Citrullus colocynthis fruit extract as effective eco-friendly corrosion inhibitor in a hydrochloric acid pickling medium for carbon steel by using both experimental and theoretical studies.

The present study focuses on an environmental approach based on the use of an eco-friendly corrosion inhibitor from the Citrullus colocynthis fruit extract for enhancement corrosion resistance of carbon steel (C-S) in acid medium as an alternative to various organic and non-organic chemical inhibitors. The evaluation of the inhibition properties of the fruit methanolic extract of Citrullus colocynthis (CCE) were performed in molar hydrochloric acid (1 M HCl) medium using gravimetric and electrochemical (potentiodynamic polarization and AC impedance) techniques as well as surface analyses. CCE is rich in amino acids, mainly citrulline and ß-(pyrazo-1-yl)-L-analine molecules. Based on the weight loss evaluation, the results demonstrated that this plant extract acts as an effective corrosion inhibitor and a protection level of 93.6% was attained at 500 ppm of CCE after 6 h of metal exposure at 303 K. According to polarization curves, CCE functions as a mixed-type inhibitor. In addition, AC impedance analyses have shown that the incorporation of CCE into the corrosive solution leads to a decrease in load capacity, while improving the charge/discharge function at the interface. This suggests the possibility of the formation of an adsorbed layer on the C-S surface. In addition, scanning electron microscope (SEM) observation, contact angle measurements, and Fourier-transform infrared spectroscopy (FTIR) analyses supported the development of a protective film over CS substrate surface afterwards addition of CCE. Langmuir and/or Temkin isotherms can be used to characterize the adsorption of this organic inhibitor on the C-S surface. X-ray photoelectron spectroscopy (XPS) has revealed that the inhibiting effect of CCE on the corrosion of C-S in 1 M HCl solution is mainly controlled by a chemisorption process and the inhibitive layer is composed of an iron oxide/hydroxide mixture where CCE molecules are incorporated. In order to understand the relationship between the molecular structure and anti-corrosion effectiveness of these inhibitor molecules, quantum chemical studies were carried out using density functional theory (DFT) and molecular dynamics (MD) simulation.

Anticancer activity, phytochemical investigation and molecular docking insights of Citrullus colocynthis (L.) fruits.

Cancer disease is regarded as one of the most significant public health issues, regardless of economic standards. Medicinal plants are now regarded as a natural source of anticancer medicines due to their antioxidant and anti-mutagenic actions. Cucurbitaceae is considered to be one of the most economically significant families. One family species is Citrullus colocynthis (L.), which has a high concentration of many active secondary chemical metabolites. Various C. colocynthis plant extracts showed cytotoxicity against some cancer cells. This study aims to identify the C. colocynthis fruit components and determine whether they have anticancer action against MIA PaCa-2 and A431 cells. High-Performance Liquid Chromatography/Quadrupole Time of Flight/Mass Spectrometry (HPLC/QTOF/MS); the technique was accustomed to investigate the compounds of the ethyl acetate (EtOAc) fruit extract. Anticancer activity was investigated on both MIAPaCa-2 and A-431 cell lines. DPPH assay for antioxidant activity was carried out. Molecular modelling was employed to help understand the molecular basis for the observed anticancer activity. 24 compounds were tentatively identified by comparing the extract's fragmentation pattern in positive mode against reference compounds spectra and literature. The EtOAc extract of C. colocynthis had effective positive results on cancer cells (MIAPaCa-2 and A-431) and was characterized by slight or no harmful effect on normal (healthy) cells. For the DPPH assay, EtOAc and BuOH extracts exhibited high antioxidant activity (86 and 76%, respectively) compared with the oxidative potential of the standard compound (Caffeic acid, 98%). One of the major cucurbitacin derivatives that LC/MS tentatively identified in the EtOAc extract was Cucurbita-5(10),6,23-triene-3ß,25-diol. During this study, docking experiments and MD simulations were carried out, which suggested the anti-pancreatic cancer activity of C. colocynthis extract to be attributed to EGFR inhibition by Cucurbita-5(10),6,23-triene-3ß,25-diol. Therefore, expansion of this type of research should be encouraged in the hope of obtaining natural therapeutics for cancerous tumors in the future, having the advantage of being cheaper, safer, and with fewer side effects.

[Three new cucurbitane-type triterpenoid glycosides from Citrullus colocynthis and their anti-inflammatory activity].

