CA2308412A1 - Echinops extract with anti-cancer activity - Google Patents

Abstract

The present invention relates to an extract of Echinops spinosus L.(Asteraceae) and organic solvent soluble fractions of the extract that may be used in the treatment of cancer.

Description

ECHINOPS EXTRACT WITH ANTI-CANCER ACTIVITY
BACKGROUND OF THE INVENTION
(a) Field of the Invention The invention relates to an extract of Echinops spinosus L. (Asteraceae) and fractions thereof for use in the treatment of cancer; the invention also relates to the preparation of the extract and the fractions and pharmaceutical compositions containing them.
(b) Description of Prior Art Cancers are uncontrolled cell proliferations that result from the accumulation of genetic changes in cells endowed with proliferative potential. After a variable latency period during which they are clini-cally silent, the malignant cells progress to aggres-sive invasive and metastatic stages with tumor forma-tion, bleeding, susceptibility to infections, and wide-spread dissimination throughout the body.
Despite important advances in treatment, cancers still account for 28% of death in Western countries.
Treatment of cancer has relied mainly on surgery, che motherapy, radiotherapy and more recently immunother apy. Significant improvement in outcome has occurred with the use of combined modalities, for a small number of cancers. However, for the most frequent types of cancers (lung, breast, colo-rectal and the leukemias) complete remission and cure has not been achieved.
Therefore, the development of new approaches for treat-ing cancer patients is critically needed particularly for those patients whose disease has progressed to a metastatic stage and are refractory to standard chemo-therapy.
The leaves of Echinops spinosus L. (Asteraceae) have previously been used in local or herbal medicine to treat warts; and a peptide having vasoconstrictive properties has been isolated from the root of the plant.
It would be highly desirable to be provided with a novel therapy for cancer which overcome the drawbacks of the method of the prior art.
SUMMARY OF THE INVENTION
One aim of the present invention is to provide a dried extract of the roots of Echinops spinosus L.
(Asteraceae) and fractions thereof that have been found to be useful in treating cancers.
In accordance with one aspect of the invention there is provided an anti-cancer pharmaceutical compo-sition comprising an acceptable, effective anti-cancer amount of an extract of roots Echinops spir_osus L.
(Asteraceae) or an organic solvent soluble fraction thereof, in association with a pharmaceutically accept-able carrier.
In accordance with another aspect of the inven tion there is provided an extract of roots of Echinops spinosus L. (ASteraceae) or an organic solvent soluble fraction thereof, for use in the treatment of cancer.
In accordance with yet another aspect of the invention there is provided a method of treating cancer comprising administering to a patient, an acceptable, effective anti-cancer amount of an extract of roots of Echinops spinosus L. (Asteraceae) or an organic solvent soluble fraction thereof.
In accordance with still another aspect of the invention there is provided a method of producing an anti-cancer agent comprising organic solvent extraction of an extract of roots of Echinops spinosus L. (Astera ceae) to produce an organic solvent soluble extract, and chromatographic separation of fractions of said organic solvent soluble extract.
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For the purpose of the present invention the following terms are defined below.
The term "anti-cancer therapy" is intended to mean growth inhibition/eradication of primary tumors, stabilization of tumor growth, inhibition of metastasis formation, or prevention of tumor formation. Further more, anticancer activity also covers any combination between our substances and other known or investiga tional anticancer agents, in order to improve the therapeutic efficacy of drugs.
BRIEF DESCRIPTION OF THE DRA~7INGS
Fig. lA illustrates the in vitro cytotoxicity of various fractions using human breast adenocarcinoma cell line, MCF7;
Fig. 1B illustrates the in vitro cytotoxicity of various fractions using human ovarian adenocarcinoma cell line, A2780;
Fig. 2 illustrates the Lung Lewis carcinoma model schedule for drug treatment and also the antime tastatic activity of 758;
Fig. 3 illustrates a schedule for drug treatment showing that doses used for the antimetastatic study have minor toxic effects to the host, since toxicity was observed only with very high doses >300; and Fig. 4 illustrates a schematic representation of the process of fractionation.
DETAILED DESCRIPTION OF THE INVENTION
The organic solvent soluble fractions of the present invention are fractions soluble in organic sol-vents such as methanol, ethanol, ethyl acetate and dimethyl sulfoxide.

