fruit composition, this chapter will focus on the key valuable constituents and their potential health effects.

Identification and characterization of the Cucurbitacins, a novel class of small-molecule inhibitors of Tropomyosin receptor kinase a

Background

NGF-TrkA is well known to play a key role in propagating and sustaining pruritogenic signals, which form the pathology of chronic pruritus. Inhibition of NGF-TrkA is a known strategy for the treatment of pruritus. In the present paper, we describe the identification, in vitro characterization, structure–activity analysis, and inhibitory evaluation of a novel TrkA inhibitory scaffold exemplified by Cucurbitacins (Cus).

Methods

Cus were identified as TrkA inhibitors in a large-scale kinase library screen. To obtain structural models of Cus as TrkA inhibitors, AutoDock was used to explore their binding to TrkA. Furthermore, PC12 cell culture systems have been used to study the effects of Cus and traditional Chinese medicinal plants (Tian Gua Di and bitter gourd leaf) extracts on the kinase activity of TrkA.

Results

Cus block the phosphorylation of TrkA on several tyrosine sites, including Tyr490, Tyr674/675, and Tyr785, and inhibit downstream Akt and MAPK phosphorylation in response to NGF in PC12 cell model systems. Furthermore, traditional Chinese medicinal plants (Tian Gua Di and bitter gourd leaf) containing Cu extracts were shown to inhibit the phosphorylation of TrkA and Akt. These data reveal mechanisms, at least partly, of the anti-pruritus bioactivity of Cus.

Conclusion

Taken together, with the recent discovery of the important role of TrkA as a therapeutic target, Cus could be the basis for the design of improved TrkA kinase inhibitors, which could someday help treat pruritus.

(CuEC) exert a hypotensive effect via regulating vascular tone

As an effective medicine for jaundice in traditional Chinese medicine, Cucumis melo L. has been widely used in China. However, its effect on vascular function is still unclear. In this study, we extracted the compounds of Cucumis melo L., and the major ingredients were identified as cucurbitacins (CuEC, cucurbitacins extracted from Cucumis melo L.), especially cucurbitacin B. We replicated the toxicity in mice by intraperitoneal injection of a high dose of CuEC (2 mg/kg) and demonstrated that the cause of death was CuEC-induced impairment of the endothelial barrier and, thus, increased vascular permeability via decreasing VE-cadherin conjunction. The administration of low doses of CuEC (1 mg/kg) led to a decline in systolic blood pressure (SBP) without causing toxicity in mice. More importantly, CuEC dramatically suppressed angiotensin II (Ang II)-induced SBP increase. Further studies demonstrated that CuEC facilitated acetylcholine-mediated vasodilation in mesenteric arteries of mice. In vitro studies showed that CuEC induced vasodilation in a dose-dependent manner in mesenteric arteries of both mice and rats. Pretreatment with CuEC inhibited phenylephrine-mediated vasoconstriction. In summary, a moderate dose of CuEC reduced SBP by improving blood vessel tension. Therefore, our study provides new experimental evidence for developing new antihypertensive drugs.

Isolation of anticancer constituents from Cucumis prophetarum var. prophetarum through bioassay-guided fractionation

BACKGROUND

Cucumis prophetarum var. prophetarum is used in Saudi folk medicine for treating liver disorders and grows widely between Abha and Khamis Mushait City, Saudi Arabia.

METHODS

Bioassay-guided fractionation and purification were used to isolate the main active constituents of Cucumis prophetarum var. prophetarum fruits. These compounds were structurally elucidated using NMR spectroscopy, mass spectral analyses and x-ray crystallography. All fractions, sub-fractions and pure compounds were screened for their anticancer activity against six cancer cell lines.

RESULTS

The greatest cytotoxic activity was found to be in the ethyl acetate fraction, resulting in the isolation of five cucurbitacin compounds [E, B, D, F-25 acetate and Hexanorcucurbitacin D]. Among the cucurbitacins that were isolated and tested cucurbitacin B and E showed potent cytotoxicity activities against all six human cancer cell lines.

CONCLUSION

Human breast cancer cell lines were found to be the most sensitive to cucurbitacins. Preliminary structure activity relationship (SAR) for cytotoxic activity of Cucurbitacins against human breast cancer cell line MDA-MB-231 has been reported.