Three new cucurbitane-type triterpenoid glycosides were separated from the ethyl acetate extract of Citrullus colocynthis by a variety of chromatographic techniques. According to the data of NMR, HR-ESI-MS, and/or comparison with the reported data, the three novel cucurbitane-type triterpenoid glycosides were identified as colocynthenin E(1), colocynthenin G(2), and colocynthenin H(3). The cell inflammation model was established with RAW264.7 macrophages exposed to lipopolysaccharide and then used to determine the anti-inflammatory activities of the three compounds. Compounds 2 and 3 showed mild anti-inflammatory activities with the IC_(50) of 48.21 and 40.11 µmol·L~(-1), respectively, compared with that(IC_(50)=7.57 µmol·L~(-1)) of the positive control dexamethasone.

Cucurbitane-type triterpenoids from the fruits of Citrullus colocynthis.

A phytochemical investigation of the fruits of Citrullus colocynthis resulted in the isolation of 21 structurally diverse cucurbitane triterpenoids, including 9 previously undescribed ones, colocynins A-I (1-9). Their absolute configurations were elucidated by means of quantum chemical electronic circular dichroism (ECD) calculations, CD exciton chirality method, and single-crystal X-ray crystallography. Colocynins A-C (1-3) represent the first examples of nonanorcucurbitane-type triterpenoids. An anti-acetylcholinesterase activity assay showed that 6, 10, 13, 18, and 20 exhibited inhibitory activities, with IC50 values ranging from 5.0 to 21.7 µM. In addition, 18 and 21 showed significant cytotoxicity against PACA, A431, and HepG2 cells, with IC50 values ranging from 0.042 to 0.60 and 3.6-14.4 µM, respectively.

Three new cucurbitane-type triterpenoid glycosides from Citrullus colocynthis and their anti-inflammatory activity / 中国中药杂志

Three new cucurbitane-type triterpenoid glycosides were separated from the ethyl acetate extract of Citrullus colocynthis by a variety of chromatographic techniques. According to the data of NMR, HR-ESI-MS, and/or comparison with the reported data, the three novel cucurbitane-type triterpenoid glycosides were identified as colocynthenin E(1), colocynthenin G(2), and colocynthenin H(3). The cell inflammation model was established with RAW264.7 macrophages exposed to lipopolysaccharide and then used to determine the anti-inflammatory activities of the three compounds. Compounds 2 and 3 showed mild anti-inflammatory activities with the IC_(50) of 48.21 and 40.11 μmol·L~(-1), respectively, compared with that(IC_(50)=7.57 μmol·L~(-1)) of the positive control dexamethasone.

Phytochemicals Mediated Synthesis of AuNPs from Citrullus colocynthis and Their Characterization.

Engineered nanoparticles that have distinctive targeted characteristics with high potency are modernistic technological innovations. In the modern era of research, nanotechnology has assumed critical importance due to its vast applications in all fields of science. Biologically synthesized nanoparticles using plants are an alternative to conventional methods. In the present study, Citrullus colocynthis (bitter apple) was used for the synthesis of gold nanoparticles (AuNPs). UV-Vis's spectroscopy, XRD, SEM and FTIR were performed to confirm the formation of AuNPs. UV-Vis's spectra showed a characteristic peak at the range of 531.5-541.5 nm. XRD peaks at 2 θ = 38°, 44°, 64° and 77°, corresponding to 111, 200, 220 and 311 planes, confirmed the crystalline nature of AuNPs. Spherical AuNPs ranged mostly between 7 and 33 nm, and were measured using SEM. The FTIR analysis confirmed the presence of phytochemicals on the surface of AuNPs. Successful synthesis of AuNPs by seed extract of Citrullus colocynthis (bitter apple) as a capping and reducing agent represents the novelty of the present study.

Cytotoxic Effect of the Crude Alcoholic Extract of the Fruits of Citrullus Colocynthis on Human Hepatocyte Carcinoma (Hep-G2).