The invention is more especially concerned with the fractions which are soluble in the organic solvents but not soluble in water.
i) Extract of Echinops spinosus L. (Asteraceae) ii) Fractions The dried extract of Echinops spinosus L.
(Asteraceae) is first treated with water to remove water soluble fractions of the extract, whereafter the residue is treated with an organic solvent, for exam-ple, ethyl acetate to dissolve the organic solvent soluble fractions.
The ethyl acetate soluble fractions are puri-fied, for example, on charcoal and/or CELITETM (trade-mark for diatomaceous earth) and individual fractions are separated by high-performance liquid chromatogra-phy.
The fractions recovered were dissolved in dimethyl sulfoxide or ethanol.
The samples when stored at -80°C retained their activity even after four months.
The organic solvent soluble fractions and extract were found to have a strong antiproliferative activity in a panel of human cancer cell lines derived from breast, ovary, prostate and lung. In vivo, the fractions and extract demonstrate antimetastatic activ-ity in animal models.
The process of fractionation is illustrated schematically in Fig. 4.
The present invention will be more readily un derstood by referring to the following examples which are given to illustrate the invention rather than to limit its scope.

_ 5 _ EXAMPLE I
In vitro antiproliferative activity Cell lines and cell culture Two cell lines were used to test for the anti s proliferative activity of various fractions: human ovarian adenocarcinoma cell line A2780, and the human breast cancer cell line MCF7. Cells were grown in RPMI
medium supplemented with 10% fetal bovine serum and penicillin-streptomycin antibiotics. Cells were main tained in culture at 37°C in an atmosphere of 5% C02.
Cvtotoxicitv assay Exponentially growing cells (2-3x103 cells/100 ~.1) were seeded in 96-well plates and incubated for 16h. Cells were then treated continuously with the fractions. 72h later, cell survival was evaluated by replacing the culture media with 150 ~1 fresh medium containing 10 mM 4-(2-hydroxyethyl)-1-piperazine-ethamesulfonic acid buffer, pH 7.4 and 50 ~1 of 2.5 mg/ml of 3-(4,5-dimethylthiazo-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) in PBS, pH 7.4, were then added. After 3-4 h of incubation at 37°C, the medium and MTT were removed, and 200 ~1 of DMSO (dimethyl sul-foxide) was added to dissolve the precipitate of reduced MTT, followed by addition of 25 ml glycine buffer (O.1M glycine plus O.1M NaCl, pH 10.5). The for-mazan crystals were then dissolved and the absorbance was determined at 570 nm with a microplate reader (BIORAD, model 450). The MTT assay distinguishes between viable and non-viable cells on the basis that physiologically active mitochondria metabolizes the MTT
only in viable cells. The IC50 was calculated as the concentration of drug causing a 50% inhibition in the absorbance compared to cells treated with solvent alone.
~ti~.f'u ~i,t~i Apoptosis assay Cells were seeded at 1 x 106 cells/T75 cm2 plate, then left to attach overnight. The cells were then continuously exposed to the extracts for 72 hrs.
Cells were then collected and washed 2x with PBS and then diluted to 1x106/100 ~,1 PBS and placed in 96 well plate. Fixation was performed with 200 ml of 70% Etha-nol with shaking at 4°C for 30 min. Cells were then washed lx with PBS, and permeabilized with 1% TRITONTM
x-100 in 0.1% sodium citrate on ice for 2 min. Cells were washed 2x with PBS, and then labeled in 50 ml/well TUNEL reaction mixture of the Boehringer Mannheim In Situ cell death detection kit at 37°C in the dark for lhr. Cells were then washed 3x with 1% BSA in PBS and resuspended in 500 ~1 PBS for analysis by flow cytome-try. The cell death Tunnel assay estimates the extent of DNA fragmentation. The fragmented DNA is labeled at the free 3' OH group using terminal deoxynucleotide transferase. Fluoroscein labels are incorporated into nucleotide polymers that are attached to the DNA frag-ments. The labeling is specific to fragmented DNA and not degraded DNA due to the required presence of the 3' OH group. Thus, the level of fluorescence as measured by a flow cytometer is correlated to the level of DNA
fragmentation, and hence to the number of apoptotic cells.
Results Methanol soluble fractions, but not water solu-ble fractions, was found to have a potent antiprolif-erative activity in both A2780 and MCF7 cell lines.
Further chromatographic fractionation of these organic soluble extract led to the isolation of 12 fractions referred to as El-E12 (Figs. lA and 1B).
Morphological changes of cells treated with E
fractions resembled those described with apoptosis-_ 7 mediated cell death. Apoptosis was examined using lad-der DNA and TUNEL Assays; it was found that some frac-tions, e.g. E4 and E5, induce apoptosis.
EXAMPLE II
In vivo study Lewis lung carcinoma cell line and cell culture The Lewis lung carcinoma clone, M47, with a high metastatic potential to the lung, was established and characterized (Brodt P., Cancer Res., 46: 2442, 1986). These cells were confirmed to be free of myco-plasma infection. Cells were maintained in RPMI-1640 medium supplemented with 10% fetal bovine serum and 1%
