1
CYTOSTATICS
(ANTINEOPLASTICS, CANCEROSTATICS)
 Cancer – main cause of premature death
 Developed countries – each fifth death caused by cancer
 Incidence depends on sex, age, race, genetic predisposition and on presence of
cancerogens in environment
 Costs on treatment extraordinary high (surgery, radiotherapy, price of drugs)
History:
1914 verification of chemical cancerogens in environment (one is usually not enough to trigger
cancer)
1947 Berenblum model (on mice):
- cancerogen in subliminal dose --- no cancer
- Repeated effect of cancer promotors --- no cancer
- cancerogen + promotor --- always cancer
 Syncancerogenesis – exposition to several cancerogens
 Cocancerogenesis – cancerogen + promotor
 Cancerogenesis: 1) Initiation, 2) promotion effect (phorbol acetate, phenobarbital) ---
manifested cancer process
CYTOSTATICS
 Research prograsms: USA (1951 NCI, Maryland, J. Hartwel); GB; Japan; China;
O.E.R.T.C. (l’Organisation européenne pour la recherge et la traitment de cancer)
Cancerogens – most important factor of cancer development
- In present time different branches of human activity use approx. 70 000 chemical substances
- Each year plus approx. 800 new substances
- Genotoxicity (mutagenity, cancerogenity) is tested from 1986 (5 % of used compounds are
cancerogens
- Some compounds are activated by usage, for example herbicides aminotriazols are mutagenic
after activation via effect of plant enzymes
- Derivatives of nitrofuran are mutagenic after activation via anaerobic processes in guts
Corelation mutagenity : cancerogenity = 92 : 8
Methodically defect, because from 26 cancerogens only 19 showed mutagenity on mice
In present time it is known more than V 30 ultimate cancerogens
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Etaps of programs for development of plant cytostatic
compound
1. Harvest (NAPRALERT, empirie – USDA, ARD)
2. Extraction
3. Primary screening (PS –lymphocytic leukemia, KB – carcinom of larynx)
ED50 ≤ 4 μg/ml
4. Repeated harvest of species showing activity
5. Activity-guided fractionation
6. Isolation, structure elucidation
7. Testing on a pannel of cancer cells
8. Further extraction → obtaining of large amount of active compound
9. Preklinical pharmacology
10. Clinical trials
 Basic point of program is screening, affecting majority of development levels
 Cytotoxic compounds (ED50 ≤ 4 μg/ml) trigger the cell lysis
 Cytostatics trigger the stasis of division of fast reproducing cells
Panel of cancer cells for testing of extracts
 B1 = B16 melanocarcinom cell kinetic and further characteristics
 LL = Lewis lung carcinom similar to main types of human cancer cells
 LE = L 1210 leukemia
 PS = P388 lymphocytic leukemia
 WA = Walker carcinosarcom 256
 CA = Adenocarcinom 755
 DL = Dunning leukemia
 FV = Friend viral leukemia
 PX = Plasmocytom NCS 38280
 P1 = Plasmocytom n. 1
 SP = P1798 Lymphosarcom
 SA = Sarcom 180
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Future
1. Prevention and improvement of methods
2. Studies of biologic characteristics of tumors
3. Gen therapy
4. Discovery and development of further cytostatics
- synthetic
- semisynthetic
- natural
which would be used for:
 direct therapeutic usage
 model or lead compounds
 starting material for preparation of more effective derivatives
 knowledge of biochemical mechanisms of activity (in correspondence to
structural heterogeneity of used compounds)
 Aim of chemotherapy: selective devitalization of cancer cells
Character of natural cytotoxic substances and
their occurrence in plant kingdom
 Character of natural cytotoxics:
 simple sugars and „small“ molecules of secondary metabolites (most
numbered)
 polymer peptides
 polymeric sugars
 glycoproteins
 Occurrence in plant kingdom:
 Apocynaceae
 Asteraceae
 Rutaceae
 Ranunculaceae
 Celastraceae
 Liliaceae (relatively at minimum)
Systematic screening of plant extracts from 1959
Till present time examined approx. 250 000 of extracts from 3500 genera