The Citrullus colocynthis L is a perennial herbaceous plant belonging to the family Cucurbitaceae. Several pharmacological investigations have been performed based on the medicinal application of Citrullus colocynthis. The anticancer and antidiabetic activities of fruit and seed extracts of Citrullus colocynthis have been studied. Newly developed anticancer/antitumor medications appear to have been developed based on the extracted chemicals from Citrullus colocynthis due to the high contents of cucurbitacins. The present study aimed to identify the cytotoxic effect of the crude alcoholic extract of plants of Citrullus colocynthis on the growth of human hepatocyte carcinoma (Hep-G2). The results of the chemical (preliminary) examination of the extract indicated that the fruits contain most of the secondary metabolites including Flavonoids, Tannins, Sapiens, Resins, Amino acids, Glycosides, Terpenes, Alkaloids, and Flavonoids. The toxicological effect of the crude extract was investigated by using six half dilutions concentrations of 20,10,5,2.5,1.25, and 0.625 µg/m at three exposure periods of 24,48, and 72 h using MTT testing. The toxicological effect of the extract appeared for all six concentrations in the Hep-G2 cell line. The highest concentration of 20 µg/ml had the highest percentage inhibition rate with a significant difference (P≤0.01) and reached 93.36 ±1.61 after 72 h of exposure. While the lowest concentration of 0.625 µg/ml was recorded rate of inhibition of 23.36 ± 2.34 after 24 h of exposure. The findings of the present study concluded that the Citrullus colocynthis is one of the most promising medicinal plants which effectively treats cancer through its inhibitory effect and fatal toxicity on cancer cells.

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.

Wound dressing of chitosan-based-crosslinked gelatin/ polyvinyl pyrrolidone embedded silver nanoparticles, for targeting multidrug resistance microbes.

Wound dressing composed of chitosan, based crosslinked gelatin/ polyvinyl pyrrolidone, embedded silver nanoparticles were fabricated using solution casting method. The membrane was characterized by FTIR, SEM and TGA. Glutaraldehyde (0.5 %) was used for the crosslinking of membrane components and associated with 7-folds boosted mechanical performance, 28 % more hydrolytic stability, 3-folds thickness reduction and morphological roughness. Silver nanoparticles were characterized by UV-vis, XRD and TEM for an average size of 9.9 nm. The membrane with higher concentration of silver nanoparticles showed maximum antibacterial activity against human pathogenic bacteria; and the measured inhibition zones ranged from 1.5 to 3 cm. The activity of the particles ranged from severe to complete reduction in Penicillin, Erythromycin and Macrolide family's resistance genes expression such as ß-Lactamase, mecA and erm. This developed membrane can serve as promising and cost-effective system against severe diabetic and burn wound infections.

Cucurbitacin E glucoside from Citrullus colocynthis inhibits testosterone-induced benign prostatic hyperplasia in mice.

Benign prostatic hyperplasia (BPH) is a common disorder in men aged over 60 years and significantly contributes to the distressing lower urinary tract symptoms. Cucurbitacins are triterpene derivatives with diverse medicinal uses including prostate diseases. Cucurbitacin E glucoside was evaluated against testosterone-induced prostatic hyperplasia in mice. Our data indicate that it significantly inhibited the increase in prostate weight and prostate index. The compound ameliorated histopathological changes in prostatic architecture and inhibited the increase in glandular epithelial length induced by testosterone. These results were confirmed by decreased expression of cyclin D1 in prostatic tissues compared to those obtained from the testosterone-alone group. Also, it showed significant antioxidant activity as evidenced by inhibiting lipid peroxides accumulation, glutathione depletion and superoxide exhaustion. Further, it exhibited anti-inflammatory activity as it decreased cyclooxygenase-2 and interleukin-1ß protein expression in prostatic tissues. Masson's trichrome staining of prostate sections indicated obvious antifibrotic activity that was supported by decreased α-smooth muscle actin expression. In conclusion, Cucurbitacin E glucoside inhibits testosterone-induced experimental BPH in mice due to, at least partly, its antiproliferative, antioxidant, anti-inflammatory, and antifibrotic effects.

Citrullus colocynthis regulates de novo lipid biosynthesis in human breast cancer cells.

BACKGROUND: Reprogrammed energy metabolism is considered a hallmark of cancer and is proposed as an important target for therapy. Uncontrolled and infinite cell proliferation needs efficient energy sources. To meet the demands of cancer cells lipid metabolism is activated. Citrullus colocynthis is a traditional medicinal plant known for its anticancer and hypolipidemic effects. AIMS: Aim of the current study was to assess the effect of C. colocynthis leaves on regulation of lipid metabolism in MCF-7, a human breast cancer cell line. METHODS: Methanolic extract of leaves and its fractions in increasing polarity-based solvents (n-hexane, chloroform, ethyl acetate and n-butanol) were prepared and analyzed for the presence of secondary metabolites in each fraction. Bioassays and apoptosis genes expression analysis was conducted to evaluate the anticancer and cytotoxic effect of breast cancer cells treated with extract and its fractions, separately. Lipid quantification and gene expression regulation of genes involve in lipid metabolism was performed to evaluate regulation of lipid metabolism. RESULTS: Results showed a significant anticancer activity of methanolic extract of C. colocynthis and two of its fractions prepared with chloroform and ethyl acetate. Quantification of lipids depicted significant increase in cholesterol and increase in triglycerides of treated cells compared to control untreated cells. Expression regulation of genes further confirmed the lipid regulation through significant down regulation of genes involve in lipid metabolism (FASN, HMGCLL1, ACSL5 and ELOVL2). CONCLUSION: The present study concludes that C. colocynthis holds strong anticancer potential through regulation of lipid metabolism and with further studies can be proposed for novel therapeutic approaches.