penicillin-streptomycin, under 5% C02. Cells were pas-saged twice a week. Stocks of cells were generated and stored as early passages (passage no. 8-10 considering the initial stock received as passage no. 1). Cells were then propagated and stocks of the same passages were established and stored in liquid nitrogen for fur-ther studies with AETERNA compounds.
For tumor induction, cells were grown to 70%
confluence in complete medium and then collected using trypsin-EDTA solution [0.05% trypsin, 0.53 mM EDTA-4Na in HgSS without Ca++, Mg++, and NaHC03; Cellgro no. 25-052-LiJ. Cells were then centrifuged and washed three times with phosphate buffer solution [D-PBS, Ca+.+ and Mg++ free; Cellgro no. 21-031-LV], and resuspended at a dilution of 0.1 to 1x106 cells/O.lml. Viability was examined by trypan blue staining and only flasks in which the viability was >95% were used for in vivo studies.
The mouse strain used in this study is C57BL/10 from the research laboratories. The animal room used has two doors, one serving as the entrance, and the other door provides direct access to wash-_ g _ ing/sterilization/incineration facilities; it permits accurate adjustment of environmental parameters includ-ing temperature, humidity, ventilation, and lighting.
Cleaning and sanitation practices are performed, on a daily basis, by personnel with appropriate training.
Tumor cell inoculation and treatment Animals were housed 5 per cage and were fed a diet of animal chow and water ad libitum. After one week acclimatization, LLC cells were transplanted sub-cutaneously, as a suspension of tumor cells [2-5x105 viable cells per 0.1m1], in the axillary region of the right flank. All animals were inoculated at the same site. Animals were subjected, on a daily basis, to general examination. Tumor growth was monitored every second or third day using calipers. Parameters measured are: tumor measured along the longest axis (length) and the perpendicular shortest axis (width) and the rela-tive tumor volume (in cm3) was calculated by the for-mula: [Length (cm) x (width cm)2]/2. When the tumor reaches a size of 0.5-1.0 cm2 (approximately 2-3 weeks), mice were randomized into three groups.
Animals were subjected to surgery to remove the primary tumor. The mice were lightly anesthetized with Forane. The skin overlying the tumor was cleaned with betadine and ethanol, in a laminar flow hood. A small skin incision (0.5-lcm) was made using a sterile scal-pel, and the tumor was carefully separated from the normal tissues (skin and muscle). LLC (at early stage of growth; 1-3 weeks) is well localized tumor and sepa-ration was easy to achieve without any significant dam-age to normal tissues. The tumor was removed, weighed and fixed for histopathology purposes. The wound was closed with surgical stainless steel clips (Autoclips;
9mm; Clay Adams, Inc., Parsippany, NJ). This site was _ g _ further disinfected with betadine and the animal was housed as described above.
Mice were randomized after surgery into a group of 5 per cage. Cages were randomly assigned to specific experimental groups. The mice were then labeled by num bers using the "ear punching" method. Mice were checked on a daily basis to ensure the absence of infection.
Animals with discomfort were sacrificed immediately. An additional extra-group of control mice was included to l0 determine the optimal timing for sacrifice in order to obtain a significant number of well localized lung metastases. This group was subjected to the same experimental procedure as group 1 with the exception of drug treatment. Based on this group, a period of two weeks after removal of the primary tumor was sufficient to obtain an average of 20-30 nodules an the lung sur-face. Therefore, a two week period after primary tumor removal was used to sacrifice treated mice.
Dosina schedule and treatment Drugs were given by gavage, using a 22G curved feeding needle [total volume of 0.5m1 per animal], on a single daily basis administration after tumor cell inoculation. Control animals were given the same volume of saline solution [0.9% sodium chloride; Abbott Lab., lot no. 12 455 WS]. The dose of each drug was normal-ized to an average of 20g body weight per animal. The schedules for drug treatment were based upon conditions described in Figs. 2 and 3.
Animal sacrifice tumor/or aq ns preparation At the end of each experiment (a total of 5-8 weeks), animals were sacrificed in a C02 Chamber and autopsied. Tumors, organs or both were removed under sterile conditions [using a laminar flow hood]. Tumors were weighed. Organs (5 per group) were examined for gross pathological changes and then fixed in 10% forma-lin. Lungs were fixed in 10% Bouin's fixative diluted in a formalin solution, and lung surface metastases were counted using a stereomicroscope at 4x magnifica-tion or a magnifying-glass, and then lungs were embed-s ded in paraffin wax according to standard procedures.
Embedded tissues were stored for future histopathologi-cal studies.
Statistical analysis The umpaired Student t-test was used to compare statistical significance among various groups.
Results Methanol soluble fraction was found to have a good antimetastatic activity in the Lewis lung carci noma model. A dose relationship was also observed (see Figs. 2 and 3).
While the invention has been described in con-nection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any varia-tions, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as follows in the scope of the appended claims.

