Simultaneous determination of cucurbitacin B and cucurbitacin E in rat plasma by UHPLC-MS/MS: A pharmacokinetics study after oral administration of cucurbitacin tablets.

Cucurbitacin B (CuB) and cucurbitacin E (CuE) are tetracyclic triterpene compounds from Cucurbitaceae, and the main bioactive compounds of cucurbitacins tablets that used to treatment of chronic hepatitis. Pharmacological research has been very comprehensive, and there are few studies on pharmacokinetics, especially about CuE. An Ultra High Performance Liquid Chromatography-tandem Mass Spectrometry (UHPLC-MS/MS) method with high selectivity, simplicity and sensitivity has been used for quantitative analysis of Cucurbitacin B (CuB) and cucurbitacin E (CuE). Plasma samples were pretreatment by Liquid-liquid extraction (LLE) method with dichloromethane. The chromatographic separation was achieved on a C18 column (Agilent Eclipse Plus, 1.8µm, 50×2.1mm) using gradient elution with water - methanol at a flow rate of 0.3mL/min and the column temperature was set at 30°C. The method was validated according to FDA guidelines. Lower limit of quantification (LLOQ) was 1.60ng/mL for CuB and 1.58ng/mL for CuE. Correlation coefficients of CuB and CuE were more than 0.99 in rat plasma. All values of intra-day and inter-day precision (RSD%) were not exceeded 15%, the accuracy (RE%) were within -5.57 to 5.20% for CuB and -3.33 to 7.37% for CuE. The mean extraction recoveries were more than 80%. Pharmacokinetic parameters were also evaluated by UHPLC-MS/MS method. The results suggestion that this method was successfully applied to pharmacokinetic study of CuB and CuE in rat plasma after oral administration cucurbitacin tablets.

Simultaneous determination of cucurbitacin IIa and cucurbitacin IIb of Hemsleya amabilis by HPLC-MS/MS and their pharmacokinetic study in normal and indomethacin-induced rats.

A selective and sensitive HPLC-MS/MS method was developed for the simultaneous determination of cucurbitacin IIa (cuIIa) and cucurbitacin IIb (cuIIb), the major bioactive cucurbitacins of Hemsleya amabilis, in rat plasma using euphadienol as internal standard (IS). After liquid-liquid extraction with dichloromethane, separation was achieved on a Syncronis HPLC C18 column (150 mm × 4.6 mm, 5 µm) using an isocratic mobile phase system consisting of acetonitrile-water (85:15, v/v) at a flow rate of 0.6 mL/min with a split ratio of 1:2. Detection was performed on a TSQ Quantum Ultra mass spectrometer equipped with an positive-ion electrospray ionization source. The lower limits of quantification (LLOQs) were 0.25 and 0.15 ng/mL for cuIIa and cuIIb, respectively. The intra- and inter-day precision was <11.5% for the LLOQs and each quality control level of the analytes, and accuracy was between -9.1 and 7.6%. The extraction recoveries of the analytes and IS from rat plasma were all >87.1%. The method was fully validated and applied to compare the pharmacokinetic profiles of the two cucurbitacins in rat plasma after oral administration of H. amabilis extract between normal and indomethacin-induced rats. Copyright © 2016 John Wiley & Sons, Ltd.

The anti-melanoma efficiency of the intratumoral injection of cucurbitacin-loaded sustained release carriers: in situ-forming implants.

Our previous studies revealed that the PLGA-based particulate systems loaded with cucurbitacin showed limited anti-melanoma efficiency in xenograft animal models after intratumoral injection, which was due to the undesirable initial burst release and the leakage of the particulate carriers from the injection site through the pinhole. In this paper, two categories of in situ-forming implants (ISFIs) for intratumoral injection, PLGA ISFIs and SAIB ISFIs, were systemically evaluated for their potentials for on solid tumor treatment via intratumoral injection. The in vitro drug release profiles of these two ISFIs were different due to the different sol-gel transition properties. The pharmacodynamics results revealed that SAIB ISFIs displayed obvious therapeutic efficiencies to melanoma, and multi-points injection of SASIB ISFIs displayed better efficiency than single-point injection. The different sol-gel transition properties and mechanism for PLGA ISFIs and SAIB ISFIs affected both the drug release and strongly impacted the pharmacokinetic parameters and pharmacodynamic effectiveness. Also, the adhesive property of SAIB to the local tissue could extend the retention and inhibit the leakage of the SAIB ISFIs, thus enhanced the anticancer effectiveness. Comparison of the various intratumoral injection systems, appropriate drug release profiles (lower initial burst and steady release) and good retention (minimum leakage from the injection site) would benefit to the antitumor effects of the intratumoral depots.