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CYTOSTATICS
1. Alkylating compounds (Cyclophosphamid, Busulphan, Chlorambucil …)
2. Antimetabolites (Cytarabin, Florouracil, Metotrexate, analogues of folic
acid, purines …)
3. Enzymes (L-asparaginase)
4. Metabolites from higher plants
inhibitors of mitosis, blocking metaphase by dissolving of microtubules
- Colchicine
- Vincaleucoblastin (VLB)
- Vincaleurocristin (VCR)
- Vindesin, Vinorelbin, Vinflunin
accelerate formation of microtubules, stabilizing them and prevent
depolymerization
- Taxans
CYTOSTATIKA
5. Intercalation substances (intercalate into neighborring
nucleotide pairs and produce frameshift mutations) and
inhibitors of topoisomerases
- Amsacrine, Doxorubicine, Mitramycine, Actinomycines
- Podophyllotoxins
- Camptothecins
6. Hormons
- glucocorticoids
- estrogens, antiestrogens
- antiandrogens
7. Other
- Cisplatin, Procarbazine
- Interferon 
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Mitotic poisons of plant origin
Effect is observed in process of mitosis (prometaphase)
 Alkaloids from Catharanthus roseus, their semisynthetic derivatives
and colchicine (or colcemide) inhibit polymeration of tubuline, avoid
the formation of microtubules and therefore block process of mitosis
in metaphasis
 Taxans inhibit depolymeration of tubuline, stimulate formation of
microtubules and prevent their disintegration. Mitosis is prolonged
from usual 30 min up to 15 hours; taxans possess radiopotentiation
effect, induce apoptosis
Functional effects of both groups are to some extend similar
At normal condition is polymeration and depolymeration of tubiline
balanced.
Colchicum autumnale – autumn crocus (Liliaceae)
Colchicine
 Present in testa and tubers
 Cytotoxic activity known from 40ies
of 20th century, blocks cell division,
do not prevent division of
chromosomes, causes
polyploidization
 Usage of desacetyl-Nmethylcolchicine
= demecolcine
during therapy of myeloid leukemia
 Today prevalently antiuratic, affects
the chemotaxis of inflammatory
cells into place of inflammation
 Series of side effects, toxic
O
O
O
O
O
N
H
R2
R1
3
R1 R2
Colchicine CH3 COCH3
Demecolcine CH3 CH3
3-demethylcolchicine H COCH3
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Colchicum autumnale L. – autumn crocus (Liliaceae)
VINBLASTINE, VINCRISTIN
Catharanthus roseus (L.) G. Don. – Madagascar periwinkle
(Apocynaceae)
 Native to Madagascar, today large cultivation in tropics and subtropics
 Originally antidiabetic, experimentally not proved, but discovered
leucopenia as a result of lowered activiy of bone marrow – antimitotic
substances
 Eli Lilly Indianolopis, USA. Gordon H. Svoboda
 Contains more than 60 alkaloids, from that approx. 20 dimeric.
 From that number is used vinblastin and vincristin and their
semisynthetic derivatives
 To obtain 1 g VCR it is necessary to process 500 kg of drug
 Development of VLB: 10,7 mil. USD, protocols about 32 000 pages
(weight 14,5 kg)
 Usage: Hodgkin disease, lymphocytic leukemia, testicular tumors,
component of highly active and aggressive chemotherapy combinations
 Main side effect of VCR: neurotoxicity
 Semisynthetic derivatives: Vindesin, Vinorelbin, Vinflunine
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Catharanthus roseus (L.) G. Don. – Madagascar periwinkle
Structure of VLB and VCR
N
H
N
COOCH3
N
R
MeO OCOCH3
N
OH
COOCH3
H
OH
Vincaleucoblastin VLB CH3
Vincaleurocristin VCR CHO
R
catharanthine
(ibogaine type)
vindoline
(aspidospermine type)
16
10
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Structure of vindesine
N
H
N
COOCH3
NMeO
N
OH
H
OH
OH
CONH2
CH3
16
10
Vindesine
(- Ac)
(- OMe + NH2)
TAXOL
Taxus brevifolia Nutt. – pacific yew (Taxaceae)
 Taxol is one of the structurally related diterpenes
 From the bark of Pacific yew (Taxus brevifolia Nutt., - Taxaceae) was firstly
isolated and described by M.C. Wani, et al.: J. Am. Chem. Soc. 93, 2325 (1971)
 Pacific yew is a tree native to west coast of North America, today widely
cultivated.