Norcolocynthenins A and B, two cucurbitane 3-nor-Triterpenoids from Citrullus colocynthis and their cytotoxicity.

Two novel cucurbitane 3-nor-triterpenoids, named norcolocynthenins A (1) and B (2), were isolated from the fruits of Citrullus colocynthis. The structures including their absolute configurations were determined by extensive spectroscopic analyses and theoretical calculations. Compound 1 features an unprecedented 5/6/6/5-fused ring system while compound 2 possesses a rare lactone moiety at modified ring A. Compounds 1 and 2 showed significant cytotoxic activity against human cancer cell lines of HL-60 (IC50 = 8.32, 6.49 µM) and PC-3 (IC50 = 31.26, 13.42 µM). The plausible biosynthetic pathway of compounds 1 and 2 via a key enzymatic Baeyer-Villiger reaction is proposed.

Spinasterol, 22,23-Dihydrospinasterol and Fernenol from Citrullus Colocynthis L. with Aphicidal Activity against Cabbage Aphid Brevicoryne Brassicae L.

Brevicoryne brassicae is a problematic pest in cabbage and other field crops. Synthetic pesticides are used to control this pest, but they are injurious for human health and the environment. The present study aimed to purify and identify the active compounds from Citrullus colocynthis leaves with an appraisal of their efficacy against B. brassicae. Separation and purification were performed via different chromatographic techniques. Molecular analysis and chemical structures were recognized by mass spectrum (MS) and nuclear magnetic resonance (NMR), respectively. Moreover, in vitro and in vivo aphicidal activity was assessed using various concentrations, i.e., 6.25, 12.5, 25 and 50 µg/mL at 12, 24, 48 and 72 h exposure. The outcome shows that mass spectrum analyses of the purified compounds suggested the molecular formulae are C30H50O and C29H50O, C29H48O. The compounds were characterized as fernenol and a mixture of spinasterol, 22,23-dihydrospinasterol by 1H-NMR and 13C-NMR spectrum analysis. The toxicity results showed that the mixture of spinasterol and 22,23-dihydrospinasterol showed LC50 values of 32.36, 44.49 and 37.50 µg/mL by contact, residual and greenhouse assay at 72 h exposure, respectively. In contrast, fernenol recorded LC50 values as 47.99, 57.46 and 58.67 µg/mL, respectively. On the other hand, spinasterol, 22,23-dihydrospinasterol showed the highest mortality, i.e., 66.67%, 53.33% and 60% while, 30%, 23.33% and 25% mortality was recorded by fernenol after 72 h at 50 µg/mL by contact, residual and greenhouse assay, respectively. This study suggests that spinasterol, 22,23-dihydrospinasterol are more effective against B. brassicae which may be introduced as an effective and suitable substitute of synthetic chemical pesticides.

[Research progress on chemical constituents of Citrullus colocynthis and their pharmacological effects].

Citrullus colocynthis is widely distributed in the desert regions of the world. C. colocynthis has shown to improve constipation, liver diseases, jaundice, typhoid fever, diabetes and asthma in traditional use. As a kind of exterritorialy medicinal material, C. colocynthis has been used in China and introduced successfully. The main active ingredients of C. colocynthis are cucurbitacin, flavonoids, alkaloids and phenolic acids, which have been proven to have antioxidant, anti-diabetic, anti-pathogenic microorganisms and anti-cancer activities in modern pharmacological research. This paper reviews the traditional application, chemical composition and pharmacological effects of C. colocynthis, and provides reference for the in-depth study for the efficacy and mechanism of different components of C. colocynthis.

Insecticidal activity and biochemical composition of Citrullus colocynthis, Cannabis indica and Artemisia argyi extracts against cabbage aphid (Brevicoryne brassicae L.).