[Study on in vivo pharmacokinetics of cucurbitacin injection in rats].

To establish a method for the determination of cucurbitacin in plasma samples, in order to study the in vivo pharmacokinetic characteristics of cucurbitacin in rats. Rats were intravenously injected with cucurbitacin. With diphenhydramine as the internal standard (IS), the plasma concentrations of cucurbitacin in rat plasma at different time points were determined by liquid chromatography tandem mass spectrometry (LC-MS/MS). With electrospray ionization source, the positive ion detection in the multiple reaction monitoring mode was conducted to determine the ion-pairs for target compound and IS were m/z 503.2/113.1 and m/z 256.0/167.2, respectively. Agilent ZOBAX SB-C18 column (2.1 mm x 50 mm, 1.8 microm) was adopted and eluted with methanol and 0.1% formic acid (55:45), and the flow rate was 0.2 mL x min(-1). DAS 2.0 software was applied to fit the blood concentration and calculate corresponding pharmacokinetic parameters. The rats were intravenously injected with cucurbitacin at the concentration of 3.0 mg x kg(-1). The target blood quality concentration show good linear relations within the range of 10.5-3 150 microg x L(-1) (R2 = 0.996), the lower limit of the standard curve was 10.5 microg x L(-1), and the signal to noise ratio S/N = 12. Intra- and inter-day precisions RSD was less than 6.9% and 14%, respectively; The accuracy RE ranged between 0.20% and 3.7%; The extraction recoveries ranged between 92.7% and 97.1%. Regarding the pharmacokinetic parameters of tail intravenous injection of cucurbitacin, AUC (0-t) was (811.615 +/- 111.578) microg x h x L(-1), (t1/2) was (1.285 +/- 1.390) h, CL was (3.627 +/- 0.487) L x h x kg(-1), and V(d) was (6.721 +/- 7.429) L x kg(-1). In this study, researchers established a simple, accurate, sensitive and highly specific method for determining the blood concentration of cucurbitacin, and reported the in vivo pharmacokinetic characteristics of cucurbitacin in rats for the first time.

Development and validation of an LC-ESI-MS/MS method for the quantitation of hemslecin A in rhesus monkey plasma and its application in pharmacokinetics.

In this study, a new LC-ESI-MS/MS-based method was validated for the quantitation of hemslecin A in rhesus monkey plasma using otophylloside A as internal standard (IS). Hemslecin A and the IS were extracted from rhesus monkey plasma using liquid-liquid extraction as the sample clean-up procedure, and were subjected to chromatography on a Phenomenex Luna CN column (150 × 2.0 mm, 3.0 µm) with the mobile phase consisting of methanol and 0.02 mol/mL ammonium acetate (55:45, v/v) at a flow rate of 0.2 mL/min. Detection was performed on an Agilent G6410B tandem mass spectrometer by positive ion electrospray ionization in multiple reaction monitoring mode, monitoring the transitions m/z 580.5 [M + NH4 ](+) → 503.4 and m/z 518.2 [M + NH4 ](+) → 345.0 for hemslecin A and IS, respectively. The assay was linear over the concentration range of 0.5-200 ng/mL and was successfully applied to a pharmacokinetic study in rhesus monkeys.

The cucurbitacins E, D and I: investigation of their cytotoxicity toward human chondrosarcoma SW 1353 cell line and their biotransformation in man liver.

Cucurbitacins are a class of natural compounds known for their numerous potential pharmacological effects. The purpose of this work was to compare the cytotoxicity of three cucurbitacins I, D, E on the chondrosarcoma SW 1353 cancer cell line and to investigate their biotransformation in man. Cucurbitacins I and D showed a very strong cytotoxicity, which was higher than that of cytochalasin D, used as a drug reference. Almost 100% of the cells were apoptotic as observed by DNA fragmentation (TUNEL assay) after 12 h with cucurbitacins I and D (1 µM) and cucurbitacin E (10 µM). In terms of IC(50) values, cucurbitacins I and E presented a higher toxicity compared to that of cucurbitacin D (MTT assay). Cucurbitacin E was readily hydrolyzed by human hepatic microsomes, leading to cucurbitacin I (K(m) 22 µM, V(max) 571 nmol/mg proteins/min). On the other hand, the three cucurbitacins were hydroxylated at a very low extent, but they were sulfated and glucuronidated. In terms of V(max)/K(m), the cucurbitacin E was the best substrate of UDP-glucuronosyltransferases. This study shows that cucurbitacins I, D and E present a potent cytotoxic activity toward the chondrosarcoma SW 1353 cell line and are metabolized as sulfate and glucuronide conjugates.

