lupane and betulin

Naturally occurring pentacyclic lupane triterpenoids such as betulin (1) or betulinic acid (2) and their synthetic derivatives display a broad spectrum of biological activities and, therefore, have been the subject of great interest. However, the use of these compounds as potential therapeutic agents is limited by their low bioavailability, high hydrophobicity, and insufficient intracellular accumulation. In this context, research on modifications of the parent structures that will improve their pharmacokinetic properties is particularly important. In the past few years, methods of synthesis as well as cytotoxic and antiparasitic properties of a series of lupane triterpenoids modified by introducing one or two triphenylphosphonium moieties at the C-2, C-3, C-28, or C-30 positions by carbon-carbon or ester bonds have been described. The presence of triphenylphosphonium groups affects not only physical properties but also the mechanism of action of a potential drug. This review summarizes published findings on synthetic methods and biological properties of the triphenylphosphonium derivatives of betulin and betulinic acid.

Topics: Antineoplastic Agents; Betulinic Acid; Esters; Molecular Structure; Pentacyclic Triterpenes; Triterpenes

Twenty lupane type A-ring azepano-triterpenoids were synthesized from betulin and its related derivatives and their antitubercular activity against

Topics: Anti-Bacterial Agents; Antitubercular Agents; DNA-Directed RNA Polymerases; Drug Design; Drug Resistance, Bacterial; Humans; Molecular Docking Simulation; Molecular Structure; Mycobacterium tuberculosis; Rifampin; Triterpenes; Tuberculosis

Betulin (BT) is a natural pentacyclic lupane-type triterpene exhibiting anticancer activity. Betulin derivatives bearing propynoyloxy and phosphate groups were prepared in an effort to improve the availability and efficacy of the drug. In this study, a comparative assessment of the in vitro anticancer activity of betulin and its four derivatives was carried out using two human breast cancer cell lines: SK-BR-3 and MCF-7. In both studied cell lines, 30-diethoxyphosphoryl-28-propynoylbetulin (compound

Topics: Alkynes; Antineoplastic Agents; Apoptosis; Breast Neoplasms; Caspases; Cell Cycle; Cell Death; Cell Line, Tumor; Cell Proliferation; Humans; L-Lactate Dehydrogenase; MCF-7 Cells; Membrane Potential, Mitochondrial; Necrosis; Phosphates; Reactive Oxygen Species; Triterpenes; Up-Regulation

Betulin is a lupane type pentacyclic triterpenoid, and commonly found in the bark of birch trees. It displays various pharmacological properties, such as antibacterial, anti-inflammation, antitumor, and antiviral. In this report, we attempted to investigate the anti-proliferative and pro-apoptotic effects of betulin on osteosarcoma cell lines. Our results revealed that betulin significantly decreased cell viability and colony formation in osteosarcoma cell lines. Dose-dependent induction of Annexin V positive cells, activated caspase 8, activated caspase 9, activated caspase 3, and the cleavage of poly (ADP-ribose) polymerase were observed after the treatment with betulin, indicating betulin induces apoptosis in osteosarcoma cell lines. mTOR has been identified as a key modulator of autophagy in response to different stresses. In this study, we found that the treatment with betulin suppressed the activation of mTOR, and increased the level of LC 3-II, the autophagy marker, in osteosarcoma cell lines. Co-administration of the autophagy inhibitor chloroquine significantly rescued the cell viability and the clonogenic activity in betulin-treated osteosarcoma cell lines. Our data showed that betulin induced autophagy, and the up-regulated autophagy positively contributed to the apoptosis. Taken together, our findings suggested that betulin may serve as a promising anti-proliferative agent for treating osteosarcoma.

Topics: Apoptosis; Autophagy; Bone Neoplasms; Caspase 3; Caspases; Cell Line, Tumor; Cell Proliferation; Cell Survival; Humans; Osteosarcoma; TOR Serine-Threonine Kinases; Triterpenes

Topics: Bile Acids and Salts; Hep G2 Cells; Hepatitis B virus; Hepatitis Delta Virus; Humans; Organic Anion Transporters, Sodium-Dependent; Receptors, Virus; Structure-Activity Relationship; Symporters; Triterpenes; Virus Internalization

Betulin and betulinic acid have been widely studied for their anticancer activities. However, their further development is limited due to low bioavailability, poor aqueous solubility, and limited intracellular accumulation. In the present study, a triphenylphosphonium cation moiety was linked to betulin and betulinic acid to specifically target them to cancer cell mitochondria. Biological characterization established that uptake of mitochondria-targeted compound 1a in the mitochondria of cancer cells was increased compared to betulin. The mitochondria-targeted derivatives of betulin and betulinic acid showed stronger cytotoxicity than their parent drugs and exhibited more cytotoxic effects in cancer cells than normal cells. The mechanisms may involve the mitochondrial apoptotic pathway, probably caused by the induction of reactive oxygen species production and reducing mitochondrial membrane potential. More importantly, 1a significantly inhibited cancer cell proliferation and migration in an in vivo zebrafish xenograft model. Collectively, these results encourage further study of 1a analogs as anticancer agents.