Plant extracts contain many active compounds, which are tremendously fruitful for plant defence against several insect pests. The prime objectives of the present study were to calculate the extraction yield and to evaluate the leaf extracts of Citrullus colocynthis (L.), Cannabis indica (L.) and Artemisia argyi (L.) against Brevicoryne brassicae and to conduct biochemical analysis by gas chromatography-mass spectrometry (GC-MS). The results suggested that when using ethanol, C. colocynthis produced a high dry yield (12.45%), followed by that of C. indica and A. argyi, which were 12.37% and 10.95%, respectively. The toxicity results showed that A. argyi was toxic to B. brassicae with an LC50 of 3.91 mg mL-1, followed by the toxicity of C. colocynthis and C. indica, exhibiting LC50 values of 6.26 and 10.04 mg mL-1, respectively, which were obtained via a residual assay; with a contact assay, the LC50 values of C. colocynthis, C. indica and A. argyi were 0.22 mg mL-1, 1.96 and 2.87 mg mL-1, respectively. The interaction of plant extracts, concentration and time revealed that the maximum mortality based on a concentration of 20 mg L-1 was 55.50%, the time-based mortality was 55% at 72 h of exposure, and the treatment-based mortality was 44.13% for A. argyi via the residual assay. On the other hand, the maximum concentration-based mortality was 74.44% at 20 mg mL-1, the time-based mortality was 66.38% after 72 h of exposure, and 57.30% treatment-based mortality was afforded by A. argyi via the contact assay. The biochemical analysis presented ten constituents in both the A. argyi and C. colocynthis extracts and twenty in that of C. indica, corresponding to 99.80%, 99.99% and 97% of the total extracts, respectively. Moreover, the detected caryophylleneonides (sesquiterpenes), α-bisabolol and dronabinol (Δ9-THC) from C. indica and erucylamide and octasiloxane hexamethyl from C. colocynthis exhibited insecticidal properties, which might be responsible for aphid mortality. However, A. argyi was evaluated for the first time against B. brassicae. It was concluded that all the plant extracts possessed significant insecticidal properties and could be introduced as botanical insecticides after field evaluations.

The Anticancer Efficiency of Citrullus colocynthis Toward the Colorectal Cancer Therapy.

BACKGROUND: Colorectal cancer (CRC) remains a major cause of death worldwide. Chemotherapy is associated with some side effects during CRC treatment. Hence, proper employment of lower toxic and approaches exerting lowest side effects are essential. The Citrullus colocynthis (C. colocynthis) seems a potential anticancerous herbal medicine (HM) against CRC mostly via various efficient compounds. METHODS: We performed a literature review regarding the anticancer traits of C. colocynthis against CRC. The possible active compounds, mechanisms, and combination therapies in vitro and in vivo or clinical trials have been also stated where found. RESULTS AND CONCLUSION: The anticancerous effects of C. colocynthis has been via a variety of pathways including apoptotic pathways (increase in caspase-3 and inhibiting STAT3 function), antioxidant and anti-inflammatory (TNF-α, nitric oxide, and pro-inflammatory cytokines such as IL-6, IL-8, and IL-1α) traits, inhibition of Wnt/ß-catenin signaling pathway, and antiangiogenesis and antimetastatic effects. Future studies will be promising regarding proper application of C. colocynthis compounds following their extraction.

Synthesis of magnetic iron oxide nanoparticles using pulp and seed aqueous extract of Citrullus colocynth and evaluation of their antimicrobial activity.

OBJECTIVES: Citrullus colocynth (CTC) is a wild medicinal plant with proven antimicrobial activity. The aim of this study is to investigate the use of its aqueous extract in producing magnetic iron oxide nanoparticles (MNPs) with improved antimicrobial activity. The cold and hot aqueous extract of seed and pulp parts of CTC, respectively, were used to produce MNPs. The particles were characterized by transmission electron microscope, energy dispersion x-ray, FTIR and their surface charge were measured. The antimicrobial activity of the produced particles was assessed against two Gram positive (Bacillus subtillis and Staphylococcus aureus) and two Gram negative (Escherichia coli and Pseudomonas aeruginosa) bacteria and well as against Candida albicans. RESULTS: MNPs synthesized using cold seed extract (S-MNP) and pulp extract (P-MNP) were spherical in shape. The size distribution was more uniform in the S-MNP (6-15 nm) compared to the P-MNP (12-45 nm). Both particles showed comparable anti-microbial potential against the tested microorganisms. At a concentration range of 0.48-1000 µg/mL, S-MNP inhibited bacterial growth by 16.0-99.0% and 10.0-91.0%; while P-MNP inhibition was 11.0-100.0% and 11.0-99.0% for Gram positive and negative bacteria; respectively. Candida albicans was the least affected microorganism with maximum inhibition of 63-88% after treatment with S-MNP and P-MNP (1 mg/mL), respectively. CONCLUSIONS: The aqueous extract of CTC can be used for synthesis of MNPs with antimicrobial activity. The described procedures are simple and can be modified for large scale green synthesis of MNPs.

