Squirting cucumber (Ecballium elaterium) contains high levels of cucurbitacins in all parts of the plant, which are indeed highly toxic when ingested.
Some curcurbitacins are present in most members of the cucumber family and they are what give the bitterness to these fruits.
The issues with E. elaterium are related to the number of different cucurbitacins present and their concentrations, hence the poisonous warnings.
This is an introduced plant which has been imported from The Mediterranean region.
Currently, it is mostly being studied in universities (fairly world wide) for suitability as a grafting
root stock because of it being disease resistant.
Control is best accomplished by digging up the plants so all
roots are removed.
Pick fruits well before they ripen so no seeds will be spread and wear disposable gloves when handling any part of the plant.
This is probably one of the few plants I would term Invasive, since it is an introduced species brought in merely because it is a curiosity of the plant world.
Be careful to bag all plants as they are removed, it might be very unadvisable to burn them unless in a well contained incinerator of the type used for disposal of chemicals. (fully enclosed, air injected, afterburner stack)
This is a little of the science investigation that was done in Malta b the Institute of Agriculture, University of Malta by A. Rich
"Introduction:
Cucurbitacins are highly oxygenated compounds abundantly found in Cucurbitaceous genera such as Citrullus, Cucumis, Cucurbita and Luffa (11).
A relatively common cucurbitacin found in Cucurbitaceous species is cucurbitacin E (CuE).
Although cucurbitacins exhibit positive effects both pharmacologically (1-3, 6, 14, 17) and in protecting the plants from certain diseases (5), they have a high degree of bitterness even at concentrations lower than 10 ppb (10).
With the emergence of new cultivars, the expression of the genes that favor the production of cucurbitacins can be enhanced leading to the production of an inedible cultivar.
To determine the efficacy of a method that detects these cucurbitacins in plant tissues we have selected an “indicator plant” that stores an abundance of these compounds.
Locally, the squirting cucumber (Ecballium elaterium) is also being used as a rootstock in general practice to graft cucurbitaceous crops, owing to the disease resistance of the squirting cucumber to several pests and diseases.
The reference cucurbitacin, in this study, was CuE.
Materials and Methods:
Ecballium elaterium tissue culture material was obtained from a callus stabilized on Murashige and Skoog (13) medium (MS, pH 5.7) containing 5 mg/l naphthalene acetic acid (NAA) and 1 mg/l benzylamino purine (BAP) and from shoot explants grown on 0.1 mg/l NAA and 1 mg/l BAP.
Local Ecballium elaterium fruit were collected from Marsascala, washed, sliced and the juice strained off.
The fresh callus material and fruit juice were dried in an
oven at 40 C for 24 hours.
For the cucurbitacin determination, the dried material was ground in a mortar until pulverized completely, homogenized with absolute ETOH (5 ml), reduced to a volume of 2 ml on a
water bath and then filtered through a 0.22 µm filter (Schleicher & Shuell, Germany).
For CuE, the dried material was extracted by CHCl3 (5 ml) and then mixed with an equal volume of petrol (12).
The filtrate was dissolved in absolute ETOH (5 ml), reduce likewise to 2 ml and then filtered through a 0.22 µm membrane pore size.
Standard CuE used to produce the standard curve was provided and authenticated by Prof. D. Lavie (Rehovot, Israel).
The solvents used were all HPLC grade obtained from Sigma Co. Ltd. (U.S.A.).
The water used for HPLC was passed through a 0.22 µm filter (Schleicher & Shuell, Germany) and degassed.
Chromatographic conditions. HPLC was performed using a Kontron Instruments HPLC system (Herts, U.K.) consisting of two HPLC pumps (Kontron 422), an Autosampler 465 and a Diode Array detector 440.
The detection was recorded on a computer via the on line Microsoft Windows program for Kontron Instruments - KromaSystem 2000 Version 1.60.
The column was a Bio-Sil C18 HL 90-5S column (Bio-Rad, CA, U.S.A., 250 x 4.6 mm i.d., 5 µm particle diameter, 90 Å pore size).
Since the elution was of the gradient type, a mobile phase of acetonitrile:water starting at a ratio of 2:8 and ending with a ratio of 45:55 at 35 minutes.
The flow rate was 2.0 ml/min and CuE was detected by UV absorption at 229 nm. Each sample was run in duplicates for 3 independent experiments.
Spectrophotometric conditions. All samples (100 µl, in duplicate), together with various concentrations of CuE standard (0.017 to 1.113 mg/ml), were mixed with 100 µl of a 2 % phosphomolybdic acid (PMA) solution (BDH, U.K.) in absolute ETOH (15) at room temperature, using a 96-well plate (NUNC, Denmark).
The absorbance was measured at 492 nm after 5 minutes on a MTP reader (STATFAX 2100, U.S.A.).
The results were expressed as percentage weight calculated on dry callus weight.
Standard curves were plotted for both analytical methods.
For the HPLC, dilutions of standard CuE were prepared in the range of 0.02 and 0.32 mg/ml, while for the spectrophotometric method dilutions ranged from 0.017 to 1.113 mg/ml were used.
CuE was quantified by HPLC by considering the peak area, while for the spectrophotometric method it was quantified by determining the optical density, and both extrapolated on the standard curve.
All quantitative determinations were subjected to regression analysis and ANOVA (one-way analysis of variance) using the BMDP/DYNAMIC v. 7.0 (Cork, Ireland) statistical package to determine the significance of the results.
Results and Discussion: The retention time of CuE, when analyzed by HPLC, was 34.01 ± 0.12 min. Figure 1 shows that CuE is distinctively collected from the fruit extract as opposed to the other cucurbitacins and their glycosides.
However, the analysis is time-consuming and therefore not suitable for processing large numbers of samples, as previously indicated (
.
In the present study, the retention time for CuE goes in accordance with the value obtained (33.92 min) for the same compound extracted from Cucurbita species by Halaweish and Tallamy (9).
The initial qualitative analysis
led to the development of a more rapid but still sensitive technique.
According to Balbaa et al. (4), a triphenyl tetrazolium test gave consistent results in assaying cucurbitacins.
Despite this, although there was a positive reaction between the tetrazolium salt and CuE , our results were inconsistent (unpublished).
Another method (16) reported for measuring cucurbitacin content in Hemsleya dolichocarpa used the dimethylaminobenzaldehyde reagent for a spectrophotometric reaction, as described in the Chinese Pharmacopoeia (7).
However, we obtained false positive results by this method in the determination of the cucurbitacin content.
In the same research work, phosphomolybdic acid was mentioned as a spraying reagent for a thin-layer chromatography densitometric method, at wavelengths of 510 nm and 600 nm.
An ethanol solution was also indicated by Stahl and Jork (15) for triterpene identification as a spraying reagent in TLC analysis."
Redhawk