Cucurbitacins as inducers of cell death and a rich source of potential anticancer compounds.

Triterpenes have been reported to induce cell death. One relevant group of this family of compounds is cucurbitacins, which have been studied as inducers of apoptosis in various cancer cell lines. The most significant mechanisms with regard to the apoptotic effects of cucurbitacins are their ability to modify transcriptional activities via nuclear factors or genes and their capability to activate or inhibit pro- or anti-apoptotic proteins. Still, while the majority of studies on these compounds have dealt with their apoptotic effects on cancer cell lines, several research groups have also explored their anti-inflammatory activities. In general, cucurbitacins are considered to be selective inhibitors of the JAK/STAT pathways; however, other mechanisms may be implicated in their apoptotic effects, including the MAPK pathway (known to be important for cancer cell proliferation and survival), PARP cleavage, expression of active caspase-3, decreased pSTAT3 and JAK3 levels, as well as decreases in various downstream STAT3 targets such as Mcl-1, Bcl-2, Bcl-xL, and cyclin D3, all of which are implicated in apoptosis and the cell cycle. Taking all these effects into account, cucurbitacins may prove useful in the treatment of different kinds of cancers, especially when used with other cytostatic agents.

New potent P-glycoprotein modulators with the cucurbitane scaffold and their synergistic interaction with doxorubicin on resistant cancer cells.

The novel cucurbitacins, balsaminagenin A and B (1-2) and balsaminoside A (3) and the know cucurbitacin karavelagenin C (4), together with five new mono or diacylated derivatives (5-9) of karavelagenin C were evaluated for multidrug resistance reversing activity on human MDR1 gene transfected mouse lymphoma cells. Compounds 2-6 exhibited a strong activity compared with that of the positive control, verapamil. Structure-activity relationships are discussed. Moreover, in the checkerboard model of combination chemotherapy, the interaction between doxorubicin and compounds 2-5 synergistically enhanced the effect of the anticancer drug. Compounds 1-4 were isolated from the aerial parts of Momordica balsamina L. The structures of the compounds were established on the basis of spectroscopic methods including 2D NMR experiments (COSY, HMQC, HMBC and NOESY).

Polymeric micelles for the solubilization and delivery of STAT3 inhibitor cucurbitacins in solid tumors.

Poly(ethylene oxide)-block-poly(epsilon-caprolactone) (PEO-b-PCL) and newly developed poly(ethylene oxide)-block-poly(alpha-benzyl carboxylate epsilon-caprolactone) (PEO-b-PBCL) micelles were evaluated for the solubilization and delivery of cucurbitacin I and B, poorly water soluble inhibitors of signal transducer and activator of transcription 3 (STAT3). Encapsulation of cucurbitacins in PEO-b-PCL and PEO-b-PBCL by co-solvent evaporation technique resulted in polymeric micelles <90 nm in diameter. The aqueous solubility of both derivatives increased from less than 0.05 mg/mL in the absence of the copolymer to around 0.30-0.44 and 0.65-0.68 mg/mL in the presence of 5000-5000 and 5000-24,000 PEO-b-PCL micelles, respectively. Maximum cucurbitacin solubilization was achieved with PEO-b-PBCL micelles for both derivatives. PEO-b-PCL micelles having longer PCL block were found to be more efficient in sustaining the rate of release for cucurbitacins. The anti-cancer and STAT3 inhibitory activity of polymeric micellar cucurbitacins were comparable with free drugs in B16.F10 melanoma cell line in vitro. Intratumoral injection of 1 mg/kg/day cucurbitacin I resulted in the regression of established B16.F10 mouse melanoma tumors in vivo. In comparison to free cucurbitacin I, PEO-b-PBCL micellar cucurbitacin I was found to provide comparable anti-cancer effects against B16.F10 tumors and limit drug levels in animal serum while maintaining high drug levels in tumor following intratumoral administration. The results indicate the potential of polymeric micelles as suitable vehicles for the delivery of cucurbitacin- I and B.