Research progress on chemical constituents of Citrullus colocynthis and their pharmacological effects / 中国中药杂志

Citrullus colocynthis is widely distributed in the desert regions of the world. C. colocynthis has shown to improve constipation, liver diseases, jaundice, typhoid fever, diabetes and asthma in traditional use. As a kind of exterritorialy medicinal material, C. colocynthis has been used in China and introduced successfully. The main active ingredients of C. colocynthis are cucurbitacin, flavonoids, alkaloids and phenolic acids, which have been proven to have antioxidant, anti-diabetic, anti-pathogenic microorganisms and anti-cancer activities in modern pharmacological research. This paper reviews the traditional application, chemical composition and pharmacological effects of C. colocynthis, and provides reference for the in-depth study for the efficacy and mechanism of different components of C. colocynthis.

Cytotoxicity of cucurbitacin E from Citrullus colocynthis against multidrug-resistant cancer cells.

BACKGROUND: Cucurbitacin E (CuE) is an oxygenated tetracyclic triterpenoid isolated from the fruits of Citrullus colocynthis (L.) Schrad. PURPOSE: This study outlines CuE's cytotoxic activity against drug-resistant tumor cell lines. Three members of ABC transporters superfamily, P-glycoprotein (P-gp), breast cancer resistance protein (BCRP) and ABCB5 were investigated, whose overexpression in tumors is tightly linked to multidrug resistance. Further factors of drug resistance studied were the tumor suppressor TP53 and the epidermal growth factor receptor (EGFR). METHODS: Cytotoxicity assays (resazurin assays) were used to investigate the activity of Citrullus colocynthis and CuE towards multidrug resistant cancer cells. Molecular docking (In silico) has been carried out to explore the CuE's mode of binding to ABC transporters (P-gp, BCRP and ABCB5). The visualization of doxorubicin uptake was done by a Spinning Disc Confocal Microscope. The assessment of proteins expression was done by western blotting analysis. COMPARE and hierarchical cluster analyses were applied to identify, which genes correlate with sensitivity or resistance to cucurbitacins (CuA, CuB, CuE, CuD, CuI, and CuK). RESULTS: Multidrug-resistant cells overexpressing P-gp or BCRP were cross-resistant to CuE. By contrast, TP53 knock-out cells were sensitive to CuE. Remarkably, resistant cells transfected with oncogenic ΔEGFR or ABCB5 were hypersensitive (collateral sensitive) to CuE. In silico analyses demonstrated that CuE is a substrate for P-gp and BCRP. Immunoblot analyses highlighted that CuE targeted EGFR and silenced its downstream signaling cascades. The most striking result that emerged from the doxorubicin uptake by ABCB5 overexpressing cells is that CuE is an effective inhibitor for ABCB5 transporter when compared with verapamil. The COMPARE analyses of transcriptome-wide expression profiles of tumor cell lines of the NCI identified common genes involved in cell cycle regulation, cellular adhesion and intracellular communication for different cucurbitacins. CONCLUSION: CuE represents a potential therapeutic candidate for the treatment of certain types of refractory tumors. To best of our knowledge, this is the first time to identify CuE and verapamil as inhibitors for ABCB5 transporter.

Colocynthenins A-D, Ring-A seco-Cucurbitane Triterpenoids from the Fruits of Citrullus colocynthis.

Four ring-A seco-cucurbitane triterpenoids, colocynthenins A-D (1-4), together with seven known cucurbitane triterpenoids (5-11), were isolated from the fruits of Citrullus colocynthis. Their structures and absolute configurations were elucidated based on spectroscopic analysis and quantum chemical ECD calculations. Compound 1 possesses an unprecedented 2,11-lactone moiety, while compound 2 is the first reported cucurbitane triterpenoid with an unusual cyano group. Compounds 1 and 3 showed acetylcholinesterase inhibitory activities in a standard in vitro assay, with IC50 values of 2.6 and 3.1 µM, respectively.