Claims (6)

WHAT IS CLAIMED IS:

1. An anti-cancer pharmaceutical composition comprising an acceptable, effective anti-cancer amount of an extract of roots of Echinops spinosus L. (Asteraceae) or an organic solvent soluble fraction -_thereof, in association with a pharmaceutically acceptable carrier.

2. An extract of roots of Echinops spinosus L.
(Asteraceae) or an organic solvent soluble fraction thereof, for use in the treatment of cancer.

3. A method of treating cancer comprising administering to a patient, an acceptable, effective anti-cancer amount of an extract of roots of Echinops spinosus L. (Asteraceae) or an organic solvent soluble fraction thereof.

4. A method of producing an anti-cancer agent comprising an organic solvent extraction of an extract of roots of Echinops spinosus L. (Asteraceae) to produce an organic solvent soluble extract, and chromatographic separation of fractions of said organic solvent soluble extract.

5. Use of a pharmaceutical composition comprising an extract of roots of Echinops spinosus L. (Asteraceae) or an organic solvent soluble fraction thereof, in association with a pharmaceutically acceptable carrier, in an amount acceptable and effective to treat cancer.

6. Use of an effective amount of an extract of roots of Echinops spinosus L. (Asteraceae) or an organic solvent soluble fraction thereof in the treatment of cancer.