Topics: Animals; Antineoplastic Agents; Apoptosis; Betulinic Acid; Cell Line, Tumor; Cell Movement; Cell Proliferation; Drug Screening Assays, Antitumor; Heterografts; Humans; Membrane Potential, Mitochondrial; Mitochondria; Neoplasm Metastasis; Neoplasm Transplantation; Organophosphorus Compounds; Pentacyclic Triterpenes; Reactive Oxygen Species; Structure-Activity Relationship; Triterpenes; Zebrafish

Some of the most valuable antimalarial compounds, including quinine and artemisinin, originated from plants. While these drugs have served important roles over many years for the treatment of malaria, drug resistance has become a widespread problem. Therefore, a critical need exists to identify new compounds that have efficacy against drug-resistant malaria strains. In the current study, extracts prepared from plants readily obtained from local sources were screened for activity against Plasmodium falciparum. Bioassay-guided fractionation was used to identify 18 compounds from five plant species. These compounds included eight lupane triterpenes (1-8), four kaempferol 3-O-rhamnosides (10-13), four kaempferol 3-O-glucosides (14-17), and the known compounds amentoflavone and knipholone. These compounds were tested for their efficacy against multi-drug-resistant malaria parasites and counterscreened against HeLa cells to measure their antimalarial selectivity. Most notably, one of the new lupane triterpenes (3) isolated from the supercritical extract of Buxus sempervirens, the common boxwood, showed activity against both drug-sensitive and -resistant malaria strains at a concentration that was 75-fold more selective for the drug-resistant malaria parasites as compared to HeLa cells. This study demonstrates that new antimalarial compounds with efficacy against drug-resistant strains can be identified from native and introduced plant species in the United States, which traditionally have received scant investigation compared to more heavily explored tropical and semitropical botanical resources from around the world.

Topics: Animals; Antimalarials; Artemisinins; Drug Resistance; Glycosides; HeLa Cells; Humans; Malaria; Molecular Structure; Nuclear Magnetic Resonance, Biomolecular; Plants, Medicinal; Plasmodium falciparum; Quinine; Triterpenes; United States

Five new lupane triterpene coumaroyl esters (1-5), together with betulin (6) and a known Buxus alkaloid, N-3-benzoyldihydrocyclomicrophylline F (7), were isolated from a CHCl3-soluble partition of a methanol extract of Buxus cochinchinensis Pierre ex Gagnep. (Buxaceae) collected in Vietnam. Isolation work was monitored using human colon cancer cells (HT-29). The structures of the new compounds (1-5) were determined on the basis of spectroscopic data interpretation. In addition to their cytotoxicity against HT-29 cells and nuclear factor-kappa B (p65) inhibitory activity in an enzyme-linked immunosorbent assay, all isolates as well as two semisynthetic compounds derived from betulin and 5, respectively, were also evaluated for their in vitro antiplasmodial activities against the drug-resistant Dd2 strain of Plasmodium falciparum and antifungal effects on the growth of the pathogenic yeast Candida albicans. The new lupane triterpene coumaroyl esters (1-5), along with a betulin derivative and the known Buxus alkaloid, were found to show significant in vitro antimalarial activities, with IC50 values ranging from 0.26 to 2.07 µM.

Topics: Alkaloids; Antimalarials; Buxus; Esters; HT29 Cells; Humans; Inhibitory Concentration 50; Molecular Structure; Plant Extracts; Plasmodium falciparum; Triterpenes; Vietnam

The lupane-type triterpene betulin (1) has been subjected to a series of structural modifications for the purpose of evaluating resultant cancer cell growth inhibitory activity. The reaction sequence 7→11→12 was especially noteworthy in providing a betulin-derived amine dimer. Other unexpected synthetic results included the 11 and 13/14→17 conversions, which yielded an imidazo derivative. X-ray crystal structures of dimer 12 and intermediate 25 are reported. All of the betulin modifications were examined for anticancer activity against the P388 murine and human cell lines. Significant cancer cell growth inhibition was found for 4, 8, 9, 15/16, 19, 20, 24, and 26, which further defines the utility of the betulin scaffold.

