Synthesis of cytotoxic 2,2-difluoroderivatives of dihydrobetulinic acid and allobetulin and study of their impact on cancer cells.
In this article, we describe the preparation and cytotoxic properties of a small focused library of lupane and 18α-oleanane triterpenoids that contain a combination of two structural motifs known to enhance the biological activities. First, we introduced two fluorine atoms to position 2 of the skeleton. Second, we synthesized a set of hemiester prodrugs, which were intended to increase the solubility and activity. Starting from betulin, we obtained two hydroxyketones (derivatives of dihydrobetulinic acid and allobetulin) and their fluorination using DAST provided 2,2-difluoro-3-oxo-compounds as the main products. Then the 3-oxo group in each derivative was reduced by NaBH4 to obtain 3β-hydroxy compounds suitable for modifying by various hemiesters. We prepared 21 compounds, 11 of them new, their cytotoxicity was tested on T lymphoblastic leukemia CCRF-CEM cells first and the most active derivatives were selected for screening on another six tumor and two non-tumor cell lines. All of them showed selectivity against cancer lines with therapeutic index between 2 and 8. All hemiesters had activity in the same range as the free hydroxyl derivatives and they would be suitable prodrugs for future in vivo experiments. Interestingly, all hemiesters of 2,2-difluorodihydrobetulonic acid had higher activity against p53 knock-out p53-/- cancer cell line than against the non-mutated analog. In active derivatives, the cell cycle was analyzed by flow cytometry and several compounds slowed down cell cycle progression through G0/G1 or S-phase.
Department of Organic Chemistry, Faculty of Science, Palacky University Olomouc, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic.
Lucie
L
Borkova
Department of Organic and Nuclear Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague 2, Czech Republic.
Lucie
L
Jasikova
Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc, Hnevotinska 5, 779 00 Olomouc, Czech Republic.
Jiri
J
Rehulka
Department of Organic and Nuclear Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague 2, Czech Republic.
Katerina
K
Frisonsova
Department of Organic Chemistry, Faculty of Science, Palacky University Olomouc, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic; Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc, Hnevotinska 5, 779 00 Olomouc, Czech Republic.
Milan
M
Urban
Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc, Hnevotinska 5, 779 00 Olomouc, Czech Republic.
Ivo
I
Frydrych
Department of Organic Chemistry, Faculty of Science, Palacky University Olomouc, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic.
Igor
I
Popa
Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc, Hnevotinska 5, 779 00 Olomouc, Czech Republic.
Marian
M
Hajduch
Department of Organic Chemistry, Faculty of Science, Palacky University Olomouc, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic.
Niall J
NJ
Dickinson
Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, 115 19 Prague 1, Czech Republic.
Martin
M
Vlk
Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc, Hnevotinska 5, 779 00 Olomouc, Czech Republic. Electronic address: dzubakp@gmail.com.
Petr
P
Dzubak
Department of Organic Chemistry, Faculty of Science, Palacky University Olomouc, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic; Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc, Hnevotinska 5, 779 00 Olomouc, Czech Republic. Electronic address: jan.sarek@gmail.com.
Jan
J
Sarek
D000972:Antineoplastic Agents, Phytogenic / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D005347:Fibroblasts / Q000187:drug effects; D006801:Humans; D006845:Hydrocarbons, Fluorinated / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D008968:Molecular Conformation; D013329:Structure-Activity Relationship; D014315:Triterpenes / Q000737:chemistry*; D014407:Tumor Cells, Cultured; D000094062:Betulinic Acid
D000972:Antineoplastic Agents, Phytogenic; D006845:Hydrocarbons, Fluorinated; D014315:Triterpenes; C098641:dihydrobetulinic acid; D000094062:Betulinic Acid; C002503:betulin
Betulinic acid; Cytotoxic; Fluoroderivatives; Synthesis; Testing