 During screening extract showed effect against different types of leukemia and
carcinosarcoms. In clinical assays (started 1983 and still continue), taxol showed
activity against cancer of ovarias, lungs, breast and malignant melanoma.
Valuable drug for treatment of metastatic carcinomas of ovaria and metastating
breast cancer.
 Rhone-Poulenc prepared Taxotere (docetaxel), which is probably more effect
and more tolerated than original paclitaxel.
 To obtain 1 kg of paclitaxel it is necessary to process bark from 2500 adult
trees. Approximated consumption of paclitaxel for treatment of ovarian cancer
is 20-25 kg per year.
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Taxus brevifolia Nutt. – Pacific yew
Taxus baccata L. – English yew, European yew
(Taxaceae)
Taxol structure
OH
O
O
O
OO
O
NH O
O
OH
OH
O
O
CH3
1
2
3
4
5
6
78
910
11
A
14
13
18
15
19
B C
D
20
16
17
Paclitaxel (Taxol)
(2'R-3'S)-N-benzoyl-
-3'-fenylisoserin
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Camptothecines
Camptotheca acuminata (Nyssaceae), Ervatamia hyeneana
(Apocynaceae), Opiorriza mungos (Rubiaceae)
 Camptotheca species – trees native in China, 0,012 % of
mixture of basis in bark
 Ervatamia species – trees native to south-east Asia
 Camptothecin inhibits DNA-topoisomerase I
 Usage: colorectal carcinomas (CRC)
 High price – approximation of Czech Republic patients is
1 000 000 000 Kč
Camptothecine structure
 Monoterpenic
chinoline „alkaloids“
 Molecule is not basic
 Do not form stable
salts with mineral
acids
 Do not react with
Mayer nor
Dragendorff reagent
N
N O
O
RO
A B C
D
E
Camptothecine, R = H
10-hydroxycamptothecine, R = OH
10-methoxykamptothecine, R = OCH3
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Glycosides of epipodophyllotoxin
Podophyllum peltatum – mayapple (Berberidaceae)
 Podophyllotoxin is not used as cytostatic, but its semi-synthetic
derivatives
 Glycoside of C-9-hydroxy isomer
 Belongs to coniferylalcohol derived lignans
 Inhibition of topoisomerase II
 Indications:
- Teniposide – urinary bladder cancer
- Etoposide – small cellular lung carcinoma, several leukemia and
Hodgkin disease
 These compounds possess nno affinity to tubuline
Structure of etoposide and teniposide
O
O
O
O
O
OOH
OH
O
O
H
H
MeO OMe
OH
CH3
7
8
4'
Etoposid, Vepesid
7
8
4'
Teniposid
S
O
O
O
O
O
OOH
OH
O
O
H
H
MeO OMe
OH
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Biosynthesis of podophylline lignans
OH
OMe
C - 
C - 
C - 
2


hydronaphtalene type
Cancerogens
Some drugs:
Metronidazol Chemicals:
Cimetidin (Tagamet) Benzidine
Nitrofurans 2-naphtylamin
Nitromack azo-pigments
Phenacetine → nitrosoderivatives -halogenated ethers
p-nitrosophenol polychlorinated biphenyls
INH
Cyclophosphamid Product of Aspergillus
flavus - aflatoxins
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CA INHIBITORS
 Flavones
 -Angelicolactone
 Benzylisothiocyanates (broccoli, cauliflower,
savoy cabage)
 Indol derivatives - betalains
 Vitamin C
 -Tocoferol, β-sitosterol
 Microelements: Selenium
 Drugs: Indomethacin