Topics: Animals; Antineoplastic Agents, Phytogenic; Betula; Drug Screening Assays, Antitumor; Humans; Leukemia P388; Mice; Molecular Structure; Structure-Activity Relationship; Triterpenes

The aim of this work was to synthesize a set of heterocyclic derivatives of lupane, lup-20(29)-ene, and 18α-oleanane, and to investigate their cytotoxic activities. Some of those heterocycles were previously known in the oleanane (allobetulin) group; however, to our knowledge the syntheses and biological activities of lupane heterocycles have not been reported before. Starting from betulin (1) and betulinic acid (2), we prepared 3-oxo compounds and 2-bromo-3-oxo compounds 3-10, 2-hydroxymethylene-3-oxo compounds 11-13 and β-oxo esters 14-16. Condensation of these intermediates with hydrazine, phenylhydrazine, hydroxylamine, or thiourea yielded the pyrazole and phenylpyrazole derivatives 17-22, pyrazolones 23-25, isoxazoles 26 and 27, and thiazoles 28-31. Fifteen compounds (14-16, 18-25, and 29-32) have not been reported before. The cytotoxicity was measured using panel of seven cancer cell lines with/without MDR phenotype and non tumor MRC-5 and BJ fibroblasts. The preferential cytotoxicity to cancer cell lines, particularly to hematological tumors was observed, the bromo acids 5, 6 showed highest activity and selectivity against tumor cells.

Topics: Antineoplastic Agents, Phytogenic; Betulinic Acid; Cell Line, Tumor; Crystallography, X-Ray; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Humans; Molecular Structure; Oleanolic Acid; Pentacyclic Triterpenes; Structure-Activity Relationship; Triterpenes

Several novel alkylidene branched lupane derivatives have been prepared. Many of these compounds showed a significant cytotoxicity. The most active compound, 2-methylene-betulonic acid, showed IC(50) values between 0.2 and 0.6 μM for 15 different human cancer cell lines. Cytotoxicity can be improved by encapsulation in liposomes. These compounds act by triggering apoptotic cell death as shown by DNA-laddering experiments and acridine orange/ethidium bromide staining.

Topics: Alkenes; Antineoplastic Agents; Cell Line, Tumor; Chemistry Techniques, Synthetic; Humans; Hydroxides; Inhibitory Concentration 50; Oxidation-Reduction; Triterpenes

In the present investigation the antiproliferative activity of thirteen derivatives of betulinic acid and betulin was tested against five different tumor cell lines. The toxicity against normal human fibroblasts (WWO70327) and the mode of cell death on HT-29 (colon cancer) as well as caspase activity induced by the most active compounds, 9 (3-O-chloroacetylbetulinic acid) and 15 (28-O-chloroacetylbetulin) were determined. Investigated derivatives exerted a dose dependent antiproliferative action at micromolar concentrations toward target tumor cell lines. Treatment of HT-29 cells for 24 h with 9 and 15 induced apoptosis, as observed by dye exclusion test (trypan blue) and confirmed by the appearance of a typical ladder pattern in the DNA fragmentation assay.

Topics: Antineoplastic Agents; Apoptosis; Betulinic Acid; Caspases; Cell Line, Tumor; Cell Survival; DNA Fragmentation; Drug Screening Assays, Antitumor; Humans; Inhibitory Concentration 50; Kinetics; Pentacyclic Triterpenes; Triterpenes

The naturally occurring cytotoxic saponin 28-O-beta-d-glucopyranosylbetulinic acid 3beta-O-alpha-l-arabinopyranoside (3) was easily synthesized along with seven bidesmosidic saponins starting from the lupane-type triterpenoids betulin (1) and betulinic acid (2). As highlighted by the preliminary cytotoxicity evaluation against A549, DLD-1, MCF7, and PC-3 human cancer cell lines, the bidesmosidic betulin saponin 22a, bearing alpha-l-rhamnopyranoside moieties at both C-3 and C-28 positions, was determined to be a potent cytotoxic agent (IC(50) 1.8-1.9 microM).

Topics: Antineoplastic Agents, Phytogenic; Betulinic Acid; Drug Screening Assays, Antitumor; Humans; Molecular Structure; Pentacyclic Triterpenes; Saponins; Structure-Activity Relationship; Triterpenes

The concise synthesis, via a stepwise glycosylation approach, of lupeol, betulin and betulinic acid O-glycosides bearing a chacotriosyl moiety at the C-3 position is described. All neosaponins as well as their rearrangement products of the germanicane-type were evaluated in vitro for their anticancer and haemolytic activities. Although betulinic acid and betulin 3beta-O-chacotriosides were neither cytotoxic nor haemolytic, their rearrangement products allobetulin and 28-oxoallobetulin 3beta-O-chacotriosides (9 and 10) exhibited a cytotoxicity profile up to fourfold superior to betulinic acid against human breast (MCF7) and prostate (PC-3) adenocarcinomas cell lines (IC(50)=10-18 microM). One important result was that only chacotriosides featuring non-polar functions at the C-28 position (6, 9 and 10) exerted a haemolytic activity against red blood cells.