Cucurbitacins: elucidation of their interactions with the cytoskeleton

Cucurbitacins, a class of toxic tetracyclic triterpenoids in Cucurbitaceae, modulate many molecular targets. Here we investigated the interactions of cucurbitacin B, E and I with cytoskeletal proteins such as microtubule and actin filaments. The effects of cucurbitacin B, E and I on microtubules and actin filaments were studied in living cells (Hela and U2OS) and in vitro using GFP markers, immunofluorescence staining and in vitro tubulin polymerization assay. Cucurbitacin B, E and I apparently affected microtubule structures in living cells and cucurbitacin E inhibited tubulin polymerization in vitro with IC50 value of 566.91 ± 113.5 µM. Cucurbitacin E did not affect the nucleation but inhibited the growth phase and steady state during microtubule assembly in vitro. In addition, cucurbitacin B, E and I all altered mitotic spindles and induced the cell cycle arrest at G2/M phase. Moreover, they all showed potent effects on actin cytoskeleton by affecting actin filaments through the depolymerization and aggregation. The interactions of cucubitacin B, E and I with microtubules and actin filaments present new insights into their modes of action.

Cucurbitacins: A Systematic Review of the Phytochemistry and Anticancer Activity

Cucurbitacins are highly oxidized tetracyclic triterpenoids that are widely present in traditional Chinese medicines (Cucurbitaceae family), possess strong anticancer activity, and are divided into 12 classes from A to T with over 200 derivatives. The eight most active cucurbitacin components against cancer are cucurbitacin B, D, E, I, IIa, L glucoside, Q, and R. Their mechanisms of action include antiproliferation, inhibition of migration and invasion, proapoptosis, and cell cycle arrest promotion. Cucurbitacins are also found to be the inhibitors of JAK-STAT3, Wnt, PI3K/Akt, and MAPK signaling pathways, which play important roles in the apoptosis and survival of cancer cells. Recently, new studies have discovered synergistic anticancer effects by using cucurbitacins together with clinically approved chemotherapeutic drugs, such as docetaxel and methotrexate. This paper provides a summary of recent research progress on the anticancer property of cucurbitacins and the various intracellular signaling pathways involved in the regulation of cancer cell proliferation, death, invasion, and migration. Therefore, cucurbitacins are a class of promising anticancer drugs to be used alone or be intergraded in current chemotherapies and radiotherapies to treat many types of cancers.

Citrullus colocynthis (L.) Schrad (bitter apple fruit): a review of its phytochemistry, pharmacology, traditional uses and nutritional potential

ETHNOPHARMACOLOGICAL RELEVANCE

Citrullus colocynthis (L.) Schrad is a valuable cucurbit plant, widely distributed in the desert areas of the world. Citrullus colocynthis fruits are usually recognized for its wide range of medicinal uses as well as pharmaceutical and nutraceutical potential. This review aims to appraise the published information on the ethnobotanical knowledge, phytochemistry, ethnopharmacology, nutraceutical potential and safety studies of Citrullus colocynthis (bitter apple) fruit, with critical analysis on the gaps and potential for future studies.

MATERIAL AND METHODS

A literature survey was performed by searching the scientific databases including PubMed, Scopus, SciFinder, Google Scholar, Web of Science, ACS as well as published books.

RESULTS

The plant has been reported to possess a wide range of traditional medicinal uses including in diabetes, leprosy, common cold, cough, asthma, bronchitis, jaundice, joint pain, cancer, toothache, wound, mastitis, and in gastrointestinal disorders such as indigestion, constipation, dysentery, gastroenteritis, colic pain and different microbial infections. Several bioactive chemical constituents from fruits were recorded, such as, glycosides, flavonoids, alkaloids, fatty acids and essential oils. The isolation and identification of curcurbitacins A, B, C, D, E, I, J, K, and L and Colocynthosides A, and B were also reported. The fruit of Citrullus colocynthis has been studied extensively for its wide range of biological activities, which include antioxidant, cytotoxic, antidiabetic, antilipidemic, insecticide, antimicrobial and anti-inflammatory. The plant was also shown to be rich in nutritional value with high protein contents and important minerals as well as edible quality of seed oil.

CONCLUSION

It is evident from the literature that Citrullus colocynthis possesses a wide range of medicinal uses and has been well studied for its antidiabetic, anticancer, antioxidant, antimicrobial and anti-inflammatory activities, while its therapeutic potential for gut, airways and cardiovascular disorders remains to be explored. Critical analysis revealed that the plant has the huge potential for pharmaceutical and nutraceutical application, with some indications for the presence of synergistic and /or side effects neutralizing combinations of activities.