Topics: Animals; Cell Line, Tumor; Cytotoxins; Erythrocytes; Hemolytic Agents; Humans; Saponins; Sheep; Triterpenes; Tropanes

Germanicane-type triterpenes allobetulin (3) and 28-oxoallobetulin (4) can be obtained by the Wagner-Meerwein rearrangement of the more available lupane-type triterpenes betulin (1) and betulinic acid (2), respectively. The medical uses of betulinic acid (2) and its derivatives are limited because of their poor hydrosolubility and pharmacokinetics properties. In order to overcome this major problem, we synthesized and studied the in vitro anticancer activity of a series of 3beta-O-monodesmosidic saponins derived from betulin (14-16), betulinic acid (20-22), allobetulin (23-28) and 28-oxoallobetulin (29-34) based on six different natural sugar residues (d-glucose, l-rhamnose, d-arabinose, d-galactose, d-mannose and d-xylose). This structure-activity relationship study confirmed that betulinic acid saponins are generally better in vitro anticancer agents than those derived from betulin with the exception of betulin 3beta-O-alpha-d-mannopyranoside (15) which exerted a potent cytotoxic activity against lung carcinoma (A-549) and colorectal adenocarcinoma (DLD-1) human cell lines with IC(50) ranging from 7.3 to 10.1mumol/L. Furthermore, although the synthesis of novel germanicane-type saponins was carried out with success, the bioactivity measured for these glycosides was not as high as we anticipated since only the 3beta-O-beta-d-glucopyranoside and 3beta-O-beta-d-galactopyranoside of allobetulin (23,24) showed moderate anticancer activity (IC(50) 30-40 micromol/L).

Topics: Adenocarcinoma; Antineoplastic Agents, Phytogenic; Betula; Cells, Cultured; Colorectal Neoplasms; Drug Screening Assays, Antitumor; Fibroblasts; Humans; Lung Neoplasms; Molecular Structure; Saponins; Structure-Activity Relationship; Triterpenes

The weak hydrosolubility of betulinic acid (3) hampers the clinical development of this natural anticancer agent. In order to circumvent this problem and to enhance the pharmacological properties of betulinic acid (3) and the lupane-type triterpenes lupeol (1), betulin (2), and methyl betulinate (7), glycosides (beta-D-glucosides, alpha-L-rhamnosides, and alpha-D-arabinosides) were synthesized and in vitro tested for cytotoxicity against three cancerous (A-549, DLD-1, and B16-F1) and one healthy (WS1) cell lines. The addition of a sugar moiety at the C-3 or C-28 position of betulin (2) resulted in a loss of cytotoxicity. In contrast, the 3-O-beta-D-glucosidation of lupeol (1) improved the activity by 7- to 12-fold (IC50 14-15.0 microM). Moreover, the results showed that cancer cell lines are 8- to 12-fold more sensitive to the 3-O-alpha-L-rhamnopyranoside derivative of betulinic acid (IC50 2.6-3.9 microM, 22) than the healthy cells (IC50 31 microM). Thus, this study indicates that 3-O-glycosides of lupane-type triterpenoids represent an interesting class of potent in vitro cytotoxic agents.

Topics: Animals; Antineoplastic Agents, Phytogenic; Betula; Betulinic Acid; Cell Line, Tumor; Cell Survival; Drug Screening Assays, Antitumor; Fibroblasts; Glycosides; Humans; Mice; Pentacyclic Triterpenes; Triterpenes

Cellular screening of various synthetic triterpenoid compounds formally derived from lupane has identified a number of analogues as potential anticancer drug candidates. Here we describe the synthesis and structure-activity relationships of betulin and betulinic acid derivatives containing an E-ring modified with different oxygen functions. Thus compounds containing the lup-18-en-21-one, lup-18-ene-21,22-dione, 18,19-secolupane, and the highly oxygenated 18,19-secolupane systems, as well as des-E-lupane derivatives, were prepared from the readily available natural pentacyclic triterpene betulin using oxidative procedures. These compounds were named betulinines. We demonstrate that only selected compounds, particularly those containing a lupane E-ring-derived unsaturated ketone or diketone function, possessed in vitro cytotoxic activity against tumor cell lines, suggesting a structure-activity relationship.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Crystallography, X-Ray; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Humans; Mice; Stereoisomerism; Structure-Activity Relationship; Triterpenes